codex

Primary Use Cases:

1. User explicitly requests codex CLI execution (Mode 1: Direct CLI)
2. Complex debugging requiring GPT second opinion (Mode 2: GPT Delegation)
3. Deep research on unfamiliar technologies (Mode 2: GPT Delegation)
4. Algorithm optimization validation (Mode 2: GPT Delegation)

Do NOT use for:

• Simple code explanations
• Routine file operations
• Standard debugging that Claude can handle directly

Mode 1: Direct CLI Execution

When: User explicitly asks to run codex CLI (codex exec, codex resume)

Workflow:

1. Utilise AskUserQuestion to evaluate and extend the users query, providing at least 5 questions, each with multi-select options to determine the best model and reasoning effort. Let the first question include options for the following combinations:

1. Execute:

codex exec --skip-git-repo-check -m --config model_reasoning_effort="" --sandbox --full-auto 2>/dev/null

1. Inform user: "You can resume with 'codex resume' anytime"

Resuming:

echo "new prompt" | codex exec --skip-git-repo-check resume --last 2>/dev/null

Mode 2: GPT Delegation for Analysis

When: Complex problem needs second opinion (async race conditions,

architecture decisions, algorithm validation)

Workflow:

1. Analyze context and identify what GPT analysis would help
2. Formulate comprehensive query with all relevant context:

- Problem statement

- Current findings

- Code snippets (if applicable)

- Error messages

- Attempted solutions

- Specific questions

1. Keep context concise but complete (<10K tokens preferred)
2. Execute: codex -p ""
3. Synthesize GPT response into actionable insights
4. Report findings with:

- Clear summary of GPT's analysis

- Specific recommendations or solutions

- Additional considerations or caveats

- Next steps if applicable

Error Handling

• Verify codex binary exists before execution: which codex
• Stop immediately on non-zero exit codes and report to user
• Request direction before retrying failed commands
• See 'High-Impact Flags Confirmation' in AskUserQuestion Tool Usage section

before using:

- --full-auto

- --sandbox danger-full-access

- --skip-git-repo-check (default, but mention to user)

Context Management

• Prioritize most relevant information when building queries
• Summarize background information if context is large
• Break complex problems into specific, answerable questions
• Avoid passing entire codebases - extract relevant snippets

This skill uses the AskUserQuestion tool for all user interactions.

Here are the standard invocation patterns:

Initial Configuration (Mode 1, Step 1)

At the start of Mode 1 execution, gather model, reasoning effort, and sandbox

mode with a single question:

Invoke the tool like this:

```text

Use AskUserQuestion with:

• Question: "Select codex configuration (model, reasoning effort, and sandbox)"
• Options:

1. "gpt-5.2-codex / high / read-only (Recommended)" - Balanced, analysis only

2. "gpt-5.2-codex / xhigh / read-only" - Max quality, analysis only

3. "gpt-5.2-codex / high / workspace-write" - Balanced, can edit files

4. "gpt-5.2-codex / xhigh / workspace-write" - Max quality, can edit files

5. "gpt-5.2 / medium / read-only" - Faster, general purpose

6. "gpt-5.2-codex / high / danger-full-access" - Network/broad access

7. "Custom" - User will specify model, effort, and sandbox separately

```

High-Impact Flags Confirmation

Before executing with --full-auto or dangerous flags:

Invoke the tool like this:

```text

Use AskUserQuestion with:

• Question: "Ready to execute with these flags: [LIST FLAGS]. Proceed?"
• Show complete command preview
• Options:

1. "Execute now" - Run as configured

2. "Modify configuration" - Change settings

3. "Cancel" - Abort

```

Post-Execution Follow-up

After codex command completes:

Invoke the tool like this:

```text

Use AskUserQuestion with:

• Question: "Codex completed. [SUMMARY]. Next steps?"
• Options:

1. "Resume with additional prompt" - Continue session

2. "Analyze results" - Review output

3. "Complete" - Finished

4. "Retry with different config" - Adjust settings

```

Error Recovery

When command fails or has warnings:

Invoke the tool like this:

```text

Use AskUserQuestion with:

• Question: "Error: [SPECIFIC ERROR]. How to proceed?"
• Show what succeeded vs failed
• Options:

1. "Resume with adjustments" - Fix and continue

2. "Retry with different config" - Change model/effort/sandbox

3. "Accept partial results" - Use what worked

4. "Invoke heal-skill" - Fix outdated SKILL.md

```

1. See 'Initial Configuration' in AskUserQuestion Tool Usage section to gather

model, reasoning effort, and sandbox mode in one question

1. Assemble the command with the appropriate options:

- -m, --model

- --config model_reasoning_effort=""

- --sandbox

- --full-auto

- -C, --cd

• After every codex command, see 'Post-Execution Follow-up' in AskUserQuestion

Tool Usage section

• When resuming, pipe the new prompt via stdin:

echo "new prompt" | codex exec resume --last 2>/dev/null. The resumed

session automatically uses the same model, reasoning effort, and sandbox mode

from the original session.

• Restate the chosen model, reasoning effort, and sandbox mode when proposing

follow-up actions.

• Stop and report failures whenever codex --version or a codex exec command

exits non-zero; request direction before retrying.

• See 'High-Impact Flags Confirmation' and 'Error Recovery' in AskUserQuestion

Tool Usage section

• When output includes warnings or partial results, see 'Error Recovery' in

AskUserQuestion Tool Usage section

When codex CLI API changes are detected (command failures, unexpected output formats, or deprecated flags):

1. Detection: Notice command failures or API mismatches during execution
2. Trigger: Flag skill for healing via /heal-skill codex
3. Analysis: Healing agent analyzes current CLI with codex --help and codex features list
4. Update: Updates skill documentation to match current API
5. Validation: Re-validates agent configuration for compatibility
6. Model Verification: Ensures only gpt-5.2 and gpt-5.2-codex models are referenced

Common Changes to Monitor:

• New or deprecated command flags
• Changes to sandbox modes or reasoning effort options
• Model availability updates
• MCP integration changes
• Session management API modifications