fix(edit-history): review round 2 — whole lines around skipped ones, full-budget reads, orphan sweep

- Forward: after a line longer than the budget, the next line is read from
  its start instead of being skipped with it when it crosses the chunk end.
- Backward: the line before a skipped long line is read whole; a floor that
  turned out to be a line start no longer stalls.
- A chunk the shared forward budget cut short is not applied (it read as one
  over-long line) but read in a later pass, so a first open of a long main
  transcript reaches the subagents in the same sync.
- Load older reads a full budget block of up to three transcripts per click,
  taking turns, instead of splitting one budget (a normal Write longer than
  the share was skipped for good).
- A subagent transcript that vanished loses its cursor, so Load older does not
  stay on forever.
- POST /api/cleanup-state forgets the history of every record it drops; a
  startup sweep deletes edit-history files no session or record owns and
  stale tmp files of other processes.
- load() rebuilds entries from known fields (string diff lines, per-edit cap
  re-applied, ids counted against the byte cap), bounds pending Bash fields
  and agent ids, and does not parse a file over 32 MiB.
- No re-read after Codeman's own keep-alive turn.
- Tests: regression tests for each of the above (they fail on the previous
  commit); the remove-during-write test now meets the write under way; the
  sync and route tests remove their stores before the temp dir, so no late
  save recreates it in /tmp.

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

docs/api-reference.md

@@ -1087,13 +1087,13 @@ Lists are capped (300 files and 50 commits per repository) while the counts stay
 
 What the Edit history panel reads (Settings → Header & Panels → Header, per-device, default off): the edits a **local claude session** made, main agent and subagents, read from its transcripts. Read-only. Every route resolves the session through `findSessionOrFail` (another user's session is `404`). Remote, Docker and non-claude sessions answer `state: 'unsupported'` and are never read.
 
-`GET /api/sessions/:id/edits[?sync=1]` lists the stored edits, newest first, without diffs: `{ state, reason?, backfillTruncated, agents, entries }`. With `sync=1` it first reads what the transcripts gained since the last read; without it the server reads nothing. `state` is `ok`, `unavailable` (stored entries only; `reason` is `no-transcript` before the session has a transcript Codeman can find, or the read error; the transcript is the one the session's hooks report, else the newest `<id>.jsonl` under the session's `CLAUDE_CONFIG_DIR` override or the server's config dir) or `unsupported` (`reason`: `remote`, `docker`, `mode`). Each entry is `{ id, ts, path, relPath, kind: 'code'|'image', tool, created, added, removed, truncated, agentId? }`, where `tool` is the edit tool, `bash` for an image a Bash call produced or `sent` for one the agent sent; `relPath` is relative to the workspace (a subagent's worktree for its edits). `agents` maps a subagent id to `{ description, agentType, worktreeBranch? }`. `backfillTruncated: true` means older edits can still be loaded.
+`GET /api/sessions/:id/edits[?sync=1]` lists the stored edits, newest first, without diffs: `{ state, reason?, backfillTruncated, agents, entries }`. With `sync=1` it first reads what the transcripts gained since the last read; without it the server reads nothing. `state` is `ok`, `unavailable` (stored entries only; `reason` is `no-transcript` before the session has a transcript Codeman can find, `removed` once the session's history was deleted, or the read error; the transcript is the one the session's hooks report, else the newest `<id>.jsonl` under the session's `CLAUDE_CONFIG_DIR` override or the server's config dir) or `unsupported` (`reason`: `remote`, `docker`, `mode`). Each entry is `{ id, ts, path, relPath, kind: 'code'|'image', tool, created, added, removed, truncated, agentId? }`, where `tool` is the edit tool, `bash` for an image a Bash call produced or `sent` for one the agent sent; `relPath` is relative to the workspace (a subagent's worktree for its edits). `agents` maps a subagent id to `{ description, agentType, worktreeBranch? }`. `backfillTruncated: true` means older edits can still be loaded.
 
 `GET /api/sessions/:id/edits/:entryId` returns one edit's diff as unified text: `{ diff, truncated }` (each edit's diff is capped at 64 KiB). `404` for an edit the session does not have.
 
-`POST /api/sessions/:id/edits/older` reads the next older block of every transcript (main and subagents share the read budget) and answers like the list.
+`POST /api/sessions/:id/edits/older` reads the next older block of up to three transcripts, a full read budget each (with more transcripts, main and subagents take turns), and answers like the list.
 
-The edits are stored per session in `~/.codeman/edit-history/<id>.json` (mode 0600, at most 500 edits and 4 MiB of diff text, the oldest dropped), deleted when the session's record is removed (a killed pinned session keeps it) and never fed into `/api/v1/search`. No route here serves a file: the panel shows thumbnails through `file-raw` inside the workspace only; an image outside it opens in the file preview, which registers it through the attachment route.
+The edits are stored per session in `~/.codeman/edit-history/<id>.json` (mode 0600, at most 500 edits and 4 MiB of diff text, the oldest dropped), deleted when the session's record is removed (a killed pinned session keeps it; at startup, a file whose session no longer exists is deleted too) and never fed into `/api/v1/search`. No route here serves a file: the panel shows thumbnails through `file-raw` inside the workspace only; an image outside it opens in the file preview, which registers it through the attachment route.
 
 ## Git worktrees of a case
 

docs/architecture-invariants.md

@@ -726,13 +726,13 @@ Matching semantics: a query containing `/` matches the relative path, otherwise
 
 **Edit history panel** (issue #643; `showEditHistory`, per-device, default OFF): which files a local claude session edited (main agent and subagents), each edit's diff, and images a Bash call produced, read from the session's transcripts by byte offset, never from git. Parser `src/edit-history-parse.ts` (pure), store `src/edit-history-store.ts`, reader `src/edit-history-local-source.ts`, sync `src/web/edit-history-sync.ts`, routes `src/web/routes/edit-history-routes.ts` (`GET /api/sessions/:id/edits[?sync=1]`, `GET …/edits/:entryId`, `POST …/edits/older`, all through `findSessionOrFail` WITH `req`), panel `edit-history-ui.js`. User guide: `docs/wiki/Working-With-Files.md` § Edit history.
 
-⚠️ **Reads only on request, opt-in all the way down.** `server.ts` builds the `EditHistorySync` and hands it to the routes; its only own calls are `remove` (through `forgetEditHistory`, when the session's persisted record goes) and `flushAll` (shutdown). No hook, no timer, no second watcher. The panel drives every read: `?sync=1` when it opens, and while it is open on that session a debounced (600 ms) re-read after a `transcript:tool_end` of an edit-capable tool (Edit, Write, MultiEdit, NotebookEdit, Bash, Agent, Task, SendUserFile), which the existing `TranscriptWatcher` already broadcasts, or the session's `session:idle` (the end of a turn, via `_onSessionIdle`; it also catches a background subagent that writes after the tool end that started it). Not `transcript:complete`: it fires on a `result` line, which claude's interactive transcript never has. A closed panel reads nothing and keeps no badge. Guarded by the "reads only on request" wiring test in `test/edit-history-sync.test.ts`.
+⚠️ **Reads only on request, opt-in all the way down.** `server.ts` builds the `EditHistorySync` and hands it to the routes; its only own calls are `remove` (through `forgetEditHistory`, when the session's persisted record goes), `sweep` (startup) and `flushAll` (shutdown). No hook, no timer, no second watcher. The panel drives every read: `?sync=1` when it opens, and while it is open on that session a debounced (600 ms) re-read after a `transcript:tool_end` of an edit-capable tool (Edit, Write, MultiEdit, NotebookEdit, Bash, Agent, Task, SendUserFile), which the existing `TranscriptWatcher` already broadcasts, or the session's `session:idle` (the end of a turn, via `_onSessionIdle`; it also catches a background subagent that writes after the tool end that started it). Not `transcript:complete`: it fires on a `result` line, which claude's interactive transcript never has. A closed panel reads nothing and keeps no badge. Guarded by the "reads only on request" wiring test in `test/edit-history-sync.test.ts`.
 
 ⚠️ **Which transcript** (`resolveClaudeTranscript`). The main transcript is the path the session's `TranscriptWatcher` follows (the hook-reported `transcript_path`), so a session is read from where its claude really writes, whatever its `CLAUDE_CONFIG_DIR`. Without a watcher (server restarted, no hook since), `findClaudeTranscript()` looks for `<claudeSessionId|id>.jsonl` under `claudeProjectsDir(session.claudeConfigDir())`: the session's own override (#255, the same dir the relaunch pin checks), else the server's. A config dir set outside Codeman (a shell profile, a wrapper) is never guessed: until the next hook such a session answers `unavailable` / `no-transcript`, and the panel says so. Subagents are `<main path without .jsonl>/subagents/agent-<id>.jsonl`. A different main file (`/clear`, resume) is read from its end with fresh cursors; the stored entries stay.
 
-⚠️ **Bounded reads.** A sync is at most `MAX_FORWARD_PASSES` (3) reads, each at most `READ_BUDGET_BYTES` (8 MiB) shared by the main transcript and all subagents (main first); a first read starts that far before the end, and "Load older" reads one older block of every transcript, the budget split between them. A line longer than a read's budget is skipped, going forward and going back. Parsing happens in the request, line by line; nothing runs on the PTY data path. One sync per session at a time, and requests during a run fold into one more run.
+⚠️ **Bounded reads.** A sync is at most `MAX_FORWARD_PASSES` (3) reads, each at most `READ_BUDGET_BYTES` (8 MiB) shared by the main transcript and all subagents (main first); a first read starts that far before the end. A file whose chunk the shared budget cut short is not applied but read in a later pass (the store would take a chunk with no line end for one line longer than the budget). "Load older" reads a full-budget block of up to `MAX_OLDER_SOURCES` (3) transcripts per click; with more, they take turns. A line longer than the budget is skipped, going forward and going back, and the line after (before) it is read whole. A subagent transcript that vanished loses its cursor, not its entries. Parsing happens in the request, line by line; nothing runs on the PTY data path. One sync per session at a time, and requests during a run fold into one more run.
 
-⚠️ **The store holds secrets.** Every diff an agent wrote ends up in `dataPath('edit-history')/<sessionId>.json`, API keys and `.env` contents included. It is written 0600 via tmp + rename (a fresh file each time, so an existing store never keeps wider bits; a new directory is created 0700) and bounded per session: `MAX_ENTRIES` (500) and `MAX_STORE_BYTES` (4 MiB of diff text and paths), oldest dropped, also on load. Each edit's diff is capped at `MAX_HUNK_BYTES` (64 KiB); the file also holds at most `MAX_PENDING_BASH` (200) unanswered Bash calls of at most 8 KiB each and `MAX_AGENTS` (501) subagent labels of at most 1 KiB per string, and `load()` drops whatever in a damaged file breaks those bounds. Writes are serialized. The store lives as long as the session's persisted record: `forgetEditHistory` runs when `cleanupSession` with `killMux` removes the record (a pinned session's record is only demoted and keeps its history), on the persisted-only `DELETE /api/sessions/:id`, and for every record `cleanupStaleSessions` drops at startup. After `remove()` nothing writes the file again, neither a sync in flight nor a later request (the session answers `unavailable` / `removed`). The store is blocked in `isSensitivePath` (`/.codeman*/edit-history/`, same reasoning as `intents.json`) and never fed to `/api/search`.
+⚠️ **The store holds secrets.** Every diff an agent wrote ends up in `dataPath('edit-history')/<sessionId>.json`, API keys and `.env` contents included. It is written 0600 via tmp + rename (a fresh file each time, so an existing store never keeps wider bits; a new directory is created 0700) and bounded per session: `MAX_ENTRIES` (500) and `MAX_STORE_BYTES` (4 MiB of diff text, paths and ids), oldest dropped, also on load. Each edit's diff is capped at `MAX_HUNK_BYTES` (64 KiB); the file also holds at most `MAX_PENDING_BASH` (200) unanswered Bash calls of at most 8,192 characters of command text each and `MAX_AGENTS` (501) subagent labels of at most 1,024 characters per string. `load()` takes the file as untrusted: one over `MAX_FILE_BYTES` (32 MiB) is not parsed, and the rest is rebuilt from its known fields under the same bounds (unknown fields and non-string diff lines dropped, the per-edit cap applied again). Writes are serialized. The store lives as long as the session's persisted record: `forgetEditHistory` runs when `cleanupSession` with `killMux` removes the record (a pinned session's record is only demoted and keeps its history), on the persisted-only `DELETE /api/sessions/:id`, for every record `cleanupStaleSessions` drops at startup and every one `POST /api/cleanup-state` drops. After that startup cleanup, `sweep` deletes the `edit-history/*.json` files whose session is neither live nor recorded (left behind by a crash between removing the record and deleting the file, or by an older build) and tmp files of other processes. After `remove()` nothing writes the file again, neither a sync in flight nor a later request (the session answers `unavailable` / `removed`). The store is blocked in `isSensitivePath` (`/.codeman*/edit-history/`, same reasoning as `intents.json`) and never fed to `/api/search`.
 
 ⚠️ **Images only through existing file surfaces.** A Bash image candidate counts only when the file's mtime lies in the call's window (start − 2 s … end + 2 s) and no entry already covers that file version; `SendUserFile` images need no window. The panel shows a thumbnail only inside the workspace, through the confined `file-raw` route. An image outside it gets no thumbnail (each would mint an attachment id per render); a click opens the shared file preview, which registers it once through `POST /api/sessions/:id/attachments` with `notify: false` (its extension allowlist and `isSensitivePath` apply). SVGs get no thumbnail. No route of this feature serves a file, least of all a transcript path.
 

docs/wiki/Working-With-Files.md

@@ -269,12 +269,12 @@ Click it for a draggable window listing the active session's edits, newest first
   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. Images outside the workspace show no thumbnail. Click one to open it in the
-  preview.
+  a thumbnail: a `.png`, `.jpg`, `.gif`, `.webp`, `.avif` or `.svg` 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. Images outside the workspace and SVGs 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.
+  subagents' alike (up to three transcripts per click; with more, they take turns).
 
 It works for local Claude sessions only. Remote (SSH), Docker and other CLIs' sessions say so instead.
 
@@ -294,7 +294,7 @@ How it reads:
   `~/.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 when you delete
-  the session. A pinned session you kill keeps its record and its history until you unpin and
+  the session (a file left behind, by a crash for instance, goes at the next start). 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. An image outside it opens like any clicked path outside the workspace (no