quest: split Codex checkout release out of worktree-agents

quest/m0/README.md

@@ -42,7 +42,8 @@ ownership-manifest design:
 - [CI flakes](/quest/m0/ci-flakes.md) - native Windows tests and Release's macOS checks fail only on real breakage
 - [Review policy](/quest/m0/review-policy.md) - CONTRIBUTING.md says whose review counts
 - [Gate bench](/quest/m0/gate-bench.md) - measure headroom admission on an idle host
-- [Agent lifecycle integration](/quest/m0/worktree-agents.md) - reclaim completed and suspended checkouts through their harness
+- [Agent lifecycle integration](/quest/m0/worktree-agents.md) - reclaim completed and suspended Claude checkouts through its hooks
+- [Codex checkouts](/quest/m0/codex-checkouts.md) - Codex agents started by `quest agent` release their checkouts on exit
 - [Agent workflow helpers](/quest/m0/helpers/README.md) - CLI commands for CI waits, PR status, claims, quest moves, and serialized merges
 
 - [Kix decision UI](/quest/m0/kix/README.md) - planning and implementation through prompts and summaries, run on the maintainer's own runners

quest/m0/codex-checkouts.md

@@ -0,0 +1,25 @@
+# [S] Codex agents release their checkouts
+
+## Goal
+
+A Codex agent that `quest agent` starts runs inside `quest worktree run`, so
+its checkout is released when the agent exits and restored when it resumes,
+without waiting for the parent chat to end or the PR to merge. Codex app
+threads stay on Codex's native archive.
+
+## Plan
+
+Split 2026-10-26 from [Agent lifecycle integration](/quest/m0/worktree-agents.md),
+since it does not depend on the Claude hooks; the decision is recorded there.
+
+- Decided 2026-10-26 (user): Codex documents no worktree hooks, only a
+  recoverable archive and a 15-worktree retention, so `quest agent` runs the
+  harness inside `quest worktree run`, which releases on exit and restores on
+  resume. Codex app threads stay on Codex's native archive.
+- Exercise a finished agent, a suspended decision, a crash, and a resumed
+  session, and confirm each checkout is released or restored.
+
+## Related
+
+- [Agent lifecycle integration](/quest/m0/worktree-agents.md) - the Claude side of checkout release
+- [Headless agents](/quest/m0/helpers/headless-agents.md) - `quest agent` start, resume, and stop

quest/m0/helpers/headless-agents.md

@@ -45,4 +45,5 @@ every user would have to add it.
 
 ## Related
 
-- [Agent lifecycle integration](/quest/m0/worktree-agents.md) - reclaims the checkouts of finished and suspended agents, including headless ones
+- [Agent lifecycle integration](/quest/m0/worktree-agents.md) - reclaims the checkouts of finished and suspended Claude agents
+- [Codex checkouts](/quest/m0/codex-checkouts.md) - `quest agent` runs Codex inside `quest worktree run`, releasing its checkout on exit

quest/m0/worktree-agents.md

@@ -2,10 +2,10 @@
 
 ## Goal
 
-Quest workflows use `quest worktree` checkout ownership through supported
-Codex and Claude lifecycle integrations. A completed or suspended worker
-releases its checkout without waiting for the parent chat to end or the PR to
-merge.
+Quest workflows use `quest worktree` checkout ownership through Claude Code's
+lifecycle hooks. A completed or suspended worker releases its checkout without
+waiting for the parent chat to end or the PR to merge. Codex is
+[its own quest](/quest/m0/codex-checkouts.md).
 
 ## Plan
 
@@ -21,8 +21,7 @@ Remaining work:
   merging into an existing file, and `quest uninstall` removes exactly those
   entries.
 - Derived defaults for a checkout the hook creates, which gets only a `name`.
-- Codex through `quest agent` running the harness inside `quest worktree run`.
-- Exercise both harnesses with a finished worker under a still-live parent,
+- Exercise Claude with a finished worker under a still-live parent,
   a suspended decision, a crash, and a restored session. Confirm live that
   `SubagentStop`'s `cwd` is the subagent's worktree, and that a hook-created
   worktree passes Claude's isolation identity check. Reconcile existing
@@ -55,7 +54,9 @@ Decisions:
 - Decided 2026-10-26 (user): Codex, which documents no worktree hooks, is
   covered by `quest agent` running it inside `quest worktree run`, which
   releases on exit and restores on resume. Codex app threads stay on Codex's
-  native archive.
+  native archive. Split the same day into
+  [Codex checkouts](/quest/m0/codex-checkouts.md), since it does not depend
+  on the Claude hooks.
 - Decided 2026-10-26 (user): agents are capped only at the harness's
   concurrent sub-agent limit, stated once in the guide; the core-count cap is
   gone, since `quest gate` holds expensive commands. The 2026-10-15 decision