32 added, 11 removed. Audit A to A.
---
name: codex-exec
description: 'Run one caller-supplied Codex command non-interactively and capture evidence. Triggers: "run Codex headless", "capture Codex evidence".'
skill_api_version: 1
user-invocable: false
hexagonal_role: driving-adapter
practices:
- pragmatic-programmer
- consumes: []
+ consumes:
+ - codex-command-packet
produces:
- codex-run-output
context_rel:
- kind: supplier-to
with: validate
context:
window: inherit
intent:
mode: none
sections:
exclude:
- HISTORY
intel_scope: none
metadata:
capabilities: [codex_exec]
- effects: []
+ effects: [run_codex_process, sandbox_tiered_workspace_and_network_effects]
canonical_status: canonical
disposition: keep_optional_adapter
tier: orchestration
dependencies: []
stability: stable
- triggers:
- - codex exec
- - spawn a codex worker
output_contract: process exit status and captured Codex output artifact
---
# Codex Exec — one-shot runtime adapter
Run exactly one caller-supplied Codex prompt and capture its result. This skill
does not choose work, retry failures, validate by itself, or control continuation.
One prompt, one process, one captured artifact is what makes the run auditable:
when nothing loops, every byte of output traces to exactly one invocation, and
a disagreement about what happened is settled by the artifact.
Named failure mode — **stdin hang**: a non-TTY run left waiting forever on an
open stdin nobody will write to; always pipe the prompt or close the stream.
Anti-pattern: granting workspace-write or network access "in case the prompt
needs it". Corrective: match the sandbox to the declared effects; a review
prompt runs read-only, full stop.
## Procedure
1. Confirm `codex login status` for the intended profile.
2. Set the working root explicitly with `-C`.
3. Match the sandbox to the requested effects: read-only for offline review,
workspace-write for authorized edits, and broader access only when the caller
explicitly requires network or external effects.
4. Pipe the prompt to stdin (or close stdin) in non-TTY execution so the process
cannot wait indefinitely for input.
- 5. Capture the final response with `-o`, JSONL, or an output schema.
- 6. Report the process exit status and captured artifact, then stop.
+ 5. A wall-clock **deadline is mandatory** — never run codex unbounded. Use the
+ caller's deadline, or the declared default of **600s (10 min)** when the
+ caller supplies none, and record which one applied. Enforce it so the whole
+ process **tree** is reaped, not just the direct child: run codex in its own
+ process group and kill the group on expiry: `setsid` (own process group) +
+ `kill -KILL -<pgid>` on the group; `--kill-after` only escalates TERM→KILL
+ and plain `timeout <secs> codex …` signals only the direct child. If the
+ wrapper cannot guarantee process-group reaping, **do not execute** — that
+ host lacks the cleanup capability this skill requires (capability
+ unavailable, fail closed). Deadline expiry is
+ **fail-closed**: the run is killed and reported as timed-out / not proven,
+ partial output preserved — never a completed review.
+ 6. Capture the final response with `-o`, JSONL, or an output schema.
+ 7. Report the typed run result, then stop: the process exit status, the captured
+ artifact path, which deadline applied and whether it fired, that the
+ process tree was reaped (a run without guaranteed reaping never starts), and whether
+ the `codex` binary was present at all. Cancellation is the caller's; this
+ skill neither retries nor continues on its own.
- A nonzero process exit is runtime evidence, not a semantic verdict. The caller
- decides whether to launch another invocation.
+ Terminal outcomes are explicit: **binary absent** (no `codex` on PATH) → report
+ unavailable and stop; **deadline expiry** → fail-closed, report the kill and
+ preserved partial output, never a completed review; **nonzero exit** → runtime
+ evidence, not a semantic verdict. The caller decides whether to launch another
+ invocation.
## Example
```bash
- printf '%s\n' "$PROMPT" | codex exec -C "$WORKSPACE" -s read-only \
- -o "$OUTPUT" -
+ # Deadline mandatory; default 600s. `setsid` puts codex in its own process
+ # group so expiry kills the whole tree, with `--kill-after` escalating
+ # TERM->KILL. No setsid (or equivalent group kill) available -> do not run:
+ # fail closed as capability-unavailable.
+ printf '%s\n' "$PROMPT" | setsid timeout --kill-after=10s "${CODEX_TIMEOUT:-600}" \
+ codex exec -C "$WORKSPACE" -s read-only -o "$OUTPUT" -
```
For a validator, the prompt must name the acceptance digest, exact subject
manifest digest, author context ID, evidence, and required checked/not-checked
report. The validator context ID must be distinct from the author's before a
`PASS` verdict is possible. When the caller elects a cross-model fresh
validator, record model identities per
the `agent-native` model-dispatch recipe and match the sandbox to
declared effects.