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 ....

Multi-repo note: Always pass --repo <name> to every command 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 context "X" --repo <name>                      → See affected execution flows
3. gitnexus detect-changes --repo <name>                   → Map current git changes to affected flows
4. Assess risk and report to user

If "Index is stale" → run gitnexus analyze in terminal.

Checklist

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

Commands

gitnexus impact — the primary tool for symbol blast radius:

gitnexus impact "validateUser" --direction upstream --repo my-app
# Optional flags: --min-confidence 0.8 --max-depth 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 --repo my-app
# → Changed: 5 symbols in 3 files
# → Affected: LoginFlow, TokenRefresh, APIMiddlewarePipeline
# → Risk: MEDIUM

Example: "What breaks if I change validateUser?"

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

# 2. Confirm affected execution flows
gitnexus context "validateUser" --repo my-app
# → Processes: LoginFlow, TokenRefresh

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