Add ChatGPT Codex provider

Add GitHub issue templates

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -0,0 +1,101 @@
+name: Bug report
+description: Report a reproducible problem with Cassady / cass
+title: "bug: "
+labels: [bug]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thanks for reporting a bug. Please include enough detail for someone to reproduce it.
+  - type: textarea
+    id: summary
+    attributes:
+      label: Summary
+      description: What went wrong?
+      placeholder: Cassady crashes when...
+    validations:
+      required: true
+  - type: textarea
+    id: steps
+    attributes:
+      label: Steps to reproduce
+      description: List the exact commands, key presses, or config changes needed to trigger the issue.
+      placeholder: |
+        1. Run `cass ...`
+        2. Press ...
+        3. See ...
+    validations:
+      required: true
+  - type: textarea
+    id: expected
+    attributes:
+      label: Expected behavior
+      description: What did you expect to happen?
+    validations:
+      required: true
+  - type: textarea
+    id: actual
+    attributes:
+      label: Actual behavior
+      description: What happened instead? Paste errors, logs, or terminal output when useful.
+      render: text
+    validations:
+      required: true
+  - type: input
+    id: version
+    attributes:
+      label: Cassady version
+      description: Output of `cass --version` or `cassady --version`.
+      placeholder: cassady 0.2.x
+    validations:
+      required: true
+  - type: dropdown
+    id: install
+    attributes:
+      label: Install method
+      options:
+        - Release archive
+        - cargo install --git
+        - cargo install --path / local build
+        - Other
+    validations:
+      required: true
+  - type: dropdown
+    id: platform
+    attributes:
+      label: Platform
+      options:
+        - macOS Apple Silicon
+        - macOS Intel
+        - Linux x86_64
+        - Linux ARM64
+        - Windows x86_64
+        - Other
+    validations:
+      required: true
+  - type: textarea
+    id: environment
+    attributes:
+      label: Environment details
+      description: Terminal, shell, provider/model, access mode, and anything notable from `cass check`. Do not include API keys.
+      placeholder: |
+        Terminal: ...
+        Shell: ...
+        Provider/model: ...
+        Access mode: ...
+        `cass check`: ...
+  - type: textarea
+    id: config
+    attributes:
+      label: Relevant configuration
+      description: Paste sanitized snippets from `~/.cass/config.json`, `providers.json`, or `models.json` if relevant. Remove API keys and secrets.
+      render: json
+  - type: checkboxes
+    id: checklist
+    attributes:
+      label: Checklist
+      options:
+        - label: I removed API keys, tokens, and other secrets from this report.
+          required: true
+        - label: I searched existing issues for a duplicate.
+          required: true

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,5 @@
+blank_issues_enabled: false
+contact_links:
+  - name: Questions and usage help
+    url: https://github.com/owenqwenstarsky/cassady/discussions
+    about: Ask questions, share setup notes, or discuss ideas before filing an issue.

.github/ISSUE_TEMPLATE/docs.yml

@@ -0,0 +1,44 @@
+name: Documentation issue
+description: Report missing, confusing, or incorrect documentation
+title: "docs: "
+labels: [documentation]
+body:
+  - type: textarea
+    id: location
+    attributes:
+      label: Documentation location
+      description: Link to the page or name the file/section, if known.
+      placeholder: README.md, docs/providers.md, docs/access-modes.md, ...
+    validations:
+      required: true
+  - type: textarea
+    id: issue
+    attributes:
+      label: What is unclear or incorrect?
+      description: Describe the gap, mistake, or confusing wording.
+    validations:
+      required: true
+  - type: textarea
+    id: suggested
+    attributes:
+      label: Suggested improvement
+      description: If you have specific wording or examples in mind, add them here.
+  - type: dropdown
+    id: impact
+    attributes:
+      label: Impact
+      options:
+        - Blocks installation or first use
+        - Causes incorrect configuration
+        - Confuses normal usage
+        - Typo or small polish
+        - Other
+    validations:
+      required: true
+  - type: checkboxes
+    id: checklist
+    attributes:
+      label: Checklist
+      options:
+        - label: I searched existing issues for a duplicate.
+          required: true

.github/ISSUE_TEMPLATE/feature_request.yml

@@ -0,0 +1,59 @@
+name: Feature request
+description: Suggest an improvement or new capability for Cassady / cass
+title: "feat: "
+labels: [enhancement]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thanks for suggesting an improvement. Please focus on the user problem and desired outcome.
+  - type: textarea
+    id: problem
+    attributes:
+      label: Problem or use case
+      description: What are you trying to do, and what makes it hard today?
+      placeholder: I want to...
+    validations:
+      required: true
+  - type: textarea
+    id: proposal
+    attributes:
+      label: Proposed behavior
+      description: Describe the change you would like to see.
+    validations:
+      required: true
+  - type: textarea
+    id: alternatives
+    attributes:
+      label: Alternatives considered
+      description: What workarounds or other designs have you considered?
+  - type: dropdown
+    id: area
+    attributes:
+      label: Area
+      options:
+        - Terminal UI
+        - Setup and configuration
+        - Providers and models
+        - Tools and file editing
+        - Safety and access modes
+        - Conversation history and resume
+        - Documentation
+        - Packaging and releases
+        - Other
+    validations:
+      required: true
+  - type: textarea
+    id: examples
+    attributes:
+      label: Examples or mockups
+      description: Add sample commands, UI text, config snippets, screenshots, or links that clarify the request.
+  - type: checkboxes
+    id: checklist
+    attributes:
+      label: Checklist
+      options:
+        - label: I searched existing issues for related requests.
+          required: true
+        - label: This request is in scope for a terminal coding agent, not a general package manager or updater.
+          required: false

.github/ISSUE_TEMPLATE/task.yml

@@ -0,0 +1,52 @@
+name: Maintenance task
+description: Track internal cleanup, refactoring, testing, CI, or release work
+title: "chore: "
+labels: [maintenance]
+body:
+  - type: textarea
+    id: goal
+    attributes:
+      label: Goal
+      description: What should be done, and why?
+    validations:
+      required: true
+  - type: textarea
+    id: scope
+    attributes:
+      label: Scope
+      description: List concrete files, modules, or workflows that are in scope.
+      placeholder: |
+        - src/...
+        - tests/...
+        - .github/workflows/...
+    validations:
+      required: true
+  - type: textarea
+    id: out_of_scope
+    attributes:
+      label: Out of scope
+      description: Note anything this task should intentionally avoid.
+  - type: textarea
+    id: acceptance
+    attributes:
+      label: Acceptance criteria
+      description: What must be true before this can be closed?
+      placeholder: |
+        - [ ] ...
+        - [ ] `cargo test --locked --all-targets` passes
+    validations:
+      required: true
+  - type: dropdown
+    id: area
+    attributes:
+      label: Area
+      options:
+        - Refactoring
+        - Tests
+        - CI
+        - Release process
+        - Dependencies
+        - Documentation maintenance
+        - Other
+    validations:
+      required: true

.github/scripts/build-pages.py

@@ -0,0 +1,111 @@
+#!/usr/bin/env python3
+"""Build the docs Markdown files into a static GitHub Pages site.
+
+This intentionally avoids themed site generators and template files. Each Markdown
+file is converted to a minimal standalone HTML page, and relative .md links are
+rewritten to the generated .html filenames.
+"""
+
+from __future__ import annotations
+
+import html
+import re
+import shutil
+from pathlib import Path, PurePosixPath
+from urllib.parse import urlsplit, urlunsplit
+
+import markdown
+
+ROOT = Path(__file__).resolve().parents[2]
+DOCS_DIR = ROOT / "docs"
+SITE_DIR = ROOT / "site"
+
+MARKDOWN_EXTENSIONS = ["fenced_code", "tables", "toc"]
+HREF_RE = re.compile(r'href="([^"]+)"')
+
+
+def output_path(source: Path) -> Path:
+    if source.name == "README.md":
+        return SITE_DIR / "index.html"
+    return SITE_DIR / f"{source.stem}.html"
+
+
+def page_title(text: str, fallback: str) -> str:
+    for line in text.splitlines():
+        if line.startswith("# "):
+            return line[2:].strip()
+    return fallback
+
+
+def rewrite_markdown_links(rendered: str) -> str:
+    def replace(match: re.Match[str]) -> str:
+        href = html.unescape(match.group(1))
+        parts = urlsplit(href)
+        if parts.scheme or parts.netloc or not parts.path.endswith(".md"):
+            return match.group(0)
+
+        url_path = PurePosixPath(parts.path)
+        if url_path.name == "README.md":
+            new_path = str(url_path.with_name("index.html"))
+        else:
+            new_path = parts.path[:-3] + ".html"
+
+        new_href = urlunsplit(("", "", new_path, parts.query, parts.fragment))
+        return f'href="{html.escape(new_href, quote=True)}"'
+
+    return HREF_RE.sub(replace, rendered)
+
+
+def render_page(source: Path) -> str:
+    text = source.read_text(encoding="utf-8")
+    title = page_title(text, "Cassady docs")
+    body = markdown.markdown(
+        text,
+        extensions=MARKDOWN_EXTENSIONS,
+        output_format="html5",
+    )
+    body = rewrite_markdown_links(body)
+
+    return "\n".join(
+        [
+            "<!doctype html>",
+            '<html lang="en">',
+            "<head>",
+            '  <meta charset="utf-8">',
+            '  <meta name="viewport" content="width=device-width, initial-scale=1">',
+            f"  <title>{html.escape(title)}</title>",
+            "</head>",
+            "<body>",
+            body,
+            "</body>",
+            "</html>",
+            "",
+        ]
+    )
+
+
+def copy_static_assets() -> None:
+    for item in DOCS_DIR.iterdir():
+        if item.suffix == ".md":
+            continue
+        destination = SITE_DIR / item.name
+        if item.is_dir():
+            shutil.copytree(item, destination)
+        elif item.is_file():
+            shutil.copy2(item, destination)
+
+
+def main() -> None:
+    if SITE_DIR.exists():
+        shutil.rmtree(SITE_DIR)
+    SITE_DIR.mkdir(parents=True)
+
+    for source in sorted(DOCS_DIR.glob("*.md")):
+        output_path(source).write_text(render_page(source), encoding="utf-8")
+
+    copy_static_assets()
+    (SITE_DIR / ".nojekyll").write_text("", encoding="utf-8")
+
+
+if __name__ == "__main__":
+    main()

.github/workflows/pages.yml

@@ -0,0 +1,67 @@
+name: Publish Markdown site
+
+on:
+  push:
+    branches:
+      - main
+    paths:
+      - 'docs/**'
+      - '.github/scripts/build-pages.py'
+      - '.github/workflows/pages.yml'
+  pull_request:
+    paths:
+      - 'docs/**'
+      - '.github/scripts/build-pages.py'
+      - '.github/workflows/pages.yml'
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
+concurrency:
+  group: github-pages
+  cancel-in-progress: false
+
+jobs:
+  build:
+    name: Build Markdown site
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.x'
+
+      - name: Install Markdown converter
+        run: python -m pip install Markdown
+
+      - name: Build site
+        run: python .github/scripts/build-pages.py
+
+      - name: Configure Pages
+        if: github.event_name != 'pull_request' && github.ref == 'refs/heads/main'
+        uses: actions/configure-pages@v5
+
+      - name: Upload Pages artifact
+        if: github.event_name != 'pull_request' && github.ref == 'refs/heads/main'
+        uses: actions/upload-pages-artifact@v3
+        with:
+          path: site
+
+  deploy:
+    name: Deploy to GitHub Pages
+    if: github.event_name != 'pull_request' && github.ref == 'refs/heads/main'
+    needs: build
+    runs-on: ubuntu-latest
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    steps:
+      - name: Deploy Pages artifact
+        id: deployment
+        uses: actions/deploy-pages@v4

.gitignore

@@ -1,2 +1,3 @@
 /target/
 /dist/
+/site/

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "cassady"
-version = "0.2.4"
+version = "0.3.0"
 edition = "2021"
 description = "Cassady/Cass minimal terminal coding agent"
 license = "MIT"
@@ -23,22 +23,26 @@ anyhow = "1"
 async-trait = "0.1"
 chrono = { version = "0.4", features = ["serde"] }
 clap = { version = "4", features = ["derive"] }
-crossterm = "0.28"
+crossterm = "0.29"
 dirs = "5"
 futures-util = "0.3"
 ignore = "0.4"
 include_dir = "0.7"
 nanoid = "0.4"
-ratatui = "0.28"
+ratatui = { version = "0.30", default-features = false, features = ["crossterm", "underline-color"] }
 regex = "1"
 pulldown-cmark = "0.12"
 reqwest = { version = "0.12", default-features = false, features = ["json", "rustls-tls", "stream"] }
+semver = "1"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
+sha2 = "0.10"
+flate2 = "1"
+tar = "0.4"
 thiserror = "1"
 tokio = { version = "1", features = ["macros", "rt-multi-thread", "sync", "time", "process", "io-util"] }
-tui-textarea = "0.6"
 unicode-width = "0.1"
+zip = { version = "2", default-features = false, features = ["deflate"] }
 
 [dev-dependencies]
 tempfile = "3"

README.md

@@ -1,16 +1,17 @@
 # Cassady / Cass
 
-Cassady (`cass`) is a terminal coding agent written in Rust. It runs an interactive chat in your project, can inspect files, apply exact edits, run shell commands when the active safety mode allows them, and persist sessions for later resume. Cassady currently talks to OpenAI-compatible providers.
+Cassady (`cass`) is a terminal coding agent written in Rust. It runs an interactive chat in your project, can inspect files, apply exact edits, run shell commands when the active safety mode allows them, and persist sessions for later resume. Cassady talks to OpenAI-compatible providers and a built-in ChatGPT Codex provider preset.
 
 The project installs two equivalent commands, `cass` and `cassady`; examples use `cass`.
 
 ## Current scope and limitations
 
-- Provider support is OpenAI-compatible chat/completions APIs only.
+- Provider support includes OpenAI-compatible chat/completions APIs plus the `ChatGPT Codex` preset for users already signed in to Codex.
 - The primary interface is an interactive terminal UI.
+- v0.2.6 adds an experimental Rust embedding API for headless sessions; it is useful for early integrations but not yet a stable long-term library contract.
 - Config and conversation state live under `~/.cass`.
 - Windows binaries are built for releases, but deeper Windows terminal, path, shell, and filesystem polish is planned for a later release.
-- Cassady is not an installer, updater, or package manager.
+- `cass update` can update release-archive installs from official GitHub releases; external package managers should still be updated through their own tools.
 
 ## Install from source
 
@@ -33,15 +34,17 @@ Start Cassady in a project directory:
 cass
 ```
 
-If Cassady cannot resolve a usable provider, model, or API key, it offers to run setup before opening a chat. You can also run setup explicitly:
+If Cassady cannot resolve a usable provider, model, or API key, it offers to run setup before opening a chat. You can also run setup or provider login explicitly:
 
 ```sh
+cass login
 cass setup
 cass check
+cass update --check
 cass
 ```
 
-The setup wizard lets you choose one or more OpenAI-compatible providers, enter the API key environment-variable name, discover models from `GET /models` when the key is available, or enter a model id manually.
+The setup wizard lets you choose one or more providers. OpenAI-compatible providers use an API key environment variable and can discover models from `GET /models` when the key is available. `ChatGPT Codex` uses your existing local Codex login (`~/.codex/auth.json`) and the Codex responses endpoint instead of a Cassady API-key environment variable.
 
 Set your provider key in the shell where you run Cassady. For example, on macOS/Linux:
 
@@ -64,13 +67,19 @@ cass [--model MODEL] [--cwd PATH]
 cass --resume <chat-id>
 cass --resume
 cass check
+cass login
+cass logout
 cass setup
+cass update
 ```
 
-`cass --resume` without an id lists saved chats for the current directory. When Cassady exits a chat, it prints a resume command for that session.
+`cass --resume` without an id lists saved chats for the current directory. `cass update` checks official GitHub releases and can update both `cass` and `cassady` in the current install directory. When Cassady exits a chat, it prints a resume command for that session.
 
 Common in-chat commands:
 
+- `/branch` or `/restore`: open the branch/restore menu.
+- `/login`: configure or update provider login settings.
+- `/logout`: remove saved provider config and associated model entries.
 - `/model <model>`: switch to a model from `~/.cass/models.json`.
 - `/new`: create a new chat for the current directory.
 - `/resume <chat>`: resume a saved chat for the current directory.
@@ -85,7 +94,7 @@ Helpful keys:
 - `Tab`: cycle reasoning effort while idle.
 - `Ctrl-O`: toggle compact/full tool output display.
 - `Ctrl-Shift-R` or `Ctrl-R`: toggle reasoning display.
-- `Esc`: request turn cancellation while a turn is running.
+- `Esc`: request turn cancellation while a turn is running; while idle, press twice within 1.5 seconds to open branch/restore.
 - `Ctrl-C` twice within 1.5 seconds: exit.
 
 ## Safety model
@@ -98,6 +107,12 @@ Cassady exposes tools according to the active access mode:
 
 Use `--readonly`, `--workspace-edit`, or `--full-access` to choose a mode at launch, or press `Shift-Tab` while idle.
 
+## Branch and restore
+
+Press `Esc` twice while idle, or type `/branch`, to browse the current conversation's branch family. Selecting an earlier user message, assistant message, tool call, or tool result creates a new branch conversation instead of truncating the original chat. The menu also lets you switch back to related branches later.
+
+Conversation-only branching is the safe default. If you choose file restore, Cassady restores only file changes it tracked from successful `write` and `edit` tools. Shell commands, manual edits, unsupported files, and hash conflicts are reported or skipped rather than overwritten blindly.
+
 ## Configuration and docs
 
 Cassady stores user-editable files in `~/.cass`:
@@ -108,16 +123,33 @@ Cassady stores user-editable files in `~/.cass`:
 - `global.md`: optional global instructions added to new chat system prompts when they fit the active request; they cannot override access modes, tool denials, approvals, or workspace boundaries.
 - `docs/`: bundled documentation installed from the current binary.
 
-API key references should usually be written as environment variables such as `"$OPENAI_API_KEY"`.
+API key references should usually be written as environment variables such as `"$OPENAI_API_KEY"`. The `ChatGPT Codex` provider is different: it stores no key in `~/.cass` and reads the bearer token from local Codex auth at check/request time.
 
 Detailed bundled docs live in this repository under [`docs/`](docs/README.md) and are installed to `~/.cass/docs` at runtime.
 
+## Experimental Rust embedding API
+
+Rust applications can import Cassady and run headless sessions without launching the TUI:
+
+```rust
+use cassady::prelude::*;
+
+let session = SessionBuilder::new()
+    .cwd(".")
+    .access_mode(AccessMode::ReadOnly)
+    .build()
+    .await?;
+```
+
+See [Experimental Rust embedding API](docs/embedding.md) for session creation, streamed events, approval handling, cancellation, and current limitations.
+
 ## More documentation
 
 - [Commands](docs/commands.md)
 - [Configuration](docs/configuration.md)
 - [Providers and models](docs/providers.md)
 - [Access modes and tool safety](docs/access-modes.md)
+- [Experimental Rust embedding API](docs/embedding.md)
 - [Workflows](docs/workflows.md)
 - [Troubleshooting](docs/troubleshooting.md)
 - [Platform notes](docs/platforms.md)

ROADMAP.md

@@ -1,5 +1,182 @@
 # Cassady (Cass) Roadmap
 
+## v0.3.0 — ChatGPT Codex Provider
+
+This release focuses on letting users who are already signed in to Codex with a ChatGPT subscription use that account from Cassady. `ChatGPT Codex` becomes a provider preset that calls the Codex responses endpoint and reads its bearer token from local Codex auth instead of an API-key environment variable. See `plans/V0_3_0_CHATGPT_CODEX_PROVIDER_PLAN.md`.
+
+### Provider Setup
+
+- [x] **Add a ChatGPT Codex provider preset.** Make `ChatGPT Codex` available from `cass login`, `/login`, and first-run setup as a distinct provider option.
+  - Use provider id `chatgpt-codex` and endpoint `https://chatgpt.com/backend-api/codex/responses`.
+  - Skip the normal API-key environment-variable prompt for this preset.
+  - Prefer the model configured in local Codex config when available, with manual model entry as a fallback.
+
+- [x] **Read local Codex auth safely.** Resolve the bearer token from `$CODEX_HOME/auth.json` or `~/.codex/auth.json` at check/request time.
+  - Support the local Codex `tokens.access_token` shape without copying the token into `~/.cass`.
+  - Give clear recovery steps when the user has not run `codex login`, signed in to the Codex app, or has an expired/missing token.
+
+### Provider Runtime
+
+- [x] **Add a ChatGPT Codex responses client.** Route `chatgpt-codex` providers to the exact Codex responses endpoint instead of the OpenAI-compatible `/chat/completions` path.
+  - Translate Cassady messages, tools, tool calls, and tool outputs to the endpoint's expected responses format.
+  - Stream assistant text, safe reasoning summaries when available, and function-call deltas back into the existing agent loop.
+
+- [x] **Keep OpenAI-compatible providers unchanged.** Refactor provider dispatch only as much as needed to support the new provider kind.
+  - Existing provider config, setup, model discovery, API-key env vars, `/model`, and `cass check` behavior should continue to work.
+  - Avoid leaking ChatGPT access tokens in errors, logs, transcripts, or config files.
+
+### Documentation and Validation
+
+- [x] **Document ChatGPT Codex prerequisites and caveats.** Update README and bundled docs for setup, config examples, `cass check`, troubleshooting, and the distinction between ChatGPT subscription-backed access and API-key providers.
+  - Make clear that Cassady uses an existing Codex login and does not implement its own browser login or token refresh flow in this release.
+  - Note that the ChatGPT backend endpoint may change outside Cassady's control.
+
+- [x] **Test Codex auth and provider behavior.** Cover Codex auth fixtures, config validation, setup catalog behavior, provider dispatch, streaming response parsing, tool calls, and secret redaction.
+  - Verify `cargo fmt` and `cargo test --locked --all-targets` pass before handoff.
+
+## v0.2.9 — Provider Login Management
+
+This release focuses on making provider configuration available from both the shell and an active Cassady chat. Users can add or update OpenAI-compatible provider/model settings with `cass login` or `/login`, and remove saved providers and their associated models with `cass logout` or `/logout`. See `plans/V0_2_9_PROVIDER_LOGIN_MANAGEMENT_PLAN.md`.
+
+### Login Commands
+
+- [x] **Add login commands for provider setup.** Make `cass login` and `/login` open the provider setup flow so users can configure providers without remembering that setup is the underlying implementation.
+  - Reuse the existing provider catalog, model discovery, model capability prompts, and safe JSON writes.
+  - Keep `/login` idle-only and reload active provider/model config after the menu closes.
+
+- [x] **Keep existing setup behavior intact.** Preserve `cass setup` and first-run setup while making login language feel natural for account/provider management.
+  - Direct `cass login` should save configuration and exit rather than unexpectedly starting a chat.
+  - Existing setup validation and missing API key guidance should continue to apply.
+
+### Logout Commands
+
+- [x] **Add a safe provider removal menu.** Make `cass logout` and `/logout` let users choose saved providers to remove from `providers.json`.
+  - Remove associated `models.json` entries for selected providers.
+  - Confirm the removal before writing changes.
+
+- [x] **Repair active defaults after removal.** Ensure `config.json` never points at a provider/model that was just removed.
+  - Select a valid remaining provider/model when possible.
+  - Clear active provider/model defaults when no providers remain so the next startup offers login/setup.
+
+### Documentation and Validation
+
+- [x] **Document provider login and logout workflows.** Update command, configuration, and workflow docs with the new shell and in-chat commands.
+  - Clarify that logout removes Cassady provider config, not environment variables or external provider accounts.
+
+- [x] **Test provider management behavior.** Cover provider/model removal, active default repair, local command parsing, and autocomplete.
+  - Verify `cargo fmt` and `cargo test --locked --all-targets` pass before handoff.
+
+## v0.2.8 — Conversation Branch and Restore
+
+This release focuses on making conversation recovery safe and explorable. Pressing `Esc` twice while idle opens a branch/restore menu where users can browse prior user messages, assistant messages, and tool calls, create a new branch from a selected checkpoint, and optionally restore Cassady-tracked file edits without destroying the original conversation. See `plans/V0_2_8_CONVERSATION_BRANCH_RESTORE_PLAN.md`.
+
+### Branch Navigation
+
+- [x] **Open a branch/restore menu with double Esc.** Add an idle `Esc`-twice shortcut that mirrors the discoverability of double `Ctrl-C` while preserving current busy-turn cancellation and approval-denial behavior.
+  - Keep draft input intact when the menu is opened or cancelled.
+  - Provide clear status text after the first `Esc` so users know a second press opens branch/restore.
+
+- [x] **Browse checkpoints across the related branch family.** Show user messages, assistant messages, tool-call requests, and tool results from the current chat and related branches.
+  - Include enough preview text, tool names, paths, timestamps, and branch labels to choose the right point.
+  - Allow switching back to the original conversation or another existing branch from the same menu.
+
+### Safe Conversation Branching
+
+- [x] **Create branches instead of destructive reverts.** Selecting a checkpoint should write a new conversation JSONL with parent/checkpoint metadata, leaving the source conversation unchanged.
+  - Support repeated branching so users can return to the menu later and branch or switch again.
+  - Keep older conversations without branch metadata loadable.
+
+- [x] **Handle tool-call checkpoints cleanly.** Branching at a specific tool call or tool result should preserve a valid provider message history.
+  - Repair partial multi-tool assistant turns with synthetic cancelled/omitted tool results where needed.
+  - Add tests for branching at user, assistant, and tool boundaries.
+
+### File Edit Restoration
+
+- [x] **Journal Cassady file edits with restorable snapshots.** Record successful `write` and `edit` tool mutations outside the model-visible transcript with before/after hashes and snapshots.
+  - Keep restore support limited to Cassady-tracked file tools; warn that shell commands and manual edits are not automatically reversible.
+  - Store enough data to restore both backward and forward between tracked checkpoints.
+
+- [x] **Offer explicit conversation-only or conversation-plus-files restore actions.** Make conversation-only branching the safe default, and require confirmation before changing workspace files.
+  - Preview files to update or delete, detect hash conflicts, and refuse unsafe overwrites by default.
+  - Use atomic writes for restored files and preserve clear status/transcript messages for skipped or conflicted paths.
+
+### Documentation and Validation
+
+- [x] **Document branch/restore workflows and limitations.** Update README and bundled docs with the double-`Esc` shortcut, menu controls, branch semantics, and file-restore safety model.
+  - Include troubleshooting for restore conflicts and unsupported shell/manual filesystem changes.
+
+- [x] **Test the branch and restore model.** Cover branch metadata, checkpoint extraction, tool-call repair, edit journaling, restore planning, and keybinding behavior where practical.
+  - Verify `cargo fmt` and `cargo test --locked --all-targets` pass before release.
+
+## v0.2.7 — Self-Update Command
+
+This release focuses on making Cassady easy to keep current after installation. The goal is to let users run one clean command, `cass update`, to check GitHub releases, choose the recommended prebuilt binary or a source-build fallback, verify what will be installed, and update both `cass` and `cassady` safely. See `plans/V0_2_7_SELF_UPDATE_COMMAND_PLAN.md`.
+
+### Update Command Experience
+
+- [x] **Add a polished `cass update` command.** Check the official Cassady GitHub releases, compare the running version to the selected release, and guide the user through an interactive update flow.
+  - Keep update independent of provider/model setup so it works even when config is missing or invalid.
+  - Support script-friendly checks with flags such as `--check`, `--dry-run`, and `--yes`.
+
+- [x] **Select the right update path.** Prefer a matching prebuilt release archive when available, with explicit `--prebuilt` and `--source` modes for users who want to choose.
+  - Support the same macOS, Linux, and Windows targets used by Cassady releases.
+  - Offer source builds for unsupported targets or users who prefer building locally.
+
+### Safe Installation
+
+- [x] **Verify and stage prebuilt artifacts before replacing binaries.** Download archives and SHA-256 files from the release, verify checksums, extract safely, and validate staged `cass`/`cassady` binaries.
+  - Reject checksum mismatches, unsafe archive paths, missing binaries, and unexpected versions.
+  - Show clear progress and failure messages without dumping raw implementation details.
+
+- [x] **Replace installed binaries cleanly.** Update the current binary and same-directory companion binary when possible, using backups and rollback on failure.
+  - Do not auto-run `sudo` or administrator prompts.
+  - Handle Windows executable replacement with a staged helper or documented manual fallback if necessary.
+
+### Source Build Fallback and Documentation
+
+- [x] **Build from release source when requested.** Download the selected release source, validate its version, check for Rust tooling, run a locked release build, and install the resulting local binaries.
+  - Keep source mode tied to release tags rather than arbitrary branches.
+  - Do not attempt cross-compilation or Rust toolchain installation in this release.
+
+- [x] **Document and test update behavior.** Update README and bundled docs for `cass update`, platform notes, troubleshooting, and package-manager caveats.
+  - Add tests for release parsing, target mapping, asset selection, checksum validation, archive extraction safety, install planning, and mocked update flows.
+
+## v0.2.6 — Rust Embedding API ✅ Completed
+
+This release focuses on adding the first intentional Rust library surface for embedding Cassady in other Rust projects. The goal is to provide the bones for programmatic, headless agent sessions: configure a workspace, start or resume an agent session, send turns, stream typed events, and handle approvals without launching the TUI. See `plans/V0_2_6_RUST_EMBEDDING_API_PLAN.md`.
+
+### Experimental Public API
+
+- [x] **Add a supported embedding module.** Provide a small `cassady::embedding` API with builder, session, turn, event, approval, and error types so callers do not need to stitch together internal modules directly.
+  - Mark the API experimental for v0.2.6 rather than promising long-term semver stability.
+  - Keep existing CLI/TUI behavior unchanged while steering library users toward the new module.
+
+- [x] **Support host-configured agent sessions.** Let Rust callers create or resume headless sessions with explicit cwd, access mode, model/provider overrides, reasoning effort, and Cassady config root.
+  - Reuse existing config files, global instructions, bundled docs, security policy, and JSONL conversation storage.
+  - Avoid requiring callers to construct CLI-specific types.
+
+### Headless Turn Execution
+
+- [x] **Run agent turns programmatically.** Add a Tokio-native API for sending one user message, streaming assistant/tool/status events, and returning the updated session or conversation state.
+  - Prevent or clearly reject overlapping turns unless the type design makes them impossible.
+  - Preserve provider streaming, tool execution, prompt generation, and context behavior from the existing agent loop.
+
+- [x] **Expose approval handling to host applications.** Allow embedded callers to approve or deny tool approval requests, especially shell commands in `workspace-edit` mode.
+  - Include request id, tool call id, tool name, arguments, and reason in approval events.
+  - Document cancellation/drop behavior for active turns.
+
+### Documentation and Validation
+
+- [x] **Add a minimal headless example.** Include a compilable Rust example that imports Cassady, starts a session, sends a prompt, and prints streamed assistant output.
+  - Note that a configured OpenAI-compatible provider and API key are still required.
+  - Show where to handle approval requests even if the first example defaults to `read-only`.
+
+- [x] **Document the experimental Rust API.** Add bundled docs and README links for setup requirements, basic usage, event handling, approvals, limitations, and current non-goals.
+  - Make clear that multi-agent orchestration, custom providers, custom tools, daemons, and stable plugin APIs are deferred.
+
+- [x] **Test embedding without a terminal.** Add integration tests that use temporary config/conversation roots and mock provider responses to verify session creation, turn streaming, resume, approval flow, and access-mode behavior.
+  - Ensure `cargo test --locked --all-targets` covers the new public API and examples.
+
 ## v0.2.4 — System Prompt Refinement
 
 This release focuses on making Cassady's system prompt clearer, more intuitive, and more useful for everyday coding work without letting it become bulky. The target is a well-structured prompt around 1,000 tokens that gives the model enough product context, safety expectations, and workflow guidance to behave consistently across read-only, workspace-edit, and full-access sessions. See `plans/V0_2_4_SYSTEM_PROMPT_REFINEMENT_PLAN.md`.

SECURITY.md

@@ -0,0 +1,64 @@
+# Security Policy
+
+## Supported Versions
+
+Security updates are provided for the latest released version of Cassady. If you are using an older version, please upgrade to the latest release before reporting an issue, unless the issue also affects the latest release.
+
+| Version | Supported |
+| ------- | --------- |
+| Latest | ✅ |
+| Older releases | ❌ |
+
+## Reporting a Vulnerability
+
+Please do **not** report security vulnerabilities in public GitHub issues, discussions, or pull requests.
+
+To report a vulnerability, use GitHub's private vulnerability reporting for this repository:
+
+1. Open the repository on GitHub.
+2. Go to **Security** → **Report a vulnerability**.
+3. Include as much detail as you can about the issue, impact, affected versions, and steps to reproduce.
+
+## What to Include
+
+Helpful reports include:
+
+- A description of the vulnerability and likely impact.
+- Steps to reproduce or a minimal proof of concept.
+- The Cassady version, operating system, shell, and terminal environment.
+- Relevant configuration details with secrets removed.
+- Any known mitigations or workarounds.
+
+Do not include live API keys, tokens, private prompts, or sensitive project files in a report. Redact secrets before sharing logs or configuration.
+
+## Response Expectations
+
+After a report is received, the maintainer will aim to:
+
+- Acknowledge the report within 7 days.
+- Confirm whether the issue is in scope and reproducible.
+- Provide status updates when there is meaningful progress.
+- Coordinate disclosure timing before publishing details publicly.
+
+Security fixes may be released as patch versions when appropriate. Public disclosure should wait until a fix or mitigation is available, unless otherwise coordinated with the maintainer.
+
+## Scope
+
+Examples of in-scope issues include vulnerabilities in Cassady that could:
+
+- Bypass documented access modes, approval prompts, or workspace boundaries.
+- Cause unintended file reads, writes, edits, or shell command execution.
+- Leak API keys, provider credentials, chat history, or local configuration.
+- Corrupt or expose session data stored under `~/.cass`.
+- Introduce unsafe behavior in bundled release artifacts.
+
+Out-of-scope issues generally include:
+
+- Vulnerabilities in third-party model providers or APIs not controlled by this project.
+- Prompt-injection behavior that does not bypass Cassady's documented safety controls.
+- Issues that require a compromised local machine, shell, dependency cache, or provider account.
+- Reports against unsupported older versions that are fixed in the latest release.
+
+## Safe Harbor
+
+Good-faith security research is welcome. Please avoid privacy violations, data destruction, service disruption, and accessing data that does not belong to you. If you follow this policy and make a good-faith effort to avoid harm, the maintainer will not pursue legal action for your research.

docs/README.md

@@ -6,11 +6,12 @@ Cassady tools may list, search, and read this directory. Mutating tools are bloc
 
 ## Contents
 
-- [Commands](commands.md): CLI forms, global flags, in-chat commands, and keys.
+- [Commands](commands.md): CLI forms, global flags, `cass update`, in-chat commands, and keys.
 - [Configuration](configuration.md): `~/.cass` files, setup, precedence, schema examples, and validation.
-- [Providers and models](providers.md): built-in OpenAI-compatible providers, custom endpoints, model discovery, and reasoning metadata.
+- [Providers and models](providers.md): built-in provider presets, custom OpenAI-compatible endpoints, ChatGPT Codex auth, model discovery, and reasoning metadata.
 - [Access modes and tool safety](access-modes.md): what tools can read, write, edit, and run in each mode.
+- [Experimental Rust embedding API](embedding.md): import Cassady from Rust, start headless sessions, stream events, and handle approvals.
 - [Workflows](workflows.md): common ways to inspect code, apply edits, run checks, switch models, and resume chats.
 - [Troubleshooting](troubleshooting.md): symptoms, likely causes, fixes, and verification commands.
-- [Platform notes](platforms.md): macOS, Linux, and Windows environment/path notes.
+- [Platform notes](platforms.md): macOS, Linux, Windows, release artifact, and update notes.
 - [Glossary](glossary.md): short definitions for Cassady terms.

docs/commands.md

@@ -8,11 +8,14 @@ Cassady installs two equivalent binaries: `cass` and `cassady`. This page uses `
 cass [OPTIONS]
 cassady [OPTIONS]
 cass check [OPTIONS]
+cass login [OPTIONS]
+cass logout [OPTIONS]
 cass setup [OPTIONS]
+cass update [OPTIONS]
 cass --resume [CHAT_ID]
 ```
 
-Run `cass --help`, `cass check --help`, or `cass setup --help` for the help generated by the current binary.
+Run `cass --help`, `cass check --help`, `cass login --help`, `cass logout --help`, `cass setup --help`, or `cass update --help` for the help generated by the current binary.
 
 ## Startup behavior
 
@@ -32,7 +35,7 @@ Resume this chat with: cass --resume <id>
 
 - `--resume [CHAT_ID]`: resume a chat, or list chats for the current cwd when no id is provided.
 - `--model MODEL`: use `MODEL` for this session.
-- `--base-url URL`: override the active provider's OpenAI-compatible base URL for this session.
+- `--base-url URL`: override the active provider's base URL or endpoint for this session.
 - `--api-key-env ENV`: read the API key from environment variable `ENV` for this session.
 - `--cwd PATH`: use `PATH` as the launch cwd and workspace root.
 - `--readonly`: force read-only mode.
@@ -53,18 +56,59 @@ Validates Cassady configuration under `~/.cass`:
 - duplicate provider/model ids.
 - model/provider references.
 - active provider and model resolution.
-- active API key availability.
+- active authentication availability.
 
-Missing API keys for inactive providers are warnings. A missing active API key is an error and `cass check` exits with a non-zero status.
+Missing API keys for inactive OpenAI-compatible providers are warnings. A missing active API key is an error. For `ChatGPT Codex`, missing or expired local Codex auth is an error when it is active. `cass check` exits with a non-zero status when errors are present.
+
+### `cass login`
+
+Runs the provider login/configuration wizard. This is the same provider setup flow used by `cass setup`, framed for adding or updating saved provider access. It can configure multiple providers, discover or manually enter models, update active defaults, and validate the saved files.
+
+`cass login` edits Cassady files under `~/.cass`; it does not create provider accounts. For `ChatGPT Codex`, sign in with `codex login` or the Codex app first; Cassady then uses local Codex auth instead of storing an API key.
+
+### `cass logout`
+
+Opens an interactive menu for removing saved providers from Cassady config. Removing a provider also removes its associated `models.json` entries. If the active provider is removed, Cassady chooses a remaining provider/model when possible. If no providers remain, active defaults are cleared and the next chat startup will offer setup/login again.
+
+`cass logout` does not delete environment variables, API keys stored elsewhere, or external provider accounts.
 
 ### `cass setup`
 
-Runs the interactive setup wizard in a terminal. It configures OpenAI-compatible providers, API key environment-variable references, and first models. It updates `config.json`, `providers.json`, and `models.json` while preserving unrelated entries where possible.
+Runs the interactive setup wizard in a terminal. It configures providers, authentication sources, and first models. OpenAI-compatible providers use API key environment-variable references; `ChatGPT Codex` uses local Codex auth. It updates `config.json`, `providers.json`, and `models.json` while preserving unrelated entries where possible.
+
+### `cass update`
+
+Checks official GitHub releases for Cassady, including Cassady prereleases, and updates the current install directory. The updater runs before provider/model config is loaded, so it can be used even if `~/.cass` is missing or invalid.
+
+By default, Cassady selects the matching prebuilt archive for the current platform, downloads the archive and `.sha256` file, verifies SHA-256, stages both `cass` and `cassady`, and replaces same-directory binaries with rollback backups. If no prebuilt archive is available, it can build from the selected release source when you choose source mode.
+
+Useful options:
+
+- `--check`: check the selected release without installing.
+- `--dry-run`: show the selected release, mode, asset, and install plan without downloading or installing.
+- `--yes` / `-y`: accept default prompts for non-interactive use.
+- `--prebuilt`: require a matching prebuilt archive.
+- `--source`: build from release source even when a prebuilt archive exists.
+- `--to TAG`: use a specific release tag such as `v0.2.7`.
+
+Examples:
+
+```sh
+cass update --check
+cass update --dry-run
+cass update
+cass update --source
+```
+
+The updater does not invoke `sudo` or administrator prompts. If the install directory is not writable, rerun the update from an install location you own or update through the same package manager or manual process you originally used.
 
 ## In-chat commands
 
 Type `/` to open command autocomplete.
 
+- `/branch` or `/restore`: open the branch/restore menu for the current conversation family.
+- `/login`: configure or update provider login settings, then reload active provider/model config.
+- `/logout`: remove saved providers and their associated models, then reload active provider/model config when any remain.
 - `/model <model>`: switch the model for future turns. Autocomplete lists models from `~/.cass/models.json`.
 - `/new`: create a new chat for the current directory.
 - `/resume <chat>`: resume a saved chat from the current directory. Autocomplete lists matching chats.
@@ -86,8 +130,13 @@ Local commands can be used only when the agent is idle.
 - `y`: approve a pending tool approval prompt.
 - `n` or `Esc`: deny a pending tool approval prompt.
 - `Esc`: request cancellation while a turn is running.
+- `Esc` twice while idle: open the branch/restore menu without discarding draft input.
 - `Ctrl-C`: request cancellation while busy; press twice within 1.5 seconds to exit.
 
+## Branch/restore notes
+
+The branch/restore menu lists related conversations plus checkpoints for user messages, assistant messages, tool-call requests, and tool results. Selecting a checkpoint creates a new branch JSONL conversation and leaves the source conversation unchanged. Conversation-only branching leaves files untouched; branch-plus-file restore applies Cassady's tracked `write`/`edit` snapshots and skips unsafe hash conflicts.
+
 ## Output notes
 
 Tool calls are shown compactly by default. Press `Ctrl-O` to expand full tool output. Provider-streamed reasoning is hidden by default unless `show_reasoning` is enabled in config or toggled at runtime.

docs/configuration.md

@@ -19,13 +19,17 @@ Run:
 cass setup
 ```
 
-Cassady also offers setup automatically when `cass` cannot resolve a usable active provider, model, or API key before starting a chat.
+Cassady also offers setup automatically when `cass` cannot resolve a usable active provider, model, or authentication source before starting a chat.
+
+For everyday provider management, `cass login` opens the same provider configuration flow with login-oriented wording. Inside an idle chat, `/login` temporarily opens that flow and reloads the active provider/model after it closes.
+
+To remove saved provider configuration, run `cass logout` or type `/logout` while idle. Logout removes selected providers from `providers.json` and removes their associated entries from `models.json`. It does not remove environment variables, local shell profile exports, or external provider accounts.
 
 The wizard uses keyboard prompts: `↑`/`↓` moves through choices, `Space` selects providers in the multi-select screen, and `Enter` submits. Text fields use the same prompt style instead of falling back to plain line input.
 
-The wizard supports configuring multiple OpenAI-compatible providers at once. If more than one provider is configured, setup asks which one should be active first. If the selected API key environment variable is set, Cassady tries to fetch models from `GET {base_url}/models` and lets you choose one. If discovery fails, it offers a retry before falling back to manual model entry. If the API key is not set, setup asks for a model id manually.
+The wizard supports configuring multiple providers at once. If more than one provider is configured, setup asks which one should be active first. For OpenAI-compatible providers, if the selected API key environment variable is set, Cassady tries to fetch models from `GET {base_url}/models` and lets you choose one. If discovery fails, it offers a retry before falling back to manual model entry. If the API key is not set, setup asks for a model id manually. For `ChatGPT Codex`, setup skips API-key prompts and reads model defaults from local Codex config when available.
 
-Setup stores API keys as environment-variable references such as `"$OPENAI_API_KEY"` by default. After setup, Cassady writes/updates `config.json`, `providers.json`, and `models.json`, validates them, and starts a chat only when the active API key is available in the current shell.
+Setup stores API keys as environment-variable references such as `"$OPENAI_API_KEY"` by default for OpenAI-compatible providers. `ChatGPT Codex` stores no API key in `~/.cass`; it reads local Codex auth at check/request time. After setup, Cassady writes/updates `config.json`, `providers.json`, and `models.json`, validates them, and starts a chat only when the active authentication source is available.
 
 ## `config.json`
 
@@ -85,14 +89,33 @@ Fields:
 
 - `id`: required unique provider id.
 - `name`: optional display name.
-- `kind`: required provider kind. Currently only `"openai-compatible"` is supported.
-- `base_url`: required OpenAI-compatible API base URL.
-- `api_key`: required string. Use either a literal key or an environment-variable reference like `"$OPENAI_API_KEY"`.
+- `kind`: required provider kind. Supported values are `"openai-compatible"` and `"chatgpt-codex"`.
+- `base_url`: required API base URL or endpoint. `chatgpt-codex` uses `https://chatgpt.com/backend-api/codex/responses`.
+- `api_key`: required for `openai-compatible` providers. Use either a literal key or an environment-variable reference like `"$OPENAI_API_KEY"`. Omit it for `chatgpt-codex`; that provider reads local Codex auth instead.
 - `default_model`: optional model id used when no default model is configured.
 - `models`: optional list of model ids associated with this provider.
 
 Only strings that start with `$` are resolved as environment variables. Cassady does not expand partial strings or `${NAME}` syntax.
 
+`ChatGPT Codex` example:
+
+```json
+{
+  "providers": [
+    {
+      "id": "chatgpt-codex",
+      "name": "ChatGPT Codex",
+      "kind": "chatgpt-codex",
+      "base_url": "https://chatgpt.com/backend-api/codex/responses",
+      "default_model": "gpt-5.5",
+      "models": ["gpt-5.5"]
+    }
+  ]
+}
+```
+
+Run `codex login` or sign in with the Codex app before using this provider. Cassady reads `$CODEX_HOME/auth.json` or `~/.codex/auth.json` and does not store the Codex access token in `~/.cass`.
+
 ## `models.json`
 
 Example:
@@ -154,7 +177,7 @@ Run:
 cass check
 ```
 
-This validates JSON syntax, expected schema, duplicate provider/model ids, model/provider references, active provider/model resolution, and API key environment-variable availability. Missing API keys for inactive providers are warnings; a missing active provider API key is an error.
+This validates JSON syntax, expected schema, duplicate provider/model ids, model/provider references, active provider/model resolution, and authentication availability. Missing API keys for inactive OpenAI-compatible providers are warnings; a missing active provider API key is an error. For `ChatGPT Codex`, missing or expired local Codex auth is an active-provider error.
 
 When setup is incomplete, `cass check` prints actionable next steps such as:
 
@@ -168,7 +191,8 @@ cass
 
 1. Edit one file at a time.
 2. Keep provider ids and model provider references in sync.
-3. Prefer API key env references over literal keys.
-4. Run `cass check` before starting a chat.
+3. Prefer API key env references over literal keys for OpenAI-compatible providers; do not paste Codex tokens into Cassady config.
+4. Prefer `cass login` and `cass logout` for routine provider changes.
+5. Run `cass check` before starting a chat.
 
 Invalid JSON, unknown fields, duplicate ids, and missing provider/model links are reported by `cass check` with the file that failed.

docs/embedding.md

@@ -0,0 +1,98 @@
+# Experimental Rust embedding API
+
+Cassady v0.2.6 includes an experimental Rust API for running headless agent sessions from another Rust program. The API is intended for early integrations and may change before Cassady declares a stable library contract.
+
+The embedding API uses the same provider configuration, global instructions, prompts, access modes, tools, and JSONL conversation storage as the `cass` terminal UI. By default it reads and writes under `~/.cass`, so run `cass setup` first or create compatible `config.json`, `providers.json`, and `models.json` files programmatically.
+
+## Minimal example
+
+```rust
+use cassady::prelude::*;
+
+#[tokio::main]
+async fn main() -> anyhow::Result<()> {
+    let session = SessionBuilder::new()
+        .cwd(std::env::current_dir()?)
+        .access_mode(AccessMode::ReadOnly)
+        .build()
+        .await?;
+
+    let mut turn = session
+        .start_turn("Summarize this project in a few sentences.")
+        .await?;
+
+    while let Some(event) = turn.next_event().await? {
+        match event {
+            Event::AssistantChunk(text) => print!("{text}"),
+            Event::Finished => break,
+            _ => {}
+        }
+    }
+
+    let session = turn.finish().await?;
+    eprintln!("\nResume chat with: cass --resume {}", session.id());
+    Ok(())
+}
+```
+
+Add Cassady from a git checkout or path dependency, and ensure your application runs on Tokio.
+
+## Creating or resuming sessions
+
+Use `SessionBuilder` to set host-controlled options:
+
+```rust
+let session = SessionBuilder::new()
+    .config_root("/tmp/my-cass-root")
+    .cwd("/path/to/workspace")
+    .access_mode(AccessMode::WorkspaceEdit)
+    .model("my-model")
+    .base_url("https://provider.example/v1")
+    .api_key_env("MY_PROVIDER_KEY")
+    .build()
+    .await?;
+
+let resumed = SessionBuilder::new()
+    .cwd("/path/to/workspace")
+    .resume(session.id())
+    .await?;
+```
+
+`build()` is equivalent to `new_session()`. Resumed and new sessions use Cassady's normal `conversations/*.jsonl` files, so CLI and embedded sessions can interoperate.
+
+## Events and approvals
+
+`Session::start_turn` consumes the session and returns a `Turn`. This type design prevents overlapping turns for the same session. Call `turn.finish().await?` after receiving `Event::Finished` to recover the updated `Session`.
+
+Important events include:
+
+- `AssistantChunk` and `ReasoningChunk`
+- `ToolCallStarted`, `ToolOutputChunk`, and `ToolResult`
+- `ApprovalRequested` and `ApprovalResolved`
+- `Status`
+- `Finished`
+
+When a tool needs approval, decide in host code:
+
+```rust
+while let Some(event) = turn.next_event().await? {
+    match event {
+        Event::ApprovalRequested(request) => {
+            eprintln!("approval needed for {}: {}", request.name, request.reason);
+            turn.deny(&request.request_id)?;
+        }
+        Event::Finished => break,
+        _ => {}
+    }
+}
+```
+
+The approval policy is the same as the TUI: shell is unavailable in `read-only`, requires approval in `workspace-edit`, and runs directly in `full-access` unless destructive-operation confirmation is enabled.
+
+## Cancellation
+
+Dropping a `Turn` aborts the underlying task. Prefer `turn.cancel().await?` when you want Cassady to repair the conversation with cancellation records before returning the session.
+
+## Current limitations
+
+The v0.2.6 API is intentionally small and experimental. It does not include custom provider traits, custom tools, plugin loading, multi-agent orchestration, background daemons, task queues, or a synchronous/blocking wrapper.

docs/platforms.md

@@ -52,9 +52,22 @@ That directory contains `config.json`, `providers.json`, `models.json`, `global.
 ## Non-interactive contexts
 
 - `cass check` is suitable for scripts and CI because it prints text and exits non-zero on errors.
+- `cass update --check` and `cass update --dry-run` are suitable for scripts that only need release status or an install plan.
+- `cass update --yes` accepts default prompts for scripted updates, but still fails instead of escalating privileges when the install directory is not writable.
 - `cass setup` requires an interactive terminal.
 - `cass` chat is an interactive terminal UI.
 
-## Release artifacts
+## Release artifacts and updates
 
-When using release archives, each archive contains both `cass` and `cassady`. Put the extracted binaries somewhere on your `PATH` or run them by explicit path. Cassady itself does not install, update, or manage PATH entries.
+When using release archives, each archive contains both `cass` and `cassady`. Put the extracted binaries somewhere on your `PATH` or run them by explicit path.
+
+`cass update` can update release-archive installs from official GitHub releases. It supports the same prebuilt targets as the release process:
+
+- macOS Apple Silicon: `aarch64-apple-darwin`
+- Linux x86_64: `x86_64-unknown-linux-gnu`
+- Linux ARM64: `aarch64-unknown-linux-gnu`
+- Windows x86_64: `x86_64-pc-windows-gnu`
+
+On macOS and Linux, the updater replaces same-directory `cass` and `cassady` binaries with backups and rollback on failure. On Windows, replacing a running `.exe` is more constrained; if automatic replacement is unavailable, Cassady leaves staged files in place and reports manual copy guidance instead of partially modifying the install.
+
+If Cassady is installed through a package manager in the future, prefer that package manager's update command instead of `cass update`.

docs/providers.md

@@ -1,14 +1,15 @@
 # Providers and models
 
-Cassady currently supports OpenAI-compatible providers. A provider supplies the base URL and API key; a model entry supplies metadata for one model id used with that provider.
+Cassady supports OpenAI-compatible providers plus a built-in `ChatGPT Codex` provider preset. A provider supplies the endpoint and authentication source; a model entry supplies metadata for one model id used with that provider.
 
 ## Built-in setup catalog
 
 The setup wizard offers these provider templates:
 
-| Provider | Provider id | Base URL | Suggested API key env var |
+| Provider | Provider id | Base URL / endpoint | Suggested auth source |
 | --- | --- | --- | --- |
 | OpenAI | `openai` | `https://api.openai.com/v1` | `OPENAI_API_KEY` |
+| ChatGPT Codex | `chatgpt-codex` | `https://chatgpt.com/backend-api/codex/responses` | local Codex auth |
 | xAI | `xai` | `https://api.x.ai/v1` | `XAI_API_KEY` |
 | Fireworks | `fireworks` | `https://api.fireworks.ai/inference/v1` | `FIREWORKS_API_KEY` |
 | Groq | `groq` | `https://api.groq.com/openai/v1` | `GROQ_API_KEY` |
@@ -21,9 +22,23 @@ The setup wizard offers these provider templates:
 
 There is also a custom OpenAI-compatible option. Custom setup asks for provider name, provider id, base URL, API key environment variable, and first model id.
 
+## Login and logout
+
+Use `cass login` to add or update provider configuration from the shell. Inside an idle chat, `/login` opens the same flow and reloads the active provider/model afterward.
+
+Use `cass logout` or `/logout` to remove saved provider entries from Cassady config. Logout also removes model metadata entries associated with the removed providers and repairs active defaults when other providers remain. It does not delete environment variables, shell profile exports, API keys stored elsewhere, or external provider accounts.
+
+## ChatGPT Codex preset
+
+`ChatGPT Codex` is for users who have already signed in with Codex. Run `codex login` or sign in with the Codex app first, then select `ChatGPT Codex` in `cass login` or `cass setup`.
+
+Cassady reads the bearer token from `$CODEX_HOME/auth.json` or `~/.codex/auth.json` at check/request time. It does not copy the access token or refresh token into `~/.cass`, and `cass check` redacts secret values. Setup prefers the `model` value from `$CODEX_HOME/config.toml` when present and otherwise offers a default/manual model id.
+
+This preset uses `kind: "chatgpt-codex"` and posts to `https://chatgpt.com/backend-api/codex/responses`. That ChatGPT backend endpoint and Codex auth file format are outside Cassady's control, so users may need to update Cassady if they change.
+
 ## Model discovery
 
-When the selected API key environment variable is available, setup tries:
+For OpenAI-compatible providers, when the selected API key environment variable is available, setup tries:
 
 ```text
 GET {base_url}/models
@@ -40,7 +55,7 @@ A custom provider should expose OpenAI-compatible chat completions behavior at t
 - optional reasoning fields or reasoning request controls;
 - optional `/models` discovery during setup.
 
-Provider protocols that are not OpenAI-compatible are not currently supported.
+Provider protocols that are not OpenAI-compatible are supported only when Cassady has an explicit provider kind for them, such as `chatgpt-codex`.
 
 ## Provider vs model metadata
 
@@ -48,7 +63,7 @@ Provider protocols that are not OpenAI-compatible are not currently supported.
 
 - provider id;
 - base URL;
-- API key reference;
+- API key reference or local auth source;
 - optional default model;
 - optional list of associated model ids.
 
@@ -99,4 +114,4 @@ Run:
 cass check
 ```
 
-This confirms that the active provider and model resolve and that the active API key environment variable is set. Missing inactive-provider keys are warnings; missing active-provider keys are errors.
+This confirms that the active provider and model resolve. For OpenAI-compatible providers it checks API key environment variables; missing inactive-provider keys are warnings and missing active-provider keys are errors. For `ChatGPT Codex`, it checks that local Codex auth contains an access token and prints recovery steps if not.

docs/troubleshooting.md

@@ -1,6 +1,6 @@
 # Troubleshooting
 
-Use `cass check` first for configuration problems. It validates files, provider/model references, and API key availability.
+Use `cass check` first for configuration problems. It validates files, provider/model references, and authentication availability.
 
 ## Missing active API key
 
@@ -24,6 +24,22 @@ cass check
 cass
 ```
 
+## Missing or expired ChatGPT Codex auth
+
+Symptom: `cass check` reports `Codex auth` errors, or chat startup says provider authentication is not available for `chatgpt-codex`.
+
+Likely cause: `ChatGPT Codex` is active but `$CODEX_HOME/auth.json` or `~/.codex/auth.json` is missing, unreadable, lacks `tokens.access_token`, or contains an expired token.
+
+Fix:
+
+```sh
+codex login
+cass check
+cass
+```
+
+You can also sign in with the Codex app if that is how your local Codex auth is managed. Cassady does not refresh or store ChatGPT/Codex tokens; it reads local Codex auth at check/request time and redacts secret values.
+
 ## Invalid API key reference
 
 Symptom: the key is not resolved the way you expect.
@@ -45,9 +61,10 @@ Likely causes:
 - wrong `base_url`;
 - network or proxy problem;
 - provider outage;
-- provider requires a different OpenAI-compatible path.
+- provider requires a different OpenAI-compatible path;
+- for `ChatGPT Codex`, the private ChatGPT backend endpoint changed or the selected model is unavailable.
 
-Fix: verify the base URL in `providers.json`, retry setup, or enter the model id manually if only `/models` discovery is failing.
+Fix: verify the base URL in `providers.json`, retry setup, or enter the model id manually if only `/models` discovery is failing. For `ChatGPT Codex`, verify that `base_url` is `https://chatgpt.com/backend-api/codex/responses`, rerun `codex login`, and try a current Codex model id.
 
 ## `/models` discovery fails
 
@@ -75,9 +92,9 @@ Then verify with a small prompt.
 
 Symptom: the assistant says the provider returned an error.
 
-Likely cause: provider-side authentication, quota, billing, or rate limit.
+Likely cause: provider-side authentication, quota, billing, or rate limit. For `ChatGPT Codex`, this can also mean your ChatGPT subscription/account does not have the requested Codex model available or the local Codex token needs to be refreshed by Codex.
 
-Fix: confirm the API key, provider account status, selected model, and provider dashboard. Cassady forwards provider failures into the chat but cannot resolve account-level issues.
+Fix: confirm the API key, provider account status, selected model, and provider dashboard. For `ChatGPT Codex`, rerun `codex login` or open Codex to refresh local auth. Cassady forwards provider failures into the chat but cannot resolve account-level issues.
 
 ## Invalid JSON or unknown config fields
 
@@ -143,6 +160,37 @@ Likely cause: Windows CRLF line endings or invisible whitespace differences.
 
 Fix: re-read the exact target region and preserve the line endings in `old_text`, or use a smaller unique snippet.
 
+## Branch/restore file conflicts
+
+Symptom: branch-plus-file restore reports conflicts or skips paths.
+
+Likely cause: the file changed outside Cassady after the tracked `write`/`edit`, the file is unsupported for snapshots, or the change came from a shell command or manual editor rather than a Cassady file tool.
+
+Fix: review the restore preview, inspect conflicted files manually, and rerun the menu with conversation-only branching if you only need to revisit the chat. Cassady will not overwrite unknown current content by default. Open the branch/restore menu again with double `Esc` or `/branch` to switch back to the original branch.
+
+## Update command problems
+
+Symptom: `cass update` cannot complete.
+
+Likely causes and fixes:
+
+- Network or GitHub API failure: retry later or verify proxy/firewall settings.
+- No matching prebuilt archive: use `cass update --source` if you have Rust installed, or download the release archive manually for a supported target.
+- SHA-256 mismatch: do not install the archive. Retry the update; if it repeats, check the GitHub release page before proceeding.
+- Missing Rust toolchain in source mode: install Rust/Cargo yourself, then rerun `cass update --source`. Cassady does not install Rust automatically.
+- Non-writable install directory: update through the original install method, move Cassady to a directory you own, or manually replace the binaries. Cassady does not run `sudo` for you.
+- PATH conflict: `cass update` updates the current executable directory. Run `which cass` / `which cassady` on macOS/Linux or `Get-Command cass` in PowerShell to confirm which binary your shell starts.
+- Windows replacement limitation: if Cassady reports that automatic replacement is unavailable, use the staged file paths it prints and copy them after the running process exits.
+
+Useful checks:
+
+```sh
+cass update --check
+cass update --dry-run
+cass --version
+cassady --version
+```
+
 ## Terminal rendering problems
 
 Symptom: the UI appears garbled or keys do not behave as expected.

docs/workflows.md

@@ -57,6 +57,36 @@ Run the smallest relevant Rust test for this change, then summarize the result.
 
 When the approval prompt appears, press `y` to approve or `n`/`Esc` to deny. Shell commands run with `sh -c` from the launch cwd and default to a 30-second timeout unless the model requests another timeout.
 
+## Manage provider login
+
+Add or update provider configuration from the shell:
+
+```sh
+cass login
+```
+
+Inside an idle chat:
+
+```text
+/login
+```
+
+Remove saved provider configuration:
+
+```sh
+cass logout
+```
+
+Inside an idle chat:
+
+```text
+/logout
+```
+
+Logout removes selected providers from Cassady's config and removes their associated model entries. It does not delete environment variables, local Codex auth, or external provider accounts.
+
+For `ChatGPT Codex`, run `codex login` or sign in with the Codex app before `cass login`. Cassady validates `~/.codex/auth.json` and uses that local token source instead of asking for an API-key environment variable.
+
 ## Switch model
 
 Inside a chat:
@@ -103,6 +133,16 @@ Inside the UI:
 
 This creates a new chat for the same cwd and model while preserving your current configuration.
 
+## Branch or restore a conversation point
+
+Press `Esc` twice while idle, or type:
+
+```text
+/branch
+```
+
+Use the menu to select a related branch or a checkpoint from a user message, assistant message, tool-call request, or tool result. Branching creates a new chat from that point and leaves the original chat available in the same menu. Choose conversation-only branching to leave files untouched, or choose branch-plus-files to restore Cassady-tracked `write`/`edit` snapshots with conflict checks.
+
 ## Check status
 
 ```text
@@ -128,4 +168,4 @@ Config files live under `~/.cass`, outside a normal project workspace. To inspec
 cass check
 ```
 
-Prefer `cass setup` for provider/model changes when possible.
+For OpenAI-compatible providers this checks API key environment variables. For `ChatGPT Codex` this checks local Codex auth and points you back to `codex login` if the token is missing or expired. Prefer `cass setup` or `cass login` for provider/model changes when possible.

examples/headless_agent.rs

@@ -0,0 +1,33 @@
+use cassady::prelude::*;
+
+#[tokio::main]
+async fn main() -> anyhow::Result<()> {
+    let session = SessionBuilder::new()
+        .cwd(std::env::current_dir()?)
+        .access_mode(AccessMode::ReadOnly)
+        .build()
+        .await?;
+
+    let mut turn = session
+        .start_turn("Summarize this project in a few sentences.")
+        .await?;
+
+    while let Some(event) = turn.next_event().await? {
+        match event {
+            Event::AssistantChunk(text) => print!("{text}"),
+            Event::ApprovalRequested(request) => {
+                eprintln!(
+                    "approval requested for {}: {}; denying in this example",
+                    request.name, request.reason
+                );
+                turn.deny(&request.request_id)?;
+            }
+            Event::Finished => break,
+            _ => {}
+        }
+    }
+
+    let session = turn.finish().await?;
+    eprintln!("\nResume chat with: cass --resume {}", session.id());
+    Ok(())
+}

plans/V0_2_6_RUST_EMBEDDING_API_PLAN.md

@@ -0,0 +1,298 @@
+# v0.2.6 Rust Embedding API Implementation Plan
+
+## Goal
+
+v0.2.6 adds the first intentional public Rust API for embedding Cassady in another Rust project. A developer should be able to add Cassady as a dependency, configure a workspace/model/access mode, start a headless agent session, send user messages, receive streamed agent events, and handle approval requests without launching the interactive TUI.
+
+Success statement:
+
+> A small Rust program can import `cassady`, start a new headless session in a workspace, stream assistant/tool events from a turn, optionally approve shell requests, and inspect the updated conversation state using documented experimental APIs.
+
+## Scope
+
+### In scope
+
+- Add an experimental embedding API module with cohesive public types instead of requiring callers to wire together internal modules directly.
+- Support starting a new headless agent session from Rust code.
+- Support resuming an existing conversation by id when using Cassady's existing conversation storage.
+- Support running one turn at a time and streaming typed events to the host application.
+- Expose approval handling for tools that require host/user consent, especially shell in `workspace-edit` mode.
+- Reuse the existing config, provider, prompt, security, conversation, and tool execution paths used by the CLI/TUI.
+- Provide simple builder/options types for cwd, access mode, model/base URL/API key overrides, reasoning effort, and Cassady config root.
+- Add a crate-level `prelude` or clearly documented imports for common embedding use.
+- Add docs and examples that show a minimal headless integration.
+- Add integration tests that exercise the public API without a terminal.
+
+### Out of scope
+
+- Declaring the Rust API stable for semver compatibility. The API should be explicitly marked experimental in v0.2.6.
+- Replacing the CLI/TUI as the primary user interface.
+- Multi-agent orchestration, task queues, background daemons, schedulers, or distributed workers.
+- Custom model provider traits or non-OpenAI-compatible protocols.
+- User-defined custom tools or plugin loading.
+- A synchronous/blocking API. The first embedding surface can require Tokio.
+- Exposing low-level terminal UI internals as supported public API.
+- Publishing to crates.io as part of this release unless separately requested.
+
+## Context and Current State
+
+Cassady already builds a library crate:
+
+- `Cargo.toml` defines `[lib] name = "cassady" path = "src/lib.rs"`.
+- `src/lib.rs` currently re-exports many internal modules directly and exposes `run()` for the CLI/TUI path.
+- `src/agent.rs` contains the core async turn loop:
+  - `AgentSettings`
+  - `AgentEvent`
+  - `AgentCommand`
+  - `run_turn(...)`
+  - `run_turn_with_commands(...)`
+- `src/app.rs` owns interactive startup, TUI state, chat creation/resume, cancellation, approval UI, and local slash commands.
+- `src/conversation.rs` persists conversations as JSONL and can create/load/list chats.
+- `src/config.rs` loads providers, models, active defaults, API key references, access mode, tool limits, and docs paths.
+- `src/security.rs` centralizes access-mode decisions.
+- `src/tools/*` implements the same tools that headless sessions should use.
+
+The current crate can technically be imported, but the supported path is unclear: callers must know which internal modules to combine, how to create base prompts, how to load config safely, how to route approval commands, and how to consume events. v0.2.6 should add a thin, intentional API layer over these internals.
+
+## Design Principles
+
+1. **Thin wrapper over proven internals.** Reuse the same agent loop and policy code as the CLI so embedded behavior matches interactive behavior.
+2. **Explicitly experimental.** Make the new API useful without promising final naming or long-term stability yet.
+3. **Headless first.** The API should not depend on `ratatui`, terminal setup, crossterm event loops, or slash-command UI state.
+4. **Host owns presentation.** Embedded callers receive typed events and decide how to display assistant chunks, tool calls, approvals, and errors.
+5. **Safe defaults.** Default to `read-only`, environment-variable API keys, existing Cassady config files, and workspace-rooted paths.
+6. **Approval is part of the API.** Hosts must be able to approve or deny requests rather than having Cassady assume a TUI is present.
+7. **Keep the first surface small.** Prefer one clear session builder and one turn-running method over exposing every internal knob.
+
+## Design
+
+### Module layout
+
+Add a new module, for example:
+
+```rust
+pub mod embedding;
+pub mod prelude;
+```
+
+`src/embedding.rs` should be the supported experimental API. Existing internal modules can remain public in v0.2.6 for compatibility, but docs should steer new users toward `cassady::embedding` or `cassady::prelude`.
+
+Suggested public surface:
+
+```rust
+pub struct SessionBuilder { ... }
+
+pub struct Session { ... }
+
+pub struct SessionOptions { ... }
+
+pub struct Turn { ... }
+
+pub enum Event { ... }
+
+pub enum Command { ... }
+
+pub struct ConversationInfo { ... }
+```
+
+The exact names can change during implementation, but they should avoid leaking TUI-specific terms.
+
+### Builder and options
+
+Provide a builder that covers common embedding setup:
+
+```rust
+let mut session = cassady::embedding::SessionBuilder::new()
+    .cwd("/path/to/project")
+    .access_mode(AccessMode::WorkspaceEdit)
+    .model("accounts/fireworks/models/qwen3p7-plus")
+    .build()
+    .await?;
+```
+
+Builder responsibilities:
+
+- Resolve and canonicalize `cwd` like CLI startup.
+- Load config from the default Cassady root unless an explicit root/path is supplied.
+- Apply model/base URL/API key env overrides without requiring a `Cli` value from callers.
+- Resolve API key availability before starting a turn and return a useful error.
+- Install or locate bundled docs as needed by `Config::load` behavior.
+- Create the base system prompt with `~/.cass/global.md` when starting a new conversation.
+- Default access mode to config/default, then builder override, then `read-only` if no config exists.
+
+Avoid requiring callers to import or construct `cli::Cli`.
+
+### New and resumed sessions
+
+Support at least:
+
+```rust
+let session = SessionBuilder::new().cwd(".").new_session().await?;
+let session = SessionBuilder::new().cwd(".").resume("chat-id").await?;
+```
+
+A `Session` should expose lightweight metadata:
+
+```rust
+session.id();
+session.cwd();
+session.model();
+session.access_mode();
+session.conversation_path();
+```
+
+The conversation should continue to be persisted in the same JSONL format so CLI and library sessions can interoperate.
+
+### Running a turn
+
+Provide a headless one-turn API that streams events:
+
+```rust
+let mut turn = session.start_turn("Explain the crate layout").await?;
+while let Some(event) = turn.next_event().await? {
+    match event {
+        Event::AssistantChunk(text) => print!("{text}"),
+        Event::ApprovalRequested(request) => {
+            turn.approve(request.id).await?;
+        }
+        Event::Finished => break,
+        _ => {}
+    }
+}
+let session = turn.finish().await?;
+```
+
+Alternative designs are acceptable, such as returning `(EventStream, CommandSink)` plus a completion handle, as long as examples are simple and approval commands are supported.
+
+The wrapper can map `agent::AgentEvent` and `agent::AgentCommand` into public embedding types. It should avoid exposing internal channel mechanics unless that is the cleanest Tokio-native API.
+
+### Event model
+
+Expose typed events that are stable enough for hosts to build UI/logging around:
+
+- assistant text chunks
+- reasoning chunks, when provider/model returns them
+- tool call started
+- tool output chunk
+- tool result
+- approval requested
+- approval resolved
+- status
+- turn finished
+- error or turn failure
+
+The public event type can wrap or re-export `agent::AgentEvent` initially, but the plan should prefer a dedicated type if it prevents low-level internals from becoming accidental API.
+
+### Approval behavior
+
+Approval requests should include:
+
+- request id
+- tool call id
+- tool name
+- arguments
+- human-readable reason
+
+The host should be able to approve or deny by request id. If the host drops the turn or never responds, cancellation/drop behavior should be documented.
+
+For v0.2.6, keep approval policy aligned with `security.rs`:
+
+- `read-only`: shell unavailable.
+- `workspace-edit`: shell asks.
+- `full-access`: shell allowed.
+
+### Cancellation and drop behavior
+
+The TUI already cancels by aborting the agent task and repairing pending records. The embedding API should define a basic behavior:
+
+- Dropping an active turn should abort the underlying task if possible.
+- A simple explicit `cancel()` method is preferred if practical.
+- Conversation repair for cancelled turns can be minimal in v0.2.6, but pending tool calls must not corrupt resumed conversations.
+
+If full parity with the TUI cancellation path is too large, document the limitation and add tests for the supported behavior.
+
+### Error handling
+
+Use a public result alias such as:
+
+```rust
+pub type Result<T> = std::result::Result<T, Error>;
+```
+
+The first pass may wrap `anyhow::Error`, but public errors should include enough context for embedding callers to distinguish:
+
+- config load errors
+- missing API key
+- provider request errors
+- conversation load/create errors
+- active turn already running
+- approval request not found or already resolved
+
+Do not panic for ordinary configuration or runtime failures.
+
+### Examples
+
+Add at least one compilable example under `examples/`, for example `examples/headless_agent.rs`:
+
+```rust
+use cassady::prelude::*;
+
+#[tokio::main]
+async fn main() -> cassady::embedding::Result<()> {
+    let mut session = SessionBuilder::new()
+        .cwd(std::env::current_dir()?)
+        .access_mode(AccessMode::ReadOnly)
+        .build()
+        .await?;
+
+    let mut turn = session.start_turn("Summarize this project.").await?;
+    while let Some(event) = turn.next_event().await? {
+        if let Event::AssistantChunk(text) = event {
+            print!("{text}");
+        }
+    }
+    turn.finish().await?;
+    Ok(())
+}
+```
+
+The example should be honest about requiring configured providers and API keys.
+
+## Implementation Steps
+
+1. **Define the experimental API shape.** Add `src/embedding.rs` with builder, session, turn, event, command/approval, and result/error types.
+2. **Add non-CLI config loading helpers.** Refactor or add helpers in `src/config.rs` so library callers can apply overrides without constructing `cli::Cli`.
+3. **Extract chat creation/resume helpers.** Move reusable prompt/global/conversation setup out of `src/app.rs` into functions usable by both TUI and embedding API.
+4. **Wrap the existing agent loop.** Use `agent::run_turn_with_commands` internally and provide a host-friendly event stream plus approval methods.
+5. **Handle turn lifecycle.** Ensure a session cannot run overlapping turns unless explicitly supported; persist and return the updated conversation after a turn finishes.
+6. **Add cancellation/drop handling.** Provide at least a documented `cancel()` path and avoid leaving pending tool-call records in a corrupted state.
+7. **Add examples and docs.** Create a headless example and a bundled docs page for the experimental Rust API.
+8. **Update README and crate exports.** Add `embedding`/`prelude` exports and a short README section pointing to the new docs.
+9. **Test the public surface.** Add integration tests with a mock OpenAI-compatible server and temporary config/conversation roots.
+
+## Tests
+
+- Unit tests for builder option precedence: default config, explicit cwd, access mode, model, base URL, API key env, and config root.
+- Integration test that starts a new session and runs a turn against `wiremock`, asserting assistant chunks and persisted conversation records.
+- Integration test that resumes an existing conversation through the embedding API.
+- Integration test for approval flow in `workspace-edit` mode using a mock tool call that requests shell approval.
+- Test that read-only sessions do not expose write/edit/shell tools through the embedded turn.
+- Test that starting a second turn while one is active returns an error or is impossible by type design.
+- Example compilation through `cargo test --examples` or equivalent.
+
+## Documentation
+
+- Add `docs/rust-api.md` or `docs/embedding.md` describing the experimental API, setup requirements, minimal example, event loop, approval handling, and limitations.
+- Link the new page from `docs/README.md` and the README.
+- Document that the API is experimental in v0.2.6 and may change before a stable 1.0-style library contract.
+- Include a note that embedded sessions use the same `~/.cass` config and conversation storage by default.
+- Mention how hosts should run `cass setup` or provide config programmatically before using the API.
+
+## Acceptance Criteria
+
+- A Rust binary in `examples/` can import `cassady`, create a headless session, run a turn, and stream assistant output without launching the TUI.
+- Embedded sessions use the same provider, prompt, security, tool, and conversation paths as the CLI.
+- Approval requests can be approved or denied programmatically.
+- New public API docs and README links clearly label the surface experimental.
+- CLI/TUI behavior remains unchanged.
+- `cargo fmt` and `cargo test --locked --all-targets` pass.

plans/V0_2_7_SELF_UPDATE_COMMAND_PLAN.md

@@ -0,0 +1,390 @@
+# v0.2.7 Self-Update Command Implementation Plan
+
+## Goal
+
+v0.2.7 adds a polished `cass update` command that can update Cassady from official GitHub releases without requiring users to manually download archives, verify checksums, unpack binaries, or rebuild from source.
+
+Success statement:
+
+> A user can run `cass update`, see the available release, choose the recommended prebuilt binary or a source build fallback, and finish with updated `cass` and `cassady` commands in the same install location.
+
+## Scope
+
+### In scope
+
+- Add a `cass update` / `cassady update` subcommand.
+- Query official Cassady GitHub releases from `owenqwenstarsky/cassady`.
+- Compare the current binary version with the latest stable release.
+- Download and install the matching prebuilt archive when available.
+- Verify prebuilt archives with the shipped `.sha256` files before installing.
+- Offer a source-build path that downloads release source for the selected tag and builds local binaries.
+- Update both shipped binaries, `cass` and `cassady`, when possible.
+- Use interactive prompts by default with clear summaries, confirmations, progress, success, and recovery messages.
+- Provide non-interactive flags for check-only and yes-to-prompts usage.
+- Keep `cass update` independent of model/provider setup so updates work even when `~/.cass` is missing or broken.
+- Add tests for release parsing, target detection, asset selection, checksum validation, archive extraction safety, and install planning.
+- Update README and bundled docs.
+
+### Out of scope
+
+- Publishing through Homebrew, apt, winget, Scoop, npm, or other package managers.
+- Automatic background updates or prompts during normal chat startup.
+- Updating Cassady when it was installed by an external package manager that should own the install directory.
+- Privilege escalation, `sudo` automation, or administrator prompts.
+- Code signing, notarization, or signature verification beyond existing SHA-256 files.
+- Downgrading by default. Installing an older tag should require an explicit flag if supported.
+- Cross-compiling in source mode. Source builds target the current host platform only.
+
+## Context and Current State
+
+Relevant files:
+
+- `Cargo.toml`: package version and two binaries, `cass` and `cassady`.
+- `src/cli.rs`: Clap command definitions currently include `check` and `setup`.
+- `src/app.rs`: top-level command dispatch; update should run before setup/config loading.
+- `src/main.rs` and `src/bin/cassady.rs`: both call `cassady::run()`.
+- `README.md` and `docs/commands.md`: command documentation.
+- `docs/platforms.md` and `docs/troubleshooting.md`: platform and recovery guidance.
+- `AGENTS.md`: release artifacts use these names:
+  - `cassady-vX.Y.Z-aarch64-apple-darwin.tar.gz`
+  - `cassady-vX.Y.Z-x86_64-unknown-linux-gnu.tar.gz`
+  - `cassady-vX.Y.Z-aarch64-unknown-linux-gnu.tar.gz`
+  - `cassady-vX.Y.Z-x86_64-pc-windows-gnu.zip`
+
+Current releases include both `cass` and `cassady` in each archive plus one `.sha256` file per archive. The update command should reuse that release contract instead of inventing a new distribution format.
+
+## Design Principles
+
+1. **Boring and recoverable.** Updating should be explicit, easy to understand, and safe to interrupt before installation starts.
+2. **Use official release artifacts first.** Prefer prebuilt archives with SHA-256 verification; fall back to source builds when the user asks or no asset matches.
+3. **No surprise setup coupling.** Users should not need a configured provider, model, or API key to update the CLI.
+4. **Respect install ownership.** Do not auto-escalate privileges or overwrite package-manager-owned paths without clear user confirmation.
+5. **Both command names stay aligned.** If the user has both `cass` and `cassady` in the install directory, update them together.
+6. **Interactive by default, scriptable when requested.** The normal path should be friendly; flags should support CI/check scripts.
+7. **Fail closed on integrity.** Missing or mismatched checksums for prebuilt artifacts must stop installation.
+
+## User Experience
+
+### Default interactive flow
+
+```text
+$ cass update
+Cassady update
+
+Current version: v0.2.6
+Latest release:  v0.2.7
+Install path:    /usr/local/bin
+Recommended:     prebuilt aarch64-apple-darwin archive
+
+Update Cassady to v0.2.7? [Y/n]
+```
+
+If the user accepts, Cassady should show concise phases:
+
+```text
+Downloading cassady-v0.2.7-aarch64-apple-darwin.tar.gz ... 8.4 MB
+Downloading cassady-v0.2.7-aarch64-apple-darwin.tar.gz.sha256 ... done
+Verifying SHA-256 ... ok
+Preparing cass and cassady ... ok
+Installing to /usr/local/bin ... ok
+Verifying installed version ... cass 0.2.7
+
+Cassady is up to date.
+```
+
+If the current version is already latest:
+
+```text
+Cassady is already up to date.
+Current version: v0.2.7
+Latest release:  v0.2.7
+```
+
+### Prebuilt or source selection
+
+The default `auto` mode should choose the prebuilt release asset when a supported target is detected. If no matching prebuilt exists, prompt for source mode:
+
+```text
+No prebuilt archive is available for this platform.
+Build Cassady v0.2.7 from source instead? [Y/n]
+```
+
+If both paths are available and the user asks for source mode:
+
+```sh
+cass update --source
+```
+
+Cassady should confirm prerequisites before building:
+
+```text
+Source build requires cargo, rustc, and a working C toolchain.
+Build Cassady v0.2.7 from release source now? [Y/n]
+```
+
+### Useful flags
+
+Add a command shape like:
+
+```sh
+cass update [OPTIONS]
+```
+
+Suggested options:
+
+- `--check`: check GitHub for the latest release and print status without installing.
+- `--yes`: accept default prompts for non-interactive use.
+- `--prebuilt`: require a matching prebuilt archive; fail instead of falling back to source.
+- `--source`: build from release source even when a prebuilt archive exists.
+- `--to TAG`: install a specific release tag such as `v0.2.7`.
+- `--dry-run`: resolve the release, target, assets, and install path without downloading or installing.
+
+Optional later flags, only if implementation needs them:
+
+- `--stable-only`: ignore prerelease tags during latest-release selection if Cassady later publishes both stable and prerelease channels.
+- `--install-dir PATH`: install into an explicit directory. This should be advanced and carefully documented because it can conflict with PATH order.
+
+Avoid adding a public `--repo` override unless needed for testing; tests can inject a mock client instead.
+
+## Design
+
+### Module layout
+
+Add a focused update module:
+
+```rust
+pub mod update;
+```
+
+Suggested internal types:
+
+```rust
+pub struct UpdateOptions { ... }
+pub enum UpdateMode { Auto, Prebuilt, Source }
+pub struct ReleaseInfo { ... }
+pub struct ReleaseAsset { ... }
+pub struct PlatformTarget { ... }
+pub struct UpdatePlan { ... }
+pub enum InstallAction { Replace, AddCompanion, SkipMissingCompanion }
+```
+
+`src/cli.rs` should add an `Update` subcommand with parsed flags. `src/app.rs` should dispatch it before setup/config loading:
+
+```rust
+if let Some(Command::Update(args)) = cli.command {
+    return crate::update::run(args).await;
+}
+```
+
+This keeps update usable even when `Config::load()` would fail.
+
+### GitHub release discovery
+
+Use the GitHub Releases API with an explicit user agent:
+
+- Latest release: `GET https://api.github.com/repos/owenqwenstarsky/cassady/releases?per_page=30` and choose the highest semver non-draft tag, including prereleases because Cassady's current release process marks releases as prereleases.
+- Specific tag: `GET https://api.github.com/repos/owenqwenstarsky/cassady/releases/tags/{tag}`
+
+Parse:
+
+- `tag_name`
+- `name`
+- `draft`
+- `prerelease`
+- `assets[].name`
+- `assets[].browser_download_url`
+- `assets[].size`
+- `tarball_url` or `zipball_url` for source mode
+
+Use `semver` to compare `env!("CARGO_PKG_VERSION")` with release tags after stripping a leading `v`. Draft releases should never be selected. Prereleases should be eligible by default while Cassady's official releases are marked as prereleases.
+
+### Platform target mapping
+
+Map the running platform to release asset targets:
+
+| OS | Arch | Target | Archive |
+| --- | --- | --- | --- |
+| macOS | `aarch64` | `aarch64-apple-darwin` | `.tar.gz` |
+| Linux | `x86_64` | `x86_64-unknown-linux-gnu` | `.tar.gz` |
+| Linux | `aarch64` | `aarch64-unknown-linux-gnu` | `.tar.gz` |
+| Windows | `x86_64` | `x86_64-pc-windows-gnu` | `.zip` |
+
+Unsupported platforms should produce a clean message and offer source mode when possible.
+
+### Prebuilt update path
+
+For tag `vX.Y.Z` and target `TARGET`, find:
+
+```text
+cassady-vX.Y.Z-TARGET.tar.gz
+cassady-vX.Y.Z-TARGET.tar.gz.sha256
+```
+
+or on Windows:
+
+```text
+cassady-vX.Y.Z-x86_64-pc-windows-gnu.zip
+cassady-vX.Y.Z-x86_64-pc-windows-gnu.zip.sha256
+```
+
+Flow:
+
+1. Download archive and checksum into a temporary staging directory.
+2. Parse the `.sha256` file and verify that the checksum filename matches the downloaded archive name.
+3. Compute SHA-256 of the archive and compare exactly.
+4. Extract into staging using path traversal checks.
+5. Require the expected binaries:
+   - Unix: `cass`, `cassady`
+   - Windows: `cass.exe`, `cassady.exe`
+6. Run the staged `cass --version` or `cassady --version` when possible and confirm the expected version.
+7. Build an install plan for the current executable directory.
+8. Confirm the final plan with the user unless `--yes` was supplied.
+9. Replace binaries with backups and rollback on failure.
+10. Verify installed version after replacement when possible.
+
+Archive extraction must reject absolute paths, `..` components, symlinks that escape staging, and unexpected top-level layouts.
+
+### Source-build update path
+
+Source mode should still be tied to a GitHub release tag, not an arbitrary branch.
+
+Flow:
+
+1. Resolve the selected release tag.
+2. Download release source from `tarball_url` or `zipball_url` into staging.
+3. Extract with the same path traversal protections as prebuilt archives.
+4. Verify `Cargo.toml` version matches the selected tag.
+5. Run:
+
+   ```sh
+   cargo build --release --locked --bins
+   ```
+
+   from the extracted source tree.
+6. Locate built binaries under `target/release/`.
+7. Run staged `--version` checks.
+8. Install using the same installer path as prebuilt updates.
+
+Before source mode starts, check for `cargo` and `rustc` on PATH and show a clear error if they are missing. Do not attempt to install Rust automatically.
+
+### Install planning and replacement
+
+Determine the current executable path with `std::env::current_exe()`, then derive the install directory. The install plan should include:
+
+- current binary path
+- sibling `cass` path
+- sibling `cassady` path
+- which binaries currently exist
+- which binaries are writable
+- whether companion binaries will be updated, added, skipped, or blocked
+
+Recommended behavior:
+
+- Always update the currently running binary name.
+- If the sibling binary exists in the same directory, update it too.
+- If the sibling binary is missing and the directory is writable, ask whether to install it.
+- If a target path is not writable, stop with an actionable message. Do not invoke `sudo` or administrator prompts automatically.
+- Use backups such as `.cass-update-backup-v0.2.6-<timestamp>` during replacement.
+- If any replacement fails, restore backups before returning an error.
+
+Unix can generally replace a running executable via atomic rename. Windows cannot reliably overwrite the running `.exe`; implement one of these approaches during coding:
+
+1. Preferred: stage replacements and spawn a small PowerShell or `cmd` helper that waits for the current process to exit, moves files into place, and writes a log.
+2. Fallback: stage replacements and print exact manual copy commands if helper launch is unavailable.
+
+Document any Windows limitation honestly in `docs/platforms.md` and `docs/troubleshooting.md`.
+
+### Output and error style
+
+Keep output concise and user-facing:
+
+- Show current version, target version, install directory, selected mode, and asset/source name before changing files.
+- Show clear phase lines for download, verify, build, install, and final verification.
+- On failure, say whether anything was changed and where staging/backups are located.
+- If update cannot proceed because the install path is not writable, tell the user which path failed and suggest reinstalling through the same method they originally used.
+
+Avoid dumping raw GitHub JSON, backtraces, or Cargo logs unless the source build fails; in that case, preserve the final relevant Cargo output and staging path.
+
+## Dependencies
+
+Likely additions to `Cargo.toml`:
+
+- `semver` for version comparison.
+- `sha2` for SHA-256 verification.
+- `tar` and `flate2` for `.tar.gz` extraction.
+- `zip` for Windows release archives and GitHub source zips if used.
+
+Prefer small, well-maintained crates. Reuse existing `reqwest`, `tokio`, `serde`, and `serde_json`.
+
+## Implementation Steps
+
+1. Add CLI parsing for `cass update` and dispatch it before setup/config loading.
+2. Add `src/update.rs` with release API types, version comparison, and target detection.
+3. Implement GitHub release fetching with a testable client abstraction or injectable base URL for tests.
+4. Implement asset selection for current platform and update mode.
+5. Implement download, progress reporting, and checksum verification for prebuilt archives.
+6. Implement safe archive extraction and staged binary validation.
+7. Implement install planning from `current_exe()` and companion binary detection.
+8. Implement Unix replacement with backups and rollback.
+9. Implement Windows staged-helper replacement or a clearly documented manual fallback.
+10. Implement source mode: source download, version validation, prerequisite checks, `cargo build --release --locked --bins`, and staged binary validation.
+11. Polish interactive prompts and `--check`, `--dry-run`, `--yes`, `--prebuilt`, `--source`, and `--to` behavior.
+12. Update docs and release notes template expectations if needed.
+13. Add tests and run full verification.
+
+## Tests
+
+Add focused unit tests for:
+
+- parsing `vX.Y.Z` tags and comparing against the current version shape
+- ignoring drafts and prereleases where applicable
+- mapping supported and unsupported platform targets
+- matching asset and checksum filenames
+- parsing `.sha256` lines generated by the release process
+- rejecting checksum filename mismatches and digest mismatches
+- rejecting archive path traversal entries
+- planning installation when only `cass`, only `cassady`, or both binaries exist
+- refusing non-writable install targets in planning or dry-run mode
+- source mode validating that `Cargo.toml` version matches the selected tag
+
+Add integration-style tests with a mock HTTP server for:
+
+- already-up-to-date response
+- latest prebuilt update plan
+- missing prebuilt with source fallback prompt path, where build execution can be mocked
+- download checksum mismatch failure
+- successful staged install into a temporary directory using fake binaries
+
+Manual checks:
+
+```sh
+cargo fmt
+cargo test --locked --all-targets
+cargo run -- update --check
+cargo run -- update --dry-run --to v0.2.7
+```
+
+For a real release candidate, test from a temporary install directory before using `cass update` on the developer's normal binary.
+
+## Documentation
+
+Update:
+
+- `README.md`: mention `cass update` in install/update and everyday command sections.
+- `docs/commands.md`: full command reference, flags, interactivity, examples, and exit behavior.
+- `docs/platforms.md`: platform-specific update support and Windows replacement notes.
+- `docs/troubleshooting.md`: network failures, checksum mismatch, no matching prebuilt, missing Rust toolchain, non-writable install directory, PATH conflicts, and rollback recovery.
+- `docs/README.md`: add any new update-related links or summaries.
+
+Document that users should prefer the package manager's update mechanism if Cassady was installed through a package manager in the future.
+
+## Acceptance Criteria
+
+- `cass update --check` reports the current/latest release without reading provider config.
+- `cass update --dry-run` shows the selected release, mode, asset/source, and install plan without modifying files.
+- On supported release targets, `cass update` can download the matching official archive, verify SHA-256, stage both binaries, and update the current install directory.
+- `cass update --source` can download release source, build with `cargo build --release --locked --bins`, and install the resulting local binaries.
+- Checksum mismatch, missing assets, unsupported platforms, missing Rust toolchain, and non-writable install paths fail with clear messages and no partial install.
+- Existing `cass` and `cassady` sibling binaries remain version-aligned after a successful update.
+- README and bundled docs explain the command accurately.
+- `cargo fmt` and `cargo test --locked --all-targets` pass.

plans/V0_2_8_CONVERSATION_BRANCH_RESTORE_PLAN.md

@@ -0,0 +1,373 @@
+# v0.2.8 Conversation Branch and Restore Implementation Plan
+
+## Goal
+
+v0.2.8 adds an in-chat branch and restore menu opened by pressing `Esc` twice while Cassady is idle. Users should be able to browse the current conversation timeline, choose a checkpoint at a user message, assistant message, or tool call, and branch from that point without destroying the original conversation. They can optionally restore Cassady-tracked file edits to match the selected checkpoint, or branch the conversation only.
+
+Success statement:
+
+> A user can press `Esc` twice, select an earlier message or tool call, create a new branch from that point, optionally restore tracked file edits, and later open the same menu from either branch to switch or branch again from the related conversation history.
+
+## Scope
+
+### In scope
+
+- Add a double-`Esc` idle shortcut that opens a branch/restore menu, similar in feel to the double-`Ctrl-C` exit affordance.
+- Keep the existing busy `Esc` behavior for turn cancellation and approval denial.
+- Add a branch-aware conversation model that creates a new conversation file when restoring to a checkpoint instead of truncating or overwriting the original chat.
+- Let users browse checkpoints for:
+  - user messages,
+  - assistant messages,
+  - assistant tool-call requests,
+  - completed tool results.
+- Preserve valid model conversation structure when branching at or around tool calls.
+- Track file mutations made by Cassady's `write` and `edit` tools with enough before/after data to restore workspace files backward or forward between tracked checkpoints.
+- Offer restore actions that clearly separate conversation-only branching from conversation-plus-file restoration.
+- Allow users to return to the original conversation or other related branches by opening the menu again.
+- Add tests for branch metadata, checkpoint extraction, valid tool-call repair, file-edit journaling, workspace restore planning, conflict detection, and keybinding behavior where practical.
+- Update README and bundled docs for the new shortcut, branch semantics, file-restore limitations, and safety prompts.
+
+### Out of scope
+
+- Rewriting arbitrary filesystem changes made by shell commands, editors, package managers, test runners, or the user outside Cassady's `write`/`edit` tools.
+- Git integration, commits, worktrees, or automatic VCS operations.
+- A visual diff editor for every file restore. v0.2.8 should show a concise restore plan and rely on safe conflict checks.
+- Merging branches or replaying assistant responses across branches.
+- Branching while an agent turn is running.
+- Changing provider message semantics beyond the minimum repair needed for valid branched conversations.
+
+## Context and Current State
+
+Relevant files and behavior:
+
+- `src/app.rs` owns the TUI event loop, current conversation, transcript blocks, double-`Ctrl-C` exit behavior, busy `Esc` cancellation, local `/new` and `/resume` commands, and turn spawning.
+- `src/conversation.rs` stores conversations as append-only JSONL with `Meta`, `System`, `User`, `Assistant`, and `Tool` records. There is no branch metadata, checkpoint API, or rewrite/create-from-prefix helper yet.
+- `src/agent.rs` appends user, assistant, and tool records during a turn. Assistant records can contain multiple tool calls, while each tool result is a separate `Record::Tool`.
+- `src/tools/edit.rs` and `src/tools/write.rs` perform atomic writes and return user-visible summaries/diffs, but they do not persist before/after snapshots that can be used for later restore.
+- `src/ui/render.rs` renders the main chat. A branch menu should be integrated as an in-TUI modal or state, not by dropping into the setup/update prompt menu in `src/menu.rs`.
+
+The key design constraint is that restore must not mean destructive truncation. Selecting an old point creates a new branch conversation and leaves the source conversation available.
+
+## Design Principles
+
+1. **Branch, do not erase.** Restoring conversation state always creates or switches to a conversation branch; the original JSONL file remains intact.
+2. **Make file restore explicit.** Conversation branching is safe and default. File restoration is a separate confirmation because it changes the workspace.
+3. **Keep model history valid.** Branches created at tool boundaries must not leave assistant tool calls without corresponding tool records.
+4. **Track only what Cassady can prove.** File restore uses durable snapshots from `write`/`edit`; unsupported shell/user changes are detected or warned about, not guessed.
+5. **Recoverable navigation.** Every branch keeps parent/checkpoint metadata so the menu can show the related branch family and let users switch or branch again.
+6. **Small, testable modules.** Put checkpoint extraction, branch creation, and file restore planning in dedicated modules rather than expanding the TUI loop with business logic.
+
+## User Experience
+
+### Shortcut behavior
+
+- While idle, first `Esc` sets status text:
+
+  ```text
+  press Esc again within 1.5s to branch or restore
+  ```
+
+- A second `Esc` within the same window opens the branch/restore menu.
+- If the input box is non-empty, do not discard it silently. The first `Esc` should keep the input and show the same status; opening the menu should preserve the draft input if the user cancels.
+- While an agent turn is running, keep the current behavior: `Esc` cancels the active turn. Do not open the branch menu while busy.
+- During approval prompts, keep `Esc` as denial for the approval request.
+
+### Main branch menu
+
+The menu should show the current branch family, not only the current JSONL prefix:
+
+```text
+Branch / Restore
+
+Current chat: 2026-06-25-101533-abcd
+
+Branches
+  • current branch
+  • original chat from before restore
+  • earlier branch: "try without refactor"
+
+Timeline
+  1. user      Add tests for config loading
+  2. assistant Proposed plan
+  3. tool      read src/config.rs ✓
+  4. assistant Found config parser
+  5. tool      edit src/config.rs ✓  file: src/config.rs
+  6. user      Make it cleaner
+```
+
+Keyboard controls should be consistent with the main TUI: up/down or `j`/`k` move, Enter selects, `Esc` cancels, and an optional `/` filter can be deferred unless cheap.
+
+### Checkpoint actions
+
+After selecting a checkpoint, show an action menu:
+
+```text
+Branch from checkpoint
+
+Selected: tool edit src/config.rs at 10:24:11
+
+  1. Branch conversation only
+  2. Branch conversation and restore tracked file edits
+  3. Preview tracked file restore plan
+  4. Cancel
+```
+
+Default should be conversation-only. The branch should get a fresh chat id, copy records through the selected checkpoint, and append branch metadata. The status should make the branch explicit:
+
+```text
+branched 2026-06-25-110212-wxyz from 2026-06-25-101533-abcd at tool edit src/config.rs
+```
+
+### Switching among related branches
+
+Opening the menu from a branch should show its ancestors and descendants. Users can switch back to an existing branch without creating another branch:
+
+```text
+Switch to branch
+
+  original  2026-06-25-101533-abcd  18 records
+  current   2026-06-25-110212-wxyz  branched at tool edit src/config.rs
+```
+
+Switching branch changes the active conversation/transcript only. It should not change files unless the user explicitly chooses a file restore action.
+
+### File restore safety
+
+When the user chooses file restoration, show a concise plan before writing:
+
+```text
+Restore tracked file edits to selected checkpoint?
+
+Will update:
+  src/config.rs        current hash matches Cassady snapshot
+  src/app.rs           current hash differs; requires confirmation or skip
+
+Will delete:
+  src/generated.rs     created after the checkpoint by Cassady write
+
+Not tracked:
+  shell command outputs and manual edits cannot be restored automatically
+
+Proceed? [y/N]
+```
+
+Rules:
+
+- If the current file hash matches the expected tracked hash, restore automatically after confirmation.
+- If the file changed outside Cassady since the relevant snapshot, mark it as a conflict and default to skipping or cancelling the whole restore.
+- For files that did not exist at the target checkpoint, delete only if the current content hash matches the tracked created-file hash.
+- Never overwrite unknown current content without an explicit conflict confirmation.
+
+## Design
+
+### Conversation branch metadata
+
+Extend the conversation metadata in a backward-compatible way. One acceptable shape is adding optional fields to `Record::Meta` with `#[serde(default)]` and `skip_serializing_if`:
+
+```rust
+Record::Meta {
+    chat_id: String,
+    created_at: String,
+    model: String,
+    cwd: String,
+    parent_chat_id: Option<String>,
+    branch_from: Option<BranchPoint>,
+}
+
+struct BranchPoint {
+    chat_id: String,
+    record_index: usize,
+    tool_call_id: Option<String>,
+    checkpoint_label: String,
+}
+```
+
+Older conversations load with no parent. Descendants can be discovered by scanning `config.conversations_dir()` for `Meta.parent_chat_id` references.
+
+Add a `conversation::create_branch(...)` helper that:
+
+1. loads the source conversation,
+2. computes a valid record prefix for the selected checkpoint,
+3. writes a new JSONL file with a fresh chat id and branch metadata,
+4. preserves the original `System` prompt and source metadata needed for branch navigation,
+5. returns the new `Conversation` for the TUI to load immediately.
+
+Do not truncate or rewrite the source conversation.
+
+### Checkpoint extraction
+
+Add a focused module such as `src/branch.rs` or `src/conversation_branch.rs` with types like:
+
+```rust
+struct Checkpoint {
+    id: String,
+    chat_id: String,
+    record_index: usize,
+    tool_call_id: Option<String>,
+    kind: CheckpointKind,
+    label: String,
+    detail: String,
+    ts: Option<String>,
+}
+
+enum CheckpointKind {
+    User,
+    Assistant,
+    ToolCall,
+    ToolResult,
+}
+```
+
+Checkpoint rules:
+
+- A user checkpoint means the branch includes that user record.
+- An assistant checkpoint means the branch includes that assistant record. If the assistant requested tools, the branch helper must repair or omit incomplete tool-call state before the next provider turn.
+- A tool-result checkpoint means the branch includes records through that tool result.
+- A tool-call checkpoint without a completed result should branch to the state immediately before executing that tool call, represented by an assistant record plus synthetic denied/cancelled tool records for any required missing calls.
+
+Because OpenAI-compatible providers require every assistant tool call to receive a tool message before the next user message, branch creation must repair partial tool-call groups. Reuse or generalize the existing cancellation repair behavior in `src/app.rs` (`finalize_cancelled_turn` and pending tool-call handling) so branched conversations remain valid.
+
+### File edit journal
+
+Add a durable edit journal separate from model-visible conversation records, for example:
+
+```text
+~/.cass/file-edits/<chat_id>.jsonl
+~/.cass/file-snapshots/<chat_id>/<tool_call_id>/<hash>.bin
+```
+
+Journal entries should be written only for successful `write` and `edit` tool calls:
+
+```rust
+struct FileEditJournalEntry {
+    chat_id: String,
+    record_index: usize,
+    tool_call_id: String,
+    tool_name: String, // write | edit
+    path: PathBuf,
+    existed_before: bool,
+    existed_after: bool,
+    before_hash: Option<String>,
+    after_hash: Option<String>,
+    before_snapshot: Option<PathBuf>,
+    after_snapshot: Option<PathBuf>,
+    ts: String,
+}
+```
+
+Implementation approach:
+
+- Add a `file_edits` module that can capture before/after bytes, hash them, store snapshots, append journal entries, and build restore plans.
+- Pass chat id / record index / tool call id into tool execution context, or wrap `write`/`edit` execution in `agent.rs` so the agent captures before/after around successful file tools.
+- Store full bytes, not just unified diffs, so restore works both backward and forward.
+- Limit snapshots to regular files. If a path is a directory, symlink, binary too large, or otherwise unsafe, skip journaling and note that restore will not cover it.
+
+The first implementation can treat text and binary bytes uniformly for snapshot storage, while still using existing `write`/`edit` tools for text operations.
+
+### Restore planning
+
+File restore should compute a target workspace state from the selected checkpoint and branch lineage:
+
+1. Determine the selected checkpoint's branch lineage back to the root conversation.
+2. Load file-edit journal entries along that lineage up to the checkpoint.
+3. For every path touched by tracked edits in the relevant branch family, compute the desired state at the checkpoint:
+   - absent if no tracked edit existed before the checkpoint and the file was created later,
+   - the last `after_snapshot` at or before the checkpoint,
+   - the `before_snapshot` for paths whose first tracked edit happened after the checkpoint.
+4. Compare the current workspace file hash to the journal's expected current hash when possible.
+5. Produce a restore plan with actions: write snapshot, delete file, skip unsupported, conflict.
+6. Apply only after explicit confirmation.
+
+For v0.2.8, if cross-branch target-state computation becomes too large, keep the algorithm conservative: support full restore for the current branch's lineage and show a clear unsupported/conflict message for unrelated sibling states. The branch metadata should still be designed so broader cross-branch restore can be added later without changing saved data.
+
+### TUI integration
+
+Add branch-menu state to `run_tui` rather than invoking `src/menu.rs` inside the alternate-screen UI. Suggested approach:
+
+- Add an enum such as `OverlayState::BranchMenu(BranchMenuState)` in `src/app.rs` or a new `src/ui/branch_menu.rs`.
+- Extend `render::RenderState` to include an optional overlay.
+- Render a centered modal with title, help text, visible items, selected row, and preview/detail panel.
+- Route key events to the overlay first while it is open.
+- On confirmed branch/switch/restore, update:
+  - `conversation`,
+  - `chat_id`,
+  - `transcript = transcript_from_loaded(...)`,
+  - active assistant/tool state,
+  - scroll/stick-to-bottom/status.
+
+Keep the TUI loop readable by moving branch operations into functions such as:
+
+```rust
+open_branch_menu(...)
+handle_branch_menu_key(...)
+apply_branch_action(...)
+```
+
+### Slash command fallback
+
+Optionally add a discoverable slash command such as `/branch` or `/restore` that opens the same menu. This is useful for users whose terminals send unusual `Esc` sequences. If added, document it as an alias for the menu rather than a separate workflow.
+
+## Implementation Steps
+
+1. **Add branch metadata and helpers.** Extend `Record::Meta` compatibly, add branch point types, implement branch-family scanning and `create_branch` from a record prefix.
+2. **Build checkpoint extraction.** Convert conversations into user/assistant/tool checkpoints with labels, previews, timestamps, and valid prefix calculations.
+3. **Repair tool-call prefixes.** Generalize pending-tool-call repair so branches created around tool calls are valid for future provider requests.
+4. **Add edit journaling.** Capture successful `write`/`edit` before/after snapshots, append a file-edit journal entry, and keep this separate from model-visible JSONL records.
+5. **Implement restore planning.** Load journal entries, compute target states, detect conflicts by hash, and apply writes/deletes safely with existing atomic-write behavior.
+6. **Add the in-TUI menu.** Implement double-`Esc` idle detection, overlay state, rendering, keyboard navigation, action confirmation, and branch/switch application.
+7. **Wire status and recovery messages.** Make every branch, switch, restore, skip, and conflict result visible in the transcript or status line.
+8. **Document the feature.** Update README and bundled docs with shortcut behavior, branch semantics, file restore coverage, and limitations around shell/manual edits.
+9. **Test and polish.** Add unit/integration tests, run formatting, and verify the TUI manually in a small repository.
+
+## Tests
+
+- `conversation` tests:
+  - old JSONL conversations without branch metadata still load,
+  - new branch metadata serializes/deserializes,
+  - `create_branch` leaves the source file unchanged,
+  - branch-family scanning finds ancestors and descendants.
+- Checkpoint tests:
+  - user, assistant, tool-call, and tool-result checkpoints are extracted with stable labels,
+  - branching at a tool result keeps valid assistant/tool ordering,
+  - branching in the middle of multi-tool assistant output repairs missing tool results.
+- File journal tests:
+  - `write` records absent-to-present and present-to-present snapshots,
+  - `edit` records before/after bytes for successful edits only,
+  - failed or denied tools do not create journal entries.
+- Restore-plan tests:
+  - restore to an earlier checkpoint rewrites tracked files to prior content,
+  - restore to a later checkpoint can reapply tracked content from snapshots,
+  - created files are deleted only when hashes match,
+  - external modifications are reported as conflicts.
+- TUI/key tests where practical:
+  - first idle `Esc` sets double-press status,
+  - second idle `Esc` opens the branch menu,
+  - busy `Esc` still cancels a turn,
+  - approval `Esc` still denies approval.
+
+Manual checks:
+
+- Start a chat, make a `write` edit, branch conversation-only from before the edit, confirm the original remains available.
+- Open the menu from the branch and switch back to the original chat.
+- Branch with file restore and verify the workspace file content matches the chosen checkpoint.
+- Trigger a conflict by manually editing a tracked file before restore and confirm Cassady refuses to overwrite it by default.
+
+## Documentation
+
+Update:
+
+- `README.md`: everyday workflow section for branching/restoring and a short safety note.
+- `docs/commands.md` or the relevant TUI guide: double-`Esc`, optional `/branch`, and menu controls.
+- `docs/troubleshooting.md`: conflicts, unsupported shell/manual edits, and how to switch back to the original branch.
+- Any keyboard shortcut table maintained in bundled docs.
+
+## Acceptance Criteria
+
+- Pressing `Esc` twice while idle opens a branch/restore menu.
+- Selecting a user, assistant, or tool checkpoint creates a new branch conversation without modifying the source conversation.
+- The branch menu can be opened from the new branch to switch back to the original or create another branch.
+- Users can choose conversation-only branching or branch-plus-file restore.
+- File restore covers successful Cassady `write`/`edit` mutations with before/after snapshots and refuses unsafe overwrites by default.
+- Branches created around tool calls produce valid future model requests.
+- Existing conversations remain loadable.
+- `cargo fmt` and `cargo test --locked --all-targets` pass.

plans/V0_2_9_PROVIDER_LOGIN_MANAGEMENT_PLAN.md

@@ -0,0 +1,135 @@
+# v0.2.9 Provider Login Management Implementation Plan
+
+## Goal
+
+This release focuses on making provider configuration available from both the shell and an active Cassady chat. Users should be able to run `cass login` or type `/login` to configure one or more OpenAI-compatible providers, and use `cass logout` or `/logout` to remove saved providers and their model entries without hand-editing JSON files.
+
+Success statement:
+
+> A user can add, switch, and remove provider/model configuration from Cassady's normal command surfaces, then continue chatting with a valid active provider.
+
+## Scope
+
+### In scope
+
+- Add `cass login` as an alias-style command for the existing setup wizard.
+- Add `/login` inside the TUI, available only while idle.
+- Add `cass logout` with an interactive provider removal menu.
+- Add `/logout` inside the TUI, available only while idle.
+- Remove provider definitions and their associated `models.json` entries together.
+- Update `config.json` active defaults after removal so they do not point at missing providers or models.
+- Reload active config after login/logout inside the TUI.
+- Document the new commands in bundled command/config docs.
+- Add focused unit tests for provider removal and local command parsing/autocomplete.
+
+### Out of scope
+
+- Browser OAuth or provider-hosted account login flows.
+- Storing literal API keys from the wizard by default.
+- Non-OpenAI-compatible provider protocols.
+- Deleting shell environment variables or secrets outside `~/.cass`.
+- Publishing, tagging, or preparing release artifacts.
+
+## Context
+
+Cassady already has most provider setup primitives:
+
+- `src/setup.rs` contains the interactive provider/model setup wizard, provider catalog, model discovery, and JSON upsert helpers.
+- `src/config.rs` owns `config.json`, `providers.json`, `models.json`, active provider/model resolution, and validation.
+- `src/app.rs` owns top-level CLI dispatch plus in-chat slash command parsing and execution.
+- `docs/commands.md`, `docs/configuration.md`, and `docs/workflows.md` document the existing `cass setup`, `cass check`, and `/model` behavior.
+
+The existing setup wizard writes provider connection definitions to `providers.json`, model metadata to `models.json`, and active defaults to `config.json`. The new login command can reuse that flow. Logout needs a new inverse operation that edits all three files consistently.
+
+## Design Principles
+
+1. Reuse setup behavior instead of creating a second provider configuration path.
+2. Keep removal explicit and reversible by avoiding broad file deletion and by preserving unrelated providers/models.
+3. Never remove API keys from the user's shell or keychain; Cassady only edits its own config files.
+4. Keep in-chat provider management idle-only, because active turns depend on a stable provider config.
+
+## Design
+
+### CLI commands
+
+Add these subcommands:
+
+```text
+cass login
+cass logout
+```
+
+`cass login` runs the same interactive wizard as `cass setup`, with text that frames the action as adding or updating provider login configuration. It may start a chat afterward when invoked from an otherwise normal chat startup path only if the existing setup outcome says it should; direct `cass login` should save config and exit.
+
+`cass logout` opens a multi-select menu of saved providers:
+
+```text
+Remove saved providers
+
+  [ ] OpenAI      openai · gpt-4.1
+  [ ] Groq        groq · llama-3.3-70b-versatile
+```
+
+After confirmation, Cassady removes the selected providers from `providers.json` and removes `models.json` entries whose `provider` matches a removed provider id. If the active provider was removed, Cassady selects the first remaining provider and one of its models. If no providers remain, `default_provider`, `default_model`, and `default_reasoning_effort` are cleared so the next `cass` run offers setup.
+
+### In-chat commands
+
+Add slash commands:
+
+```text
+/login
+/logout
+```
+
+Both commands are idle-only. Because the TUI uses the alternate screen and raw input mode, command execution should temporarily leave the TUI, run the existing menu-driven flow in the normal terminal, reload config, then re-enter the TUI and append a status block.
+
+After `/login`, reload `Config` from disk and keep the current conversation open. If the active provider/model changed, future turns use the new provider and model. The status block should show the active provider and model.
+
+After `/logout`, reload `Config` when a provider remains. If no provider remains or config cannot resolve, keep the chat open but append a clear status/error telling the user to run `/login` before sending another turn.
+
+### Provider/model removal helper
+
+Add reusable setup/config helpers:
+
+- `configured_providers(root) -> Vec<ProviderLogoutCandidate>`
+- `remove_providers(root, provider_ids) -> LogoutResult`
+
+`LogoutResult` should include removed provider ids, removed model count, remaining provider count, and the new active provider/model when one exists. This keeps CLI output, TUI status, and tests deterministic.
+
+## Implementation Steps
+
+1. Add the v0.2.9 roadmap entry and this plan.
+2. Add `Login` and `Logout` CLI variants and dispatch them from `app::run`.
+3. Refactor setup mode text as needed so `cass login` can share the setup wizard.
+4. Implement provider removal helpers in `src/setup.rs` using existing config structs.
+5. Add menu-driven `setup::logout(root)` for CLI and TUI use.
+6. Add `/login` and `/logout` to local command parsing, autocomplete, and idle command handling.
+7. Add a small terminal leave/re-enter helper around blocking login/logout menus inside the TUI.
+8. Update command/config/workflow docs.
+9. Add focused tests for removal behavior and command parsing/autocomplete.
+
+## Tests
+
+- Removing one provider preserves unrelated providers and models.
+- Removing the active provider chooses a valid remaining provider/model.
+- Removing all providers clears active defaults.
+- Removing an unknown provider id is rejected.
+- `/login` and `/logout` parse only with no arguments.
+- Command autocomplete lists `/login` and `/logout`.
+- `cargo fmt` passes.
+- `cargo test --locked --all-targets` passes when practical.
+
+## Documentation
+
+- Update `docs/commands.md` with `cass login`, `cass logout`, `/login`, and `/logout`.
+- Update `docs/configuration.md` to point users toward login/logout for managed provider edits.
+- Update `docs/workflows.md` with login/logout examples near model/provider workflows.
+
+## Acceptance Criteria
+
+- `cass login` opens the provider setup wizard and exits after saving direct login changes.
+- `cass logout` removes selected providers and their models with confirmation.
+- `/login` and `/logout` work from an idle chat and reload active provider config afterward.
+- Removing the active provider never leaves `config.json` pointing at a missing provider/model.
+- Existing `cass setup`, first-run setup, `cass check`, and `/model` behavior still work.
+- `cargo fmt` and `cargo test --locked --all-targets` pass.

plans/V0_3_0_CHATGPT_CODEX_PROVIDER_PLAN.md

@@ -0,0 +1,234 @@
+# v0.3.0 ChatGPT Codex Provider Implementation Plan
+
+## Goal
+
+This release adds a first-class `ChatGPT Codex` provider preset so users who are already signed in to Codex with a ChatGPT subscription can run Cassady without creating a separate API-key environment variable. The preset should call `https://chatgpt.com/backend-api/codex/responses` and resolve its bearer token from the local Codex auth config by default.
+
+Success statement:
+
+> A user who has already run `codex login` or signed in through the Codex app can select `ChatGPT Codex` in `cass login`, pass `cass check`, and send Cassady turns through their Codex subscription without copying tokens into Cassady config.
+
+## Scope
+
+### In scope
+
+- Add `ChatGPT Codex` as a built-in provider preset in the setup/login catalog.
+- Add a provider kind/client for the ChatGPT Codex responses endpoint rather than forcing it through `/chat/completions` URL construction.
+- Read the default access token from the local Codex auth file, normally `$CODEX_HOME/auth.json` or `~/.codex/auth.json`.
+- Support the observed Codex auth shape with `tokens.access_token`, while keeping token values out of Cassady config, logs, check output, and error text.
+- Prefer the Codex-configured model from `$CODEX_HOME/config.toml` when available, with a safe manual model fallback.
+- Teach `cass check` to validate that local Codex auth is present and usable for the active `ChatGPT Codex` provider.
+- Add docs explaining prerequisites, setup flow, token-source behavior, expiration troubleshooting, and the distinction between ChatGPT subscription access and API-key providers.
+- Add focused tests with temporary Codex-home fixtures and mocked streaming responses.
+
+### Out of scope
+
+- Implementing Cassady's own browser OAuth/device-login flow for ChatGPT.
+- Storing or refreshing ChatGPT/Codex tokens in Cassady-owned config files.
+- Reverse engineering unrelated ChatGPT backend endpoints beyond the requested Codex responses endpoint.
+- Guaranteeing compatibility if the private ChatGPT backend endpoint or Codex auth file format changes.
+- Replacing OpenAI-compatible provider support or changing existing provider presets.
+- Release tagging, packaging, or GitHub release creation.
+
+## Context or Current State
+
+Cassady's provider stack is currently centered on OpenAI-compatible chat completions:
+
+- `src/setup.rs` owns the built-in provider catalog, setup/login prompts, model discovery via `GET {base_url}/models`, and writes to `providers.json`/`models.json`/`config.json`.
+- `src/config.rs` defines `ProviderDefinition`, validates provider registries, resolves `api_key` values from literals or environment-variable references, and currently accepts only `kind = "openai-compatible"`.
+- `src/agent.rs` constructs `OpenAiCompatibleProvider` directly from resolved config.
+- `src/providers/openai_compatible.rs` appends `/chat/completions`, sends OpenAI-compatible chat payloads, and parses OpenAI-compatible streaming deltas.
+- `docs/providers.md`, `docs/configuration.md`, `docs/commands.md`, `docs/workflows.md`, and `README.md` describe provider setup as API-key/environment-variable based.
+
+The new preset differs in two important ways:
+
+1. Authentication should come from Codex's local login state, not from a Cassady environment-variable API key.
+2. The endpoint is a Codex-specific responses endpoint (`https://chatgpt.com/backend-api/codex/responses`), so Cassady needs an endpoint-specific provider client or a more general provider dispatch layer.
+
+Local Codex auth is expected to live under Codex home, normally `~/.codex/auth.json`, with a shape like:
+
+```json
+{
+  "auth_mode": "chatgpt",
+  "tokens": {
+    "access_token": "...",
+    "refresh_token": "...",
+    "account_id": "..."
+  },
+  "last_refresh": "..."
+}
+```
+
+Cassady should treat this file as sensitive input: read it only when resolving the active provider token, never copy the access token into Cassady-owned JSON, and never print token contents.
+
+## Design Principles
+
+1. **Use Codex login state, do not own ChatGPT auth.** Cassady should integrate with an existing Codex login and tell users to run `codex login` or sign in to Codex when auth is missing or expired.
+2. **Keep provider protocols explicit.** Do not pretend the ChatGPT Codex endpoint is OpenAI-compatible if it needs different URL construction, request shape, or stream parsing.
+3. **Avoid token leakage.** Token values must not be stored in `~/.cass`, included in transcripts, surfaced in `cass check`, or embedded in test snapshots.
+4. **Keep existing setup stable.** Existing providers should continue to use environment-variable API keys and `/models` discovery without extra Codex dependencies.
+5. **Fail with clear recovery steps.** Missing Codex auth should produce actionable messages, not generic provider errors.
+
+## Design
+
+### Provider catalog and setup UX
+
+Add a built-in catalog entry:
+
+| Provider | Provider id | Kind | Endpoint | Token source |
+| --- | --- | --- | --- | --- |
+| ChatGPT Codex | `chatgpt-codex` | `chatgpt-codex` | `https://chatgpt.com/backend-api/codex/responses` | Local Codex auth |
+
+In `cass login`/`cass setup`, selecting this provider should skip the normal `API key environment variable` prompt and instead show a prerequisite check:
+
+```text
+ChatGPT Codex uses your local Codex login.
+
+✓ Found Codex auth at ~/.codex/auth.json
+```
+
+If the file or access token is missing:
+
+```text
+ChatGPT Codex needs a local Codex login.
+Run `codex login` or sign in with the Codex app, then run `cass login` again.
+```
+
+Model selection should prefer, in order:
+
+1. The `model` value from `$CODEX_HOME/config.toml` when present.
+2. A known default Codex model constant only if the project already has a current default available.
+3. Manual model id entry.
+
+Do not call `GET /models` for `chatgpt-codex` unless a verified endpoint is added later; model discovery remains an OpenAI-compatible setup behavior.
+
+### Provider configuration shape
+
+Extend provider config without breaking existing files. One possible JSON shape is:
+
+```json
+{
+  "id": "chatgpt-codex",
+  "name": "ChatGPT Codex",
+  "kind": "chatgpt-codex",
+  "base_url": "https://chatgpt.com/backend-api/codex/responses",
+  "auth": { "type": "codex_local" },
+  "default_model": "gpt-5.5",
+  "models": ["gpt-5.5"]
+}
+```
+
+Implementation may choose an equivalent internal representation, but it should preserve these properties:
+
+- Existing `api_key` string behavior remains valid for OpenAI-compatible providers.
+- `chatgpt-codex` providers can omit environment-variable API keys.
+- `cass check` can distinguish missing local Codex auth from missing API-key env vars.
+- Serialized config does not contain the Codex access token.
+
+### Codex auth resolution
+
+Add a small resolver module, for example `src/codex_auth.rs`, with helpers like:
+
+- `codex_home() -> PathBuf`: `$CODEX_HOME` when set, otherwise `~/.codex`.
+- `codex_auth_path() -> PathBuf`: `$CODEX_AUTH_FILE` for tests/overrides when set, otherwise `{codex_home}/auth.json`.
+- `load_codex_access_token() -> Result<CodexAccessToken>`: parse `tokens.access_token` and return a redacted/display-safe token wrapper.
+- `check_codex_auth() -> CodexAuthStatus`: report path found, auth mode, access-token presence, optional JWT expiration, and recovery hints.
+
+If the access token looks like a JWT, parse the `exp` claim without validating the signature so Cassady can warn or fail early when the token is expired. Token refresh itself should stay out of scope unless Codex exposes a stable documented local refresh interface.
+
+Read the token at request time rather than caching it during setup. This allows a separate Codex process to refresh `auth.json` between Cassady turns.
+
+### Provider dispatch
+
+Refactor provider construction so `src/agent.rs` does not instantiate only `OpenAiCompatibleProvider`. A simple first step is an enum:
+
+```rust
+enum ProviderClient {
+    OpenAiCompatible(OpenAiCompatibleProvider),
+    ChatGptCodex(ChatGptCodexProvider),
+}
+```
+
+Both variants should expose a common `complete(messages, tools, tx)` async method returning the existing `CompletionResult`. This preserves the current agent loop, tool execution, conversation storage, and TUI behavior.
+
+### ChatGPT Codex responses client
+
+Add a new provider module, for example `src/providers/chatgpt_codex.rs`, that:
+
+- Posts to the exact configured endpoint, defaulting to `https://chatgpt.com/backend-api/codex/responses`.
+- Sends `Authorization: Bearer <local Codex access token>`.
+- Includes the active model and converted message/tool context in the endpoint's expected responses format.
+- Streams assistant text into `AgentEvent::AssistantChunk`.
+- Streams reasoning summaries into `AgentEvent::ReasoningChunk` only when the endpoint provides a safe reasoning summary field.
+- Converts function/tool call deltas into Cassady `StoredToolCall` values.
+- Converts Cassady tool results back into the endpoint's function-call-output input shape on the next turn.
+- Redacts authentication details from non-success response errors.
+
+The exact request/stream schema should be verified against the endpoint during implementation and captured in mocked fixtures. If the endpoint rejects a field used by OpenAI-compatible providers, keep the Codex payload minimal rather than adding compatibility shims that risk breaking the flow.
+
+### Check and troubleshooting behavior
+
+For active `chatgpt-codex` providers, `cass check` should report status like:
+
+```text
+✓ active provider: chatgpt-codex
+✓ endpoint: https://chatgpt.com/backend-api/codex/responses
+✓ Codex auth: ~/.codex/auth.json contains an access token
+```
+
+Failure should point to recovery:
+
+```text
+✗ Codex auth: no access token found in ~/.codex/auth.json
+  Run `codex login` or sign in with the Codex app, then rerun `cass check`.
+```
+
+Do not print the token, account id, refresh token, or full auth JSON.
+
+## Implementation Steps
+
+1. Add the v0.3.0 roadmap entry and this implementation plan.
+2. Extend provider config types/validation to support `kind = "chatgpt-codex"` and a non-env local Codex auth source while preserving existing OpenAI-compatible files.
+3. Add `src/codex_auth.rs` for Codex home discovery, auth-file parsing, redacted status reporting, and optional JWT expiration checks.
+4. Add `ChatGPT Codex` to `src/setup.rs` provider catalog and branch setup behavior so it skips API-key env prompts and `/models` discovery.
+5. Refactor provider construction in `src/agent.rs` behind a small provider dispatch enum or trait.
+6. Implement `src/providers/chatgpt_codex.rs` with endpoint-specific request conversion, streaming parsing, tool-call conversion, and redacted errors.
+7. Update `cass check` so active and inactive provider checks understand Codex-local auth separately from environment-variable API keys.
+8. Update README and bundled docs for the new preset, prerequisites, config example, troubleshooting, and known endpoint/auth caveats.
+9. Add unit tests for config parsing/validation, Codex auth fixtures, setup catalog behavior, and provider dispatch.
+10. Add mocked streaming tests for the ChatGPT Codex client, including text, tool calls, tool outputs, auth failures, and redaction.
+
+## Tests
+
+- `providers.json` with existing OpenAI-compatible providers still parses and validates.
+- A `chatgpt-codex` provider with local Codex auth validates without `api_key`/env-var availability.
+- Missing `~/.codex/auth.json` produces a clear `cass check` error for an active `chatgpt-codex` provider.
+- A fixture `auth.json` with `tokens.access_token` resolves a token but redacts it in display and errors.
+- Expired JWT-like access tokens are detected when possible and produce a recovery hint.
+- Setup/login catalog includes `ChatGPT Codex` and skips the API-key env-var prompt for that provider.
+- Model selection uses `$CODEX_HOME/config.toml` `model` when available, with manual fallback.
+- Provider dispatch selects `ChatGptCodexProvider` only for `kind = "chatgpt-codex"`.
+- Mocked Codex streaming responses produce assistant chunks and final `CompletionResult.content`.
+- Mocked Codex function-call streams produce Cassady `StoredToolCall` values and accept subsequent tool output messages.
+- Provider error messages never include access tokens, refresh tokens, or raw auth JSON.
+- `cargo fmt` passes.
+- `cargo test --locked --all-targets` passes when practical.
+
+## Documentation
+
+- Update `README.md` setup/provider sections with `ChatGPT Codex` as a subscription-backed option.
+- Update `docs/providers.md` with the new preset, endpoint, token-source behavior, and private-endpoint caveat.
+- Update `docs/configuration.md` with the extended provider schema and a safe example that uses local Codex auth.
+- Update `docs/commands.md` and `docs/workflows.md` for `cass login`, `cass check`, and troubleshooting steps.
+- Update `docs/troubleshooting.md` with missing/expired Codex auth, unsupported model, and backend endpoint failure guidance.
+
+## Acceptance Criteria
+
+- `cass login` offers `ChatGPT Codex` as a provider preset.
+- Selecting `ChatGPT Codex` does not ask for an API-key environment variable by default.
+- Cassady reads the access token from local Codex auth at request/check time and never stores that token under `~/.cass`.
+- Active `chatgpt-codex` sessions call `https://chatgpt.com/backend-api/codex/responses` instead of appending `/chat/completions`.
+- Normal OpenAI-compatible providers continue to work unchanged.
+- `cass check` gives clear success/failure output for local Codex auth without leaking secrets.
+- README and bundled docs explain the prerequisite of signing in to Codex first.
+- `cargo fmt` and `cargo test --locked --all-targets` pass.

src/agent.rs

@@ -2,8 +2,8 @@ use crate::access::AccessMode;
 use crate::config::{Config, ReasoningEffort};
 use crate::conversation::{now_ts, Conversation, Record, StoredToolCall};
 use crate::prompt;
-use crate::providers::openai_compatible::{OpenAiCompatibleProvider, OpenAiCompatibleSettings};
 use crate::providers::types::ModelMessage;
+use crate::providers::ProviderClient;
 use crate::security::PolicyDecision;
 use crate::tools::{self, ToolContext, ToolRuntimeEvent};
 use anyhow::Result;
@@ -85,34 +85,21 @@ pub async fn run_turn_with_commands(
         ts: now_ts(),
     })?;
 
-    let api_key = match settings.config.resolved_api_key() {
-        Ok(api_key) => api_key,
+    let reasoning_effort = settings
+        .reasoning_effort
+        .clamp_for_model(settings.config.model_metadata.as_ref());
+    let provider = match ProviderClient::from_config(&settings.config, reasoning_effort) {
+        Ok(provider) => provider,
         Err(err) => {
             append_visible_assistant(
                 &mut conversation,
                 &tx,
-                format!("I couldn't start the turn because the API key is not available: {err}"),
+                format!("I couldn't start the turn because provider authentication is not available: {err}"),
             )?;
             let _ = tx.send(AgentEvent::TurnFinished);
             return Ok(conversation);
         }
     };
-    let reasoning_request_format = settings
-        .config
-        .model_metadata
-        .as_ref()
-        .map(|model| model.reasoning.request_format)
-        .unwrap_or_default();
-    let reasoning_effort = settings
-        .reasoning_effort
-        .clamp_for_model(settings.config.model_metadata.as_ref());
-    let provider = OpenAiCompatibleProvider::new(OpenAiCompatibleSettings {
-        model: settings.config.model.clone(),
-        base_url: settings.config.active_provider.base_url.clone(),
-        api_key,
-        reasoning_effort,
-        reasoning_request_format,
-    });
 
     let docs_dir = settings.config.docs_dir();
     let tool_ctx = ToolContext {
@@ -304,10 +291,19 @@ pub async fn run_turn_with_commands(
             let (runtime_tx, mut runtime_rx) = mpsc::unbounded_channel::<ToolRuntimeEvent>();
             let mut call_tool_ctx = tool_ctx.clone();
             call_tool_ctx.runtime_tx = Some(runtime_tx);
+            let file_edit_snapshot = crate::file_edits::begin_tool_edit(
+                &settings.config.root,
+                &conversation.id,
+                conversation.records.len(),
+                &call_id,
+                &call_name,
+                &call_arguments,
+                &call_tool_ctx,
+            );
             let output = {
                 let execute = tools::execute_with_approval(
                     &call_name,
-                    call_arguments,
+                    call_arguments.clone(),
                     &call_tool_ctx,
                     approved,
                 );
@@ -325,6 +321,11 @@ pub async fn run_turn_with_commands(
                 }
                 output
             };
+            if output.ok {
+                if let Some(snapshot) = file_edit_snapshot {
+                    let _ = crate::file_edits::finish_tool_edit(&settings.config.root, snapshot);
+                }
+            }
             let _ = tx.send(AgentEvent::ToolResult {
                 id: call_id.clone(),
                 name: call_name.clone(),

src/app.rs

@@ -1,5 +1,5 @@
 use crate::agent::{self, AgentCommand, AgentEvent, AgentSettings};
-use crate::cli::{self, Command};
+use crate::cli::{self, Cli, Command};
 use crate::config::{self, Config, ModelDefinition, ReasoningEffort};
 use crate::conversation::{self, Conversation, Record};
 use crate::prompt;
@@ -21,6 +21,10 @@ const TOOL_CANCELLED_MESSAGE: &str = "Tool execution cancelled by user.";
 
 pub async fn run() -> Result<()> {
     let mut cli = cli::parse();
+    if let Some(Command::Update(args)) = cli.command.clone() {
+        return crate::update::run(args).await;
+    }
+
     if matches!(cli.command, Some(Command::Check)) {
         let report = crate::check::run(&cli)?;
         print!("{}", report.render());
@@ -30,6 +34,16 @@ pub async fn run() -> Result<()> {
         return Ok(());
     }
 
+    if matches!(cli.command, Some(Command::Login)) {
+        let _ = crate::setup::run(&cli, crate::setup::SetupMode::Login).await?;
+        return Ok(());
+    }
+
+    if matches!(cli.command, Some(Command::Logout)) {
+        let _ = crate::setup::logout(&config::cass_root())?;
+        return Ok(());
+    }
+
     if matches!(cli.command, Some(Command::Setup)) {
         let outcome = crate::setup::run(&cli, crate::setup::SetupMode::Explicit).await?;
         if !outcome.start_session {
@@ -66,7 +80,7 @@ pub async fn run() -> Result<()> {
         return Ok(());
     }
 
-    if config.resolved_api_key().is_err() {
+    if config.ensure_provider_auth().is_err() {
         let outcome = crate::setup::run(&cli, crate::setup::SetupMode::Auto).await?;
         if !outcome.start_session {
             return Ok(());
@@ -80,7 +94,7 @@ pub async fn run() -> Result<()> {
         (create_new_conversation(&config, &cwd)?, None)
     };
 
-    run_tui(config, cwd, conversation, warning).await
+    run_tui(config, cwd, conversation, warning, cli).await
 }
 
 fn resolve_cwd(cwd: Option<PathBuf>) -> Result<PathBuf> {
@@ -113,6 +127,40 @@ fn list_chats(config: &Config, cwd: &std::path::Path) -> Result<()> {
     Ok(())
 }
 
+async fn run_login_menu_from_tui(
+    terminal: &mut terminal::CassTerminal,
+    cli: &Cli,
+) -> Result<crate::setup::SetupOutcome> {
+    terminal::suspend(terminal)?;
+    let result = crate::setup::run(cli, crate::setup::SetupMode::Login).await;
+    let resume_result = terminal::resume(terminal);
+    match (result, resume_result) {
+        (Ok(outcome), Ok(())) => Ok(outcome),
+        (Err(err), Ok(())) => Err(err),
+        (Ok(_), Err(err)) => Err(err),
+        (Err(err), Err(resume_err)) => Err(err.context(format!(
+            "also failed to restore the chat screen: {resume_err}"
+        ))),
+    }
+}
+
+fn run_logout_menu_from_tui(
+    terminal: &mut terminal::CassTerminal,
+    root: &Path,
+) -> Result<crate::setup::LogoutResult> {
+    terminal::suspend(terminal)?;
+    let result = crate::setup::logout(root);
+    let resume_result = terminal::resume(terminal);
+    match (result, resume_result) {
+        (Ok(outcome), Ok(())) => Ok(outcome),
+        (Err(err), Ok(())) => Err(err),
+        (Ok(_), Err(err)) => Err(err),
+        (Err(err), Err(resume_err)) => Err(err.context(format!(
+            "also failed to restore the chat screen: {resume_err}"
+        ))),
+    }
+}
+
 fn finalize_cancelled_turn(
     config: &Config,
     chat_id: &str,
@@ -182,6 +230,7 @@ async fn run_tui(
     cwd: PathBuf,
     mut conversation: Conversation,
     warning: Option<String>,
+    cli: Cli,
 ) -> Result<()> {
     let mut terminal = terminal::enter()?;
     let mut transcript = Vec::new();
@@ -204,6 +253,8 @@ async fn run_tui(
     let mut reasoning_effort = config.reasoning_effort;
     let mut scroll: u16 = 0;
     let mut last_ctrl_c: Option<Instant> = None;
+    let mut last_esc: Option<Instant> = None;
+    let mut branch_menu: Option<BranchMenuState> = None;
     let mut handle: Option<JoinHandle<Result<Conversation>>> = None;
     let mut cancel_requested = false;
     let mut current_turn_start_len: Option<usize> = None;
@@ -215,6 +266,7 @@ async fn run_tui(
     let mut chat_id = conversation.id.clone();
     let mut autofill_selected = 0usize;
     let mut pending_approval: Option<PendingApproval> = None;
+    let mut provider_ready = true;
 
     loop {
         drain_agent_events(
@@ -328,6 +380,7 @@ async fn run_tui(
             )?
         };
 
+        let overlay_view = branch_menu.as_ref().map(BranchMenuState::overlay_view);
         terminal.draw(|f| {
             render::render(
                 f,
@@ -345,7 +398,12 @@ async fn run_tui(
                     show_reasoning,
                     reasoning_effort,
                     scroll,
-                    autofill: autofill.as_ref(),
+                    autofill: if branch_menu.is_some() {
+                        None
+                    } else {
+                        autofill.as_ref()
+                    },
+                    overlay: overlay_view.as_ref(),
                 },
             )
         })?;
@@ -354,6 +412,43 @@ async fn run_tui(
             match event {
                 Event::Key(key) if key.kind == KeyEventKind::Press => {
                     let busy = handle.is_some();
+                    if branch_menu.is_some() {
+                        match handle_branch_menu_key(
+                            key.code,
+                            &mut branch_menu,
+                            &config,
+                            &cwd,
+                            &mut conversation,
+                            &mut chat_id,
+                            &mut transcript,
+                            &mut active_assistant,
+                            &mut active_reasoning,
+                            &mut active_tools,
+                            &mut status,
+                        ) {
+                            Ok(BranchMenuOutcome::None) => {}
+                            Ok(BranchMenuOutcome::Changed) => {
+                                stick_to_bottom = true;
+                                scroll = bottom_scroll(
+                                    &terminal,
+                                    &input,
+                                    &transcript,
+                                    show_full_tools,
+                                    show_reasoning,
+                                )?;
+                            }
+                            Err(err) => {
+                                branch_menu = None;
+                                status = format!("branch menu failed: {err}");
+                                transcript.push(TranscriptBlock {
+                                    kind: TranscriptKind::Error,
+                                    title: "branch".into(),
+                                    content: err.to_string(),
+                                });
+                            }
+                        }
+                        continue;
+                    }
                     if busy {
                         if let Some(pending) = pending_approval.clone() {
                             match key.code {
@@ -425,11 +520,13 @@ async fn run_tui(
                                 }
                                 cancel_requested = true;
                                 last_ctrl_c = Some(now);
+                                last_esc = None;
                                 status = "turn cancellation requested; press Ctrl-C again within 1.5s to exit".into();
                             } else {
                                 input.clear();
                                 autofill_selected = 0;
                                 last_ctrl_c = Some(now);
+                                last_esc = None;
                                 status = "press Ctrl-C again within 1.5s to exit".into();
                             }
                         }
@@ -439,8 +536,31 @@ async fn run_tui(
                             }
                             cancel_requested = true;
                             last_ctrl_c = None;
+                            last_esc = None;
                             status = "turn cancellation requested".into();
                         }
+                        (KeyCode::Esc, _) => {
+                            let now = Instant::now();
+                            if last_esc
+                                .map(|t| now.duration_since(t) <= Duration::from_millis(1500))
+                                .unwrap_or(false)
+                            {
+                                match BranchMenuState::open(&config, &conversation) {
+                                    Ok(menu) => {
+                                        branch_menu = Some(menu);
+                                        last_esc = None;
+                                        status = "branch/restore menu".into();
+                                    }
+                                    Err(err) => {
+                                        last_esc = None;
+                                        status = format!("branch menu failed: {err}");
+                                    }
+                                }
+                            } else {
+                                last_esc = Some(now);
+                                status = "press Esc again within 1.5s to branch or restore".into();
+                            }
+                        }
                         (KeyCode::BackTab, _) => {
                             if busy {
                                 status = "mode can be changed when idle".into();
@@ -576,6 +696,172 @@ async fn run_tui(
                                 input.clear();
                             } else if input.trim_start().starts_with('/') {
                                 match parse_local_command(&input) {
+                                    Ok(LocalCommand::Branch) => {
+                                        if busy {
+                                            status = "branch menu can be opened when idle".into();
+                                        } else {
+                                            match BranchMenuState::open(&config, &conversation) {
+                                                Ok(menu) => {
+                                                    branch_menu = Some(menu);
+                                                    input.clear();
+                                                    autofill_selected = 0;
+                                                    status = "branch/restore menu".into();
+                                                }
+                                                Err(err) => {
+                                                    status = format!("branch menu failed: {err}");
+                                                    transcript.push(TranscriptBlock {
+                                                        kind: TranscriptKind::Error,
+                                                        title: "branch".into(),
+                                                        content: err.to_string(),
+                                                    });
+                                                }
+                                            }
+                                        }
+                                    }
+                                    Ok(LocalCommand::Login) => {
+                                        if busy {
+                                            status = "login can be opened when idle".into();
+                                        } else {
+                                            input.clear();
+                                            autofill_selected = 0;
+                                            match run_login_menu_from_tui(&mut terminal, &cli).await
+                                            {
+                                                Ok(_) => match Config::load(&cli) {
+                                                    Ok(updated) => {
+                                                        config = updated;
+                                                        reasoning_effort = config.reasoning_effort;
+                                                        provider_ready = true;
+                                                        let content = format!(
+                                                            "active provider: {}\nactive model: {}",
+                                                            config.provider_id, config.model
+                                                        );
+                                                        transcript.push(TranscriptBlock {
+                                                            kind: TranscriptKind::Status,
+                                                            title: "login".into(),
+                                                            content,
+                                                        });
+                                                        status = "login updated".into();
+                                                    }
+                                                    Err(err) => {
+                                                        provider_ready = false;
+                                                        status = format!(
+                                                            "login saved with issues: {err}"
+                                                        );
+                                                        transcript.push(TranscriptBlock {
+                                                            kind: TranscriptKind::Error,
+                                                            title: "login".into(),
+                                                            content: format!(
+                                                                "Provider config could not be loaded: {err}"
+                                                            ),
+                                                        });
+                                                    }
+                                                },
+                                                Err(err) => {
+                                                    status = format!("login cancelled: {err}");
+                                                    transcript.push(TranscriptBlock {
+                                                        kind: TranscriptKind::Error,
+                                                        title: "login".into(),
+                                                        content: err.to_string(),
+                                                    });
+                                                }
+                                            }
+                                            if stick_to_bottom {
+                                                scroll = bottom_scroll(
+                                                    &terminal,
+                                                    &input,
+                                                    &transcript,
+                                                    show_full_tools,
+                                                    show_reasoning,
+                                                )?;
+                                            }
+                                        }
+                                    }
+                                    Ok(LocalCommand::Logout) => {
+                                        if busy {
+                                            status = "logout can be opened when idle".into();
+                                        } else {
+                                            input.clear();
+                                            autofill_selected = 0;
+                                            match run_logout_menu_from_tui(
+                                                &mut terminal,
+                                                &config.root,
+                                            ) {
+                                                Ok(result) => {
+                                                    if result.removed_provider_ids.is_empty() {
+                                                        transcript.push(TranscriptBlock {
+                                                            kind: TranscriptKind::Status,
+                                                            title: "logout".into(),
+                                                            content: "logout cancelled".into(),
+                                                        });
+                                                        status = "logout cancelled".into();
+                                                    } else if result.remaining_provider_count == 0 {
+                                                        provider_ready = false;
+                                                        transcript.push(TranscriptBlock {
+                                                            kind: TranscriptKind::Status,
+                                                            title: "logout".into(),
+                                                            content: format!(
+                                                                "removed providers: {}\nremoved model entries: {}\nno providers remain; run /login before sending another message",
+                                                                result.removed_provider_ids.join(", "),
+                                                                result.removed_model_count
+                                                            ),
+                                                        });
+                                                        status = "no provider configured".into();
+                                                    } else {
+                                                        match Config::load(&cli) {
+                                                            Ok(updated) => {
+                                                                config = updated;
+                                                                reasoning_effort =
+                                                                    config.reasoning_effort;
+                                                                provider_ready = true;
+                                                                transcript.push(TranscriptBlock {
+                                                                    kind: TranscriptKind::Status,
+                                                                    title: "logout".into(),
+                                                                    content: format!(
+                                                                        "removed providers: {}\nremoved model entries: {}\nactive provider: {}\nactive model: {}",
+                                                                        result.removed_provider_ids.join(", "),
+                                                                        result.removed_model_count,
+                                                                        config.provider_id,
+                                                                        config.model
+                                                                    ),
+                                                                });
+                                                                status = "logout updated".into();
+                                                            }
+                                                            Err(err) => {
+                                                                provider_ready = false;
+                                                                status = format!(
+                                                                    "logout saved with issues: {err}"
+                                                                );
+                                                                transcript.push(TranscriptBlock {
+                                                                    kind: TranscriptKind::Error,
+                                                                    title: "logout".into(),
+                                                                    content: format!(
+                                                                        "Provider config could not be loaded: {err}"
+                                                                    ),
+                                                                });
+                                                            }
+                                                        }
+                                                    }
+                                                }
+                                                Err(err) => {
+                                                    status = format!("logout cancelled: {err}");
+                                                    transcript.push(TranscriptBlock {
+                                                        kind: TranscriptKind::Error,
+                                                        title: "logout".into(),
+                                                        content: err.to_string(),
+                                                    });
+                                                }
+                                            }
+                                            if stick_to_bottom {
+                                                scroll = bottom_scroll(
+                                                    &terminal,
+                                                    &input,
+                                                    &transcript,
+                                                    show_full_tools,
+                                                    show_reasoning,
+                                                )?;
+                                            }
+                                        }
+                                    }
                                     Ok(LocalCommand::Status) => {
                                         let content = chat_status(
                                             &chat_id,
@@ -738,6 +1024,24 @@ async fn run_tui(
                                 }
                             } else if busy {
                                 status = "agent is still running".into();
+                            } else if !provider_ready {
+                                status = "run /login before sending a message".into();
+                                transcript.push(TranscriptBlock {
+                                    kind: TranscriptKind::Error,
+                                    title: "provider".into(),
+                                    content:
+                                        "No active provider is configured. Run /login before sending another message."
+                                            .into(),
+                                });
+                                if stick_to_bottom {
+                                    scroll = bottom_scroll(
+                                        &terminal,
+                                        &input,
+                                        &transcript,
+                                        show_full_tools,
+                                        show_reasoning,
+                                    )?;
+                                }
                             } else {
                                 let msg = input.trim_end().to_string();
                                 current_turn_start_len = Some(conversation.records.len());
@@ -859,6 +1163,12 @@ async fn run_tui(
         {
             last_ctrl_c = None;
         }
+        if last_esc
+            .map(|t| t.elapsed() > Duration::from_millis(1500))
+            .unwrap_or(false)
+        {
+            last_esc = None;
+        }
     }
 }
 
@@ -868,6 +1178,337 @@ struct PendingApproval {
     block_index: usize,
 }
 
+#[derive(Debug, Clone)]
+enum BranchMenuMode {
+    Main,
+    Actions(crate::branch::Checkpoint),
+}
+
+#[derive(Debug, Clone)]
+struct BranchMenuState {
+    mode: BranchMenuMode,
+    selected: usize,
+    family: crate::branch::BranchFamily,
+}
+
+#[derive(Debug, Clone)]
+enum BranchMenuItem {
+    Switch(String),
+    Checkpoint(crate::branch::Checkpoint),
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum BranchMenuOutcome {
+    None,
+    Changed,
+}
+
+impl BranchMenuState {
+    fn open(config: &Config, conversation: &Conversation) -> Result<Self> {
+        let family = crate::branch::load_family(&config.conversations_dir(), conversation)?;
+        Ok(Self {
+            mode: BranchMenuMode::Main,
+            selected: 0,
+            family,
+        })
+    }
+
+    fn overlay_view(&self) -> render::OverlayView {
+        match &self.mode {
+            BranchMenuMode::Main => render::OverlayView {
+                title: "Branch / Restore".into(),
+                help: "Enter select · Esc cancel · ↑/↓ move".into(),
+                selected: self.selected,
+                items: self
+                    .main_items()
+                    .into_iter()
+                    .map(|item| match item {
+                        BranchMenuItem::Switch(id) => {
+                            let branch = self.family.branches.iter().find(|b| b.id == id);
+                            let mut label = if branch.is_some_and(|b| b.current) {
+                                format!("current branch {id}")
+                            } else {
+                                format!("switch to {id}")
+                            };
+                            if branch.and_then(|b| b.parent_chat_id.as_ref()).is_none() {
+                                label.push_str(" (root)");
+                            }
+                            render::OverlayItem {
+                                label,
+                                detail: branch.and_then(|b| b.branch_label.clone()).unwrap_or_else(
+                                    || {
+                                        branch
+                                            .map(|b| format!("{} records", b.record_count))
+                                            .unwrap_or_default()
+                                    },
+                                ),
+                            }
+                        }
+                        BranchMenuItem::Checkpoint(checkpoint) => render::OverlayItem {
+                            label: format!("{} · {}", checkpoint.chat_id, checkpoint.label),
+                            detail: checkpoint.detail,
+                        },
+                    })
+                    .collect(),
+            },
+            BranchMenuMode::Actions(checkpoint) => render::OverlayView {
+                title: "Branch from checkpoint".into(),
+                help: format!(
+                    "{} · Enter select · Esc back",
+                    crate::branch::checkpoint_title(checkpoint)
+                ),
+                selected: self.selected,
+                items: vec![
+                    render::OverlayItem {
+                        label: "Branch conversation only".into(),
+                        detail: "safe default; leaves files unchanged".into(),
+                    },
+                    render::OverlayItem {
+                        label: "Branch conversation and restore tracked files".into(),
+                        detail: "applies safe Cassady write/edit snapshots; conflicts are skipped"
+                            .into(),
+                    },
+                    render::OverlayItem {
+                        label: "Preview tracked file restore plan".into(),
+                        detail: "show file actions in transcript".into(),
+                    },
+                    render::OverlayItem {
+                        label: "Cancel".into(),
+                        detail: String::new(),
+                    },
+                ],
+            },
+        }
+    }
+
+    fn main_items(&self) -> Vec<BranchMenuItem> {
+        let mut items = Vec::new();
+        for branch in &self.family.branches {
+            items.push(BranchMenuItem::Switch(branch.id.clone()));
+        }
+        for checkpoint in &self.family.checkpoints {
+            items.push(BranchMenuItem::Checkpoint(checkpoint.clone()));
+        }
+        items
+    }
+
+    fn len(&self) -> usize {
+        match self.mode {
+            BranchMenuMode::Main => self.main_items().len(),
+            BranchMenuMode::Actions(_) => 4,
+        }
+    }
+}
+
+#[allow(clippy::too_many_arguments)]
+fn handle_branch_menu_key(
+    code: KeyCode,
+    menu: &mut Option<BranchMenuState>,
+    config: &Config,
+    _cwd: &Path,
+    conversation: &mut Conversation,
+    chat_id: &mut String,
+    transcript: &mut Vec<TranscriptBlock>,
+    active_assistant: &mut Option<usize>,
+    active_reasoning: &mut Option<usize>,
+    active_tools: &mut HashMap<String, usize>,
+    status: &mut String,
+) -> Result<BranchMenuOutcome> {
+    let Some(state) = menu.as_mut() else {
+        return Ok(BranchMenuOutcome::None);
+    };
+    match code {
+        KeyCode::Esc => match state.mode {
+            BranchMenuMode::Main => {
+                *menu = None;
+                *status = "branch menu cancelled".into();
+            }
+            BranchMenuMode::Actions(_) => {
+                state.mode = BranchMenuMode::Main;
+                state.selected = 0;
+            }
+        },
+        KeyCode::Up | KeyCode::Char('k') => {
+            state.selected = state.selected.saturating_sub(1);
+        }
+        KeyCode::Down | KeyCode::Char('j') => {
+            let max = state.len().saturating_sub(1);
+            state.selected = state.selected.saturating_add(1).min(max);
+        }
+        KeyCode::Enter => {
+            return apply_branch_menu_selection(
+                menu,
+                config,
+                conversation,
+                chat_id,
+                transcript,
+                active_assistant,
+                active_reasoning,
+                active_tools,
+                status,
+            );
+        }
+        _ => {}
+    }
+    Ok(BranchMenuOutcome::None)
+}
+
+#[allow(clippy::too_many_arguments)]
+fn apply_branch_menu_selection(
+    menu: &mut Option<BranchMenuState>,
+    config: &Config,
+    conversation: &mut Conversation,
+    chat_id: &mut String,
+    transcript: &mut Vec<TranscriptBlock>,
+    active_assistant: &mut Option<usize>,
+    active_reasoning: &mut Option<usize>,
+    active_tools: &mut HashMap<String, usize>,
+    status: &mut String,
+) -> Result<BranchMenuOutcome> {
+    let Some(state) = menu.as_mut() else {
+        return Ok(BranchMenuOutcome::None);
+    };
+    match &state.mode {
+        BranchMenuMode::Main => {
+            let items = state.main_items();
+            let Some(item) = items.get(state.selected).cloned() else {
+                return Ok(BranchMenuOutcome::None);
+            };
+            match item {
+                BranchMenuItem::Switch(id) => {
+                    let (loaded, warning) = Conversation::load(&config.conversations_dir(), &id)?;
+                    *conversation = loaded;
+                    *chat_id = conversation.id.clone();
+                    *transcript = transcript_from_loaded(conversation, warning);
+                    *active_assistant = None;
+                    *active_reasoning = None;
+                    active_tools.clear();
+                    *status = format!("switched to branch {chat_id}");
+                    *menu = None;
+                    Ok(BranchMenuOutcome::Changed)
+                }
+                BranchMenuItem::Checkpoint(checkpoint) => {
+                    state.mode = BranchMenuMode::Actions(checkpoint);
+                    state.selected = 0;
+                    Ok(BranchMenuOutcome::None)
+                }
+            }
+        }
+        BranchMenuMode::Actions(checkpoint) => {
+            let selected = state.selected;
+            let checkpoint = checkpoint.clone();
+            match selected {
+                0 => branch_from_checkpoint(
+                    menu,
+                    config,
+                    &checkpoint,
+                    false,
+                    conversation,
+                    chat_id,
+                    transcript,
+                    active_assistant,
+                    active_reasoning,
+                    active_tools,
+                    status,
+                ),
+                1 => branch_from_checkpoint(
+                    menu,
+                    config,
+                    &checkpoint,
+                    true,
+                    conversation,
+                    chat_id,
+                    transcript,
+                    active_assistant,
+                    active_reasoning,
+                    active_tools,
+                    status,
+                ),
+                2 => {
+                    let plan = crate::file_edits::plan_restore(
+                        &config.root,
+                        &checkpoint.chat_id,
+                        checkpoint.record_index,
+                    )?;
+                    transcript.push(TranscriptBlock {
+                        kind: TranscriptKind::Status,
+                        title: "restore preview".into(),
+                        content: crate::file_edits::summarize_plan(&plan),
+                    });
+                    *status = "restore plan previewed".into();
+                    *menu = None;
+                    Ok(BranchMenuOutcome::Changed)
+                }
+                _ => {
+                    state.mode = BranchMenuMode::Main;
+                    state.selected = 0;
+                    Ok(BranchMenuOutcome::None)
+                }
+            }
+        }
+    }
+}
+
+#[allow(clippy::too_many_arguments)]
+fn branch_from_checkpoint(
+    menu: &mut Option<BranchMenuState>,
+    config: &Config,
+    checkpoint: &crate::branch::Checkpoint,
+    restore_files: bool,
+    conversation: &mut Conversation,
+    chat_id: &mut String,
+    transcript: &mut Vec<TranscriptBlock>,
+    active_assistant: &mut Option<usize>,
+    active_reasoning: &mut Option<usize>,
+    active_tools: &mut HashMap<String, usize>,
+    status: &mut String,
+) -> Result<BranchMenuOutcome> {
+    let (source, _) = Conversation::load(&config.conversations_dir(), &checkpoint.chat_id)?;
+    let branch = crate::branch::create_branch(&config.conversations_dir(), &source, checkpoint)?;
+    let old_id = checkpoint.chat_id.clone();
+    *conversation = branch;
+    *chat_id = conversation.id.clone();
+    *transcript = transcript_from_loaded(conversation, None);
+    *active_assistant = None;
+    *active_reasoning = None;
+    active_tools.clear();
+
+    let mut restore_status = String::new();
+    if restore_files {
+        let plan = crate::file_edits::plan_restore(
+            &config.root,
+            &checkpoint.chat_id,
+            checkpoint.record_index,
+        )?;
+        let summary = crate::file_edits::summarize_plan(&plan);
+        let outcome = crate::file_edits::apply_restore_plan(&plan)?;
+        restore_status = format!(
+            "; restored files: {} applied, {} skipped, {} conflicts",
+            outcome.applied, outcome.skipped, outcome.conflicts
+        );
+        transcript.push(TranscriptBlock {
+            kind: if outcome.conflicts == 0 {
+                TranscriptKind::Status
+            } else {
+                TranscriptKind::Error
+            },
+            title: "file restore".into(),
+            content: format!(
+                "{summary}\n\nApplied: {}\nSkipped: {}\nConflicts: {}",
+                outcome.applied, outcome.skipped, outcome.conflicts
+            ),
+        });
+    }
+
+    *status = format!(
+        "branched {chat_id} from {old_id} at {}{}",
+        crate::branch::checkpoint_title(checkpoint),
+        restore_status
+    );
+    *menu = None;
+    Ok(BranchMenuOutcome::Changed)
+}
+
 struct AgentEventContext<'a> {
     terminal: &'a terminal::CassTerminal,
     input: &'a str,
@@ -1243,6 +1884,9 @@ fn assistant_content_matches(a: &str, b: &str) -> bool {
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 enum LocalCommand {
+    Branch,
+    Login,
+    Logout,
     Model(String),
     New,
     Resume(String),
@@ -1257,6 +1901,24 @@ struct CommandSpec {
 }
 
 const COMMANDS: &[CommandSpec] = &[
+    CommandSpec {
+        name: "branch",
+        usage: "/branch",
+        description: "open branch/restore menu",
+        takes_value: false,
+    },
+    CommandSpec {
+        name: "login",
+        usage: "/login",
+        description: "configure provider login settings",
+        takes_value: false,
+    },
+    CommandSpec {
+        name: "logout",
+        usage: "/logout",
+        description: "remove saved providers and models",
+        takes_value: false,
+    },
     CommandSpec {
         name: "model",
         usage: "/model <model>",
@@ -1507,6 +2169,24 @@ fn parse_local_command(input: &str) -> std::result::Result<LocalCommand, String>
     };
 
     match command {
+        "/branch" | "/restore" => {
+            if parts.next().is_some() {
+                return Err("usage: /branch".into());
+            }
+            Ok(LocalCommand::Branch)
+        }
+        "/login" => {
+            if parts.next().is_some() {
+                return Err("usage: /login".into());
+            }
+            Ok(LocalCommand::Login)
+        }
+        "/logout" => {
+            if parts.next().is_some() {
+                return Err("usage: /logout".into());
+            }
+            Ok(LocalCommand::Logout)
+        }
         "/model" => {
             let Some(model) = parts.next() else {
                 return Err("usage: /model <model>".into());
@@ -1950,12 +2630,43 @@ mod tests {
         assert!(command_autofill("/new", 0).is_none());
     }
 
+    #[test]
+    fn command_autofill_lists_login_and_logout_commands() {
+        let menu = command_autofill("/log", 0).unwrap();
+
+        let labels = menu
+            .items
+            .iter()
+            .map(|item| item.label.as_str())
+            .collect::<Vec<_>>();
+        assert_eq!(labels, vec!["/login", "/logout"]);
+        assert_eq!(menu.items[0].insert, "/login");
+        assert_eq!(menu.items[1].insert, "/logout");
+    }
+
     #[test]
     fn parse_local_command_accepts_new_without_args() {
         assert_eq!(parse_local_command("/new").unwrap(), LocalCommand::New);
         assert_eq!(parse_local_command("/new extra"), Err("usage: /new".into()));
     }
 
+    #[test]
+    fn parse_local_command_accepts_login_and_logout_without_args() {
+        assert_eq!(parse_local_command("/login").unwrap(), LocalCommand::Login);
+        assert_eq!(
+            parse_local_command("/logout").unwrap(),
+            LocalCommand::Logout
+        );
+        assert_eq!(
+            parse_local_command("/login extra"),
+            Err("usage: /login".into())
+        );
+        assert_eq!(
+            parse_local_command("/logout extra"),
+            Err("usage: /logout".into())
+        );
+    }
+
     #[test]
     fn cancelled_turn_repairs_missing_tool_results() {
         let root = tempdir().unwrap();

src/branch.rs

@@ -0,0 +1,435 @@
+use crate::conversation::{self, BranchPoint, Conversation, Record, StoredToolCall};
+use anyhow::{bail, Context, Result};
+use serde::{Deserialize, Serialize};
+use std::collections::{BTreeMap, BTreeSet, HashSet};
+use std::fs::{self, File, OpenOptions};
+use std::io::{BufRead, BufReader, Write};
+use std::path::Path;
+
+const TOOL_CANCELLED_MESSAGE: &str = "Tool execution cancelled by user.";
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum CheckpointKind {
+    User,
+    Assistant,
+    ToolCall,
+    ToolResult,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Checkpoint {
+    pub id: String,
+    pub chat_id: String,
+    pub record_index: usize,
+    pub tool_call_id: Option<String>,
+    pub kind: CheckpointKind,
+    pub label: String,
+    pub detail: String,
+    pub ts: Option<String>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct BranchSummary {
+    pub id: String,
+    pub created_at: String,
+    pub parent_chat_id: Option<String>,
+    pub branch_label: Option<String>,
+    pub record_count: usize,
+    pub current: bool,
+}
+
+#[derive(Debug, Clone)]
+pub struct BranchFamily {
+    pub branches: Vec<BranchSummary>,
+    pub checkpoints: Vec<Checkpoint>,
+}
+
+pub fn checkpoint_records(records: &[Record], chat_id: &str) -> Vec<Checkpoint> {
+    let mut checkpoints = Vec::new();
+    for (idx, record) in records.iter().enumerate() {
+        match record {
+            Record::User { content, ts } => checkpoints.push(Checkpoint {
+                id: format!("{chat_id}:{idx}:user"),
+                chat_id: chat_id.to_string(),
+                record_index: idx,
+                tool_call_id: None,
+                kind: CheckpointKind::User,
+                label: "user".into(),
+                detail: preview(content),
+                ts: Some(ts.clone()),
+            }),
+            Record::Assistant {
+                content,
+                reasoning,
+                tool_calls,
+                ts,
+                ..
+            } => {
+                let detail = if content.trim().is_empty() {
+                    preview(reasoning)
+                } else {
+                    preview(content)
+                };
+                checkpoints.push(Checkpoint {
+                    id: format!("{chat_id}:{idx}:assistant"),
+                    chat_id: chat_id.to_string(),
+                    record_index: idx,
+                    tool_call_id: None,
+                    kind: CheckpointKind::Assistant,
+                    label: "assistant".into(),
+                    detail,
+                    ts: Some(ts.clone()),
+                });
+                for call in tool_calls {
+                    checkpoints.push(Checkpoint {
+                        id: format!("{chat_id}:{idx}:tool_call:{}", call.id),
+                        chat_id: chat_id.to_string(),
+                        record_index: idx,
+                        tool_call_id: Some(call.id.clone()),
+                        kind: CheckpointKind::ToolCall,
+                        label: format!("tool call {}", call.name),
+                        detail: tool_call_detail(call),
+                        ts: Some(ts.clone()),
+                    });
+                }
+            }
+            Record::Tool {
+                tool_call_id,
+                name,
+                ok,
+                content,
+                ts,
+            } => checkpoints.push(Checkpoint {
+                id: format!("{chat_id}:{idx}:tool_result:{tool_call_id}"),
+                chat_id: chat_id.to_string(),
+                record_index: idx,
+                tool_call_id: Some(tool_call_id.clone()),
+                kind: CheckpointKind::ToolResult,
+                label: format!("tool {name} {}", if *ok { "✓" } else { "✗" }),
+                detail: preview(content),
+                ts: Some(ts.clone()),
+            }),
+            _ => {}
+        }
+    }
+    checkpoints
+}
+
+pub fn load_family(conversations_dir: &Path, current: &Conversation) -> Result<BranchFamily> {
+    let metas = load_all_metas(conversations_dir)?;
+    let root = root_for(&current.id, &metas);
+    let mut ids = BTreeSet::new();
+    for id in metas.keys() {
+        if root_for(id, &metas) == root {
+            ids.insert(id.clone());
+        }
+    }
+    ids.insert(current.id.clone());
+
+    let mut branches = Vec::new();
+    let mut checkpoints = Vec::new();
+    for id in ids {
+        let Ok((conversation, _)) = Conversation::load(conversations_dir, &id) else {
+            continue;
+        };
+        let meta = conversation.meta();
+        branches.push(BranchSummary {
+            id: conversation.id.clone(),
+            created_at: meta
+                .as_ref()
+                .map(|m| m.created_at.clone())
+                .unwrap_or_default(),
+            parent_chat_id: meta.as_ref().and_then(|m| m.parent_chat_id.clone()),
+            branch_label: meta
+                .as_ref()
+                .and_then(|m| m.branch_from.as_ref().map(|p| p.checkpoint_label.clone())),
+            record_count: conversation.records.len(),
+            current: conversation.id == current.id,
+        });
+        checkpoints.extend(checkpoint_records(&conversation.records, &conversation.id));
+    }
+    branches.sort_by(|a, b| b.created_at.cmp(&a.created_at));
+    checkpoints.sort_by(|a, b| {
+        a.chat_id
+            .cmp(&b.chat_id)
+            .then(a.record_index.cmp(&b.record_index))
+            .then(a.id.cmp(&b.id))
+    });
+    Ok(BranchFamily {
+        branches,
+        checkpoints,
+    })
+}
+
+pub fn create_branch(
+    conversations_dir: &Path,
+    source: &Conversation,
+    checkpoint: &Checkpoint,
+) -> Result<Conversation> {
+    if source.id != checkpoint.chat_id {
+        bail!(
+            "checkpoint {} belongs to {}, not {}",
+            checkpoint.id,
+            checkpoint.chat_id,
+            source.id
+        );
+    }
+    if checkpoint.record_index >= source.records.len() {
+        bail!("checkpoint record index is out of range");
+    }
+
+    fs::create_dir_all(conversations_dir)?;
+    let id = conversation::new_chat_id();
+    let path = conversations_dir.join(format!("{id}.jsonl"));
+    let mut records = Vec::new();
+    let meta = source
+        .meta()
+        .context("source conversation is missing metadata")?;
+    records.push(Record::Meta {
+        chat_id: id.clone(),
+        created_at: conversation::now_ts(),
+        model: meta.model,
+        cwd: meta.cwd,
+        parent_chat_id: Some(source.id.clone()),
+        branch_from: Some(BranchPoint {
+            chat_id: source.id.clone(),
+            record_index: checkpoint.record_index,
+            tool_call_id: checkpoint.tool_call_id.clone(),
+            checkpoint_label: checkpoint_title(checkpoint),
+        }),
+    });
+
+    let prefix = valid_prefix(source, checkpoint)?;
+    records.extend(prefix);
+    repair_pending_tool_calls(&mut records);
+
+    let mut file = OpenOptions::new()
+        .create_new(true)
+        .write(true)
+        .open(&path)
+        .with_context(|| format!("creating branch conversation {}", path.display()))?;
+    for record in &records {
+        writeln!(file, "{}", serde_json::to_string(record)?)?;
+    }
+    file.flush()?;
+
+    Ok(Conversation { id, path, records })
+}
+
+fn valid_prefix(source: &Conversation, checkpoint: &Checkpoint) -> Result<Vec<Record>> {
+    let mut end = checkpoint.record_index + 1;
+    if matches!(checkpoint.kind, CheckpointKind::ToolCall) {
+        end = checkpoint.record_index + 1;
+    }
+    let mut prefix = source.records[..end].to_vec();
+
+    // Drop the source meta; the branch writes its own meta record.
+    if matches!(prefix.first(), Some(Record::Meta { .. })) {
+        prefix.remove(0);
+    }
+
+    // For a tool-call checkpoint, keep the assistant turn but do not copy any
+    // later tool result. The repair step below writes cancelled tool results so
+    // the next provider request remains valid.
+    Ok(prefix)
+}
+
+pub fn repair_pending_tool_calls(records: &mut Vec<Record>) {
+    let mut pending: Vec<(String, String)> = Vec::new();
+    for record in records.iter() {
+        match record {
+            Record::Assistant { tool_calls, .. } => {
+                pending = tool_calls
+                    .iter()
+                    .map(|call| (call.id.clone(), call.name.clone()))
+                    .collect();
+            }
+            Record::Tool { tool_call_id, .. } => pending.retain(|(id, _)| id != tool_call_id),
+            Record::User { .. } => pending.clear(),
+            _ => {}
+        }
+    }
+    let seen: HashSet<String> = records
+        .iter()
+        .filter_map(|record| match record {
+            Record::Tool { tool_call_id, .. } => Some(tool_call_id.clone()),
+            _ => None,
+        })
+        .collect();
+    for (id, name) in pending {
+        if seen.contains(&id) {
+            continue;
+        }
+        records.push(Record::Tool {
+            tool_call_id: id,
+            name,
+            ok: false,
+            content: TOOL_CANCELLED_MESSAGE.to_string(),
+            ts: conversation::now_ts(),
+        });
+    }
+}
+
+fn load_all_metas(conversations_dir: &Path) -> Result<BTreeMap<String, (Option<String>, String)>> {
+    let mut out = BTreeMap::new();
+    if !conversations_dir.exists() {
+        return Ok(out);
+    }
+    for entry in fs::read_dir(conversations_dir)? {
+        let entry = entry?;
+        let path = entry.path();
+        if path.extension().and_then(|s| s.to_str()) != Some("jsonl") {
+            continue;
+        }
+        let Some(id) = path.file_stem().and_then(|s| s.to_str()) else {
+            continue;
+        };
+        if let Ok(Some((parent, cwd))) = read_meta_parent_cwd(&path) {
+            out.insert(id.to_string(), (parent, cwd));
+        }
+    }
+    Ok(out)
+}
+
+fn read_meta_parent_cwd(path: &Path) -> Result<Option<(Option<String>, String)>> {
+    let file = File::open(path)?;
+    for line in BufReader::new(file).lines().take(10) {
+        let line = line?;
+        if line.trim().is_empty() {
+            continue;
+        }
+        let record: Record = serde_json::from_str(&line)?;
+        if let Record::Meta {
+            parent_chat_id,
+            cwd,
+            ..
+        } = record
+        {
+            return Ok(Some((parent_chat_id, cwd)));
+        }
+    }
+    Ok(None)
+}
+
+fn root_for(id: &str, metas: &BTreeMap<String, (Option<String>, String)>) -> String {
+    let mut current = id.to_string();
+    let mut seen = HashSet::new();
+    while seen.insert(current.clone()) {
+        let Some((Some(parent), _)) = metas.get(&current) else {
+            break;
+        };
+        current = parent.clone();
+    }
+    current
+}
+
+pub fn checkpoint_title(checkpoint: &Checkpoint) -> String {
+    if checkpoint.detail.is_empty() {
+        checkpoint.label.clone()
+    } else {
+        format!("{}: {}", checkpoint.label, checkpoint.detail)
+    }
+}
+
+fn tool_call_detail(call: &StoredToolCall) -> String {
+    let mut detail = String::new();
+    if let Some(path) = call.arguments.get("path").and_then(|v| v.as_str()) {
+        detail = format!("file: {path}");
+    } else if let Some(command) = call.arguments.get("command").and_then(|v| v.as_str()) {
+        detail = command.to_string();
+    }
+    if detail.is_empty() {
+        preview(&call.arguments.to_string())
+    } else {
+        preview(&detail)
+    }
+}
+
+fn preview(content: &str) -> String {
+    content
+        .lines()
+        .find(|line| !line.trim().is_empty())
+        .unwrap_or("")
+        .chars()
+        .take(96)
+        .collect()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use serde_json::json;
+    use tempfile::tempdir;
+
+    fn base_records(id: &str) -> Vec<Record> {
+        vec![
+            Record::Meta {
+                chat_id: id.into(),
+                created_at: "now".into(),
+                model: "m".into(),
+                cwd: "/tmp".into(),
+                parent_chat_id: None,
+                branch_from: None,
+            },
+            Record::System {
+                content: "s".into(),
+            },
+            Record::User {
+                content: "u".into(),
+                ts: "t".into(),
+            },
+            Record::Assistant {
+                content: "a".into(),
+                reasoning: String::new(),
+                reasoning_field: None,
+                tool_calls: vec![StoredToolCall {
+                    id: "call1".into(),
+                    name: "read".into(),
+                    arguments: json!({"path":"x"}),
+                }],
+                ts: "t".into(),
+            },
+        ]
+    }
+
+    #[test]
+    fn checkpoints_include_tool_calls() {
+        let checkpoints = checkpoint_records(&base_records("c"), "c");
+        assert!(checkpoints.iter().any(|c| c.kind == CheckpointKind::User));
+        assert!(checkpoints
+            .iter()
+            .any(|c| c.kind == CheckpointKind::Assistant));
+        assert!(checkpoints
+            .iter()
+            .any(|c| c.kind == CheckpointKind::ToolCall));
+    }
+
+    #[test]
+    fn create_branch_does_not_modify_source_and_repairs_pending_tools() {
+        let dir = tempdir().unwrap();
+        let source = Conversation {
+            id: "source".into(),
+            path: dir.path().join("source.jsonl"),
+            records: base_records("source"),
+        };
+        let checkpoint = checkpoint_records(&source.records, &source.id)
+            .into_iter()
+            .find(|c| c.kind == CheckpointKind::Assistant)
+            .unwrap();
+        let branch = create_branch(dir.path(), &source, &checkpoint).unwrap();
+        assert_ne!(branch.id, source.id);
+        assert!(
+            source
+                .records
+                .iter()
+                .filter(|r| matches!(r, Record::Tool { .. }))
+                .count()
+                == 0
+        );
+        assert!(branch
+            .records
+            .iter()
+            .any(|r| matches!(r, Record::Tool { ok: false, .. })));
+    }
+}

src/check.rs

@@ -1,5 +1,9 @@
 use crate::cli::Cli;
-use crate::config::{self, ApiKeyReference, Config, ModelsFile, ProvidersFile};
+use crate::codex_auth;
+use crate::config::{
+    self, ApiKeyReference, Config, ModelsFile, ProvidersFile, CHATGPT_CODEX_PROVIDER_KIND,
+    DEFAULT_PROVIDER_KIND,
+};
 use anyhow::{Context, Result};
 use std::fs;
 use std::path::{Path, PathBuf};
@@ -72,6 +76,9 @@ impl CheckReport {
                     "cass".into(),
                 ];
             }
+            if error.contains("Codex auth") {
+                return vec!["codex login".into(), "cass check".into(), "cass".into()];
+            }
         }
         vec!["cass setup".into()]
     }
@@ -191,29 +198,83 @@ fn check_active_config(report: &mut CheckReport, cfg: &Config, providers: &Provi
     report
         .successes
         .push(format!("active provider: {}", cfg.provider_id));
+    let endpoint_label = if cfg.active_provider.kind == CHATGPT_CODEX_PROVIDER_KIND {
+        "active provider endpoint"
+    } else {
+        "active provider base URL"
+    };
     report.successes.push(format!(
-        "active provider base URL: {}",
+        "{endpoint_label}: {}",
         cfg.active_provider.base_url
     ));
     report
         .successes
         .push(format!("active model: {}", cfg.model));
 
-    check_api_key(report, "api key", &cfg.active_provider.api_key, true);
+    check_provider_auth(
+        report,
+        "api key",
+        &cfg.active_provider.kind,
+        &cfg.active_provider.api_key,
+        true,
+    );
 
     for provider in &providers.providers {
         if provider.id == cfg.provider_id {
             continue;
         }
-        check_api_key(
+        check_provider_auth(
             report,
             &format!("provider `{}` api key", provider.id),
+            &provider.kind,
             &provider.api_key,
             false,
         );
     }
 }
 
+fn check_provider_auth(
+    report: &mut CheckReport,
+    label: &str,
+    kind: &str,
+    api_key: &str,
+    active: bool,
+) {
+    match kind {
+        DEFAULT_PROVIDER_KIND => check_api_key(report, label, api_key, active),
+        CHATGPT_CODEX_PROVIDER_KIND => check_codex_auth(report, active),
+        _ if active => report
+            .errors
+            .push(format!("provider kind `{kind}` is unsupported")),
+        _ => report
+            .warnings
+            .push(format!("provider kind `{kind}` is unsupported")),
+    }
+}
+
+fn check_codex_auth(report: &mut CheckReport, active: bool) {
+    let status = codex_auth::check_codex_auth();
+    if status.is_usable() {
+        if active {
+            report
+                .successes
+                .push(format!("Codex auth: {}", status.summary()));
+        }
+    } else if active {
+        report.errors.push(format!(
+            "Codex auth: {}. {}",
+            status.summary(),
+            status.recovery_hint()
+        ));
+    } else {
+        report.warnings.push(format!(
+            "Codex auth: {}. {}",
+            status.summary(),
+            status.recovery_hint()
+        ));
+    }
+}
+
 fn check_api_key(report: &mut CheckReport, label: &str, spec: &str, active: bool) {
     match config::api_key_reference(spec) {
         Ok(ApiKeyReference::Env(name)) => match std::env::var(&name) {

src/cli.rs

@@ -1,4 +1,4 @@
-use clap::{Parser, Subcommand};
+use clap::{Args, Parser, Subcommand};
 use std::path::PathBuf;
 
 #[derive(Debug, Parser, Clone)]
@@ -44,8 +44,41 @@ pub struct Cli {
 pub enum Command {
     /// Validate Cass config files.
     Check,
+    /// Configure or update OpenAI-compatible provider login settings.
+    Login,
+    /// Remove saved providers and their models.
+    Logout,
     /// Configure an OpenAI-compatible provider and first model.
     Setup,
+    /// Update Cassady from official GitHub releases.
+    Update(UpdateArgs),
+}
+
+#[derive(Debug, Args, Clone, PartialEq, Eq)]
+pub struct UpdateArgs {
+    /// Check the latest release without installing.
+    #[arg(long)]
+    pub check: bool,
+
+    /// Show what would be updated without downloading or installing.
+    #[arg(long)]
+    pub dry_run: bool,
+
+    /// Accept default prompts for non-interactive use.
+    #[arg(long, short = 'y')]
+    pub yes: bool,
+
+    /// Require a matching prebuilt archive and do not fall back to source.
+    #[arg(long, conflicts_with = "source")]
+    pub prebuilt: bool,
+
+    /// Build from release source even when a prebuilt archive exists.
+    #[arg(long, conflicts_with = "prebuilt")]
+    pub source: bool,
+
+    /// Install a specific release tag, such as v0.2.7.
+    #[arg(long, value_name = "TAG")]
+    pub to: Option<String>,
 }
 
 pub fn parse() -> Cli {

src/codex_auth.rs

@@ -0,0 +1,311 @@
+use anyhow::{bail, Context, Result};
+use serde::Deserialize;
+use serde_json::Value;
+use std::fs;
+use std::path::{Path, PathBuf};
+use std::time::{SystemTime, UNIX_EPOCH};
+
+#[derive(Debug, Clone)]
+pub struct CodexAccessToken {
+    value: String,
+}
+
+impl CodexAccessToken {
+    pub fn new(value: String) -> Result<Self> {
+        if value.trim().is_empty() {
+            bail!("Codex access token is empty");
+        }
+        Ok(Self { value })
+    }
+
+    pub fn as_secret(&self) -> &str {
+        &self.value
+    }
+
+    pub fn redacted(&self) -> &'static str {
+        "<Codex access token>"
+    }
+}
+
+impl std::fmt::Display for CodexAccessToken {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(self.redacted())
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct CodexAuthStatus {
+    pub path: PathBuf,
+    pub auth_mode: Option<String>,
+    pub has_access_token: bool,
+    pub expires_at: Option<i64>,
+    pub expired: bool,
+    pub error: Option<String>,
+}
+
+impl CodexAuthStatus {
+    pub fn is_usable(&self) -> bool {
+        self.error.is_none() && self.has_access_token && !self.expired
+    }
+
+    pub fn recovery_hint(&self) -> &'static str {
+        "Run `codex login` or sign in with the Codex app, then rerun `cass check`."
+    }
+
+    pub fn summary(&self) -> String {
+        if self.is_usable() {
+            if let Some(auth_mode) = &self.auth_mode {
+                format!(
+                    "{} contains an access token (auth mode: {auth_mode})",
+                    pretty_path(&self.path)
+                )
+            } else {
+                format!("{} contains an access token", pretty_path(&self.path))
+            }
+        } else if let Some(error) = &self.error {
+            format!("{}: {error}", pretty_path(&self.path))
+        } else if self.expired {
+            format!(
+                "{} contains an expired access token",
+                pretty_path(&self.path)
+            )
+        } else {
+            format!(
+                "{} does not contain an access token",
+                pretty_path(&self.path)
+            )
+        }
+    }
+}
+
+#[derive(Debug, Deserialize)]
+struct CodexAuthFile {
+    auth_mode: Option<String>,
+    tokens: Option<CodexTokens>,
+}
+
+#[derive(Debug, Deserialize)]
+struct CodexTokens {
+    access_token: Option<String>,
+}
+
+pub fn codex_home() -> PathBuf {
+    std::env::var_os("CODEX_HOME")
+        .map(PathBuf::from)
+        .or_else(|| dirs::home_dir().map(|home| home.join(".codex")))
+        .unwrap_or_else(|| PathBuf::from(".codex"))
+}
+
+pub fn codex_auth_path() -> PathBuf {
+    std::env::var_os("CODEX_AUTH_FILE")
+        .map(PathBuf::from)
+        .unwrap_or_else(|| codex_home().join("auth.json"))
+}
+
+pub fn codex_config_path() -> PathBuf {
+    std::env::var_os("CODEX_CONFIG_FILE")
+        .map(PathBuf::from)
+        .unwrap_or_else(|| codex_home().join("config.toml"))
+}
+
+pub fn load_codex_access_token() -> Result<CodexAccessToken> {
+    load_codex_access_token_from_path(&codex_auth_path())
+}
+
+pub fn load_codex_access_token_from_path(path: &Path) -> Result<CodexAccessToken> {
+    let text = fs::read_to_string(path).with_context(|| {
+        format!(
+            "Codex auth not found at {}; run `codex login` or sign in with the Codex app",
+            pretty_path(path)
+        )
+    })?;
+    let parsed: CodexAuthFile = serde_json::from_str(&text)
+        .with_context(|| format!("parsing Codex auth at {}", pretty_path(path)))?;
+    let token = parsed
+        .tokens
+        .and_then(|tokens| tokens.access_token)
+        .filter(|token| !token.trim().is_empty())
+        .with_context(|| {
+            format!(
+                "no access token found in {}; run `codex login` or sign in with the Codex app",
+                pretty_path(path)
+            )
+        })?;
+    if jwt_is_expired(&token) == Some(true) {
+        bail!(
+            "Codex access token in {} is expired; run `codex login` or sign in with the Codex app",
+            pretty_path(path)
+        );
+    }
+    CodexAccessToken::new(token)
+}
+
+pub fn check_codex_auth() -> CodexAuthStatus {
+    check_codex_auth_at(&codex_auth_path())
+}
+
+pub fn check_codex_auth_at(path: &Path) -> CodexAuthStatus {
+    let mut status = CodexAuthStatus {
+        path: path.to_path_buf(),
+        auth_mode: None,
+        has_access_token: false,
+        expires_at: None,
+        expired: false,
+        error: None,
+    };
+
+    let text = match fs::read_to_string(path) {
+        Ok(text) => text,
+        Err(err) => {
+            status.error = Some(format!("not readable ({err})"));
+            return status;
+        }
+    };
+    let parsed: CodexAuthFile = match serde_json::from_str(&text) {
+        Ok(parsed) => parsed,
+        Err(err) => {
+            status.error = Some(format!("invalid JSON ({err})"));
+            return status;
+        }
+    };
+    status.auth_mode = parsed.auth_mode;
+    let token = parsed
+        .tokens
+        .and_then(|tokens| tokens.access_token)
+        .filter(|token| !token.trim().is_empty());
+    if let Some(token) = token {
+        status.has_access_token = true;
+        status.expires_at = jwt_expiration(&token);
+        status.expired = jwt_is_expired(&token).unwrap_or(false);
+    }
+    status
+}
+
+pub fn read_codex_default_model() -> Option<String> {
+    read_codex_default_model_from_path(&codex_config_path())
+}
+
+pub fn read_codex_default_model_from_path(path: &Path) -> Option<String> {
+    let text = fs::read_to_string(path).ok()?;
+    for line in text.lines() {
+        let line = line.trim();
+        if line.starts_with('#') || !line.starts_with("model") {
+            continue;
+        }
+        let Some((key, value)) = line.split_once('=') else {
+            continue;
+        };
+        if key.trim() != "model" {
+            continue;
+        }
+        let value = value.trim();
+        let value = value
+            .strip_prefix('"')
+            .and_then(|v| v.strip_suffix('"'))
+            .or_else(|| value.strip_prefix('\'').and_then(|v| v.strip_suffix('\'')))
+            .unwrap_or(value)
+            .trim();
+        if !value.is_empty() {
+            return Some(value.to_string());
+        }
+    }
+    None
+}
+
+fn jwt_is_expired(token: &str) -> Option<bool> {
+    let exp = jwt_expiration(token)?;
+    let now = SystemTime::now().duration_since(UNIX_EPOCH).ok()?.as_secs() as i64;
+    Some(exp <= now)
+}
+
+fn jwt_expiration(token: &str) -> Option<i64> {
+    let mut parts = token.split('.');
+    let _header = parts.next()?;
+    let payload = parts.next()?;
+    let bytes = base64_url_decode(payload).ok()?;
+    let json: Value = serde_json::from_slice(&bytes).ok()?;
+    json.get("exp")?.as_i64()
+}
+
+fn base64_url_decode(input: &str) -> Result<Vec<u8>, String> {
+    let mut bits = 0u32;
+    let mut bit_count = 0u8;
+    let mut out = Vec::new();
+    for byte in input.bytes() {
+        let value = match byte {
+            b'A'..=b'Z' => byte - b'A',
+            b'a'..=b'z' => byte - b'a' + 26,
+            b'0'..=b'9' => byte - b'0' + 52,
+            b'-' | b'+' => 62,
+            b'_' | b'/' => 63,
+            b'=' => break,
+            _ => return Err("invalid base64 character".into()),
+        } as u32;
+        bits = (bits << 6) | value;
+        bit_count += 6;
+        if bit_count >= 8 {
+            bit_count -= 8;
+            out.push(((bits >> bit_count) & 0xff) as u8);
+        }
+    }
+    Ok(out)
+}
+
+pub fn pretty_path(path: &Path) -> String {
+    if let Some(home) = dirs::home_dir() {
+        if let Ok(rest) = path.strip_prefix(&home) {
+            return format!("~/{}", rest.display());
+        }
+    }
+    path.display().to_string()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use tempfile::tempdir;
+
+    #[test]
+    fn reads_access_token_without_displaying_it() {
+        let dir = tempdir().unwrap();
+        let path = dir.path().join("auth.json");
+        fs::write(
+            &path,
+            r#"{"auth_mode":"chatgpt","tokens":{"access_token":"secret-token"}}"#,
+        )
+        .unwrap();
+
+        let token = load_codex_access_token_from_path(&path).unwrap();
+        assert_eq!(token.as_secret(), "secret-token");
+        assert_eq!(token.to_string(), "<Codex access token>");
+    }
+
+    #[test]
+    fn check_reports_missing_token_without_secret_fields() {
+        let dir = tempdir().unwrap();
+        let path = dir.path().join("auth.json");
+        fs::write(
+            &path,
+            r#"{"tokens":{"refresh_token":"refresh-secret","account_id":"acct"}}"#,
+        )
+        .unwrap();
+
+        let status = check_codex_auth_at(&path);
+        assert!(!status.is_usable());
+        let summary = status.summary();
+        assert!(!summary.contains("refresh-secret"));
+        assert!(!summary.contains("acct"));
+    }
+
+    #[test]
+    fn reads_model_from_codex_config() {
+        let dir = tempdir().unwrap();
+        let path = dir.path().join("config.toml");
+        fs::write(&path, "model = \"gpt-test\"\n").unwrap();
+
+        assert_eq!(
+            read_codex_default_model_from_path(&path).as_deref(),
+            Some("gpt-test")
+        );
+    }
+}

src/config.rs

@@ -9,6 +9,11 @@ use std::path::{Path, PathBuf};
 pub const DEFAULT_PROVIDER_ID: &str = "fireworks";
 pub const DEFAULT_PROVIDER_NAME: &str = "Fireworks";
 pub const DEFAULT_PROVIDER_KIND: &str = "openai-compatible";
+pub const CHATGPT_CODEX_PROVIDER_ID: &str = "chatgpt-codex";
+pub const CHATGPT_CODEX_PROVIDER_NAME: &str = "ChatGPT Codex";
+pub const CHATGPT_CODEX_PROVIDER_KIND: &str = "chatgpt-codex";
+pub const CHATGPT_CODEX_RESPONSES_URL: &str = "https://chatgpt.com/backend-api/codex/responses";
+pub const CHATGPT_CODEX_DEFAULT_MODEL: &str = "gpt-5.5";
 pub const DEFAULT_MODEL: &str = "accounts/fireworks/models/qwen3p7-plus";
 pub const DEFAULT_BASE_URL: &str = "https://api.fireworks.ai/inference/v1";
 pub const DEFAULT_API_KEY_ENV: &str = "FIREWORKS_API_KEY";
@@ -61,6 +66,7 @@ pub struct ProviderDefinition {
     pub name: Option<String>,
     pub kind: String,
     pub base_url: String,
+    #[serde(default, skip_serializing_if = "String::is_empty")]
     pub api_key: String,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub default_model: Option<String>,
@@ -128,7 +134,7 @@ pub struct ResolvedProviderConfig {
     pub name: Option<String>,
     pub kind: String,
     pub base_url: String,
-    /// Either a literal API key or an env-var reference like "$FIREWORKS_API_KEY".
+    /// Either a literal API key, an env-var reference like "$FIREWORKS_API_KEY", or empty for provider kinds that use external local auth.
     pub api_key: String,
     pub default_model: Option<String>,
     pub models: Vec<String>,
@@ -151,6 +157,34 @@ pub struct Config {
     pub docs_dir: PathBuf,
 }
 
+#[derive(Debug, Clone, Default)]
+pub struct ConfigOverrides {
+    pub model: Option<String>,
+    pub base_url: Option<String>,
+    pub api_key_env: Option<String>,
+    pub access_mode: Option<AccessMode>,
+}
+
+impl ConfigOverrides {
+    pub fn from_cli(cli: &Cli) -> Self {
+        let access_mode = if cli.readonly {
+            Some(AccessMode::ReadOnly)
+        } else if cli.workspace_edit {
+            Some(AccessMode::WorkspaceEdit)
+        } else if cli.full_access {
+            Some(AccessMode::FullAccess)
+        } else {
+            None
+        };
+        Self {
+            model: cli.model.clone(),
+            base_url: cli.base_url.clone(),
+            api_key_env: cli.api_key_env.clone(),
+            access_mode,
+        }
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum ApiKeyReference {
     Env(String),
@@ -287,17 +321,29 @@ pub fn models_path(root: &Path) -> PathBuf {
 
 impl Config {
     pub fn load(cli: &Cli) -> Result<Self> {
-        Self::load_from_root(cass_root(), cli)
+        Self::load_with_overrides(cass_root(), ConfigOverrides::from_cli(cli))
     }
 
-    pub fn load_from_root(root: PathBuf, cli: &Cli) -> Result<Self> {
+    pub fn load_with_overrides(root: PathBuf, overrides: ConfigOverrides) -> Result<Self> {
         fs::create_dir_all(root.join("conversations"))
             .with_context(|| format!("creating {}", root.join("conversations").display()))?;
         let docs_dir = crate::docs::install(&root)?;
-        Self::load_from_root_with_docs(root, docs_dir, cli)
+        Self::load_from_root_with_docs_and_overrides(root, docs_dir, overrides)
+    }
+
+    pub fn load_from_root(root: PathBuf, cli: &Cli) -> Result<Self> {
+        Self::load_with_overrides(root, ConfigOverrides::from_cli(cli))
     }
 
     pub fn load_from_root_with_docs(root: PathBuf, docs_dir: PathBuf, cli: &Cli) -> Result<Self> {
+        Self::load_from_root_with_docs_and_overrides(root, docs_dir, ConfigOverrides::from_cli(cli))
+    }
+
+    pub fn load_from_root_with_docs_and_overrides(
+        root: PathBuf,
+        docs_dir: PathBuf,
+        overrides: ConfigOverrides,
+    ) -> Result<Self> {
         fs::create_dir_all(&root).with_context(|| format!("creating {}", root.display()))?;
         let providers = load_or_create_default_provider_registry(&root)?;
         let models = load_or_create_default_model_registry(&root)?;
@@ -330,19 +376,13 @@ impl Config {
             }
         }
 
-        if cli.readonly {
-            cfg.default_access_mode = AccessMode::ReadOnly;
-        }
-        if cli.workspace_edit {
-            cfg.default_access_mode = AccessMode::WorkspaceEdit;
-        }
-        if cli.full_access {
-            cfg.default_access_mode = AccessMode::FullAccess;
+        if let Some(access_mode) = overrides.access_mode {
+            cfg.default_access_mode = access_mode;
         }
 
-        let requested_model = requested_model(file.as_ref(), cli);
+        let requested_model = requested_model(file.as_ref(), &overrides);
         let provider_id_from_config = requested_provider_id(file.as_ref(), &providers);
-        let legacy = legacy_provider_override(file.as_ref(), cli);
+        let legacy = legacy_provider_override(file.as_ref(), &overrides);
 
         let mut provider = resolve_provider(
             requested_model.as_deref().unwrap_or(DEFAULT_MODEL),
@@ -353,10 +393,10 @@ impl Config {
             &models,
         )?;
 
-        if let Some(base_url) = &cli.base_url {
+        if let Some(base_url) = &overrides.base_url {
             provider.base_url = base_url.clone();
         }
-        if let Some(api_key_env) = &cli.api_key_env {
+        if let Some(api_key_env) = &overrides.api_key_env {
             provider.api_key = format!("${api_key_env}");
         }
 
@@ -395,6 +435,14 @@ impl Config {
     pub fn resolved_api_key(&self) -> Result<String> {
         resolve_api_key(&self.active_provider.api_key)
     }
+
+    pub fn ensure_provider_auth(&self) -> Result<()> {
+        match self.active_provider.kind.as_str() {
+            DEFAULT_PROVIDER_KIND => self.resolved_api_key().map(|_| ()),
+            CHATGPT_CODEX_PROVIDER_KIND => crate::codex_auth::load_codex_access_token().map(|_| ()),
+            kind => bail!("unsupported provider kind `{kind}`"),
+        }
+    }
 }
 
 impl ProviderDefinition {
@@ -501,6 +549,10 @@ pub fn api_key_reference(spec: &str) -> Result<ApiKeyReference> {
     Ok(ApiKeyReference::Literal)
 }
 
+pub fn is_supported_provider_kind(kind: &str) -> bool {
+    matches!(kind, DEFAULT_PROVIDER_KIND | CHATGPT_CODEX_PROVIDER_KIND)
+}
+
 pub fn resolve_api_key(spec: &str) -> Result<String> {
     match api_key_reference(spec)? {
         ApiKeyReference::Env(name) => {
@@ -542,7 +594,7 @@ pub fn validate_registries(
                 "providers.json: provider `{}` kind must not be empty",
                 provider.id
             ));
-        } else if provider.kind != DEFAULT_PROVIDER_KIND {
+        } else if !is_supported_provider_kind(&provider.kind) {
             out.errors.push(format!(
                 "providers.json: provider `{}` uses unsupported kind `{}`",
                 provider.id, provider.kind
@@ -559,9 +611,18 @@ pub fn validate_registries(
                 provider.id
             ));
         }
-        if let Err(err) = api_key_reference(&provider.api_key) {
-            out.errors.push(format!(
-                "providers.json: provider `{}` has invalid api_key: {err}",
+        if provider.kind == DEFAULT_PROVIDER_KIND {
+            if let Err(err) = api_key_reference(&provider.api_key) {
+                out.errors.push(format!(
+                    "providers.json: provider `{}` has invalid api_key: {err}",
+                    provider.id
+                ));
+            }
+        } else if provider.kind == CHATGPT_CODEX_PROVIDER_KIND
+            && !provider.api_key.trim().is_empty()
+        {
+            out.warnings.push(format!(
+                "providers.json: provider `{}` ignores api_key because ChatGPT Codex uses local Codex auth",
                 provider.id
             ));
         }
@@ -706,8 +767,8 @@ pub fn find_model_for_provider<'a>(
         .find(|m| m.provider == provider_id && m.id == model_id)
 }
 
-fn requested_model(file: Option<&ConfigFile>, cli: &Cli) -> Option<String> {
-    cli.model.clone().or_else(|| {
+fn requested_model(file: Option<&ConfigFile>, overrides: &ConfigOverrides) -> Option<String> {
+    overrides.model.clone().or_else(|| {
         file.and_then(|f| {
             f.default_model
                 .clone()
@@ -738,13 +799,13 @@ struct LegacyProviderOverride {
 
 fn legacy_provider_override(
     file: Option<&ConfigFile>,
-    cli: &Cli,
+    overrides: &ConfigOverrides,
 ) -> Option<LegacyProviderOverride> {
-    let base_url = cli
+    let base_url = overrides
         .base_url
         .clone()
         .or_else(|| file.and_then(|f| f.base_url.clone()));
-    let api_key = cli
+    let api_key = overrides
         .api_key_env
         .as_ref()
         .map(|env| format!("${env}"))

src/conversation.rs

@@ -14,6 +14,10 @@ pub enum Record {
         created_at: String,
         model: String,
         cwd: String,
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        parent_chat_id: Option<String>,
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        branch_from: Option<BranchPoint>,
     },
     System {
         content: String,
@@ -40,6 +44,15 @@ pub enum Record {
     },
 }
 
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
+pub struct BranchPoint {
+    pub chat_id: String,
+    pub record_index: usize,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub tool_call_id: Option<String>,
+    pub checkpoint_label: String,
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
 pub struct StoredToolCall {
     pub id: String,
@@ -92,6 +105,8 @@ impl Conversation {
             created_at: now_ts(),
             model: model.to_string(),
             cwd: cwd.display().to_string(),
+            parent_chat_id: None,
+            branch_from: None,
         })?;
         convo.append(Record::System {
             content: base_system,
@@ -161,6 +176,37 @@ impl Conversation {
             _ => None,
         })
     }
+
+    pub fn meta(&self) -> Option<ConversationMeta> {
+        self.records.iter().find_map(|r| match r {
+            Record::Meta {
+                chat_id,
+                created_at,
+                model,
+                cwd,
+                parent_chat_id,
+                branch_from,
+            } => Some(ConversationMeta {
+                chat_id: chat_id.clone(),
+                created_at: created_at.clone(),
+                model: model.clone(),
+                cwd: cwd.clone(),
+                parent_chat_id: parent_chat_id.clone(),
+                branch_from: branch_from.clone(),
+            }),
+            _ => None,
+        })
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct ConversationMeta {
+    pub chat_id: String,
+    pub created_at: String,
+    pub model: String,
+    pub cwd: String,
+    pub parent_chat_id: Option<String>,
+    pub branch_from: Option<BranchPoint>,
 }
 
 pub fn list_chats(conversations_dir: &Path, cwd: &Path) -> Result<Vec<ChatSummary>> {

src/embedding.rs

@@ -0,0 +1,563 @@
+//! Experimental Rust embedding API for running Cassady without the TUI.
+//!
+//! This module provides the first Rust-native surface for embedding Cassady in
+//! another application. It reuses Cassady's existing runtime behavior while
+//! giving the host application control over event presentation, turn lifecycle,
+//! and approval decisions.
+
+use crate::access::AccessMode;
+use crate::agent::{self, AgentCommand, AgentEvent, AgentSettings};
+use crate::config::{Config, ConfigOverrides, ReasoningEffort};
+use crate::conversation::{self, Conversation, Record};
+use crate::prompt;
+use serde_json::Value;
+use std::collections::BTreeSet;
+use std::fs;
+use std::path::{Path, PathBuf};
+use thiserror::Error;
+use tokio::sync::mpsc;
+use tokio::task::JoinHandle;
+
+const TURN_CANCELLED_MESSAGE: &str = "Turn cancelled by host.";
+const TOOL_CANCELLED_MESSAGE: &str = "Tool execution cancelled by host.";
+
+pub type Result<T> = std::result::Result<T, Error>;
+
+#[derive(Debug, Error)]
+pub enum Error {
+    #[error("configuration error: {0}")]
+    Config(#[source] anyhow::Error),
+    #[error("conversation error: {0}")]
+    Conversation(#[source] anyhow::Error),
+    #[error("agent error: {0}")]
+    Agent(#[source] anyhow::Error),
+    #[error("agent task failed: {0}")]
+    Join(#[source] tokio::task::JoinError),
+    #[error("turn is already closed")]
+    TurnClosed,
+    #[error("approval request `{0}` is not pending")]
+    ApprovalNotPending(String),
+    #[error("turn session state is unavailable")]
+    MissingSession,
+}
+
+impl Error {
+    fn config(err: anyhow::Error) -> Self {
+        Self::Config(err)
+    }
+
+    fn conversation(err: anyhow::Error) -> Self {
+        Self::Conversation(err)
+    }
+
+    fn agent(err: anyhow::Error) -> Self {
+        Self::Agent(err)
+    }
+}
+
+#[derive(Debug, Clone, Default)]
+pub struct SessionBuilder {
+    config_root: Option<PathBuf>,
+    cwd: Option<PathBuf>,
+    access_mode: Option<AccessMode>,
+    model: Option<String>,
+    base_url: Option<String>,
+    api_key_env: Option<String>,
+    reasoning_effort: Option<ReasoningEffort>,
+}
+
+impl SessionBuilder {
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    pub fn config_root(mut self, root: impl Into<PathBuf>) -> Self {
+        self.config_root = Some(root.into());
+        self
+    }
+
+    pub fn cwd(mut self, cwd: impl Into<PathBuf>) -> Self {
+        self.cwd = Some(cwd.into());
+        self
+    }
+
+    pub fn access_mode(mut self, mode: AccessMode) -> Self {
+        self.access_mode = Some(mode);
+        self
+    }
+
+    pub fn model(mut self, model: impl Into<String>) -> Self {
+        self.model = Some(model.into());
+        self
+    }
+
+    pub fn base_url(mut self, base_url: impl Into<String>) -> Self {
+        self.base_url = Some(base_url.into());
+        self
+    }
+
+    pub fn api_key_env(mut self, api_key_env: impl Into<String>) -> Self {
+        self.api_key_env = Some(api_key_env.into());
+        self
+    }
+
+    pub fn reasoning_effort(mut self, effort: ReasoningEffort) -> Self {
+        self.reasoning_effort = Some(effort);
+        self
+    }
+
+    pub async fn build(self) -> Result<Session> {
+        self.new_session().await
+    }
+
+    pub async fn new_session(self) -> Result<Session> {
+        let PreparedSession {
+            config,
+            cwd,
+            mode,
+            reasoning_effort,
+        } = self.prepare().await?;
+        let conversation = create_new_conversation(&config, &cwd)?;
+        Ok(Session {
+            config,
+            cwd,
+            mode,
+            reasoning_effort,
+            conversation,
+            resume_warning: None,
+        })
+    }
+
+    pub async fn resume(self, chat_id: impl AsRef<str>) -> Result<Session> {
+        let PreparedSession {
+            config,
+            cwd,
+            mode,
+            reasoning_effort,
+        } = self.prepare().await?;
+        let (conversation, warning) =
+            Conversation::load(&config.conversations_dir(), chat_id.as_ref())
+                .map_err(Error::conversation)?;
+        Ok(Session {
+            config,
+            cwd,
+            mode,
+            reasoning_effort,
+            conversation,
+            resume_warning: warning,
+        })
+    }
+
+    async fn prepare(self) -> Result<PreparedSession> {
+        let root = self.config_root.unwrap_or_else(crate::config::cass_root);
+        let overrides = ConfigOverrides {
+            model: self.model,
+            base_url: self.base_url,
+            api_key_env: self.api_key_env,
+            access_mode: self.access_mode,
+        };
+        let config = Config::load_with_overrides(root, overrides).map_err(Error::config)?;
+        config.ensure_provider_auth().map_err(Error::config)?;
+        let cwd = resolve_cwd(self.cwd).map_err(Error::config)?;
+        let mode = config.default_access_mode;
+        let reasoning_effort = self
+            .reasoning_effort
+            .unwrap_or(config.reasoning_effort)
+            .clamp_for_model(config.model_metadata.as_ref());
+        Ok(PreparedSession {
+            config,
+            cwd,
+            mode,
+            reasoning_effort,
+        })
+    }
+}
+
+struct PreparedSession {
+    config: Config,
+    cwd: PathBuf,
+    mode: AccessMode,
+    reasoning_effort: ReasoningEffort,
+}
+
+#[derive(Debug)]
+pub struct Session {
+    config: Config,
+    cwd: PathBuf,
+    mode: AccessMode,
+    reasoning_effort: ReasoningEffort,
+    conversation: Conversation,
+    resume_warning: Option<String>,
+}
+
+impl Session {
+    pub fn id(&self) -> &str {
+        &self.conversation.id
+    }
+
+    pub fn cwd(&self) -> &Path {
+        &self.cwd
+    }
+
+    pub fn model(&self) -> &str {
+        &self.config.model
+    }
+
+    pub fn access_mode(&self) -> AccessMode {
+        self.mode
+    }
+
+    pub fn reasoning_effort(&self) -> ReasoningEffort {
+        self.reasoning_effort
+    }
+
+    pub fn conversation_path(&self) -> &Path {
+        &self.conversation.path
+    }
+
+    pub fn records(&self) -> &[Record] {
+        &self.conversation.records
+    }
+
+    pub fn resume_warning(&self) -> Option<&str> {
+        self.resume_warning.as_deref()
+    }
+
+    pub fn info(&self) -> ConversationInfo {
+        ConversationInfo {
+            id: self.conversation.id.clone(),
+            cwd: self.cwd.clone(),
+            model: self.config.model.clone(),
+            access_mode: self.mode,
+            reasoning_effort: self.reasoning_effort,
+            path: self.conversation.path.clone(),
+            record_count: self.conversation.records.len(),
+        }
+    }
+
+    pub async fn start_turn(self, user_message: impl Into<String>) -> Result<Turn> {
+        let message = user_message.into();
+        let turn_start_len = self.conversation.records.len();
+        let (event_tx, event_rx) = mpsc::unbounded_channel::<AgentEvent>();
+        let (command_tx, command_rx) = mpsc::unbounded_channel::<AgentCommand>();
+        let settings = AgentSettings {
+            config: self.config.clone(),
+            cwd: self.cwd.clone(),
+            mode: self.mode,
+            reasoning_effort: self.reasoning_effort,
+        };
+        let conversation = self.conversation.clone();
+        let task_message = message.clone();
+        let handle = tokio::spawn(agent::run_turn_with_commands(
+            conversation,
+            task_message,
+            settings,
+            event_tx,
+            command_rx,
+        ));
+        Ok(Turn {
+            session: Some(self),
+            handle: Some(handle),
+            event_rx,
+            command_tx: Some(command_tx),
+            pending_approvals: BTreeSet::new(),
+            turn_start_len,
+            user_message: message,
+        })
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct ConversationInfo {
+    pub id: String,
+    pub cwd: PathBuf,
+    pub model: String,
+    pub access_mode: AccessMode,
+    pub reasoning_effort: ReasoningEffort,
+    pub path: PathBuf,
+    pub record_count: usize,
+}
+
+#[derive(Debug)]
+pub struct Turn {
+    session: Option<Session>,
+    handle: Option<JoinHandle<anyhow::Result<Conversation>>>,
+    event_rx: mpsc::UnboundedReceiver<AgentEvent>,
+    command_tx: Option<mpsc::UnboundedSender<AgentCommand>>,
+    pending_approvals: BTreeSet<String>,
+    turn_start_len: usize,
+    user_message: String,
+}
+
+impl Turn {
+    pub async fn next_event(&mut self) -> Result<Option<Event>> {
+        match self.event_rx.recv().await {
+            Some(event) => {
+                let event = Event::from_agent(event);
+                match &event {
+                    Event::ApprovalRequested(request) => {
+                        self.pending_approvals.insert(request.request_id.clone());
+                    }
+                    Event::ApprovalResolved { request_id, .. } => {
+                        self.pending_approvals.remove(request_id);
+                    }
+                    _ => {}
+                }
+                Ok(Some(event))
+            }
+            None => Ok(None),
+        }
+    }
+
+    pub fn approve(&mut self, request_id: impl AsRef<str>) -> Result<()> {
+        self.resolve_approval(request_id.as_ref(), true)
+    }
+
+    pub fn deny(&mut self, request_id: impl AsRef<str>) -> Result<()> {
+        self.resolve_approval(request_id.as_ref(), false)
+    }
+
+    pub async fn finish(mut self) -> Result<Session> {
+        let handle = self.handle.take().ok_or(Error::TurnClosed)?;
+        let conversation = match handle.await.map_err(Error::Join)? {
+            Ok(conversation) => conversation,
+            Err(err) => return Err(Error::agent(err)),
+        };
+        let mut session = self.session.take().ok_or(Error::MissingSession)?;
+        session.conversation = conversation;
+        self.command_tx = None;
+        Ok(session)
+    }
+
+    pub async fn cancel(mut self) -> Result<Session> {
+        if let Some(handle) = &self.handle {
+            handle.abort();
+        }
+        if let Some(handle) = self.handle.take() {
+            match handle.await {
+                Ok(Ok(conversation)) => {
+                    let mut session = self.session.take().ok_or(Error::MissingSession)?;
+                    session.conversation = conversation;
+                    self.command_tx = None;
+                    return Ok(session);
+                }
+                Ok(Err(err)) => return Err(Error::agent(err)),
+                Err(err) if err.is_cancelled() => {}
+                Err(err) => return Err(Error::Join(err)),
+            }
+        }
+        let mut session = self.session.take().ok_or(Error::MissingSession)?;
+        session.conversation = finalize_cancelled_turn(
+            &session.config,
+            &session.conversation.id,
+            self.turn_start_len,
+            &self.user_message,
+        )?;
+        self.command_tx = None;
+        Ok(session)
+    }
+
+    fn resolve_approval(&mut self, request_id: &str, approved: bool) -> Result<()> {
+        if !self.pending_approvals.remove(request_id) {
+            return Err(Error::ApprovalNotPending(request_id.to_string()));
+        }
+        let tx = self.command_tx.as_ref().ok_or(Error::TurnClosed)?;
+        tx.send(AgentCommand::ApprovalDecision {
+            request_id: request_id.to_string(),
+            approved,
+        })
+        .map_err(|_| Error::TurnClosed)
+    }
+}
+
+impl Drop for Turn {
+    fn drop(&mut self) {
+        if let Some(handle) = &self.handle {
+            handle.abort();
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+pub enum Event {
+    AssistantChunk(String),
+    ReasoningChunk(String),
+    ToolCallStarted {
+        id: String,
+        name: String,
+        arguments: Value,
+    },
+    ToolOutputChunk {
+        id: String,
+        name: String,
+        stream: String,
+        content: String,
+    },
+    ToolResult {
+        id: String,
+        name: String,
+        ok: bool,
+        content: String,
+    },
+    ApprovalRequested(ApprovalRequest),
+    ApprovalResolved {
+        request_id: String,
+        approved: bool,
+    },
+    Status(String),
+    Finished,
+}
+
+impl Event {
+    fn from_agent(event: AgentEvent) -> Self {
+        match event {
+            AgentEvent::AssistantChunk(text) => Self::AssistantChunk(text),
+            AgentEvent::ReasoningChunk(text) => Self::ReasoningChunk(text),
+            AgentEvent::ToolCallStarted {
+                id,
+                name,
+                arguments,
+            } => Self::ToolCallStarted {
+                id,
+                name,
+                arguments,
+            },
+            AgentEvent::ToolOutputChunk {
+                id,
+                name,
+                stream,
+                content,
+            } => Self::ToolOutputChunk {
+                id,
+                name,
+                stream,
+                content,
+            },
+            AgentEvent::ToolResult {
+                id,
+                name,
+                ok,
+                content,
+            } => Self::ToolResult {
+                id,
+                name,
+                ok,
+                content,
+            },
+            AgentEvent::ApprovalRequested {
+                request_id,
+                tool_call_id,
+                name,
+                arguments,
+                reason,
+            } => Self::ApprovalRequested(ApprovalRequest {
+                request_id,
+                tool_call_id,
+                name,
+                arguments,
+                reason,
+            }),
+            AgentEvent::ApprovalResolved {
+                request_id,
+                approved,
+            } => Self::ApprovalResolved {
+                request_id,
+                approved,
+            },
+            AgentEvent::Status(status) => Self::Status(status),
+            AgentEvent::TurnFinished => Self::Finished,
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct ApprovalRequest {
+    pub request_id: String,
+    pub tool_call_id: String,
+    pub name: String,
+    pub arguments: Value,
+    pub reason: String,
+}
+
+fn resolve_cwd(cwd: Option<PathBuf>) -> anyhow::Result<PathBuf> {
+    let cwd = cwd.unwrap_or(std::env::current_dir()?);
+    cwd.canonicalize()
+        .map_err(anyhow::Error::from)
+        .map_err(|err| anyhow::anyhow!("resolving cwd {}: {err}", cwd.display()))
+}
+
+fn create_new_conversation(config: &Config, cwd: &Path) -> Result<Conversation> {
+    let global = fs::read_to_string(config.global_path()).ok();
+    let base = prompt::build_base_system_prompt(global.as_deref());
+    Conversation::create(&config.conversations_dir(), &config.model, cwd, base)
+        .map_err(Error::conversation)
+}
+
+fn finalize_cancelled_turn(
+    config: &Config,
+    chat_id: &str,
+    turn_start_len: usize,
+    turn_message: &str,
+) -> Result<Conversation> {
+    let (mut conversation, _) =
+        Conversation::load(&config.conversations_dir(), chat_id).map_err(Error::conversation)?;
+
+    if conversation.records.len() <= turn_start_len {
+        conversation
+            .append(Record::User {
+                content: turn_message.to_string(),
+                ts: conversation::now_ts(),
+            })
+            .map_err(Error::conversation)?;
+    }
+
+    for (id, name) in pending_tool_calls(&conversation.records) {
+        conversation
+            .append(Record::Tool {
+                tool_call_id: id,
+                name,
+                ok: false,
+                content: TOOL_CANCELLED_MESSAGE.to_string(),
+                ts: conversation::now_ts(),
+            })
+            .map_err(Error::conversation)?;
+    }
+
+    if !matches!(
+        conversation.records.last(),
+        Some(Record::Assistant { content, tool_calls, .. })
+            if content == TURN_CANCELLED_MESSAGE && tool_calls.is_empty()
+    ) {
+        conversation
+            .append(Record::Assistant {
+                content: TURN_CANCELLED_MESSAGE.to_string(),
+                reasoning: String::new(),
+                reasoning_field: None,
+                tool_calls: Vec::new(),
+                ts: conversation::now_ts(),
+            })
+            .map_err(Error::conversation)?;
+    }
+
+    Ok(conversation)
+}
+
+fn pending_tool_calls(records: &[Record]) -> Vec<(String, String)> {
+    let mut pending = Vec::new();
+    for record in records {
+        match record {
+            Record::Assistant { tool_calls, .. } => {
+                pending = tool_calls
+                    .iter()
+                    .map(|call| (call.id.clone(), call.name.clone()))
+                    .collect();
+            }
+            Record::Tool { tool_call_id, .. } => {
+                pending.retain(|(id, _)| id != tool_call_id);
+            }
+            Record::User { .. } => pending.clear(),
+            _ => {}
+        }
+    }
+    pending
+}

src/file_edits.rs

@@ -0,0 +1,470 @@
+use crate::tools::{self, ToolContext};
+use anyhow::{Context, Result};
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
+use sha2::{Digest, Sha256};
+use std::collections::BTreeMap;
+use std::fs::{self, OpenOptions};
+use std::io::Write;
+use std::path::{Path, PathBuf};
+
+const MAX_SNAPSHOT_BYTES: u64 = 10 * 1024 * 1024;
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
+pub struct FileEditJournalEntry {
+    pub chat_id: String,
+    pub record_index: usize,
+    pub tool_call_id: String,
+    pub tool_name: String,
+    pub path: PathBuf,
+    pub existed_before: bool,
+    pub existed_after: bool,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub before_hash: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub after_hash: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub before_snapshot: Option<PathBuf>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub after_snapshot: Option<PathBuf>,
+    pub ts: String,
+}
+
+#[derive(Debug, Clone)]
+pub struct PendingFileEditSnapshot {
+    pub chat_id: String,
+    pub record_index: usize,
+    pub tool_call_id: String,
+    pub tool_name: String,
+    pub path: PathBuf,
+    before: SnapshotState,
+}
+
+#[derive(Debug, Clone)]
+enum SnapshotState {
+    Missing,
+    File { bytes: Vec<u8>, hash: String },
+    Unsupported,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct RestorePlan {
+    pub actions: Vec<RestoreAction>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum RestoreAction {
+    Write {
+        path: PathBuf,
+        snapshot: PathBuf,
+        desired_hash: String,
+        expected_current_hash: Option<String>,
+        conflict: bool,
+    },
+    Delete {
+        path: PathBuf,
+        expected_current_hash: Option<String>,
+        conflict: bool,
+    },
+    Skip {
+        path: PathBuf,
+        reason: String,
+    },
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct RestoreOutcome {
+    pub applied: usize,
+    pub skipped: usize,
+    pub conflicts: usize,
+}
+
+pub fn begin_tool_edit(
+    cass_root: &Path,
+    chat_id: &str,
+    record_index: usize,
+    tool_call_id: &str,
+    tool_name: &str,
+    args: &Value,
+    ctx: &ToolContext,
+) -> Option<PendingFileEditSnapshot> {
+    if !matches!(tool_name, "write" | "edit") {
+        return None;
+    }
+    let path_arg = args.get("path")?.as_str()?;
+    let path =
+        tools::path::resolve_for_write(path_arg, &ctx.cwd, ctx.mode, &ctx.blocked_write_roots)
+            .ok()?;
+    let before = snapshot_state(&path).unwrap_or(SnapshotState::Unsupported);
+    // Ensure journal directories are creatable before executing, but do not fail
+    // the tool if Cassady cannot journal; restore will simply be unavailable.
+    let _ = fs::create_dir_all(cass_root.join("file-edits"));
+    let _ = fs::create_dir_all(cass_root.join("file-snapshots"));
+    Some(PendingFileEditSnapshot {
+        chat_id: chat_id.to_string(),
+        record_index,
+        tool_call_id: tool_call_id.to_string(),
+        tool_name: tool_name.to_string(),
+        path,
+        before,
+    })
+}
+
+pub fn finish_tool_edit(cass_root: &Path, pending: PendingFileEditSnapshot) -> Result<()> {
+    let after = snapshot_state(&pending.path).unwrap_or(SnapshotState::Unsupported);
+    if matches!(pending.before, SnapshotState::Unsupported)
+        || matches!(after, SnapshotState::Unsupported)
+    {
+        return Ok(());
+    }
+    if same_state(&pending.before, &after) {
+        return Ok(());
+    }
+
+    let (existed_before, before_hash, before_snapshot) = store_snapshot(
+        cass_root,
+        &pending.chat_id,
+        &pending.tool_call_id,
+        "before",
+        &pending.before,
+    )?;
+    let (existed_after, after_hash, after_snapshot) = store_snapshot(
+        cass_root,
+        &pending.chat_id,
+        &pending.tool_call_id,
+        "after",
+        &after,
+    )?;
+
+    let entry = FileEditJournalEntry {
+        chat_id: pending.chat_id.clone(),
+        record_index: pending.record_index,
+        tool_call_id: pending.tool_call_id,
+        tool_name: pending.tool_name,
+        path: pending.path,
+        existed_before,
+        existed_after,
+        before_hash,
+        after_hash,
+        before_snapshot,
+        after_snapshot,
+        ts: crate::conversation::now_ts(),
+    };
+    append_journal(cass_root, &pending.chat_id, &entry)
+}
+
+pub fn load_journal(cass_root: &Path, chat_id: &str) -> Result<Vec<FileEditJournalEntry>> {
+    let path = journal_path(cass_root, chat_id);
+    if !path.exists() {
+        return Ok(Vec::new());
+    }
+    let content =
+        fs::read_to_string(&path).with_context(|| format!("reading {}", path.display()))?;
+    let mut out = Vec::new();
+    for (idx, line) in content.lines().enumerate() {
+        if line.trim().is_empty() {
+            continue;
+        }
+        let entry: FileEditJournalEntry = serde_json::from_str(line)
+            .with_context(|| format!("parsing {} line {}", path.display(), idx + 1))?;
+        out.push(entry);
+    }
+    out.sort_by_key(|entry| entry.record_index);
+    Ok(out)
+}
+
+pub fn plan_restore(
+    cass_root: &Path,
+    chat_id: &str,
+    target_record_index: usize,
+) -> Result<RestorePlan> {
+    let entries = load_journal(cass_root, chat_id)?;
+    let mut by_path: BTreeMap<PathBuf, Vec<FileEditJournalEntry>> = BTreeMap::new();
+    for entry in entries {
+        by_path.entry(entry.path.clone()).or_default().push(entry);
+    }
+
+    let mut actions = Vec::new();
+    for (path, mut entries) in by_path {
+        entries.sort_by_key(|entry| entry.record_index);
+        let latest = entries.last().cloned();
+        let desired = entries
+            .iter()
+            .rev()
+            .find(|entry| entry.record_index <= target_record_index)
+            .cloned();
+        let first_after = entries
+            .iter()
+            .find(|entry| entry.record_index > target_record_index)
+            .cloned();
+
+        let (want_exists, want_hash, want_snapshot) = if let Some(entry) = desired {
+            (entry.existed_after, entry.after_hash, entry.after_snapshot)
+        } else if let Some(entry) = first_after {
+            (
+                entry.existed_before,
+                entry.before_hash,
+                entry.before_snapshot,
+            )
+        } else {
+            continue;
+        };
+
+        let expected_current_hash = latest.and_then(|entry| entry.after_hash);
+        let current_hash = hash_existing_file(&path)?;
+        let conflict = expected_current_hash.is_some()
+            && current_hash.is_some()
+            && expected_current_hash != current_hash;
+
+        if want_exists {
+            match (want_hash, want_snapshot) {
+                (Some(desired_hash), Some(snapshot)) => actions.push(RestoreAction::Write {
+                    path,
+                    snapshot,
+                    desired_hash,
+                    expected_current_hash,
+                    conflict,
+                }),
+                _ => actions.push(RestoreAction::Skip {
+                    path,
+                    reason: "missing desired snapshot".into(),
+                }),
+            }
+        } else {
+            let conflict = conflict
+                || (current_hash.is_some()
+                    && expected_current_hash.is_none()
+                    && current_hash != expected_current_hash);
+            actions.push(RestoreAction::Delete {
+                path,
+                expected_current_hash,
+                conflict,
+            });
+        }
+    }
+
+    Ok(RestorePlan { actions })
+}
+
+pub fn apply_restore_plan(plan: &RestorePlan) -> Result<RestoreOutcome> {
+    let mut outcome = RestoreOutcome {
+        applied: 0,
+        skipped: 0,
+        conflicts: 0,
+    };
+    for action in &plan.actions {
+        match action {
+            RestoreAction::Write {
+                path,
+                snapshot,
+                conflict,
+                ..
+            } => {
+                if *conflict {
+                    outcome.conflicts += 1;
+                    continue;
+                }
+                let bytes = fs::read(snapshot)
+                    .with_context(|| format!("reading snapshot {}", snapshot.display()))?;
+                crate::tools::write::atomic_write(path, &bytes)
+                    .with_context(|| format!("restoring {}", path.display()))?;
+                outcome.applied += 1;
+            }
+            RestoreAction::Delete { path, conflict, .. } => {
+                if *conflict {
+                    outcome.conflicts += 1;
+                    continue;
+                }
+                if path.exists() {
+                    fs::remove_file(path)
+                        .with_context(|| format!("deleting {}", path.display()))?;
+                    outcome.applied += 1;
+                } else {
+                    outcome.skipped += 1;
+                }
+            }
+            RestoreAction::Skip { .. } => outcome.skipped += 1,
+        }
+    }
+    Ok(outcome)
+}
+
+pub fn summarize_plan(plan: &RestorePlan) -> String {
+    if plan.actions.is_empty() {
+        return "No tracked file edits need restoration for this checkpoint.".into();
+    }
+    let mut lines = Vec::new();
+    for action in &plan.actions {
+        match action {
+            RestoreAction::Write { path, conflict, .. } => lines.push(format!(
+                "{} update {}",
+                if *conflict { "CONFLICT" } else { "will" },
+                path.display()
+            )),
+            RestoreAction::Delete { path, conflict, .. } => lines.push(format!(
+                "{} delete {}",
+                if *conflict { "CONFLICT" } else { "will" },
+                path.display()
+            )),
+            RestoreAction::Skip { path, reason } => {
+                lines.push(format!("skip {}: {reason}", path.display()))
+            }
+        }
+    }
+    lines.join("\n")
+}
+
+fn snapshot_state(path: &Path) -> Result<SnapshotState> {
+    match fs::metadata(path) {
+        Ok(metadata) => {
+            if !metadata.is_file() || metadata.len() > MAX_SNAPSHOT_BYTES {
+                return Ok(SnapshotState::Unsupported);
+            }
+            let bytes = fs::read(path)?;
+            let hash = sha256_hex(&bytes);
+            Ok(SnapshotState::File { bytes, hash })
+        }
+        Err(err) if err.kind() == std::io::ErrorKind::NotFound => Ok(SnapshotState::Missing),
+        Err(err) => Err(err.into()),
+    }
+}
+
+fn same_state(a: &SnapshotState, b: &SnapshotState) -> bool {
+    match (a, b) {
+        (SnapshotState::Missing, SnapshotState::Missing) => true,
+        (SnapshotState::File { hash: a, .. }, SnapshotState::File { hash: b, .. }) => a == b,
+        _ => false,
+    }
+}
+
+fn store_snapshot(
+    cass_root: &Path,
+    chat_id: &str,
+    tool_call_id: &str,
+    side: &str,
+    state: &SnapshotState,
+) -> Result<(bool, Option<String>, Option<PathBuf>)> {
+    match state {
+        SnapshotState::Missing => Ok((false, None, None)),
+        SnapshotState::Unsupported => Ok((false, None, None)),
+        SnapshotState::File { bytes, hash } => {
+            let dir = cass_root
+                .join("file-snapshots")
+                .join(chat_id)
+                .join(tool_call_id);
+            fs::create_dir_all(&dir)?;
+            let path = dir.join(format!("{side}-{hash}.bin"));
+            if !path.exists() {
+                fs::write(&path, bytes)?;
+            }
+            Ok((true, Some(hash.clone()), Some(path)))
+        }
+    }
+}
+
+fn append_journal(cass_root: &Path, chat_id: &str, entry: &FileEditJournalEntry) -> Result<()> {
+    let path = journal_path(cass_root, chat_id);
+    if let Some(parent) = path.parent() {
+        fs::create_dir_all(parent)?;
+    }
+    let mut file = OpenOptions::new().create(true).append(true).open(&path)?;
+    writeln!(file, "{}", serde_json::to_string(entry)?)?;
+    file.flush()?;
+    Ok(())
+}
+
+fn journal_path(cass_root: &Path, chat_id: &str) -> PathBuf {
+    cass_root
+        .join("file-edits")
+        .join(format!("{chat_id}.jsonl"))
+}
+
+fn hash_existing_file(path: &Path) -> Result<Option<String>> {
+    match fs::metadata(path) {
+        Ok(metadata) => {
+            if !metadata.is_file() || metadata.len() > MAX_SNAPSHOT_BYTES {
+                return Ok(None);
+            }
+            Ok(Some(sha256_hex(&fs::read(path)?)))
+        }
+        Err(err) if err.kind() == std::io::ErrorKind::NotFound => Ok(None),
+        Err(err) => Err(err.into()),
+    }
+}
+
+fn sha256_hex(bytes: &[u8]) -> String {
+    let digest = Sha256::digest(bytes);
+    digest.iter().map(|b| format!("{b:02x}")).collect()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::access::AccessMode;
+    use tempfile::tempdir;
+
+    fn tool_ctx(cwd: &Path) -> ToolContext {
+        ToolContext {
+            mode: AccessMode::WorkspaceEdit,
+            cwd: cwd.to_path_buf(),
+            read_roots: vec![cwd.to_path_buf()],
+            blocked_write_roots: Vec::new(),
+            model_result_limit: 1000,
+            runtime_tx: None,
+        }
+    }
+
+    #[test]
+    fn journal_and_restore_rewinds_write() {
+        let root = tempdir().unwrap();
+        let work = tempdir().unwrap();
+        let path = work.path().join("a.txt");
+        fs::write(&path, "old").unwrap();
+        let ctx = tool_ctx(work.path());
+        let pending = begin_tool_edit(
+            root.path(),
+            "chat",
+            3,
+            "call",
+            "write",
+            &serde_json::json!({"path":"a.txt"}),
+            &ctx,
+        )
+        .unwrap();
+        fs::write(&path, "new").unwrap();
+        finish_tool_edit(root.path(), pending).unwrap();
+
+        let plan = plan_restore(root.path(), "chat", 2).unwrap();
+        assert_eq!(plan.actions.len(), 1);
+        let outcome = apply_restore_plan(&plan).unwrap();
+        assert_eq!(outcome.applied, 1);
+        assert_eq!(fs::read_to_string(&path).unwrap(), "old");
+    }
+
+    #[test]
+    fn restore_detects_external_conflict() {
+        let root = tempdir().unwrap();
+        let work = tempdir().unwrap();
+        let path = work.path().join("a.txt");
+        fs::write(&path, "old").unwrap();
+        let ctx = tool_ctx(work.path());
+        let pending = begin_tool_edit(
+            root.path(),
+            "chat",
+            3,
+            "call",
+            "write",
+            &serde_json::json!({"path":"a.txt"}),
+            &ctx,
+        )
+        .unwrap();
+        fs::write(&path, "new").unwrap();
+        finish_tool_edit(root.path(), pending).unwrap();
+        fs::write(&path, "manual").unwrap();
+        let plan = plan_restore(root.path(), "chat", 2).unwrap();
+        assert!(matches!(
+            &plan.actions[0],
+            RestoreAction::Write { conflict: true, .. }
+        ));
+    }
+}

src/lib.rs

@@ -1,19 +1,25 @@
 pub mod access;
 pub mod agent;
 pub mod app;
+pub mod branch;
 pub mod check;
 pub mod cli;
+pub mod codex_auth;
 pub mod config;
 pub mod conversation;
 pub mod docs;
+pub mod embedding;
 pub mod error;
+pub mod file_edits;
 pub mod menu;
+pub mod prelude;
 pub mod prompt;
 pub mod providers;
 pub mod security;
 pub mod setup;
 pub mod tools;
 pub mod ui;
+pub mod update;
 
 pub async fn run() -> anyhow::Result<()> {
     app::run().await

src/prelude.rs

@@ -0,0 +1,7 @@
+//! Common imports for Cassady's experimental Rust embedding API.
+
+pub use crate::access::AccessMode;
+pub use crate::config::ReasoningEffort;
+pub use crate::embedding::{
+    ApprovalRequest, ConversationInfo, Event, Session, SessionBuilder, Turn,
+};

src/providers/chatgpt_codex.rs

@@ -0,0 +1,493 @@
+use super::types::{CompletionResult, ModelMessage};
+use crate::agent::AgentEvent;
+use crate::codex_auth::load_codex_access_token;
+use crate::config::{ReasoningEffort, CHATGPT_CODEX_RESPONSES_URL};
+use crate::conversation::StoredToolCall;
+use crate::tools::ToolSpec;
+use anyhow::{bail, Result};
+use futures_util::StreamExt;
+use reqwest::Client;
+use serde_json::{json, Value};
+use std::collections::BTreeMap;
+use tokio::sync::mpsc;
+
+#[derive(Debug, Clone)]
+pub struct ChatGptCodexProvider {
+    client: Client,
+    model: String,
+    endpoint: String,
+    reasoning_effort: ReasoningEffort,
+}
+
+#[derive(Debug, Clone)]
+pub struct ChatGptCodexSettings {
+    pub model: String,
+    pub endpoint: String,
+    pub reasoning_effort: ReasoningEffort,
+}
+
+#[derive(Debug, Default, Clone)]
+struct PartialFunctionCall {
+    call_id: Option<String>,
+    name: Option<String>,
+    arguments: String,
+}
+
+impl ChatGptCodexProvider {
+    pub fn new(settings: ChatGptCodexSettings) -> Self {
+        Self {
+            client: Client::new(),
+            model: settings.model,
+            endpoint: normalize_endpoint(&settings.endpoint),
+            reasoning_effort: settings.reasoning_effort,
+        }
+    }
+
+    pub async fn complete(
+        &self,
+        messages: Vec<ModelMessage>,
+        tools: Vec<ToolSpec>,
+        tx: &mpsc::UnboundedSender<AgentEvent>,
+    ) -> Result<CompletionResult> {
+        let token = load_codex_access_token()?;
+        let secret = token.as_secret().to_string();
+        let body = responses_body(&self.model, messages, tools, self.reasoning_effort);
+        let resp = self
+            .client
+            .post(&self.endpoint)
+            .bearer_auth(token.as_secret())
+            .json(&body)
+            .send()
+            .await?;
+        if !resp.status().is_success() {
+            let status = resp.status();
+            let text = resp.text().await.unwrap_or_default();
+            bail!(
+                "ChatGPT Codex returned {status}: {}",
+                redact_secret(&text, &secret)
+            );
+        }
+
+        let mut state = StreamState::default();
+        let mut buf = String::new();
+        let mut stream = resp.bytes_stream();
+        while let Some(chunk) = stream.next().await {
+            let chunk = chunk?;
+            let chunk_text = String::from_utf8_lossy(&chunk).replace("\r\n", "\n");
+            buf.push_str(&chunk_text);
+            while let Some(pos) = buf.find("\n\n") {
+                let frame = buf[..pos].to_string();
+                buf = buf[pos + 2..].to_string();
+                process_frame(&frame, &mut state, tx)?;
+            }
+        }
+        if !buf.trim().is_empty() {
+            process_frame(&buf, &mut state, tx)?;
+        }
+
+        Ok(state.finish())
+    }
+}
+
+#[derive(Debug, Default)]
+struct StreamState {
+    content: String,
+    reasoning: String,
+    reasoning_field: Option<String>,
+    partials: BTreeMap<String, PartialFunctionCall>,
+}
+
+impl StreamState {
+    fn finish(self) -> CompletionResult {
+        let tool_calls = self
+            .partials
+            .into_iter()
+            .filter_map(|(key, partial)| {
+                let name = partial.name?;
+                let id = partial.call_id.unwrap_or(key);
+                let arguments = serde_json::from_str(&partial.arguments)
+                    .unwrap_or_else(|_| json!({"_raw": partial.arguments}));
+                Some(StoredToolCall {
+                    id,
+                    name,
+                    arguments,
+                })
+            })
+            .collect();
+        CompletionResult {
+            content: self.content,
+            reasoning: self.reasoning,
+            reasoning_field: self.reasoning_field,
+            tool_calls,
+        }
+    }
+}
+
+fn responses_body(
+    model: &str,
+    messages: Vec<ModelMessage>,
+    tools: Vec<ToolSpec>,
+    reasoning_effort: ReasoningEffort,
+) -> Value {
+    let mut instructions = Vec::new();
+    let mut input = Vec::new();
+    for message in messages {
+        match message {
+            ModelMessage::System { content } => instructions.push(content),
+            ModelMessage::User { content } => input.push(json!({
+                "type": "message",
+                "role": "user",
+                "content": [{"type": "input_text", "text": content}]
+            })),
+            ModelMessage::Assistant {
+                content,
+                reasoning: _,
+                reasoning_field: _,
+                tool_calls,
+            } => {
+                if !content.is_empty() {
+                    input.push(json!({
+                        "type": "message",
+                        "role": "assistant",
+                        "content": [{"type": "output_text", "text": content}]
+                    }));
+                }
+                for call in tool_calls {
+                    input.push(json!({
+                        "type": "function_call",
+                        "call_id": call.id,
+                        "name": call.name,
+                        "arguments": call.arguments.to_string()
+                    }));
+                }
+            }
+            ModelMessage::Tool {
+                tool_call_id,
+                name: _,
+                content,
+            } => input.push(json!({
+                "type": "function_call_output",
+                "call_id": tool_call_id,
+                "output": content
+            })),
+        }
+    }
+
+    let mut body = json!({
+        "model": model,
+        "input": input,
+        "tools": tools_to_responses(tools),
+        "stream": true,
+        "store": false
+    });
+    if !instructions.is_empty() {
+        body["instructions"] = Value::String(instructions.join("\n\n"));
+    }
+    if let Some(effort) = reasoning_effort.request_value() {
+        body["reasoning"] = json!({"effort": effort, "summary": "auto"});
+    }
+    body
+}
+
+fn tools_to_responses(tools: Vec<ToolSpec>) -> Vec<Value> {
+    tools
+        .into_iter()
+        .map(|tool| {
+            json!({
+                "type": "function",
+                "name": tool.name,
+                "description": tool.description,
+                "parameters": tool.parameters
+            })
+        })
+        .collect()
+}
+
+fn process_frame(
+    frame: &str,
+    state: &mut StreamState,
+    tx: &mpsc::UnboundedSender<AgentEvent>,
+) -> Result<()> {
+    for line in frame.lines() {
+        let line = line.trim();
+        if !line.starts_with("data:") {
+            continue;
+        }
+        let data = line.trim_start_matches("data:").trim();
+        if data == "[DONE]" || data.is_empty() {
+            continue;
+        }
+        let value: Value = serde_json::from_str(data)?;
+        handle_event(&value, state, tx)?;
+    }
+    Ok(())
+}
+
+fn handle_event(
+    value: &Value,
+    state: &mut StreamState,
+    tx: &mpsc::UnboundedSender<AgentEvent>,
+) -> Result<()> {
+    let event_type = value
+        .get("type")
+        .and_then(Value::as_str)
+        .unwrap_or_default();
+    match event_type {
+        "response.output_text.delta" | "response.message.delta" | "output_text.delta" => {
+            if let Some(delta) = string_field(value, &["delta", "text"]) {
+                push_content(state, tx, delta);
+            }
+        }
+        "response.reasoning_summary_text.delta"
+        | "response.reasoning_text.delta"
+        | "response.reasoning.delta"
+        | "reasoning.delta" => {
+            if let Some(delta) = string_field(value, &["delta", "text"]) {
+                push_reasoning(state, tx, "reasoning_summary", delta);
+            }
+        }
+        "response.function_call_arguments.delta" | "function_call_arguments.delta" => {
+            let key = event_key(value);
+            let partial = state.partials.entry(key).or_default();
+            if let Some(delta) = string_field(value, &["delta", "arguments_delta"]) {
+                partial.arguments.push_str(delta);
+            }
+        }
+        "response.function_call_arguments.done" | "function_call_arguments.done" => {
+            let key = event_key(value);
+            let partial = state.partials.entry(key).or_default();
+            if let Some(arguments) = string_field(value, &["arguments"]) {
+                partial.arguments = arguments.to_string();
+            }
+            if let Some(call_id) = string_field(value, &["call_id", "id"]) {
+                partial.call_id = Some(call_id.to_string());
+            }
+            if let Some(name) = string_field(value, &["name"]) {
+                partial.name = Some(name.to_string());
+            }
+        }
+        "response.output_item.added"
+        | "response.output_item.done"
+        | "output_item.added"
+        | "output_item.done" => {
+            if let Some(item) = value.get("item") {
+                handle_item(item, state, tx, event_type.ends_with("done"));
+            }
+        }
+        "response.completed" | "response.done" => {
+            if state.content.is_empty() {
+                if let Some(response) = value.get("response") {
+                    extract_final_response(response, state, tx);
+                }
+            }
+        }
+        _ => {
+            if let Some(item) = value.get("item") {
+                handle_item(item, state, tx, false);
+            } else if let Some(delta) = value
+                .get("delta")
+                .and_then(Value::as_str)
+                .filter(|_| event_type.contains("output_text"))
+            {
+                push_content(state, tx, delta);
+            }
+        }
+    }
+    Ok(())
+}
+
+fn handle_item(
+    item: &Value,
+    state: &mut StreamState,
+    tx: &mpsc::UnboundedSender<AgentEvent>,
+    final_item: bool,
+) {
+    match item.get("type").and_then(Value::as_str).unwrap_or_default() {
+        "message" => {
+            if final_item && state.content.is_empty() {
+                for content in item
+                    .get("content")
+                    .and_then(Value::as_array)
+                    .into_iter()
+                    .flatten()
+                {
+                    if matches!(
+                        content.get("type").and_then(Value::as_str),
+                        Some("output_text")
+                    ) {
+                        if let Some(text) = content.get("text").and_then(Value::as_str) {
+                            push_content(state, tx, text);
+                        }
+                    }
+                }
+            }
+        }
+        "reasoning" => {
+            for summary in item
+                .get("summary")
+                .and_then(Value::as_array)
+                .into_iter()
+                .flatten()
+            {
+                if let Some(text) = summary.get("text").and_then(Value::as_str) {
+                    push_reasoning(state, tx, "reasoning_summary", text);
+                }
+            }
+        }
+        "function_call" => {
+            let key = item
+                .get("call_id")
+                .or_else(|| item.get("id"))
+                .or_else(|| item.get("item_id"))
+                .and_then(Value::as_str)
+                .unwrap_or("call")
+                .to_string();
+            let partial = state.partials.entry(key.clone()).or_default();
+            if let Some(call_id) = item
+                .get("call_id")
+                .or_else(|| item.get("id"))
+                .and_then(Value::as_str)
+            {
+                partial.call_id = Some(call_id.to_string());
+            }
+            if let Some(name) = item.get("name").and_then(Value::as_str) {
+                partial.name = Some(name.to_string());
+            }
+            if let Some(arguments) = item.get("arguments").and_then(Value::as_str) {
+                partial.arguments = arguments.to_string();
+            }
+        }
+        _ => {}
+    }
+}
+
+fn extract_final_response(
+    response: &Value,
+    state: &mut StreamState,
+    tx: &mpsc::UnboundedSender<AgentEvent>,
+) {
+    for item in response
+        .get("output")
+        .and_then(Value::as_array)
+        .into_iter()
+        .flatten()
+    {
+        handle_item(item, state, tx, true);
+    }
+}
+
+fn push_content(state: &mut StreamState, tx: &mpsc::UnboundedSender<AgentEvent>, text: &str) {
+    state.content.push_str(text);
+    let _ = tx.send(AgentEvent::AssistantChunk(text.to_string()));
+}
+
+fn push_reasoning(
+    state: &mut StreamState,
+    tx: &mpsc::UnboundedSender<AgentEvent>,
+    field: &'static str,
+    text: &str,
+) {
+    state
+        .reasoning_field
+        .get_or_insert_with(|| field.to_string());
+    state.reasoning.push_str(text);
+    let _ = tx.send(AgentEvent::ReasoningChunk(text.to_string()));
+}
+
+fn string_field<'a>(value: &'a Value, fields: &[&str]) -> Option<&'a str> {
+    fields.iter().find_map(|field| value.get(*field)?.as_str())
+}
+
+fn event_key(value: &Value) -> String {
+    string_field(
+        value,
+        &["call_id", "item_id", "output_item_id", "id", "output_index"],
+    )
+    .map(str::to_string)
+    .or_else(|| {
+        value
+            .get("output_index")
+            .and_then(Value::as_u64)
+            .map(|n| n.to_string())
+    })
+    .unwrap_or_else(|| "call".to_string())
+}
+
+fn normalize_endpoint(endpoint: &str) -> String {
+    let endpoint = endpoint.trim();
+    if endpoint.is_empty() {
+        CHATGPT_CODEX_RESPONSES_URL.to_string()
+    } else {
+        endpoint.to_string()
+    }
+}
+
+fn redact_secret(text: &str, secret: &str) -> String {
+    if secret.is_empty() {
+        text.to_string()
+    } else {
+        text.replace(secret, "<redacted>")
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use tokio::sync::mpsc;
+
+    #[test]
+    fn responses_body_uses_function_call_items() {
+        let body = responses_body(
+            "gpt-test",
+            vec![
+                ModelMessage::System {
+                    content: "system".into(),
+                },
+                ModelMessage::User {
+                    content: "hello".into(),
+                },
+                ModelMessage::Assistant {
+                    content: String::new(),
+                    reasoning: String::new(),
+                    reasoning_field: None,
+                    tool_calls: vec![StoredToolCall {
+                        id: "call_1".into(),
+                        name: "read".into(),
+                        arguments: json!({"path":"README.md"}),
+                    }],
+                },
+                ModelMessage::Tool {
+                    tool_call_id: "call_1".into(),
+                    name: "read".into(),
+                    content: "ok".into(),
+                },
+            ],
+            Vec::new(),
+            ReasoningEffort::Off,
+        );
+
+        assert_eq!(body["model"], "gpt-test");
+        assert_eq!(body["instructions"], "system");
+        assert!(body["input"].as_array().unwrap().iter().any(|item| {
+            item.get("type").and_then(Value::as_str) == Some("function_call_output")
+        }));
+    }
+
+    #[test]
+    fn stream_parser_collects_text_and_function_call() {
+        let (tx, _rx) = mpsc::unbounded_channel();
+        let mut state = StreamState::default();
+        process_frame(
+            "data: {\"type\":\"response.output_text.delta\",\"delta\":\"hi\"}\n\ndata: {\"type\":\"response.output_item.added\",\"item\":{\"type\":\"function_call\",\"call_id\":\"call_1\",\"name\":\"read\",\"arguments\":\"{\\\"path\\\":\\\"README.md\\\"}\"}}\n\n",
+            &mut state,
+            &tx,
+        )
+        .unwrap();
+        let result = state.finish();
+
+        assert_eq!(result.content, "hi");
+        assert_eq!(result.tool_calls.len(), 1);
+        assert_eq!(result.tool_calls[0].id, "call_1");
+        assert_eq!(result.tool_calls[0].name, "read");
+    }
+}

src/providers/mod.rs

@@ -1,2 +1,62 @@
+pub mod chatgpt_codex;
 pub mod openai_compatible;
 pub mod types;
+
+use crate::agent::AgentEvent;
+use crate::config::{Config, ReasoningEffort, CHATGPT_CODEX_PROVIDER_KIND, DEFAULT_PROVIDER_KIND};
+use crate::providers::chatgpt_codex::{ChatGptCodexProvider, ChatGptCodexSettings};
+use crate::providers::openai_compatible::{OpenAiCompatibleProvider, OpenAiCompatibleSettings};
+use crate::providers::types::{CompletionResult, ModelMessage};
+use crate::tools::ToolSpec;
+use anyhow::{bail, Result};
+use tokio::sync::mpsc;
+
+#[derive(Debug, Clone)]
+pub enum ProviderClient {
+    OpenAiCompatible(OpenAiCompatibleProvider),
+    ChatGptCodex(ChatGptCodexProvider),
+}
+
+impl ProviderClient {
+    pub fn from_config(config: &Config, reasoning_effort: ReasoningEffort) -> Result<Self> {
+        match config.active_provider.kind.as_str() {
+            DEFAULT_PROVIDER_KIND => {
+                let api_key = config.resolved_api_key()?;
+                let reasoning_request_format = config
+                    .model_metadata
+                    .as_ref()
+                    .map(|model| model.reasoning.request_format)
+                    .unwrap_or_default();
+                Ok(Self::OpenAiCompatible(OpenAiCompatibleProvider::new(
+                    OpenAiCompatibleSettings {
+                        model: config.model.clone(),
+                        base_url: config.active_provider.base_url.clone(),
+                        api_key,
+                        reasoning_effort,
+                        reasoning_request_format,
+                    },
+                )))
+            }
+            CHATGPT_CODEX_PROVIDER_KIND => Ok(Self::ChatGptCodex(ChatGptCodexProvider::new(
+                ChatGptCodexSettings {
+                    model: config.model.clone(),
+                    endpoint: config.active_provider.base_url.clone(),
+                    reasoning_effort,
+                },
+            ))),
+            kind => bail!("unsupported provider kind `{kind}`"),
+        }
+    }
+
+    pub async fn complete(
+        &self,
+        messages: Vec<ModelMessage>,
+        tools: Vec<ToolSpec>,
+        tx: &mpsc::UnboundedSender<AgentEvent>,
+    ) -> Result<CompletionResult> {
+        match self {
+            Self::OpenAiCompatible(provider) => provider.complete(messages, tools, tx).await,
+            Self::ChatGptCodex(provider) => provider.complete(messages, tools, tx).await,
+        }
+    }
+}

src/setup.rs

@@ -1,8 +1,11 @@
 use crate::check;
 use crate::cli::Cli;
+use crate::codex_auth;
 use crate::config::{
     self, ConfigFile, ModelDefinition, ModelsFile, ProviderDefinition, ProvidersFile,
-    ReasoningEffort, ReasoningMetadata, ReasoningRequestFormat, DEFAULT_PROVIDER_KIND,
+    ReasoningEffort, ReasoningMetadata, ReasoningRequestFormat, CHATGPT_CODEX_DEFAULT_MODEL,
+    CHATGPT_CODEX_PROVIDER_ID, CHATGPT_CODEX_PROVIDER_KIND, CHATGPT_CODEX_PROVIDER_NAME,
+    CHATGPT_CODEX_RESPONSES_URL, DEFAULT_PROVIDER_KIND,
 };
 use crate::menu::{Menu, MenuItem, TextPrompt};
 use anyhow::{bail, Context, Result};
@@ -18,6 +21,7 @@ use std::time::Duration;
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum SetupMode {
     Explicit,
+    Login,
     Auto,
 }
 
@@ -45,6 +49,23 @@ pub struct SetupSelection {
     pub supports_reasoning: bool,
 }
 
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct ProviderLogoutCandidate {
+    pub id: String,
+    pub name: Option<String>,
+    pub default_model: Option<String>,
+    pub model_count: usize,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct LogoutResult {
+    pub removed_provider_ids: Vec<String>,
+    pub removed_model_count: usize,
+    pub remaining_provider_count: usize,
+    pub active_provider: Option<String>,
+    pub active_model: Option<String>,
+}
+
 #[derive(Debug, Deserialize)]
 struct ModelsResponse {
     data: Vec<ModelItem>,
@@ -57,7 +78,12 @@ struct ModelItem {
 
 fn print_banner() {
     println!("Cassady setup");
-    println!("Configure an OpenAI-compatible provider, API key environment variable, and model.");
+    println!("Configure a provider, authentication source, and model.");
+}
+
+fn print_login_banner() {
+    println!("Cassady login");
+    println!("Add or update a provider, authentication source, and model.");
 }
 
 fn section(title: &str) {
@@ -125,6 +151,12 @@ pub fn provider_catalog() -> Vec<ProviderCatalogEntry> {
             base_url: "https://api.openai.com/v1",
             api_key_env: "OPENAI_API_KEY",
         },
+        ProviderCatalogEntry {
+            name: CHATGPT_CODEX_PROVIDER_NAME,
+            id: CHATGPT_CODEX_PROVIDER_ID,
+            base_url: CHATGPT_CODEX_RESPONSES_URL,
+            api_key_env: "",
+        },
         ProviderCatalogEntry {
             name: "xAI",
             id: "xai",
@@ -187,10 +219,16 @@ pub async fn run(cli: &Cli, mode: SetupMode) -> Result<SetupOutcome> {
     fs::create_dir_all(&root).with_context(|| format!("creating {}", root.display()))?;
 
     if !io::stdin().is_terminal() {
-        bail!("setup is interactive; run `cass setup` in a terminal");
+        match mode {
+            SetupMode::Login => bail!("login is interactive; run `cass login` in a terminal"),
+            _ => bail!("setup is interactive; run `cass setup` in a terminal"),
+        }
     }
 
-    print_banner();
+    match mode {
+        SetupMode::Login => print_login_banner(),
+        _ => print_banner(),
+    }
 
     match mode {
         SetupMode::Explicit => {
@@ -206,6 +244,7 @@ pub async fn run(cli: &Cli, mode: SetupMode) -> Result<SetupOutcome> {
                 });
             }
         }
+        SetupMode::Login => {}
         SetupMode::Auto => {
             println!();
             hint("Cassady needs this before starting your first chat.");
@@ -233,29 +272,129 @@ pub async fn run(cli: &Cli, mode: SetupMode) -> Result<SetupOutcome> {
 
     let report = check::run(cli)?;
     if report.has_errors() {
-        if std::env::var(&active_api_key_env).is_err() {
-            section("Setup saved");
+        if !active_api_key_env.is_empty() && std::env::var(&active_api_key_env).is_err() {
+            section(match mode {
+                SetupMode::Login => "Login saved",
+                _ => "Setup saved",
+            });
             warn("Your active provider API key is not available in this shell.");
             hint(format!("Set it with: export {active_api_key_env}=..."));
             hint("Then run: cass");
         } else {
-            section("Setup saved with issues");
+            section(match mode {
+                SetupMode::Login => "Login saved with issues",
+                _ => "Setup saved with issues",
+            });
             print!("{}", report.render());
-            hint("Run `cass setup` to try again or edit ~/.cass/config.json manually.");
+            hint(match mode {
+                SetupMode::Login => {
+                    "Run `cass login` to try again or edit ~/.cass/config.json manually."
+                }
+                _ => "Run `cass setup` to try again or edit ~/.cass/config.json manually.",
+            });
         }
         return Ok(SetupOutcome {
             start_session: false,
         });
     }
 
-    section("Setup complete");
+    section(match mode {
+        SetupMode::Login => "Login complete",
+        _ => "Setup complete",
+    });
     success("Configuration saved and validated");
-    info("Starting your first Cassady session…");
+    match mode {
+        SetupMode::Login => info("Provider configuration is ready."),
+        _ => info("Starting your first Cassady session…"),
+    }
     Ok(SetupOutcome {
         start_session: true,
     })
 }
 
+pub fn logout(root: &Path) -> Result<LogoutResult> {
+    fs::create_dir_all(root).with_context(|| format!("creating {}", root.display()))?;
+    if !io::stdin().is_terminal() {
+        bail!("logout is interactive; run `cass logout` in a terminal");
+    }
+    let candidates = configured_providers(root)?;
+    if candidates.is_empty() {
+        bail!("no providers are configured; run `cass login` to add one");
+    }
+
+    section("Cassady logout");
+    warn("This removes provider entries from Cassady config only. It does not delete environment variables or provider accounts.");
+
+    let items = candidates
+        .iter()
+        .map(|candidate| {
+            let label = candidate.name.as_deref().unwrap_or(&candidate.id);
+            let model = candidate
+                .default_model
+                .as_deref()
+                .unwrap_or("no default model");
+            MenuItem::with_detail(
+                label.to_string(),
+                format!(
+                    "{} · {} · {} model{}",
+                    candidate.id,
+                    model,
+                    candidate.model_count,
+                    if candidate.model_count == 1 { "" } else { "s" }
+                ),
+            )
+        })
+        .collect();
+    let selected =
+        Menu::new("Remove saved providers", items).select_many(&BTreeSet::new(), true)?;
+    let provider_ids = selected
+        .into_iter()
+        .map(|idx| candidates[idx].id.clone())
+        .collect::<Vec<_>>();
+    let label = provider_ids.join(", ");
+    if !ask_yes_no(
+        &format!("Remove {label} and associated model entries?"),
+        false,
+    )? {
+        println!("Logout cancelled.");
+        return Ok(LogoutResult {
+            removed_provider_ids: Vec::new(),
+            removed_model_count: 0,
+            remaining_provider_count: candidates.len(),
+            active_provider: None,
+            active_model: None,
+        });
+    }
+
+    let result = remove_providers(root, &provider_ids)?;
+    if result.removed_provider_ids.is_empty() {
+        println!("No providers removed.");
+    } else {
+        success(format!(
+            "Removed {} provider{} and {} model entr{}",
+            result.removed_provider_ids.len(),
+            if result.removed_provider_ids.len() == 1 {
+                ""
+            } else {
+                "s"
+            },
+            result.removed_model_count,
+            if result.removed_model_count == 1 {
+                "y"
+            } else {
+                "ies"
+            }
+        ));
+        if let Some(provider) = &result.active_provider {
+            let model = result.active_model.as_deref().unwrap_or("no default model");
+            info(format!("Active provider is now {provider} ({model})"));
+        } else {
+            warn("No providers remain. Run `cass login` before starting a chat.");
+        }
+    }
+    Ok(result)
+}
+
 #[derive(Debug, Clone)]
 struct ChosenProvider {
     name: String,
@@ -344,24 +483,39 @@ async fn configure_provider(
     key_value("id", &provider.id);
     key_value("endpoint", &provider.base_url);
 
-    let api_key_env = ask_default("API key environment variable", &provider.api_key_env)?;
-    if !looks_like_env_var(&api_key_env) {
-        warn(format!(
-            "`{api_key_env}` is an unusual environment variable name. Continuing."
-        ));
-    }
-    let api_key = match std::env::var(&api_key_env) {
-        Ok(value) if !value.is_empty() => {
-            success(format!("{api_key_env} is set"));
-            Some(value)
+    let (api_key_env, api_key) = if is_chatgpt_codex_provider(&provider.id) {
+        info(
+            "ChatGPT Codex uses your local Codex login instead of an API-key environment variable.",
+        );
+        let status = codex_auth::check_codex_auth();
+        if status.is_usable() {
+            success(format!("Codex auth: {}", status.summary()));
+        } else {
+            warn(format!("Codex auth: {}", status.summary()));
+            hint(status.recovery_hint());
         }
-        _ => {
+        (String::new(), None)
+    } else {
+        let api_key_env = ask_default("API key environment variable", &provider.api_key_env)?;
+        if !looks_like_env_var(&api_key_env) {
             warn(format!(
-                "{api_key_env} is not set in this shell. Setup can still be saved."
+                "`{api_key_env}` is an unusual environment variable name. Continuing."
             ));
-            hint(format!("Later, run: export {api_key_env}=..."));
-            None
         }
+        let api_key = match std::env::var(&api_key_env) {
+            Ok(value) if !value.is_empty() => {
+                success(format!("{api_key_env} is set"));
+                Some(value)
+            }
+            _ => {
+                warn(format!(
+                    "{api_key_env} is not set in this shell. Setup can still be saved."
+                ));
+                hint(format!("Later, run: export {api_key_env}=..."));
+                None
+            }
+        };
+        (api_key_env, api_key)
     };
 
     let model_id = choose_model(&provider, api_key.as_deref()).await?;
@@ -424,6 +578,15 @@ fn choose_active_provider(selections: &[SetupSelection]) -> Result<usize> {
 async fn choose_model(provider: &ChosenProvider, api_key: Option<&str>) -> Result<String> {
     section("Model");
 
+    if is_chatgpt_codex_provider(&provider.id) {
+        if let Some(model) = codex_auth::read_codex_default_model() {
+            success(format!("Found Codex default model: {model}"));
+            return ask_default("Model id", &model);
+        }
+        warn("Could not find a model in local Codex config. Using a safe default; edit it if needed.");
+        return ask_default("Model id", CHATGPT_CODEX_DEFAULT_MODEL);
+    }
+
     let Some(api_key) = api_key else {
         warn("Model discovery was skipped because the API key is not available in this shell.");
         hint("Enter the model id manually now; Cassady will use it after the key is exported.");
@@ -538,7 +701,9 @@ pub fn apply_setups(root: &Path, selections: &[SetupSelection], active_index: us
     for selection in selections {
         validate_provider_id(&selection.provider_id)?;
         validate_base_url(&selection.base_url)?;
-        if selection.api_key_env.trim().is_empty() {
+        if !is_chatgpt_codex_provider(&selection.provider_id)
+            && selection.api_key_env.trim().is_empty()
+        {
             bail!("API key environment variable must not be empty");
         }
         if selection.model_id.trim().is_empty() {
@@ -565,13 +730,207 @@ pub fn apply_setups(root: &Path, selections: &[SetupSelection], active_index: us
     Ok(())
 }
 
+pub fn configured_providers(root: &Path) -> Result<Vec<ProviderLogoutCandidate>> {
+    let providers = load_providers_or_empty(root)?;
+    let models = load_models_or_empty(root)?;
+    Ok(providers
+        .providers
+        .into_iter()
+        .map(|provider| {
+            let model_count = models
+                .models
+                .iter()
+                .filter(|model| model.provider == provider.id)
+                .count();
+            ProviderLogoutCandidate {
+                id: provider.id,
+                name: provider.name,
+                default_model: provider.default_model,
+                model_count,
+            }
+        })
+        .collect())
+}
+
+pub fn remove_providers(root: &Path, provider_ids: &[String]) -> Result<LogoutResult> {
+    if provider_ids.is_empty() {
+        bail!("select at least one provider to remove");
+    }
+    let selected: BTreeSet<String> = provider_ids
+        .iter()
+        .map(|id| id.trim().to_string())
+        .collect();
+    if selected.iter().any(|id| id.is_empty()) {
+        bail!("provider id must not be empty");
+    }
+
+    fs::create_dir_all(root).with_context(|| format!("creating {}", root.display()))?;
+    let mut config_file = load_config_or_default(root)?;
+    let mut providers = load_providers_or_empty(root)?;
+    let mut models = load_models_or_empty(root)?;
+
+    let existing: BTreeSet<String> = providers
+        .providers
+        .iter()
+        .map(|provider| provider.id.clone())
+        .collect();
+    for id in &selected {
+        if !existing.contains(id) {
+            bail!("provider `{id}` is not configured");
+        }
+    }
+
+    let removed_provider_ids = providers
+        .providers
+        .iter()
+        .filter(|provider| selected.contains(&provider.id))
+        .map(|provider| provider.id.clone())
+        .collect::<Vec<_>>();
+    providers
+        .providers
+        .retain(|provider| !selected.contains(&provider.id));
+
+    let before_models = models.models.len();
+    models
+        .models
+        .retain(|model| !selected.contains(&model.provider));
+    let removed_model_count = before_models - models.models.len();
+
+    repair_active_defaults(&mut config_file, &providers, &models);
+
+    write_json_pretty(&config::providers_path(root), &providers)?;
+    write_json_pretty(&config::models_path(root), &models)?;
+    write_json_pretty(&config::config_path(root), &config_file)?;
+
+    Ok(LogoutResult {
+        removed_provider_ids,
+        removed_model_count,
+        remaining_provider_count: providers.providers.len(),
+        active_provider: config_file.default_provider,
+        active_model: config_file.default_model,
+    })
+}
+
+fn repair_active_defaults(
+    config_file: &mut ConfigFile,
+    providers: &ProvidersFile,
+    models: &ModelsFile,
+) {
+    if providers.providers.is_empty() {
+        config_file.default_provider = None;
+        config_file.default_model = None;
+        config_file.default_reasoning_effort = None;
+        return;
+    }
+
+    let current_provider = config_file
+        .default_provider
+        .as_ref()
+        .filter(|id| {
+            providers
+                .providers
+                .iter()
+                .any(|provider| provider.id == **id)
+        })
+        .cloned();
+    let provider_id =
+        current_provider.unwrap_or_else(|| choose_provider_with_model(providers, models));
+    let model = config_file
+        .default_model
+        .as_ref()
+        .filter(|model| model_belongs_to_provider(models, &provider_id, model))
+        .cloned()
+        .or_else(|| default_model_for_provider(providers, models, &provider_id));
+
+    config_file.default_provider = Some(provider_id);
+    config_file.default_model = model;
+    if let Some(effort) = config_file.default_reasoning_effort {
+        if let Some(model_id) = config_file.default_model.as_deref() {
+            let model = models.models.iter().find(|model| {
+                model.provider == config_file.default_provider.as_deref().unwrap_or_default()
+                    && model.id == model_id
+            });
+            config_file.default_reasoning_effort = Some(effort.clamp_for_model(model));
+        }
+    }
+}
+
+fn choose_provider_with_model(providers: &ProvidersFile, models: &ModelsFile) -> String {
+    providers
+        .providers
+        .iter()
+        .find(|provider| {
+            provider
+                .default_model
+                .as_ref()
+                .is_some_and(|model| model_belongs_to_provider(models, &provider.id, model))
+                || provider
+                    .models
+                    .iter()
+                    .any(|model| model_belongs_to_provider(models, &provider.id, model))
+                || models
+                    .models
+                    .iter()
+                    .any(|model| model.provider == provider.id)
+        })
+        .or_else(|| providers.providers.first())
+        .map(|provider| provider.id.clone())
+        .unwrap_or_default()
+}
+
+fn default_model_for_provider(
+    providers: &ProvidersFile,
+    models: &ModelsFile,
+    provider_id: &str,
+) -> Option<String> {
+    let provider = providers
+        .providers
+        .iter()
+        .find(|provider| provider.id == provider_id)?;
+    provider
+        .default_model
+        .as_ref()
+        .filter(|model| model_belongs_to_provider(models, provider_id, model))
+        .cloned()
+        .or_else(|| {
+            provider
+                .models
+                .iter()
+                .find(|model| model_belongs_to_provider(models, provider_id, model))
+                .cloned()
+        })
+        .or_else(|| {
+            models
+                .models
+                .iter()
+                .find(|model| model.provider == provider_id)
+                .map(|model| model.id.clone())
+        })
+}
+
+fn model_belongs_to_provider(models: &ModelsFile, provider_id: &str, model_id: &str) -> bool {
+    models
+        .models
+        .iter()
+        .any(|model| model.provider == provider_id && model.id == model_id)
+}
+
 fn upsert_provider(providers: &mut ProvidersFile, selection: &SetupSelection) {
+    let is_codex = is_chatgpt_codex_provider(&selection.provider_id);
     let new_entry = ProviderDefinition {
         id: selection.provider_id.clone(),
         name: Some(selection.provider_name.clone()),
-        kind: DEFAULT_PROVIDER_KIND.to_string(),
+        kind: if is_codex {
+            CHATGPT_CODEX_PROVIDER_KIND.to_string()
+        } else {
+            DEFAULT_PROVIDER_KIND.to_string()
+        },
         base_url: selection.base_url.clone(),
-        api_key: format!("${}", selection.api_key_env),
+        api_key: if is_codex {
+            String::new()
+        } else {
+            format!("${}", selection.api_key_env)
+        },
         default_model: Some(selection.model_id.clone()),
         models: vec![selection.model_id.clone()],
     };
@@ -664,6 +1023,10 @@ fn validate_base_url(base_url: &str) -> Result<()> {
     }
 }
 
+fn is_chatgpt_codex_provider(id: &str) -> bool {
+    id == CHATGPT_CODEX_PROVIDER_ID
+}
+
 fn looks_like_env_var(value: &str) -> bool {
     let mut chars = value.chars();
     let Some(first) = chars.next() else {

src/ui/render.rs

@@ -5,7 +5,7 @@ use crate::ui::theme;
 use pulldown_cmark::{CodeBlockKind, Event, HeadingLevel, Parser, Tag, TagEnd};
 use ratatui::layout::{Constraint, Direction, Layout};
 use ratatui::prelude::*;
-use ratatui::widgets::{Paragraph, Wrap};
+use ratatui::widgets::{Block, Borders, Clear, Paragraph, Wrap};
 use std::path::Path;
 use unicode_width::UnicodeWidthChar;
 
@@ -26,7 +26,20 @@ pub struct TranscriptBlock {
     pub content: String,
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
+pub struct OverlayView {
+    pub title: String,
+    pub help: String,
+    pub items: Vec<OverlayItem>,
+    pub selected: usize,
+}
+
+#[derive(Debug, Clone)]
+pub struct OverlayItem {
+    pub label: String,
+    pub detail: String,
+}
+
 pub struct RenderState<'a> {
     pub app_name: &'a str,
     pub chat_id: &'a str,
@@ -42,6 +55,7 @@ pub struct RenderState<'a> {
     pub reasoning_effort: ReasoningEffort,
     pub scroll: u16,
     pub autofill: Option<&'a AutoFillMenu>,
+    pub overlay: Option<&'a OverlayView>,
 }
 
 pub fn render(f: &mut Frame<'_>, state: &RenderState<'_>) {
@@ -74,6 +88,10 @@ pub fn render(f: &mut Frame<'_>, state: &RenderState<'_>) {
 
     let footer = truncate_end(&footer_text(state), chunks[3].width as usize);
     f.render_widget(Paragraph::new(footer).style(theme::footer()), chunks[3]);
+
+    if let Some(overlay) = state.overlay {
+        render_overlay(f, f.area(), overlay);
+    }
 }
 
 pub fn transcript_area(area: Rect, input: &str) -> Rect {
@@ -116,6 +134,61 @@ fn autofill_height(menu: Option<&AutoFillMenu>) -> u16 {
     menu.map(|menu| menu.items.len().min(6) as u16).unwrap_or(0)
 }
 
+fn render_overlay(f: &mut Frame<'_>, area: Rect, overlay: &OverlayView) {
+    let max_width = area.width.max(1);
+    let preferred_width = area.width.saturating_mul(4).saturating_div(5).max(40);
+    let width = preferred_width.min(max_width);
+    let max_height = area.height.saturating_sub(2).max(1);
+    let preferred_height = (overlay.items.len() as u16 + 5).max(8);
+    let height = preferred_height.min(max_height);
+    let x = area.x + area.width.saturating_sub(width) / 2;
+    let y = area.y + area.height.saturating_sub(height) / 2;
+    let rect = Rect::new(x, y, width, height);
+    f.render_widget(Clear, rect);
+    let block = Block::default()
+        .title(overlay.title.clone())
+        .borders(Borders::ALL)
+        .style(theme::menu());
+    let inner = block.inner(rect);
+    f.render_widget(block, rect);
+
+    let visible = inner.height.saturating_sub(2) as usize;
+    let selected = overlay.selected.min(overlay.items.len().saturating_sub(1));
+    let start = if selected >= visible && visible > 0 {
+        selected + 1 - visible
+    } else {
+        0
+    };
+    let end = (start + visible).min(overlay.items.len());
+    let mut lines = Vec::new();
+    lines.push(Line::styled(
+        truncate_end(&overlay.help, inner.width as usize),
+        Style::default().fg(Color::DarkGray),
+    ));
+    for idx in start..end {
+        let item = &overlay.items[idx];
+        let marker = if idx == selected { "›" } else { " " };
+        let mut text = format!("{marker} {}", item.label);
+        if !item.detail.is_empty() {
+            text.push_str("  ");
+            text.push_str(&item.detail);
+        }
+        let style = if idx == selected {
+            theme::selection()
+        } else {
+            theme::menu()
+        };
+        lines.push(Line::styled(
+            truncate_end(&text, inner.width as usize),
+            style,
+        ));
+    }
+    f.render_widget(
+        Paragraph::new(Text::from(lines)).wrap(Wrap { trim: false }),
+        inner,
+    );
+}
+
 fn render_autofill_menu(f: &mut Frame<'_>, area: Rect, menu: &AutoFillMenu) {
     if area.height == 0 || menu.items.is_empty() {
         return;

src/ui/terminal.rs

@@ -27,3 +27,26 @@ pub fn leave(mut terminal: CassTerminal) -> Result<()> {
     terminal.show_cursor()?;
     Ok(())
 }
+
+pub fn suspend(terminal: &mut CassTerminal) -> Result<()> {
+    disable_raw_mode()?;
+    execute!(
+        terminal.backend_mut(),
+        LeaveAlternateScreen,
+        DisableMouseCapture
+    )?;
+    terminal.show_cursor()?;
+    Ok(())
+}
+
+pub fn resume(terminal: &mut CassTerminal) -> Result<()> {
+    enable_raw_mode()?;
+    execute!(
+        terminal.backend_mut(),
+        EnterAlternateScreen,
+        EnableMouseCapture
+    )?;
+    terminal.clear()?;
+    terminal.hide_cursor()?;
+    Ok(())
+}

tests/config_tests.rs

@@ -127,6 +127,37 @@ fn reasoning_defaults_to_supported_medium_for_model_metadata() {
     );
 }
 
+#[test]
+fn validation_accepts_chatgpt_codex_without_api_key() {
+    let providers = ProvidersFile {
+        providers: vec![ProviderDefinition {
+            id: config::CHATGPT_CODEX_PROVIDER_ID.into(),
+            name: Some(config::CHATGPT_CODEX_PROVIDER_NAME.into()),
+            kind: config::CHATGPT_CODEX_PROVIDER_KIND.into(),
+            base_url: config::CHATGPT_CODEX_RESPONSES_URL.into(),
+            api_key: String::new(),
+            default_model: Some(config::CHATGPT_CODEX_DEFAULT_MODEL.into()),
+            models: vec![config::CHATGPT_CODEX_DEFAULT_MODEL.into()],
+        }],
+    };
+    let models = ModelsFile {
+        models: vec![config::ModelDefinition {
+            id: config::CHATGPT_CODEX_DEFAULT_MODEL.into(),
+            provider: config::CHATGPT_CODEX_PROVIDER_ID.into(),
+            display_name: None,
+            context_length: None,
+            max_output_tokens: None,
+            supports_tools: true,
+            supports_streaming: true,
+            reasoning: Default::default(),
+        }],
+    };
+
+    let summary = config::validate_registries(None, &providers, &models);
+
+    assert!(summary.errors.is_empty(), "{:?}", summary.errors);
+}
+
 #[test]
 fn validation_rejects_duplicate_provider_ids() {
     let providers = ProvidersFile {

tests/conversation_tests.rs

@@ -23,3 +23,22 @@ fn conversation_appends_loads_and_lists_by_cwd() {
     assert_eq!(chats[0].id, convo.id);
     assert_eq!(chats[0].first_user_preview, "hello world");
 }
+
+#[test]
+fn legacy_meta_without_branch_fields_still_loads() {
+    let root = tempdir().unwrap();
+    let id = "legacy";
+    std::fs::write(
+        root.path().join(format!("{id}.jsonl")),
+        r#"{"type":"meta","chat_id":"legacy","created_at":"now","model":"m","cwd":"/tmp"}
+{"type":"system","content":"base"}
+"#,
+    )
+    .unwrap();
+
+    let (loaded, warning) = Conversation::load(root.path(), id).unwrap();
+    assert!(warning.is_none());
+    let meta = loaded.meta().unwrap();
+    assert_eq!(meta.parent_chat_id, None);
+    assert_eq!(meta.branch_from, None);
+}

tests/docs_tests.rs

@@ -59,6 +59,7 @@ fn expected_bundled_docs_exist() {
         "configuration.md",
         "providers.md",
         "access-modes.md",
+        "embedding.md",
         "workflows.md",
         "troubleshooting.md",
         "platforms.md",

tests/embedding_tests.rs

@@ -0,0 +1,315 @@
+use cassady::access::AccessMode;
+use cassady::config::ReasoningEffort;
+use cassady::conversation::Record;
+use cassady::embedding::{Event, SessionBuilder};
+use serde_json::json;
+use tempfile::tempdir;
+use wiremock::matchers::{body_string_contains, method, path};
+use wiremock::{Mock, MockServer, ResponseTemplate};
+
+fn sse(body: &str) -> ResponseTemplate {
+    ResponseTemplate::new(200).set_body_raw(body.as_bytes().to_vec(), "text/event-stream")
+}
+
+fn content_sse(content: &str) -> ResponseTemplate {
+    sse(&format!(
+        "data: {{\"choices\":[{{\"index\":0,\"delta\":{{\"content\":{}}}}}]}}\r\n\r\ndata: [DONE]\r\n\r\n",
+        serde_json::to_string(content).unwrap()
+    ))
+}
+
+fn tool_call_sse(id: &str, name: &str, arguments: &str) -> ResponseTemplate {
+    sse(&format!(
+        "data: {{\"choices\":[{{\"index\":0,\"delta\":{{\"tool_calls\":[{{\"index\":0,\"id\":\"{id}\",\"type\":\"function\",\"function\":{{\"name\":\"{name}\",\"arguments\":{}}}}}]}}}}]}}\r\n\r\ndata: [DONE]\r\n\r\n",
+        serde_json::to_string(arguments).unwrap()
+    ))
+}
+
+fn write_test_config(root: &std::path::Path, base_url: &str) {
+    std::fs::write(
+        root.join("providers.json"),
+        serde_json::to_string_pretty(&json!({
+            "providers": [{
+                "id": "test-provider",
+                "kind": "openai-compatible",
+                "base_url": base_url,
+                "api_key": "test-key",
+                "default_model": "test-model",
+                "models": ["test-model"]
+            }]
+        }))
+        .unwrap(),
+    )
+    .unwrap();
+    std::fs::write(
+        root.join("models.json"),
+        serde_json::to_string_pretty(&json!({
+            "models": [{
+                "id": "test-model",
+                "provider": "test-provider",
+                "context_length": 128,
+                "max_output_tokens": 64,
+                "reasoning": {
+                    "supported": true,
+                    "required": false,
+                    "default_effort": "off",
+                    "request_format": "reasoning_effort"
+                }
+            }]
+        }))
+        .unwrap(),
+    )
+    .unwrap();
+    std::fs::write(
+        root.join("config.json"),
+        serde_json::to_string_pretty(&json!({
+            "default_provider": "test-provider",
+            "default_model": "test-model",
+            "default_reasoning_effort": "off"
+        }))
+        .unwrap(),
+    )
+    .unwrap();
+}
+
+#[tokio::test]
+async fn embedded_session_runs_turn_and_streams_events() {
+    let server = MockServer::start().await;
+    Mock::given(method("POST"))
+        .and(path("/chat/completions"))
+        .respond_with(content_sse("Hello from embedded Cassady."))
+        .expect(1)
+        .mount(&server)
+        .await;
+
+    let root = tempdir().unwrap();
+    let cwd = tempdir().unwrap();
+    write_test_config(root.path(), &server.uri());
+
+    let session = SessionBuilder::new()
+        .config_root(root.path())
+        .cwd(cwd.path())
+        .access_mode(AccessMode::ReadOnly)
+        .reasoning_effort(ReasoningEffort::Off)
+        .build()
+        .await
+        .unwrap();
+
+    assert_eq!(session.model(), "test-model");
+    assert_eq!(session.access_mode(), AccessMode::ReadOnly);
+
+    let mut turn = session.start_turn("say hi").await.unwrap();
+    let mut streamed = String::new();
+    while let Some(event) = turn.next_event().await.unwrap() {
+        match event {
+            Event::AssistantChunk(chunk) => streamed.push_str(&chunk),
+            Event::Finished => break,
+            _ => {}
+        }
+    }
+    let session = turn.finish().await.unwrap();
+
+    assert_eq!(streamed, "Hello from embedded Cassady.");
+    assert!(session.records().iter().any(|record| matches!(
+        record,
+        Record::Assistant { content, .. } if content == "Hello from embedded Cassady."
+    )));
+    assert!(session.conversation_path().is_file());
+}
+
+#[tokio::test]
+async fn builder_overrides_config_for_model_endpoint_key_mode_and_reasoning() {
+    let server = MockServer::start().await;
+    Mock::given(method("POST"))
+        .and(path("/chat/completions"))
+        .and(body_string_contains("\"model\":\"test-model\""))
+        .and(body_string_contains("\"reasoning_effort\":\"low\""))
+        .respond_with(content_sse("Overrides worked."))
+        .expect(1)
+        .mount(&server)
+        .await;
+
+    let root = tempdir().unwrap();
+    let cwd = tempdir().unwrap();
+    write_test_config(root.path(), "https://wrong.example/v1");
+    let env_name = "CASSADY_EMBEDDING_TEST_KEY";
+    let old = std::env::var(env_name).ok();
+    std::env::set_var(env_name, "test-key-from-env");
+
+    let session = SessionBuilder::new()
+        .config_root(root.path())
+        .cwd(cwd.path())
+        .access_mode(AccessMode::WorkspaceEdit)
+        .model("test-model")
+        .base_url(server.uri())
+        .api_key_env(env_name)
+        .reasoning_effort(ReasoningEffort::Low)
+        .build()
+        .await
+        .unwrap();
+
+    assert_eq!(session.access_mode(), AccessMode::WorkspaceEdit);
+    assert_eq!(session.reasoning_effort(), ReasoningEffort::Low);
+
+    let mut turn = session.start_turn("check overrides").await.unwrap();
+    while let Some(event) = turn.next_event().await.unwrap() {
+        if matches!(event, Event::Finished) {
+            break;
+        }
+    }
+    let _session = turn.finish().await.unwrap();
+
+    if let Some(old) = old {
+        std::env::set_var(env_name, old);
+    } else {
+        std::env::remove_var(env_name);
+    }
+}
+
+#[tokio::test]
+async fn embedded_session_can_resume_existing_conversation() {
+    let server = MockServer::start().await;
+    Mock::given(method("POST"))
+        .and(path("/chat/completions"))
+        .respond_with(content_sse("First turn."))
+        .expect(1)
+        .mount(&server)
+        .await;
+
+    let root = tempdir().unwrap();
+    let cwd = tempdir().unwrap();
+    write_test_config(root.path(), &server.uri());
+
+    let session = SessionBuilder::new()
+        .config_root(root.path())
+        .cwd(cwd.path())
+        .access_mode(AccessMode::ReadOnly)
+        .build()
+        .await
+        .unwrap();
+    let mut turn = session.start_turn("first").await.unwrap();
+    while let Some(event) = turn.next_event().await.unwrap() {
+        if matches!(event, Event::Finished) {
+            break;
+        }
+    }
+    let session = turn.finish().await.unwrap();
+    let id = session.id().to_string();
+    let record_count = session.records().len();
+
+    let resumed = SessionBuilder::new()
+        .config_root(root.path())
+        .cwd(cwd.path())
+        .resume(&id)
+        .await
+        .unwrap();
+
+    assert_eq!(resumed.id(), id);
+    assert_eq!(resumed.records().len(), record_count);
+    assert!(resumed.resume_warning().is_none());
+}
+
+#[tokio::test]
+async fn embedded_approval_flow_can_approve_shell() {
+    let server = MockServer::start().await;
+    Mock::given(method("POST"))
+        .and(path("/chat/completions"))
+        .and(body_string_contains("exit code: 0"))
+        .respond_with(content_sse("Approved shell."))
+        .with_priority(1)
+        .expect(1)
+        .mount(&server)
+        .await;
+    Mock::given(method("POST"))
+        .and(path("/chat/completions"))
+        .respond_with(tool_call_sse(
+            "call_shell",
+            "shell",
+            r#"{"command":"touch marker"}"#,
+        ))
+        .with_priority(10)
+        .expect(1)
+        .mount(&server)
+        .await;
+
+    let root = tempdir().unwrap();
+    let cwd = tempdir().unwrap();
+    write_test_config(root.path(), &server.uri());
+    let marker = cwd.path().join("marker");
+
+    let session = SessionBuilder::new()
+        .config_root(root.path())
+        .cwd(cwd.path())
+        .access_mode(AccessMode::WorkspaceEdit)
+        .build()
+        .await
+        .unwrap();
+
+    let mut turn = session.start_turn("run shell").await.unwrap();
+    let mut saw_request = false;
+    let mut saw_resolved = false;
+    while let Some(event) = turn.next_event().await.unwrap() {
+        match event {
+            Event::ApprovalRequested(request) => {
+                saw_request = true;
+                assert_eq!(request.name, "shell");
+                assert!(!marker.exists());
+                turn.approve(&request.request_id).unwrap();
+            }
+            Event::ApprovalResolved { approved, .. } => {
+                saw_resolved = approved;
+            }
+            Event::Finished => break,
+            _ => {}
+        }
+    }
+    let session = turn.finish().await.unwrap();
+
+    assert!(saw_request);
+    assert!(saw_resolved);
+    assert!(marker.exists());
+    assert!(session.records().iter().any(|record| matches!(
+        record,
+        Record::Tool { name, ok, content, .. }
+            if name == "shell" && *ok && content.contains("exit code: 0")
+    )));
+}
+
+#[tokio::test]
+async fn read_only_embedding_does_not_advertise_mutating_tools() {
+    let server = MockServer::start().await;
+    Mock::given(method("POST"))
+        .and(path("/chat/completions"))
+        .respond_with(content_sse("Readonly."))
+        .expect(1)
+        .mount(&server)
+        .await;
+
+    let root = tempdir().unwrap();
+    let cwd = tempdir().unwrap();
+    write_test_config(root.path(), &server.uri());
+
+    let session = SessionBuilder::new()
+        .config_root(root.path())
+        .cwd(cwd.path())
+        .access_mode(AccessMode::ReadOnly)
+        .build()
+        .await
+        .unwrap();
+    let mut turn = session.start_turn("inspect only").await.unwrap();
+    while let Some(event) = turn.next_event().await.unwrap() {
+        if matches!(event, Event::Finished) {
+            break;
+        }
+    }
+    let _session = turn.finish().await.unwrap();
+
+    let requests = server.received_requests().await.unwrap();
+    let body = String::from_utf8_lossy(&requests[0].body);
+    assert!(body.contains("\"name\":\"ls\""));
+    assert!(body.contains("\"name\":\"read\""));
+    assert!(body.contains("\"name\":\"grep\""));
+    assert!(!body.contains("\"name\":\"write\""));
+    assert!(!body.contains("\"name\":\"edit\""));
+    assert!(!body.contains("\"name\":\"shell\""));
+}

tests/setup_tests.rs

@@ -5,7 +5,7 @@ use wiremock::matchers::{header, method, path};
 use wiremock::{Mock, MockServer, ResponseTemplate};
 
 #[test]
-fn provider_catalog_contains_expected_openai_compatible_providers() {
+fn provider_catalog_contains_expected_providers() {
     let catalog = setup::provider_catalog();
     let ids: Vec<_> = catalog.iter().map(|entry| entry.id).collect();
 
@@ -13,6 +13,7 @@ fn provider_catalog_contains_expected_openai_compatible_providers() {
         ids,
         vec![
             "openai",
+            "chatgpt-codex",
             "xai",
             "fireworks",
             "groq",
@@ -148,6 +149,33 @@ fn apply_setup_upserts_selected_provider_model_and_preserves_unrelated_entries()
     );
 }
 
+#[test]
+fn apply_setup_writes_chatgpt_codex_without_api_key() {
+    let root = tempdir().unwrap();
+
+    setup::apply_setup(
+        root.path(),
+        &SetupSelection {
+            provider_id: config::CHATGPT_CODEX_PROVIDER_ID.into(),
+            provider_name: config::CHATGPT_CODEX_PROVIDER_NAME.into(),
+            base_url: config::CHATGPT_CODEX_RESPONSES_URL.into(),
+            api_key_env: String::new(),
+            model_id: config::CHATGPT_CODEX_DEFAULT_MODEL.into(),
+            supports_tools: true,
+            supports_reasoning: true,
+        },
+    )
+    .unwrap();
+
+    let providers: ProvidersFile =
+        serde_json::from_str(&std::fs::read_to_string(root.path().join("providers.json")).unwrap())
+            .unwrap();
+    let provider = &providers.providers[0];
+    assert_eq!(provider.id, config::CHATGPT_CODEX_PROVIDER_ID);
+    assert_eq!(provider.kind, config::CHATGPT_CODEX_PROVIDER_KIND);
+    assert!(provider.api_key.is_empty());
+}
+
 #[test]
 fn apply_setups_writes_multiple_providers_and_active_choice() {
     let root = tempdir().unwrap();
@@ -197,6 +225,146 @@ fn apply_setups_writes_multiple_providers_and_active_choice() {
     );
 }
 
+#[test]
+fn remove_providers_removes_models_and_preserves_active_provider() {
+    let root = tempdir().unwrap();
+    let selections = vec![
+        SetupSelection {
+            provider_id: "openai".into(),
+            provider_name: "OpenAI".into(),
+            base_url: "https://api.openai.com/v1".into(),
+            api_key_env: "OPENAI_API_KEY".into(),
+            model_id: "gpt-4.1".into(),
+            supports_tools: true,
+            supports_reasoning: true,
+        },
+        SetupSelection {
+            provider_id: "groq".into(),
+            provider_name: "Groq".into(),
+            base_url: "https://api.groq.com/openai/v1".into(),
+            api_key_env: "GROQ_API_KEY".into(),
+            model_id: "llama-3.3-70b-versatile".into(),
+            supports_tools: true,
+            supports_reasoning: false,
+        },
+    ];
+    setup::apply_setups(root.path(), &selections, 0).unwrap();
+
+    let result = setup::remove_providers(root.path(), &["groq".to_string()]).unwrap();
+
+    assert_eq!(result.removed_provider_ids, vec!["groq"]);
+    assert_eq!(result.removed_model_count, 1);
+    assert_eq!(result.remaining_provider_count, 1);
+    assert_eq!(result.active_provider.as_deref(), Some("openai"));
+    assert_eq!(result.active_model.as_deref(), Some("gpt-4.1"));
+
+    let providers: ProvidersFile =
+        serde_json::from_str(&std::fs::read_to_string(root.path().join("providers.json")).unwrap())
+            .unwrap();
+    assert_eq!(providers.providers.len(), 1);
+    assert_eq!(providers.providers[0].id, "openai");
+
+    let models: ModelsFile =
+        serde_json::from_str(&std::fs::read_to_string(root.path().join("models.json")).unwrap())
+            .unwrap();
+    assert_eq!(models.models.len(), 1);
+    assert_eq!(models.models[0].provider, "openai");
+}
+
+#[test]
+fn remove_active_provider_selects_remaining_provider_and_model() {
+    let root = tempdir().unwrap();
+    let selections = vec![
+        SetupSelection {
+            provider_id: "openai".into(),
+            provider_name: "OpenAI".into(),
+            base_url: "https://api.openai.com/v1".into(),
+            api_key_env: "OPENAI_API_KEY".into(),
+            model_id: "gpt-4.1".into(),
+            supports_tools: true,
+            supports_reasoning: true,
+        },
+        SetupSelection {
+            provider_id: "groq".into(),
+            provider_name: "Groq".into(),
+            base_url: "https://api.groq.com/openai/v1".into(),
+            api_key_env: "GROQ_API_KEY".into(),
+            model_id: "llama-3.3-70b-versatile".into(),
+            supports_tools: true,
+            supports_reasoning: false,
+        },
+    ];
+    setup::apply_setups(root.path(), &selections, 1).unwrap();
+
+    let result = setup::remove_providers(root.path(), &["groq".to_string()]).unwrap();
+
+    assert_eq!(result.active_provider.as_deref(), Some("openai"));
+    assert_eq!(result.active_model.as_deref(), Some("gpt-4.1"));
+    let config: ConfigFile =
+        serde_json::from_str(&std::fs::read_to_string(root.path().join("config.json")).unwrap())
+            .unwrap();
+    assert_eq!(config.default_provider.as_deref(), Some("openai"));
+    assert_eq!(config.default_model.as_deref(), Some("gpt-4.1"));
+}
+
+#[test]
+fn remove_all_providers_clears_active_defaults() {
+    let root = tempdir().unwrap();
+    setup::apply_setup(
+        root.path(),
+        &SetupSelection {
+            provider_id: "openai".into(),
+            provider_name: "OpenAI".into(),
+            base_url: "https://api.openai.com/v1".into(),
+            api_key_env: "OPENAI_API_KEY".into(),
+            model_id: "gpt-4.1".into(),
+            supports_tools: true,
+            supports_reasoning: true,
+        },
+    )
+    .unwrap();
+
+    let result = setup::remove_providers(root.path(), &["openai".to_string()]).unwrap();
+
+    assert_eq!(result.remaining_provider_count, 0);
+    assert!(result.active_provider.is_none());
+    assert!(result.active_model.is_none());
+
+    let config: ConfigFile =
+        serde_json::from_str(&std::fs::read_to_string(root.path().join("config.json")).unwrap())
+            .unwrap();
+    assert!(config.default_provider.is_none());
+    assert!(config.default_model.is_none());
+
+    let models: ModelsFile =
+        serde_json::from_str(&std::fs::read_to_string(root.path().join("models.json")).unwrap())
+            .unwrap();
+    assert!(models.models.is_empty());
+}
+
+#[test]
+fn remove_unknown_provider_fails() {
+    let root = tempdir().unwrap();
+    setup::apply_setup(
+        root.path(),
+        &SetupSelection {
+            provider_id: "openai".into(),
+            provider_name: "OpenAI".into(),
+            base_url: "https://api.openai.com/v1".into(),
+            api_key_env: "OPENAI_API_KEY".into(),
+            model_id: "gpt-4.1".into(),
+            supports_tools: true,
+            supports_reasoning: true,
+        },
+    )
+    .unwrap();
+
+    let err = setup::remove_providers(root.path(), &["missing".to_string()]).unwrap_err();
+    assert!(err
+        .to_string()
+        .contains("provider `missing` is not configured"));
+}
+
 #[test]
 fn needs_initial_setup_detects_empty_and_default_only_roots() {
     let root = tempdir().unwrap();