gitnexus-impact-analysis

# Impact Analysis with GitNexus ## When to Use - "Is it safe to change this function?" - "What will break if I modify X?" - "Show me the blast radius" - "Who uses this code?" - Before making non-trivial code changes - Before committing — to understand what your changes affect ## Workflow ``` 1. gitnexus_impact({target: "X", direction: "upstream"}) → What depends on this 2. READ gitnexus://repo/{name}/processes → Check affected execution flows 3. gitnexus_detect_changes() → Map current git changes to affected flows 4. Assess risk and report to user ``` > If "Index is stale" → run `npx gitnexus analyze` in terminal. ## Checklist ``` - [ ] gitnexus_impact({target, direction: "upstream"}) to find dependents - [ ] Review d=1 items first (these WILL BREAK) - [ ] Check high-confidence (>0.8) dependencies - [ ] READ processes to check affected execution flows - [ ] gitnexus_detect_changes() for pre-commit check - [ ] Assess risk level and report to user ``` ## Understanding Output | Depth | Risk Level | Meaning | |-------|-----------|---------| | d=1 | **WILL BREAK** | Direct callers/importers | | d=2 | LIKELY AFFECTED | Indirect dependencies | | d=3 | MAY NEED TESTING | Transitive effects | ## Risk Assessment | Affected | Risk | |----------|------| | <5 symbols, few processes | LOW | | 5-15 symbols, 2-5 processes | MEDIUM | | >15 symbols or many processes | HIGH | | Critical path (auth, payments) | CRITICAL | ## Tools **gitnexus_impact** — the primary tool for symbol blast radius: ``` gitnexus_impact({ target: "validateUser", direction: "upstream", minConfidence: 0.8, maxDepth: 3 }) → d=1 (WILL BREAK): - loginHandler (src/auth/login.ts:42) [CALLS, 100%] - apiMiddleware (src/api/middleware.ts:15) [CALLS, 100%] → d=2 (LIKELY AFFECTED): - authRouter (src/routes/auth.ts:22) [CALLS, 95%] ``` **gitnexus_detect_changes** — git-diff based impact analysis: ``` gitnexus_detect_changes({scope: "staged"}) → Changed: 5 symbols in 3 files → Affected: LoginFlow, TokenRefresh, APIMiddlewarePipeline → Risk: MEDIUM ``` ## Example: "What breaks if I change validateUser?" ``` 1. gitnexus_impact({target: "validateUser", direction: "upstream"}) → d=1: loginHandler, apiMiddleware (WILL BREAK) → d=2: authRouter, sessionManager (LIKELY AFFECTED) 2. READ gitnexus://repo/my-app/processes → LoginFlow and TokenRefresh touch validateUser 3. Risk: 2 direct callers, 2 processes = MEDIUM ```