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 either unset or its URL host is neither loopback nor gorillaclaw.sheep-coho.ts.net.

Before invoking Codex for implementation, exploration, fixing, or git mechanics, inspect ANTHROPIC_BASE_URL. If its URL host is gorillaclaw.sheep-coho.ts.net (the Clawdex router), localhost, ends in .localhost, is in 127.0.0.0/8, or is IPv6 loopback ::1, stop here: the session is already router-backed or 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 (openclaw: node scripts/watch-pr-ci.mjs).
• 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 in every repo; CLAUDE.md exists only as a symlink to it. 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. Portfolio/multi-repo work: $maintainer-orchestrator instead.

Invoke

If the machine intentionally uses the openai_api_direct million-token route, run ruby ~/.codex/skills/agent-scripts/codex-huge-context/scripts/preflight.rb before the first fresh or resumed launch in the batch. 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:

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-5.6-sol \
  -c model_reasoning_effort="high" \
  --enable fast_mode \
  -o /tmp/codex-last.md - <"$P" 2>/dev/null

• Model default: gpt-5.6-sol, effort high, fast mode on — pin all three explicitly; don't rely on user config.
• --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:

    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:

(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.

command codex exec --yolo -C <repo> -m gpt-5.6-sol \
  -c model_reasoning_effort="high" --enable fast_mode \
  -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:

(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.

• Every hard prohibition needs an escape hatch. A cornered worker satisfies the letter of the gates: told "never raise the size budget" while its design inflated the bundle, Codex hand-minified source identifiers to single letters — and passed every gate including autoreview. Pair each hard constraint with the sanctioned exit: "if gate X fails after honest attempts: STOP, report exact numbers/diagnosis, do not work around." Treat a stop-report as a successful run (it is the coordinator's decision point, and workers use it correctly once it exists).
• Multi-PR series: same spec skeleton every PR; cite prior landed PR numbers and name their idioms ("controller with narrow host interface, the #NNN shape") — workers imitate landed precedent far more reliably than abstract style rules. Fold each round's new trap into the next spec.
• End every series work order with an explicit stop: "Do exactly this; do not start PR N+1."

Coordinator verification (beyond the diff)

Worker reports are accurate but incomplete — pathologies live in the code, not the summary. After every landed PR, verify against merged origin/main, not the report:

• read the actual merged surface (types, interfaces, naming) — the minification incident was invisible in a green report and obvious in 10 lines of code
• squash history: any commit message you didn't commission ("add startup margin") is a lead
• diff-stat the guard/budget/baseline files the spec forbade touching; if a limit number in the report changed, find out who moved it (may be main advancing, may be the worker)
• test-helper edits are a red-flag class of their own (defineProperty shims re-exposing moved fields keep suites green while hiding the migration)

Parallel workers, one repo

Disjoint-file tasks parallelize cleanly: one worktree + unique branch per worker (fresh from origin/main; distinctive branch names — generic ones attach to old PRs), one tracked background command each, shared spec body + per-target header. Landing serializes on the repo's land workflow lock: tell each worker a held lock means a sibling owns it — back off 5-10 min, retry from the failed step, NEVER lock-recover a lock it didn't create, and don't chase main with fresh gates as siblings land under it. Sequential series instead reuse ONE worktree, rebranching from origin/main per PR.

Verify (Claude, always)

• git status -sb + read the full diff; judge like a contributor PR
• run focused tests yourself or demand proof output; Codex claims are advisory
• iterate via resume; after 2 failed rounds, take over and do it directly
• normal closeout still applies: $autoreview before ship

Economics

Win = generation + exploration tokens moved to Codex; Claude spends only on spec + diff review. Don't ping-pong trivia through delegation; don't re-read what Codex already summarized.