Update Code-Spec - Capture Executable Contracts

When you learn something valuable (from debugging, implementing, or discussion), use this skill to update the relevant code-spec documents.

Timing: After completing a task, fixing a bug, or discovering a new pattern

Code-Spec First Rule (CRITICAL)

In this project, "spec" for implementation work means code-spec:

• Executable contracts (not principle-only text)
• Concrete signatures, payload fields, env keys, and boundary behavior
• Testable validation/error behavior

If the change touches infra or cross-layer contracts, code-spec depth is mandatory.