Address the D agentType removal + two #124 review findings on the CC bridge's
subagent points:
- **Payloads from base()**: `subagentStart/StopPayload` bypassed `base()`, so the
SubagentStart/SubagentStop stdin payloads omitted the CC-promised `session_id`
and `cwd`. Replaced both with a single `subagentPayload()` built from `base(child)`
(the child's session_id/cwd when the child is available) + `agent_id` +
`agent_type` (+ `stop_hook_active` on Stop).
- **SubagentStop runs in the child cwd**: the listener called `runPoint(..., {})`
with no agent, so the hook ran in the executor/server cwd. It now looks the
child up via `ctx.get('agents').get(info.id)` — still recoverable because
`subagent/end` fires from the service's detached `.then` BEFORE the tool caller
disposes the child — and passes `{ agent: child }`, matching SubagentStart.
New regression: server cwd ≠ child cwd, a `pwd` SubagentStop hook proves it
ran in the CHILD workspace (proven red by neutering the lookup).
- **agent_type is a constant**: `info.agentType` no longer exists (removed on the
subagent branch); both points now report the `SUBAGENT_TYPE = "general-purpose"`
constant (Claude Code's Task-tool default), so a hooks.json default/`*`/empty
`agent_type` matcher fires. Updated the README matcher-subject note and the
bridge/coverage tests (dropped their agentType emits).
- **e2e comment**: hooks.e2e.ts said `./hooks.json` loads from the session cwd;
corrected to process-level (server launch cwd), with the hook itself running
in the session cwd.