Assess Impact

HARD GATE — Run this skill before plan-work whenever a change touches an existing module, symbol, or file used by more than one caller. Skip only for net-new code with no existing dependents.

Find the blast radius of the proposed change before a single line is written.

Modes

• Default: full impact analysis (dependents + affected stories + test coverage mapping)
• --lightweight: Fast fan-in/fan-out only (<10s). Maps callers and imports without test coverage mapping. Used by build-epic step 2 as a pre-plan gate. Risk score > 7 triggers a mandatory grill-me session before proceeding.

Process

1. Identify the target

Name the symbol, module, or file being changed. If the user hasn't specified, ask one question: "What exactly are you changing?"

2. Find dependents

grep -rn "[symbol-name]" . --include="*.ts" | grep -v node_modules
git log --oneline -10 -- [file-path]

→ verify: test -f specs/IMPACT_LATEST.md || test -d specs/bugs

3. Map to release plan stories

Read specs/release-plan.yaml + epic capsule directories (if it exists). For each dependent found in Step 2, identify which story owns that module. List stories that will be affected by the change.

→ verify: test -f specs/release-plan.yaml && grep -ci "stor" specs/release-plan.yaml

4. List test coverage

Find tests that exercise the target:

grep -rn "[symbol-name]" . --include="*.test.*" --include="*.spec.*"

→ verify: test -d specs/epics || test -d skills

5. Classify risk

Level	Condition
Low	≤ 2 callers, all covered by tests
Medium	3–10 callers, partial test coverage
High	> 10 callers, or shared API/interface, or no tests

6. Write specs/IMPACT_LATEST.md

## Target
[symbol or file being changed]

## Dependents ([count])
- [file]: [caller or usage]

## Affected Stories
- Story [X.Y]: [title]

## Test Coverage
- [test file]: covers [scenario]
- Gap: [untested behavior]

## Risk: Low / Medium / High
[One-sentence rationale]

## Recommended action
[Proceed / Add tests first / Discuss design]

→ verify: grep "Risk:" specs/IMPACT_LATEST.md

Suggest plan-work once risk is understood and any test gaps are noted.

Risk score gating

In --lightweight mode (used by build-epic step 2), assign a numeric risk score (1–10):

• Fan-in (how many callers): 0–4 points
• Fan-out (how many dependencies the module itself uses): 0–3 points
• Recent churn (git log --oneline -5 count): 0–3 points

Risk score > 7: Gate — require a grill-me session before proceeding to implementation. Document the grill-me result in the impact report at specs/IMPACT-<epic>-<story>.md.