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Impact Gate Impact Gate Impact Gate

Impact Analysis

Impact analysis answers a fundamental question: given a code change, which E2E tests need to run?

How It Works

The impact engine takes a git diff and maps each changed file to the route families it belongs to. A route family represents a product feature (e.g., “channels”, “messaging”, “settings”) with associated source paths, test directories, and user flows.

channel.go changed
  -> belongs to "channels" family
    -> specs live in specs/functional/channels/
      -> run those tests, flag coverage gaps

Three Mapping Strategies

  1. Route families — the route-families.json manifest maps source file patterns to features
  2. Dependency graph — static reverse-dependency analysis catches transitive impacts (a utility changed, so all consumers are affected)
  3. Traceability — file-to-test mappings from CI execution history provide empirical evidence of which tests exercise which files

Running Impact Analysis

Terminal window
npx impact-gate impact --path . --since origin/main

The impact command prints a deterministic summary to stdout. Use plan when you want .e2e-ai-agents/plan.json and .e2e-ai-agents/ci-summary.md artifacts with impactedFamilies, runSet, confidence, and decision.

Building the Route Families Manifest

For accurate results, build a manifest that maps your codebase to features:

Terminal window
# Offline scan (free, no API key)
npx impact-gate train --no-enrich --path .


# With LLM enrichment for better metadata
npx impact-gate train --path .

The scanner uses directory matching, test-derived discovery, server-derived grouping, and name matching to build file-to-family mappings. LLM enrichment adds URL routes, priority levels, and human-readable flow descriptions.

Interpreting Results

Each impacted family in the output includes:

  • confidence — how certain the mapping is (heuristic, traceability, or AI-confirmed)
  • impactLevel — direct change vs. transitive dependency
  • runSet — the specific spec files to execute
  • gaps — user flows with no test coverage for the changed code