feat(edit-history): edit history panel for local claude sessions

Part 1 of #643 (local sessions only; remote follows as its own PR). An
opt-in, per-device header button opens a panel with the active session's
edits, newest first: every Edit/Write/MultiEdit/NotebookEdit of the main
agent and its subagents with its diff, plus images a Bash call rendered or
the agent sent. Remote, Docker and non-claude sessions answer `unsupported`.

- Reads only on request: `?sync=1` when the panel opens; while it is open on
  that session it re-reads after an edit-capable `transcript:tool_end` or a
  `transcript:complete` from the existing transcript watcher. No hook, timer,
  second watcher or new SSE event; a wiring guard pins it.
- Main transcript: the path the transcript watcher follows (hook-reported),
  else `<id>.jsonl` under the session's own CLAUDE_CONFIG_DIR override or
  the server's config dir. A config dir set outside Codeman is found with
  the next hook; until then the panel says so.
- Store: dataPath('edit-history')/<id>.json, 0600 via tmp+rename, capped at
  500 entries and 4 MiB of diff text per session, deleted with the session,
  blocked in isSensitivePath, never fed to /api/search. Every route goes
  through findSessionOrFail with req.
- Images only through existing file surfaces: file-raw inside the
  workspace, the attachment route with notify:false outside it.
- textContent rendering, bounded byte-offset reads, marker-class header
  button, hidden on phones (locked in the mobile policy test).

Docs: Working-With-Files, Settings-Reference, architecture invariants, API
reference, CLAUDE.md key pattern.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

docs/wiki/Settings-Reference.md

@@ -61,7 +61,7 @@ supervised by systemd or launchd; npm installs report as non-updatable. See
 Chips for every optional header control, with a live preview of the resulting header:
 
 Run, Font Size, System Stats, Redraw Terminal, Response Viewer, Away Digest, Session
-Manager, Attachments, File Viewer, Multi-monitor, Split, Tiles, Plan Usage, Lifecycle Log, Monitor,
+Manager, Attachments, Edit history, File Viewer, Multi-monitor, Split, Tiles, Plan Usage, Lifecycle Log, Monitor,
 Project Insights, File Browser, Subagents, Approvals Inbox, Read My Mind, Ultracode Agents,
 Ultracode Windows, Cron.
 
@@ -77,6 +77,12 @@ several projects. **Git status: git timeout** (per device, 5 to 120 seconds, def
 long one git command may run before that repository is reported as unreadable; raise it for
 repositories on a slow network share.
 
+**Edit history** (per device, off by default, never on phones) adds a header button for the
+active session's edit history: every edit the agent and its subagents made, with its diff, and
+images it produced. Local Claude sessions only. Nothing is read until you open the window, and it
+stores those diffs (secrets included) under `~/.codeman/edit-history/`; see
+[Working With Files](Working-With-Files#edit-history).
+
 Most default to off. The stock desktop header is system stats, File Viewer, Tiles, and the gear.
 **Header Stats Style** picks how the system stats and plan usage are drawn: *Compact*
 (default; two pills with a ring beside every value), *Tiles* (label over value with a bar underneath) or *As before* (the bars and the `5H · 7D` chip). Desktop only, per device.

docs/wiki/Working-With-Files.md

@@ -253,6 +253,52 @@ that repository's own configuration on the host). The
 data comes from `GET /api/sessions/:id/git-status` and `GET /api/sessions/:id/git-diff`
 (see the [API reference](https://github.com/Ark0N/Codeman/blob/master/docs/api-reference.md)).
 
+## Edit history
+
+The Git panel shows what is different now. The edit history shows what the agent did, one edit
+at a time, including edits that were later undone or committed. Turn on **App Settings → Header &
+Panels → Header → Edit history** (per device, off by default) and a clock button appears in the
+header next to Attachments. It is not shown on phones.
+
+Click it for a draggable window listing the active session's edits, newest first:
+
+- One row per Edit, Write or MultiEdit, with `new` for a file the agent created, `edit` otherwise,
+  and the lines added and removed. **Click a row** to see that edit's diff inline, coloured like the
+  Git panel; a diff over 64 KB is cut short. **Click the path** to open the file in the preview.
+- Edits made by subagents carry a chip with the subagent's task; hover it for the agent type and
+  its worktree branch. **Main agent only** hides them. **Group by file** puts the edits under
+  their file, with the totals on the file's row.
+- Images an agent produced with a shell command (a render, a plot, a screenshot) appear as rows with
+  a thumbnail: a `.png`, `.jpg`, `.gif`, `.webp` or `.avif` path named in the command or its output
+  counts when the file's modification time falls within that command's run. Images the agent sent
+  you count as well. Click one to open it in the preview.
+- **Load older** reads further back in the conversation.
+
+It works for local Claude sessions only. Remote (SSH), Docker and other CLIs' sessions say so instead.
+
+How it reads:
+
+- **Only while you look.** The history is read from the session's Claude transcript when you open
+  the window, and again after each edit while it stays open on that session. A closed window reads
+  nothing, and Codeman does no work in the background for sessions nobody looks at.
+- **The transcript is found through the session's hooks.** Each prompt tells Codeman where the
+  session's transcript is. Right after a server restart, before the next prompt, Codeman looks in
+  the session's `CLAUDE_CONFIG_DIR` if you set one for it in Codeman, else in the default config
+  directory. A `CLAUDE_CONFIG_DIR` set outside Codeman (in a shell profile or a wrapper script)
+  is only known after the next prompt; until then the window says "No transcript found for this
+  session yet".
+- **The history is stored, and it holds secrets.** Every diff an agent wrote is copied to
+  `~/.codeman/edit-history/<session-id>.json`, including API keys or `.env` contents it edited. The file is
+  readable by your user only, capped at 500 edits and 4 MiB of diff text per session (the oldest
+  are dropped), never part of search, blocked from every file route, and deleted with the session.
+- **Images go through the existing file routes.** A thumbnail inside the workspace uses the File
+  Viewer's route; one outside it is registered like a clicked path (no notification, same
+  file-type allowlist and sensitive-file blocklist). No new route serves a file.
+
+The data comes from `GET /api/sessions/:id/edits`, `GET /api/sessions/:id/edits/:entryId` and
+`POST /api/sessions/:id/edits/older` (see the
+[API reference](https://github.com/Ark0N/Codeman/blob/master/docs/api-reference.md)).
+
 ## Gotchas
 
 - **The viewer follows the active session's workspace.** Switching tabs changes what you are