Agent-Skills.md

Agent Skills: GitNexus Impact Analysis

Blast radius analysis via GitNexus CLI (gitnexus). CLI ONLY - NO MCP server exists, never use readMcpResource with gitnexus:// URIs. TRIGGERS - what breaks if I change, blast radius, impact analysis, safe to modify.

UncategorizedID: terrylica/cc-skills/impact

Repository

terrylica/cc-skills
terrylicaLicense: MIT
264

Install this agent skill to your local

pnpm dlx add-skill https://github.com/terrylica/cc-skills/tree/HEAD/plugins/gitnexus-tools/skills/impact

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plugins/gitnexus-tools/skills/impact/SKILL.md

Skill Metadata

Name
impact
Description
"Blast radius analysis via GitNexus CLI (gitnexus). CLI ONLY - NO MCP server exists, never use readMcpResource with gitnexus:// URIs. TRIGGERS - what breaks if I change, blast radius, impact analysis, safe to modify."

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.

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."