fix(edit-history): review round 1 — record-bound deletion, load-time bounds, older reads per source

- The history is deleted when the session's persisted record goes (forgetEditHistory):
  kill via cleanupSession (a pinned record is only demoted and keeps it), the
  persisted-only DELETE, and stale cleanup at startup. After remove() neither a sync in
  flight nor a later request writes the file again; writes are serialized.
- load() re-bounds a damaged file: cursors, pending Bash calls (MAX_PENDING_BASH) and
  subagent labels (MAX_AGENTS, oldest unused dropped first).
- Load older reads one block of every transcript, budget split between them, and only
  the files it asked for; a block short of budget reads its end. A line longer than the
  budget is skipped going back as well (floorMidLine).
- Concurrent first callers share one store; a forward request folded with an older one
  still reads forward.
- Images outside the workspace get no thumbnail (one attachment id per render); a click
  opens the shared preview, which registers once with notify: false.
- Docs: per-edit diff cap, deletion rule, load-time bounds, thumbnails, follow triggers.

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

docs/wiki/Working-With-Files.md

@@ -262,7 +262,7 @@ 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,
+- One row per Edit or Write, 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
@@ -271,16 +271,19 @@ Click it for a draggable window listing the active session's edits, newest first
 - 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.
+  you count as well. Images outside the workspace show no thumbnail. Click one to open it in the
+  preview.
+- **Load older** reads further back in the conversation, in the main agent's transcript and the
+  subagents' alike.
 
 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 window, and again after each tool call that can change files and at the end of each turn,
+  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
@@ -290,10 +293,12 @@ How it reads:
 - **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.
+  are dropped), never part of search, blocked from every file route, and deleted when you delete
+  the session. A pinned session you kill keeps its record and its history until you unpin and
+  delete it.
 - **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.
+  Viewer's route. An image outside it opens like any clicked path outside the workspace (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