fix(edit-history): a remote read with many subagents spans several round trips

The read script carries one case line per subagent cursor, and the whole
script is one argument of the ssh line, which Linux caps at 128 KiB. From
about 1000 subagents the command failed with E2BIG. The cursors have no cap
and the stored conversation is read first, so the session stayed unavailable
and not even a /clear got past it.

A read with more than 300 subagent requests now takes several round trips.
The cut is by name range, not only by count: the script takes a file no case
line names for a new one, so plain groups would read each other's files as
new. Each round trip walks only the names between its cuts, through one awk,
so a new file lands in exactly one range. Budget and meta budget carry over,
and a later round trip still lists its files, because a requested file missing
from the result loses its cursor. A failed round trip fails the whole read and
nothing of it reaches the store. A read of up to 300 runs no awk at all.

Each round of the 60-seed fuzz is also cut at a random size and compared with
the local reader. Run outside the suite too: bash --posix, BusyBox and mawk,
and bash 3.2 in a container, which is macOS sh. That shell cannot parse a case
inside $(...), so the names come from a shell function.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/architecture-invariants.md

@@ -768,7 +768,9 @@ Matching semantics: a query containing `/` matches the relative path, otherwise
 
 Paths, agent descriptions and diff lines render via `textContent` only (browser test with a hostile path). The header button uses the marker-class pattern (`btn-edit-history--hidden`) and stays off phones (`mobile.css`, locked in `test/mobile-header-buttons-policy.test.ts`). Docker and non-claude sessions answer `unsupported` and are never read.
 
-⚠️ **Remote (SSH) sessions: read over ssh, never woken.** The sync stays path-based; its deps get the session, and `server.ts` routes them to the local reader or to `remote-files.ts`. `transcriptPath` is one ssh round trip (`buildRemoteClaudeTranscriptLocateCommand`): first the conversation the claude process in the session's remote pane writes now (its `<config dir>/sessions/<pid>.json`, found through the pane's process tree, since a remote host sends Codeman no hooks), else the most recently written `<config dir>/projects/*/<id>.jsonl` of the stored history's conversation, `<claudeSessionId>` and `<id>` (`remoteTranscriptIds`; nothing moves `claudeSessionId` after a remote `/clear`, and no fixed order is right both after a `/clear` and after a respawn that resumed the launch conversation); the result is an absolute path on the host. A read pass is one more round trip (`buildRemoteClaudeEditSourcesCommand`) with the local reader's semantics: offset clamped to the size, a block with `len` ends at `offset + len`, a new file reads its tail, one budget shared main-first, `onlyRequested` for "Load older", at most 8 KiB of `meta.json` per subagent (within a 4 MiB meta budget). `test/remote-edit-sources.test.ts` runs both scripts on a real `sh` against a temp `$HOME` and compares the read byte for byte with `readClaudeEditSources` on seeded random transcripts, so `/clear` catch-up, "Load older", cursors and the store LRU behave remotely as locally. Every request value reaches the script only after validation (id `[A-Za-z0-9._-]`, relPath `main` or `subagents/agent-<id>.jsonl`, integer offsets) and shellescaped; the scripts run under `sh -c` with `LC_ALL=C`. The config dir is an absolute `CLAUDE_CONFIG_DIR` of the ssh command's environment, else `$HOME/.claude` (claude's own rule); the remote claude runs under `$SHELL -i -l -c`, the lookup under a plain `sh`, so a value set only in a login or interactive profile (`.profile`, `.bash_profile`, `.zshrc`) is not seen. A read's timeout grows with its byte cap (`remoteEditSourcesTimeoutMs`: 30 s plus the transfer at 256 KiB/s), since a forward pass may carry 13 MiB and "Load older" 29 MiB. ⚠️ **Never wakes:** the reads go through `buildRemoteFileCommand` + `runWithRemoteSshLimit` (`ConnectTimeout=10`), so a sleeping host is a connect timeout and the panel shows `unavailable` with the stored entries; the edit-history read path reaches neither `remote-wake.ts` nor `session-routes.ts`, even transitively (guard in `test/remote-edit-sources.test.ts`). Without hooks there is no `transcript:tool_end`, so an open panel re-reads on `session:idle` and the refresh button only.
+⚠️ **Remote (SSH) sessions: read over ssh, never woken.** The sync stays path-based; its deps get the session, and `server.ts` routes them to the local reader or to `remote-files.ts`. `transcriptPath` is one ssh round trip (`buildRemoteClaudeTranscriptLocateCommand`): first the conversation the claude process in the session's remote pane writes now (its `<config dir>/sessions/<pid>.json`, found through the pane's process tree, since a remote host sends Codeman no hooks), else the most recently written `<config dir>/projects/*/<id>.jsonl` of the stored history's conversation, `<claudeSessionId>` and `<id>` (`remoteTranscriptIds`; nothing moves `claudeSessionId` after a remote `/clear`, and no fixed order is right both after a `/clear` and after a respawn that resumed the launch conversation); the result is an absolute path on the host. A read pass is one more round trip (`buildRemoteClaudeEditSourcesCommand`), or several with more than 300 subagent requests (below), with the local reader's semantics: offset clamped to the size, a block with `len` ends at `offset + len`, a new file reads its tail, one budget shared main-first, `onlyRequested` for "Load older", at most 8 KiB of `meta.json` per subagent (within a 4 MiB meta budget per read, which the local reader does not have: a meta comes only with a subagent's first read, so one past the budget is never sent and that subagent shows its id instead of its description). `test/remote-edit-sources.test.ts` runs both scripts on a real `sh` against a temp `$HOME` and compares the read byte for byte with `readClaudeEditSources` on seeded random transcripts, so `/clear` catch-up, "Load older", cursors and the store LRU behave remotely as locally. Every request value reaches the script only after validation (id `[A-Za-z0-9._-]`, relPath `main` or `subagents/agent-<id>.jsonl`, integer offsets) and shellescaped; the scripts run under `sh -c` with `LC_ALL=C`. The config dir is an absolute `CLAUDE_CONFIG_DIR` of the ssh command's environment, else `$HOME/.claude` (claude's own rule); the remote claude runs under `$SHELL -i -l -c`, the lookup under a plain `sh`, so a value set only in a login or interactive profile (`.profile`, `.bash_profile`, `.zshrc`) is not seen. A round trip's timeout grows with its byte cap (`remoteEditSourcesTimeoutMs`: 30 s plus the transfer at 256 KiB/s), since a forward pass may carry 13 MiB and "Load older" 29 MiB. ⚠️ **Never wakes:** the reads go through `buildRemoteEditHistoryCommand` (`buildRemoteFileCommand` with `exec`, so a timeout reaches ssh and not only the local `sh -c`, which on dash stays its parent) + `runWithRemoteSshLimit` (`ConnectTimeout=10`), so a sleeping host is a connect timeout and the panel shows `unavailable` with the stored entries; the edit-history read path reaches neither `remote-wake.ts` nor `session-routes.ts`, even transitively (guard in `test/remote-edit-sources.test.ts`). Without hooks there is no `transcript:tool_end`, so an open panel re-reads on `session:idle` and the refresh button only.
+
+⚠️ **A read with more than 300 subagent requests spans several round trips** (`planRemoteEditSourceRounds`, `EDIT_SOURCE_REQUESTS_PER_ROUND_TRIP`). The script is one argument of the ssh line, Linux caps a single argv string at 128 KiB (`E2BIG` at about 1000 subagents), the cursors have no cap and the stored conversation is read first, so one script for all of them left a long history `unavailable`, and not even a `/clear` got past it. The cut is by NAME RANGE, not only by count: the script takes a file no `case` line names for a new one (its tail, its meta), so plain groups would read each other's files as new. Each round trip walks only the names between its cuts (one `awk` per round trip, never a fork per file), so a new file lands in exactly one range. Main comes with the first round trip, budget and meta budget carry over, and a later round trip still lists its files, because a requested file missing from the result loses its cursor. A failed round trip fails the whole read and nothing of it reaches the store; each one takes its own limiter slot. The merged result equals the local reader's, byte for byte (the fuzz test cuts every read at a random size). A read of up to 300 runs no `awk` at all. ⚠️ No `case` inside a `$(…)`: bash 3.2, macOS `sh`, cannot parse it, which is why the names come from a shell function.
 
 ### Config backups
 

docs/remote-sessions.md

@@ -419,7 +419,7 @@ still has it.
 
 **Not available over ssh (by choice, not by accident):** editing a file (writes would
 need SFTP; `docs/file-viewer-edit-plan.md` §6), office-document previews and
-generated thumbnails (both need the bytes on the server's disk — no remote file is ever
+generated thumbnails (both need the bytes on the server's disk: no remote file is ever
 spilled onto the server, the Edit history store's diffs being the one exception), the
 file-tree/picker listings, and `tail-file`. Those routes
 are still local-only, so with an `sshfs` mount in place they read the mounted copy —