feat(hooks): add Codex lifecycle snapshots and bounded context

[davidfilat]

Codex users can now opt into project-local brain context with brain install-hooks --agent codex and remove it with brain uninstall-hooks --agent codex. The existing Claude Code default is preserved. Fixes #22.

The shared installer preserves unrelated settings and hook commands, rejects foreign scripts and symlinks, and installs one SessionStart handler for startup, resume, clear, and compaction. The hook uses the existing CLI to resolve redirected brains, fails open, and limits Codex execution to five seconds.

Codex snapshots retain complete UTF-8 rows within 8 KiB and direct the agent to fetch the full index when truncated. Codex wiring complements Astra's native notes/history with page references and current-page reads. Installation never changes model settings, enables experiments, or writes memory automatically.

Validation

• All 49 tests pass on Node 18.20.8, 20.20.2, and 22.22.2.
• Pinned Codex CLI 0.153.4 with an isolated configuration and local mock Responses endpoint: verified configuration discovery/trust, startup, resume after app-server restart, and manual/automatic compaction context delivery in model requests.
• A synthetic slow CLI timed out after 5,003 ms; the Codex turn still completed.
• A 500-page multilingual fixture shrank from 22,321 to 8,164 injected bytes; five-run median latency was 62.6 ms uncapped versus 64.4 ms bounded. This is an output-size improvement, not a claimed latency or token-count improvement.

Compatibility limits

Codex CLI 0.153.4 is the tested supported baseline; older releases were not validated. The hook requires Node 18+ and POSIX sh/awk. Its generated absolute command requires uninstalling before moving a project and reinstalling at the destination.

Live Astra experimental-rollover recall and desktop behavior remain unverified. The available sign-in cannot exercise the launch-gated experiment, and a mock endpoint does not prove native notes/history behavior. The documentation explicitly retains wired instructions and CLI reads as the fallback.

[robinv8]

Summary

This is a careful, opt-in Codex SessionStart integration that keeps the Claude Code default intact. The shared installer quotes absolute Codex commands, refuses symlinks and foreign scripts, merges without clobbering unrelated hook groups, and the hook fails open, resolves brainRoot, covers startup|resume|clear|compact, and prefix-truncates to 8 KiB of whole UTF-8 rows. Hook tests (19/19) pass locally; remaining nits are generated-text formatting and one jargon comment in the shipped script.

Issue counts by severity

• bugs: 0
• suggestions: 1
• nits: 1

[robinv8]

Thanks for the Codex hooks — merged.