gitnexus-impact-analysis

name	gitnexus-impact-analysis
description	Use when the user wants to know what will break if they change something, or needs safety analysis before editing code. Examples: "Is it safe to change X?", "What depends on this?", "What will break?"

Impact Analysis with GitNexus

IMPORTANT — How to use GitNexus: GitNexus is a standalone CLI tool. Run it directly via gitnexus <command> in the Bash tool. Do NOT use mcpl call gitnexus ... or npx gitnexus ... — gitnexus is installed globally and invoked by name.

Multi-repo note: Always pass --repo <name> to every command that operates on a specific repo to avoid "multiple repositories" errors.

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 "X" --direction upstream --repo <name>  → What depends on this
2. gitnexus detect-changes --repo <name>                   → Map current git changes to affected flows
3. Assess risk and report to user

If the index is stale (gitnexus status) → run gitnexus analyze.

Checklist

- [ ] gitnexus impact "X" --direction upstream --repo <name> to find dependents
- [ ] Review d=1 items first (these WILL BREAK)
- [ ] Check high-confidence (>0.8) dependencies
- [ ] gitnexus detect-changes --repo <name> 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

CLI Commands Reference

All commands are run directly via the Bash tool. Do not use mcpl or npx.

Command	What it gives you	Example
gitnexus impact "<symbol>" --direction upstream --repo <name>	Symbol blast radius at depth 1/2/3 with confidence	gitnexus impact "validateUser" --direction upstream --repo <name>
gitnexus impact "<symbol>" --direction upstream --min-confidence 0.8 --max-depth 3 --repo <name>	Filtered blast radius
gitnexus detect-changes --repo <name>	Git-diff based impact analysis	gitnexus detect-changes --repo <name>
gitnexus status	Index freshness check	gitnexus status

impact — the primary command for symbol blast radius:

gitnexus impact "validateUser" --direction upstream --min-confidence 0.8 --max-depth 3 --repo <name>

→ 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%]

detect-changes — git-diff based impact analysis:

gitnexus detect-changes --repo <name>

→ Changed: 5 symbols in 3 files
→ Affected: LoginFlow, TokenRefresh, APIMiddlewarePipeline
→ Risk: MEDIUM

Example: "What breaks if I change validateUser?"

1. gitnexus impact "validateUser" --direction upstream --repo my-app
   → d=1: loginHandler, apiMiddleware (WILL BREAK)
   → d=2: authRouter, sessionManager (LIKELY AFFECTED)

2. Risk: 2 direct callers, 2 processes = MEDIUM