fix(hooks): guard subagent stops and rewake from the parent transcript

Two defects in the background-task hook scripts.

SubagentStop had no handler at all. When a subagent launched background work and
one watcher ended while others were still running, Claude could publish the
worker's last progress sentence as its final result, abandoning the live tasks.
A new guard pairs launched task IDs against completed ones and confirms liveness
by scanning /proc/<pid>/fd for an open tasks/<id>.output handle, blocking the
stop only while genuinely-live work remains. It fails open — allowing the stop —
when /proc is unavailable, nothing was launched, or everything finished.

The rewake helper watched only input.transcript_path. A subagent has its own
transcript, but Claude writes the completion queue-operation to the PARENT
transcript, so the record it waited for never appeared and the wake never fired.
It now watches both paths, but only when the relationship is provable: the
transcript's parent directory is subagents/ and its grandparent basename equals
input.session_id. It also now requires operation === 'enqueue'.

The rewake marker moves V2 -> V3; refreshStaleCodemanHooks treats absence of the
current marker as stale, so existing cases self-heal on next launch (the same
mechanism as the V1 -> V2 bump). Ownership matches on marker PREFIXES, so a
future bump still recognises older Codeman handlers and never adopts a user's.

12 tests fail on unmodified master, e.g.
  expected '[{"matcher":"Bash",…' to contain 'CODEMAN_BACKGROUND_REWAKE_V3'
  expected 'Background command bg-report-1 comple…' to contain '<codeman-background-result>'

docs/claude-code-hooks-reference.md

@@ -149,9 +149,17 @@ to Claude as a system reminder. This implies `"async": true`; ordinary async
 hooks do not wake an idle turn, and their output waits for the next interaction.
 
 Codeman uses this on `PostToolUse(Bash)`: a self-contained Node helper extracts
-the background task ID from the Bash result, watches the session transcript for
-the matching completion notification, and exits 2. It does not send terminal
-input, so it cannot submit a user's partially written prompt.
+the background task ID from the Bash result, watches the originating transcript
+and, for subagents, the top-level parent transcript for the matching completion
+notification, and exits 2. Claude records a subagent's Bash result in its
+`subagents/agent-*.jsonl` file but queues completion in the lead session JSONL.
+The task ID keeps each wake targeted. The helper does not send terminal input,
+so it cannot submit a user's partially written prompt.
+
+For script-dispatched Codex work, `codex-run.sh` writes the final response
+between `CODEMAN_RESULT_BEGIN/END` markers in the background task output. The
+rewake helper includes a maximum of 64 KiB of that report in its feedback. UI
+subagent discovery and dispatcher result delivery are separate contracts.
 
 ### Notification
 
@@ -219,6 +227,16 @@ Or to allow exit:
 
 **Use Cases**: Control nested loops, verify subagent output.
 
+The hook input includes `agent_id`, `agent_transcript_path`, and
+`last_assistant_message`. Like `Stop`, a command hook can return
+`{"decision":"block","reason":"..."}` to keep the subagent running and feed
+the reason back to it.
+
+Codeman uses this to prevent premature reports from workers that still own live
+Monitor or background-Bash processes. It derives candidate task IDs from the
+subagent transcript, but requires a matching live Linux process descriptor for
+`tasks/<id>.output`; historical task text by itself is not treated as active.
+
 ### TeammateIdle
 
 **When**: When an agent-team teammate is about to go idle.