GitNexus Impact Analysis
CLI ONLY — no MCP server exists. Never usereadMcpResourcewithgitnexus://URIs.
Analyze the blast radius of changing a symbol — who calls it, what processes it participates in, and what tests cover it.
Self-Evolving Skill: This skill improves through use. If instructions are wrong, parameters drifted, or a workaround was needed — fix this file immediately, don't defer. Only update for real, reproducible issues.
When to Use
- Before modifying a function with many callers
- "What breaks if I change X?"
- "Is it safe to modify Y?"
- "What's the blast radius of changing Z?"
Workflow
Step 0: Pre-flight — Ensure CLI Is Callable
The gitnexus binary is installed via npm/mise. The mise shim may fail if node isn't active in the current project. Run this pre-flight before any gitnexus command:
# Test if gitnexus is actually callable (not just a broken shim)
gitnexus --version 2>/dev/null || mise use node@25.8.0All commands below run from the repo root. If multiple repos are indexed in the workspace, add --repo <repo-name> to specify the target. Otherwise --repo is optional.
Step 1: Auto-Reindex If Stale
gitnexus statusIf stale (indexed commit ≠ HEAD), automatically reindex before proceeding — do not ask the user:
gitnexus analyzeThen re-check status to confirm index is current.
Step 2: Upstream Blast Radius
gitnexus impact "<symbol>" --depth 3This shows everything that depends on the symbol (callers, transitive callers up to depth 3).
If multiple candidates are returned, disambiguate:
gitnexus impact "<symbol>" --uid "<full-uid>" --depth 3
# or
gitnexus impact "<symbol>" --file "<file-path>" --depth 3Step 3: Downstream Dependencies (Optional)
gitnexus impact "<symbol>" --direction downstream --depth 3Shows what the symbol depends on — useful for understanding if dependencies might change.
Step 4: Test Coverage
gitnexus impact "<symbol>" --include-testsShows which test files exercise this symbol.
Step 5: Risk Assessment
Based on the number of direct dependents:
| Dependents | Risk Level | Recommendation |
|---|---|---|
| < 5 | LOW | Safe to modify with basic testing |
| 5–20 | MEDIUM | Review all callers, run related tests |
| 20–50 | HIGH | Consider backward-compatible API, extensive testing |
| 50+ | CRITICAL | Needs deprecation strategy, phased migration |
Step 6: Structured Report
Present:
- Risk level with dependent count
- Top affected processes — execution flows that include this symbol
- Direct callers — functions/methods that call this directly
- Test coverage — tests that exercise this symbol (or gaps)
- Recommendation — safe to modify, needs tests, needs migration plan
Example
User: "What breaks if I change RangeBarProcessor?"
gitnexus impact "RangeBarProcessor" --depth 3
gitnexus impact "RangeBarProcessor" --include-testsOutput: "CRITICAL risk — 73 dependents across 12 processes. 8 test files cover it. Recommend backward-compatible changes only."
Post-Execution Reflection
After this skill completes, reflect before closing the task:
- Locate yourself. — Find this SKILL.md's canonical path before editing.
- What failed? — Fix the instruction that caused it.
- What worked better than expected? — Promote to recommended practice.
- What drifted? — Fix any script, reference, or dependency that no longer matches reality.
- Log it. — Evolution-log entry with trigger, fix, and evidence.
Do NOT defer. The next invocation inherits whatever you leave behind.