Add todo mode and replace the plan with TODO.md

docs/operations.md

@@ -73,7 +73,7 @@ Agents don't commit; byre does. Each `user.message` event records `head`, the wo
 
 byre chooses the Claude session ID (`vendor_session_id`) up front, so every session can be resumed. Processes start on demand: the first message after a restart resumes the session with `--resume`. Sessions are `running` from the moment a turn is sent until its `result` arrives; on startup, every session still marked `running` was cut off mid-turn, and byre resumes it and sends a message telling the agent to re-check the working tree. Stopping the server kills all agent processes. Merging or discarding a task kills its sessions and marks them `completed`.
 
-Every session gets byre's guidance (`guidance` in `internal/agents/guidance.go`): ask questions with `ask_human`, end each turn with a final message that summarizes it (including every departure from the plan), don't commit (byre commits each turn), and don't push, touch other branches or run git maintenance. It is passed as `--append-system-prompt`, which Claude Code records on a session's first request and reuses on resume, so a running session keeps the text it started with; a `UserPromptSubmit` hook also attaches it as `additionalContext` to every user turn, which reaches existing sessions too.
+Every session gets byre's guidance (`guidance` in `internal/agents/guidance.go`): ask questions with `ask_human`, end each turn with a final message that summarizes it (including every departure from the plan), don't commit (byre commits each turn), and don't push, touch other branches or run git maintenance. A task started from a `TODO.md` item gets one more line naming the item and telling the agent to remove it from `TODO.md` in its worktree when the work is done (`taskGuidance`; see "Todo"). It is passed as `--append-system-prompt`, which Claude Code records on a session's first request and reuses on resume, so a running session keeps the text it started with; a `UserPromptSubmit` hook also attaches it as `additionalContext` to every user turn, which reaches existing sessions too.
 
 A Stop hook (`bounceProseQuestion` in `internal/agents/guidance.go`) bounces a turn whose final message asks the human something in prose: if `ask_human` wasn't called during the turn and the final message (`last_assistant_message`) has a sentence ending in `?` outside code spans, code blocks, quotes and blockquotes, the stop is blocked once with an instruction to ask through `ask_human`. The per-turn flags reset when the next user message is sent. Claude Code reports the block as a "Stop hook error" notification; that is expected. An agent told explicitly to ask in plain text will refuse the bounce.
 
@@ -102,6 +102,14 @@ Messages byre itself sends an agent (actor `byre`: the restart notice, Sync and
 
 The task switcher (⌘K, or the navbar crumb) lists active tasks with their session state and open inbox item count, live while it is open. Tasks with inbox items come first; within each group, the task least recently visited in this browser comes first (never-visited tasks before all others, ties in the server's order: projects by name, tasks newest first). Visit times are kept in the browser's localStorage under `byre.visits`, stamped when a task is selected and again when it is left. Typing filters them and adds a last row that creates a task with the typed text as its title, in the current task's project (the first project when no task is selected); Enter picks the highlighted row. Picking a task here or in the Tasks view selects it and, if neither pane shows the Transcript tab, switches a pane that isn't showing Tasks to it.
 
+## Todo
+
+A project's `TODO.md` is read from the root of its default branch in the project's checkout (`git cat-file blob <default branch>:TODO.md`), so it shows what has been merged, not uncommitted edits in the checkout. `GET /api/projects/{id}/todo` returns `exists` and the parsed `items` (`internal/todo`): every top-level list item (`-`, `*`, `+`, `1.` or `1)` at the start of a line) is an item. Its first line, with any `[ ]` checkbox removed, is its `title`; the lines indented under it (and lines continuing it without a blank line between) are its `body`, with the common indentation removed; `section` is the nearest heading above it. Checked items (`[x]`) are skipped, list markers inside fenced code don't count, and paragraphs between items are ignored.
+
+The title is the item's identity. `POST /api/projects/{id}/todo/tasks` with a `title` re-reads `TODO.md`, refuses an unknown title (404) or one an active task already has (409), creates a task from the default branch with that title and `todo_item` (the `tasks.todo_item` column, empty for other tasks), and starts its session as the requesting user with `todoPrompt` (`internal/agents/tasks.go`): the item as written, and an instruction to remove it from `TODO.md` in the worktree when the work is done. The agent's guidance names the item too (`taskGuidance`, see "Agent sessions"), so the instruction survives compaction and resumes. The agent removes the item on its own branch, so the removal lands on the default branch in the same squash commit as the work.
+
+The **Todo** tab lists each project's items, grouped by section, with each body rendered as Markdown. An item with an active task whose `todo_item` equals its title shows that task's session state as a link to the task instead of a **Start** button. **Start** posts the item with the composer's default model, selects the new task and shows its transcript. The tab fetches every project's `TODO.md` when it opens, when the project list changes, when the SSE stream reconnects, and refetches a project's on `task.merged`; a change pushed to the default branch outside byre shows the next time one of those happens.
+
 ## Inbox
 
 Agents ask questions with the `ask_human` MCP tool. Each question carries a `context` with the background the human needs to answer without reading the transcript, and its choices are written inline in that context as Markdown list items: `- ( ) text` for pick-one choices, with exactly one `- (*) text` marking the recommendation, or `- [ ] text` for pick-any choices, with `- [x] text` marking the recommended ones. There is no separate list of options. byre parses the choices out of `context` (`internal/agents/choices.go`; list items inside code fences and blockquotes don't count) and stores their text in the payload as `options`, with `multiple` (pick-any) and `recommended`. The UI renders the context as Markdown with a radio button or checkbox in place of each choice's marker. A malformed call (no `context` or `why_blocked`, fewer than two choices, pick-one and pick-any choices mixed, a pick-one question without exactly one recommendation, two choices with the same text, an unknown attachment kind, a foreign `thread_id`) is rejected with a message saying what to fix, and nothing is filed. The call returns the item's id as `question_id`. An agent withdraws a question it no longer needs answered (the human answered it in a chat message, say) with the `cancel_question` MCP tool and that id: an `open` question of its own session becomes `dismissed` with no `resolved_by` (its `inbox.updated` event has actor `agent`), which also stops a blocking one from holding back delivery; anything else is rejected with a message saying why. Each turn's final message (as a `report`) and each agent error (a turn that ends in error without a human interrupt, a process that dies mid-turn) also files an item.