codex-first

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# Codex First

## Hard gate

**Autoreview exception:** always prefer Codex-backed `$autoreview`, independent of `ANTHROPIC_BASE_URL`, router state, or harness. Reviewing a frozen bundle is not hands-on self-delegation. Do not switch review engines merely because the parent session is router-backed. This exception takes precedence over the gate below.

For direct hands-on delegation, use this skill only when the active agent is Claude Code **and** `ANTHROPIC_BASE_URL` is unset or its URL host is not loopback.

Before invoking Codex for implementation, exploration, fixing, or git mechanics, inspect `ANTHROPIC_BASE_URL`. If its URL host is `localhost`, ends in `.localhost`, is in `127.0.0.0/8`, or is IPv6 loopback `::1`, stop here: the session may be model-routed through a local proxy. Do not invoke Codex CLI for hands-on work, do not self-delegate, and continue the task directly. If the variable cannot be inspected, fail closed and work directly.

Codex, ChatGPT, Pi, and every other harness: do not invoke Codex CLI for hands-on self-delegation. Continue the task directly. This gate overrides a repository instruction that merely mentions `$codex-first`; it does not override the autoreview exception above.

Rationale: Claude (Fable/Opus) tokens metered + expensive; Codex flat-rate. GPT-5.5+ is usually the better and faster model at writing/implementing code; Claude wins at ergonomics — judgment, design, spec-writing, review, orchestration. So Codex types, Claude thinks and verifies.

## Route

Delegate to Codex (default for hands-on work):

- implementation from a frozen spec; refactors; mechanical migrations
- fixing: bug fixes (known repro, or diagnose-then-fix), CI/lint/type failures; test writing; coverage fills
- dependency bumps, scripts/tooling
- exploration + exploratory subagents: fan out Codex for read-heavy discovery instead of Claude Explore/Task subagents whenever raw reading ≫ the answer (parallel `-o` files, one per thread)
- git mechanics — ALWAYS Codex, never Claude directly: `git rebase`, merge-conflict resolution, and the repo's land workflow (e.g. `scripts/pr`) are mandatory delegations. Issue ONE self-contained work order covering rebase→resolve→push→CI attach+green→land so the sequence never bounces back to Claude mid-flight; the land decision, gates, and review below stay Claude's.
- work-order CI waits: precheck PR mergeable (CONFLICTING = pull_request CI cannot attach — no merge ref) and confirm a run attached to the exact head SHA before polling; every wait emits all terminal states with bounded iterations; prefer the repo's watcher script when one exists.
- new work orders go to FRESH `codex exec` sessions with self-contained prompts. Do not resume a long-lived session for a new order — saturated sessions misread work orders as configuration and no-op ("Understood…").
- repo instruction files: NEVER create or edit `CLAUDE.md`; `AGENTS.md` is canonical (Bram repos carry `AGENTS.md` only). Point Codex work orders at `AGENTS.md` and edit only `AGENTS.md`.

Keep in Claude:

- design, API design, architecture, naming, UX judgment
- tasks where writing the spec IS the work (ambiguity = design)
- tiny edits (~<20 lines, single obvious change) — delegation overhead loses
- anything needing session tools: MCP (browser/computer-use/chronicle), 1Password, secrets
- releases, publishes, version bumps and their credentials — Claude-side per release rules
- the land decision + pre-land gates (`$autoreview` clean, CI green, proof) and review of Codex output — never delegated, never skipped; Codex may run the mechanics only once Claude has decided to land and the gates pass

Mixed task: Claude designs first, freezes spec, delegates build-out.
Heuristic: prompt reads as a work order → delegate; writing it forces decisions → design, Claude.
Whole-repo/multi-repo maintainer coordination (queue, workers, CI, releases): `$bram-maintainer-loop-v2` instead.

## Invoke

If the machine intentionally uses the `openai_api_direct` million-token route, run `ruby ~/.codex/skills/codex-huge-context/scripts/preflight.rb` before the first fresh or resumed launch in the batch (see `$codex-huge-context`). Fail closed if it cannot deliver the Keychain credential; never work around it by overriding the provider or using ordinary Codex authentication.

Prompt via temp file, never inline quoting:

```bash
P=$(mktemp); cat >"$P" <<'EOF'
<goal, repo + key paths, constraints ("don't touch X"), non-goals, proof expected, output shape>
EOF
command codex exec --yolo -C <repo> \
  -m gpt-6.1-sol \
  -c model_reasoning_effort="high" \
  -o /tmp/codex-last.md - <"$P" 2>/dev/null
```

- Model default: `gpt-6.1-sol`, effort `high` — pin both explicitly; don't rely on user config.
- Never fast mode: no `--enable fast_mode`, on any route.
- `--yolo` is the house default; Codex may run commands/tests freely. Keep prompts scoped to the target repo.
- `command codex` bypasses any interactive shell alias. If codex isn't on PATH, it depends on how it was installed:
  - node/standalone install: `fnm exec --using default -- codex`
  - ChatGPT desktop app: the CLI ships bundled at `/Applications/ChatGPT.app/Contents/Resources/codex`. Expose **that** binary with an **exec-wrapper, not a symlink**. Ensure `~/.local/bin` stays on PATH (for zsh, persist the export in `~/.zshrc`), then:
    ```sh
    mkdir -p "$HOME/.local/bin"
    export PATH="$HOME/.local/bin:$PATH"
    if [ -e "$HOME/.local/bin/codex" ] || [ -L "$HOME/.local/bin/codex" ]; then
      printf '%s\n' 'codex launcher already exists; leaving it unchanged' >&2
    else
      printf '#!/bin/sh\nexec "/Applications/ChatGPT.app/Contents/Resources/codex" "$@"\n' > "$HOME/.local/bin/codex" && chmod +x "$HOME/.local/bin/codex"
    fi
    ```
    Or install the self-contained CLI via `curl -fsSL https://chatgpt.com/codex/install.sh | sh`, which needs no wrapper.
- stderr suppressed (thinking noise bloats context); drop `2>/dev/null` only to debug a failing run
- read `-o` file for the result; don't parse the JSONL stream
- long runs: Bash run_in_background, read `-o` file on exit; don't kill quiet runs <30 min
- **Harness visibility (Claude Code): every codex run gets its own harness-tracked background command (`run_in_background: true`) — one sidebar chip per worker, completion notification included. Chain setup steps (installs, worktree prep) INSIDE that tracked command. Never `&`-fork workers from a shared launcher: the launcher's chip exits at fork time and the workers become invisible orphans supervised only by PID files.**
- parallel independent tasks OK: separate repos/dirs, separate `-o` files, one tracked background command per worker
- outside a git repo add `--skip-git-repo-check`

Follow-up fixes — cheaper than fresh runs, keeps context. `resume` has no `-C`/`--yolo`: run from the repo dir, spell the long flag:

```bash
(cd <repo> && command codex exec resume --last \
  --dangerously-bypass-approvals-and-sandbox \
  -o /tmp/codex-last.md - <"$P2" 2>/dev/null)
```

## Liveness watchdog (long monitored runs)

For runs you must not babysit, trade the stderr suppression for a log and watch its mtime; read only the `-o` file into context, never the log body.

```bash
command codex exec --yolo -C <repo> -m gpt-6.1-sol \
  -c model_reasoning_effort="high" \
  -o "$OUT" - <"$P" > "$LOG" 2>&1
# Claude Code: run the line above as its own Bash run_in_background call
# (tracked chip + completion notification). Append `&` + a PID file ONLY in
# environments without tracked backgrounding.
```

- Capture the session id immediately: `grep -m1 "session id:" "$LOG"`. `resume --last` is cwd-filtered but races with any parallel Codex on the machine — with the id saved, recovery is deterministic.
- Watchdog loop (Claude Code: `Monitor` tool; else a bg shell): every 60s, if the codex process is alive but `$LOG` mtime is older than ~300s, treat it as hung. Because stderr (thinking stream) is in the log, mtime stays fresh during long reasoning — 5 min of true silence is a real hang, not thinking.
- Recovery: kill the pid, then resume the SAME session with an explicit id so no context is lost:

```bash
(cd <repo> && command codex exec resume <session-id> \
  --dangerously-bypass-approvals-and-sandbox \
  -o "$OUT" - <<< "You were interrupted. Continue exactly where you left off; finish the task and produce the required final report.")
```

- Exit watchdog silently when the process ends normally (the run's own completion signal covers it); emit only on staleness.
- Verified on codex-cli 0.144.4: `codex exec resume [SESSION_ID] [PROMPT]`, `--last`, cwd-filtering, `--all`.

## Prompt contract

Codex starts with zero session context. Every prompt: goal, exact repo/paths, constraints, non-goals, proof expected (exact test command), output shape ("report files changed + test output"). Spec quality decides success.

## Verify (Claude, always)

From BramVR/mac-agent-scripts, MIT.

More from BramVR/mac-agent-scripts