Understand Code

Mode: READ-ONLY throughout. No edits during this skill.

Step 1: Scope Discovery

Use Glob and Grep to locate relevant files:

Glob: src/**/*<keyword>*
Grep: "<keyword>" in src/

Collect:

• Entry point (controller, command, route handler, event listener)
• Domain / business logic files
• Adapter files (repository, HTTP client, external service)
• Test files (unit + integration)

Step 2: Code Tracing

Read files in dependency order:

1. Entry point — what triggers this code path?
2. Application layer — what orchestration happens?
3. Domain — what business rules apply?
4. Adapters — how does the system persist or call out?

Limit: Read at most 8 files. If scope is larger, narrow the argument.

Step 3: Invariant Mapping

Check which invariants apply. The registry is at GLOBAL_INVARIANTS.md.

For each applicable INV:

• Is it currently enforced in the code you read?
• Are there gaps? (Note them — do NOT fix during this skill)

Step 4: Summary Report

## Code Understanding: <argument>

**Entry Point:** <file:line — method/endpoint/event>

**Call Chain:**
<Layer1> → <Layer2> → <Layer3>

**Key Data Flow:**

1. <input> received at <layer>
2. <transformation or validation>
3. <persistence/response>

**Domain Rules:**

- <rule 1>

**Test Coverage:**

- Unit: <files or "none found">
- Integration: <files or "none found">

**Gaps / Risks (observe only — do not fix here):**

- <gap 1>

**Next Step:**

- <if debugging>: hypothesis to test first
- <if modifying>: safe entry point for edits

Constraints

• Read-only. Do not edit files.
• Do not propose fixes — only document gaps.
• Do not run tests or gate.