Consult Codex

Consult Codex

Multi-turn consultation with Codex CLI. Maintains a conversation across multiple turns using session persistence.

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, inspecting an artifact passed by path, or reading files outside the workspace, and tell Codex to keep any scratch files it writes under .turbo/. Pass the same -s value on every resume turn of the consultation: a resume turn takes its sandbox from its own command line, and without the flag it falls back to the codex config, where a trusted project runs workspace-write.

Omit -m, leaving the consultation on codex's configured model. When the user named a model for this consultation, add -m <model> to every codex exec command in this skill, resume turns included, and pass the name verbatim.

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.

Every codex exec invocation requires --skip-git-repo-check, resume turns included. Outside a git repository codex aborts before doing any work, printing Not inside a trusted directory and --skip-git-repo-check was not specified., and never writes the -o file.

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, and print the absolute path prefix it produces:

CODEX_TAG=$(head -c 4 /dev/urandom | xxd -p) && mkdir -p "$PWD/.turbo/codex" && echo "$PWD/.turbo/codex/$CODEX_TAG"

Substitute the printed value for <prefix> in every later command of this consultation. Shell variables do not survive between Bash tool calls, and an earlier cd in a compound command leaves the session in a different directory, so a relative path resolves against that directory instead.

Number the -o file by turn — <prefix>-1.txt for the first, <prefix>-2.txt for the next, and so on. A turn that reuses the previous turn's path finds that turn's complete answer waiting there, so a read landing before the current turn finishes returns the wrong answer with nothing to mark it as stale.

codex exec --skip-git-repo-check -s read-only -o "<prefix>-1.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.
• <merit_only>: When a recommendation is wanted, bar answers that appeal to scope.
• <verdict_line>: When the consultation runs until Codex approves, fix the line that ends every response and terminates the loop.
• <style_constraints>: When the answer must follow a house style, name the shapes that style forbids.

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.

When Codex must judge claims against a source, state in <grounding_rules> whether the material provided is the complete source or an excerpt. When a verdict can turn on something being absent, provide the complete relevant sections: given an excerpt, Codex reports what the excerpt leaves out as unverifiable or missing. Pass the complete source, or its path for Codex to read, whenever it fits. When an excerpt is unavoidable, confirm before running that every passage the claims under judgment rest on made it into the material provided.

When the consultation concerns an artifact Codex can inspect itself, pass its path and let Codex choose how to inspect it, rather than attaching excerpts or other material extracted from it.

When a recommendation is wanted, add <merit_only>: state that "out of scope" or "leave it alone" is not an acceptable argument on its own, and that recommending no change must be justified on technical merit. Pair it with <compact_output_contract> demanding one pick per decision, the reasoning, and the strongest counterargument to that pick, with hedging across options ruled out. When the question lists options, state in that contract that the pick may be a named alternative outside the list when it is sounder than every listed option.

When the consultation runs until Codex approves, add <verdict_line>: require every response to end with exactly one fixed line stating the verdict, in a designated positive or negative form, carrying nothing else, and require the response to state before that line what the verdict rests on: the artifacts, sources, and checks inspected. Terminate the loop when that line reaches the positive form with that evidence stated, so a politely worded answer does not end it early and agreement does not go unrecognized. Pair it with <compact_output_contract> demanding that each finding ship a ready-to-paste replacement rather than an instruction, which keeps a round cheap enough to iterate.

When the consultation is a prose rewrite bound by a house style, add <style_constraints> naming the shapes that style forbids in the first prompt, so they do not have to be corrected across follow-up turns. Common ones: prefixing a summary with a grammatical subject the convention omits, expanding a pronoun to its full noun phrase at every occurrence, and splitting a sentence so a condition is restated in both halves.

Instruct Codex to answer the consultation itself rather than delegating to a peer review or consultation skill that crosses back to Claude. The prompt has already crossed the tool boundary; a further crossing that fails mid-flight leaves this run holding a question instead of an answer.

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 "<prefix>-ctx.txt" | codex exec --skip-git-repo-check -s read-only -o "<prefix>-1.txt" "<question>"

A cat that fails does not stop the run: codex executes on the bare prompt, burns the full timeout, and returns nothing. Read the stderr chrome for the cat error rather than waiting on the -o file.

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. Write the context file with the Write tool so nothing is interpreted on the way in. Keep backticks, $, and straight double quotes out of the quoted argument even in text you wrote: the first two stay live inside it, and a double quote ends it. When the prompt itself must carry any of them, as when it quotes a title or a passage, write the whole prompt and its context to one file with the Write tool and pass -, so stdin is the entire prompt:

cat "<prefix>-prompt.txt" | codex exec --skip-git-repo-check -s read-only -o "<prefix>-1.txt" -

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. Use a filter that reads the stream to its end: one that exits early, such as grep -m or a trailing head, closes the pipe and kills the run.

A grep filter also hides startup failures, whose messages carry neither session id: nor the word error, leaving a missing -o file as the only symptom. When the -o file is absent and the call returned promptly with neither a task ID nor a Command timed out error, codex aborted at startup: re-run with unfiltered stderr before diagnosing anything else.

Run via the Bash tool as a foreground call (timeout: 600000, the foreground 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 current turn's -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 that 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 the next turn's -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.