/codex-explain

name: codex-explain
description: "Explain complex code via Codex exec. Use when: understanding complex logic, tracing data flow, onboarding to unfamiliar code. Not for: code review (use codex-code-review), exploration (use code-explore). Output: structured explanation at chosen depth."
allowed-tools: Read, Grep, Glob, Bash(node:*), Write

Codex Explain Skill

Trigger

• Keywords: explain code, what does this do, how does this work, code walkthrough

When NOT to Use

• Code review (use `codex-code-review`)
• Bug investigation (use `bug-fix` or `issue-analyze`)
• Architecture overview (use `code-explore`)

Workflow

Read target → [Collect context] → Codex explain → Output explanation

Step 1: Read Target File

Read file content. If `--lines` specified, extract only that range.

Step 2: Codex Explanation

Dispatch per `@skills/codex-code-review/references/codex-transport.md` § Start with the explanation prompt. See `references/codex-prompt-explain.md`.

Depth Levels

| Level | Description | | ------ | ---------------------------------------------------- | | brief | One-sentence summary | | normal | Functional overview + execution flow + key concepts (default) | | deep | + Design patterns + complexity + issues + dependencies |

Output

## Code Explanation: <target>
- **Depth**: brief / normal / deep
- **Summary**: <functional overview>
- **Execution flow**: <key paths>
- **Key concepts**: <patterns, abstractions>

Verification

• [ ] Codex independently researched project context (imports, callers)
• [ ] Explanation matches requested depth level
• [ ] Key concepts are identified and explained

References

• Explanation prompt: `references/codex-prompt-explain.md`

Examples

Input: /codex-explain src/service/order/order.service.ts
Action: Read file → Codex explain (normal) → Functional summary + detailed explanation

Input: /codex-explain src/service/xxx.ts --depth deep
Action: Read file → Codex explain (deep) → Patterns + complexity + issues

Input: /codex-explain src/xxx.ts --lines 50-100
Action: Read lines 50-100 → Codex explain → Focused explanation