Consult Codex Skill for Codex

Consult Codex

Multi-turn consultation with Codex CLI. Maintains a conversation across multiple turns using session persistence, unlike single-shot /codex-exec.

Step 1: Gather Context

Identify the 2-5 files most relevant to the problem. Formulate a clear, specific question. Include what has been tried and relevant constraints.

Step 2: Start Session

Run codex exec with -o to capture the response cleanly. Default to -s read-only for safety. Use -s workspace-write when the consultation requires running code or reading files outside the workspace.

All codex Bash calls require dangerouslyDisableSandbox: true (network access to OpenAI API). Use .turbo/ as the temp directory — it is in the working directory (sandbox-writable), gitignored, and avoids $TMPDIR path mismatches between sandbox and non-sandbox mode.

Non-piped codex exec invocations require < /dev/null to avoid hanging on stdin. Codex reads from stdin whenever stdin is non-TTY, and in subprocess contexts the harness leaves stdin connected to a pipe that never EOFs — codex blocks forever, printing only Reading additional input from stdin.... The piped form (cat file | codex exec "...") is safe — cat closes the pipe after the file.

Generate a random session tag at the start to keep files unique for parallel use:

CODEX_TAG=$(head -c 4 /dev/urandom | xxd -p) && mkdir -p .turbo/codex
codex exec -s read-only -o ".turbo/codex/$CODEX_TAG.txt" "<question>" < /dev/null

Prompt Shaping

Structure the question using XML tags for clearer Codex responses:

• <task>: The concrete question and relevant context.
• <compact_output_contract>: Desired output shape and brevity requirements.
• <structured_output_contract>: Same purpose but for structured/schema responses.
• <grounding_rules>: When claims must be evidence-based (review, research, root-cause analysis).
• <dig_deeper_nudge>: Push past surface-level findings to check for second-order failures.
• <verification_loop>: When correctness matters — ask Codex to verify before finalizing.

Example prompt for a diagnosis question:

<task>Diagnose why the auth middleware rejects valid tokens after the session refactor.</task>
<compact_output_contract>Return: (1) most likely root cause, (2) evidence, (3) smallest safe next step.</compact_output_contract>
<grounding_rules>Ground every claim in the provided context or tool outputs. Label hypotheses explicitly.</grounding_rules>

For correctness-critical questions, add <verification_loop> asking Codex to verify its answer before finalizing.

Keep prompts compact, with tight output contracts. One clear task per Codex turn.

For context that does not belong in the argument, write a context file with the Write tool and pipe it via stdin. The prompt stays as the argument, context pipes in as <stdin> automatically:

cat ".turbo/codex/$CODEX_TAG-ctx.txt" | codex exec -s read-only -o ".turbo/codex/$CODEX_TAG.txt" "<question>"

Route text you did not author through this channel whatever its size — a diff, file contents, a code comment, a plan or spec, third-party feedback, command output. Keep backticks and $ out of the quoted argument even in text you wrote, since both stay live inside it. Write the context file with the Write tool so nothing is interpreted on the way in.

Parse the session id: line from the CLI output. This UUID is needed for follow-up turns.

The session id: line appears only in the stderr chrome, never on stdout and never in the -o file. When a follow-up turn may be needed, do not discard stderr with 2>/dev/null or capture stdout alone — either silently drops the session id and makes resume impossible. If output must be truncated, 2>&1 | grep for session id: so the id is always retained.

Run via the Bash tool as a foreground call (timeout: 600000, the Bash maximum; do not set run_in_background) per turn. A larger timeout is not honored: the harness backgrounds the call immediately and hard-kills codex at 600s, truncating its output. A consult that outlives a valid timeout is normally force-backgrounded: the result carries a task ID and the run continues to completion, so recover the answer by reading the -o file, then reading it again once the <task-notification> reports completion. For a backgrounded run the session id: is in the task's output file rather than the immediate tool result, so grep that file for it when a follow-up turn is needed. An over-max timeout also returns a task ID but truncates the output at 600s, so check the file for a complete answer rather than assuming the run finished. Rarely the result is an error exit (code 143) reading Command timed out after <duration> with no task ID; codex was hard-killed and the -o file was never written, so resume the session id from Step 2 with a fresh -o path and an instruction to answer immediately, rather than re-running the consult from scratch. Never wait with Monitor, and never return the task ID or an interim file snapshot as the result — each is a false-empty return.

Step 3: Read and Evaluate Response

The -o file contains only Codex's response (cleaner than stdout, which includes CLI chrome and tool-use logs). Read from .turbo/codex/$CODEX_TAG.txt. If the output is too large for the Read tool, read stdout from the Bash tool result instead.

Assess whether:

• The answer is sufficient and actionable
• Follow-up questions would improve the answer
• The response contradicts known project facts (verify before accepting)

If no follow-up is needed, skip to the Synthesize step.

Step 4: Follow Up

Resume the session with the parsed session ID (not --last, which is unsafe for parallel use):

codex exec resume <session-id> -o ".turbo/codex/$CODEX_TAG.txt" "<follow-up question>" < /dev/null

When the follow-up carries text you did not author, write it to a file with the Write tool and pass - so the prompt is read from stdin instead:

cat ".turbo/codex/$CODEX_TAG-followup.txt" | codex exec resume <session-id> -o ".turbo/codex/$CODEX_TAG.txt" -

With -, stdin is the whole prompt rather than a <stdin> block appended to an argument, so instruction and context share the one file. Leave off < /dev/null here — the pipe supplies stdin, and cat sends EOF.

The -s flag is not available for resume. It inherits sandbox settings from the original session.

Return to Step 3. Cap at 5 turns to prevent runaway conversations.

Step 5: Synthesize

Summarize the key insights from the consultation. Cross-reference suggestions with project documentation and conventions before applying. Codex suggestions are starting points, not guaranteed solutions.