docs(skill): clarify integration test triggers

shared/skills/implementation/integration-test-write/SKILL.md

@@ -1,10 +1,20 @@
 ---
 name: integration-test-write
-description: Add focused integration tests for connected system behavior.
+description: Use when adding or changing tests for behavior across a real boundary, such as an API and database, filesystem command, or cooperating services. Not for isolated unit behavior.
 ---
 
 # Integration Test Write
 
-Identify the integration boundary, required setup, and meaningful success and failure cases.
+Use when verifying behavior across a real application boundary, such as an API and database, a command and filesystem, or cooperating services.
 
-Keep the test deterministic and limited to the behavior under change.
+## Workflow
+
+1. Name the boundary under test and the production path the test must exercise. Keep unit-level details covered by unit tests.
+2. Reuse the repository's integration-test setup. Start only the services and data stores required for this behavior.
+3. Prepare minimal isolated data and control external inputs. Prevent test runs from touching user data, shared environments, or live services.
+4. Cover a successful interaction and the failure or rejection path that matters to the change. Include transaction, retry, or cleanup behavior only when it is part of the contract.
+5. Assert persisted or externally observable outcomes, including relevant status, response, and side effects.
+6. Clean up created resources even when assertions fail. Make repeated runs safe and independent.
+7. Run the focused integration test and report required services, results, and any unavailable environment.
+
+Avoid turning an integration test into a full end-to-end suite when a narrower boundary proves the contract.