GitNexus Impact Analysis

CLI ONLY — no MCP server exists. Never use readMcpResource with gitnexus:// 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@25.8.0

All 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 status

If stale (indexed commit ≠ HEAD), automatically reindex before proceeding — do not ask the user:

gitnexus analyze

Then re-check status to confirm index is current.

Step 2: Upstream Blast Radius

gitnexus impact "<symbol>" --depth 3

This 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 3

Step 3: Downstream Dependencies (Optional)

gitnexus impact "<symbol>" --direction downstream --depth 3

Shows what the symbol depends on — useful for understanding if dependencies might change.

Step 4: Test Coverage

gitnexus impact "<symbol>" --include-tests

Shows 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-tests

Output: "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.