docs(skill): clarify impact analysis triggers

shared/skills/planning/change-impact-analysis/SKILL.md

@@ -1,12 +1,19 @@
 ---
 name: change-impact-analysis
-description: Determine what a proposed change may affect.
+description: Use before implementation when a proposed code, configuration, data, or workflow change has uncertain callers, compatibility effects, dependencies, or blast radius. Return an impact analysis without implementing it.
 ---
 
 # Change Impact Analysis
 
-Use when the blast radius or compatibility impact is uncertain.
+Use before a change when its consumers, compatibility effects, or blast radius are uncertain.
 
-Inspect callers, dependencies, configuration, tests, and affected workflows.
+## Workflow
 
-Return affected areas, risks, and recommended verification. Separate facts from assumptions.
+1. Define the proposed change and the behavior or contract it affects.
+2. Locate direct callers, related implementations, shared helpers, configuration, generated output, and relevant tests. Start with exact-path and symbol searches; broaden only when the flow is unclear.
+3. Trace likely impact through runtime paths, persisted data, client integrations, deployment, and documentation as applicable.
+4. Identify compatibility concerns, failure modes, security or data-loss risks, and dependencies on version or environment.
+5. Separate confirmed impacts from assumptions and unknowns. Do not treat a possible downstream effect as a fact without evidence.
+6. Recommend proportionate verification tied to the risks found.
+
+Return a concise impact map: affected areas, evidence, risks, unknowns, and checks. Do not implement the proposal unless asked.