Engineering Metrics & Validation

This page documents how we plan to measure effectiveness of our solutions.

What We Measure

• DOM performance: render cycles, fragment diff time, reflow frequency
• State consistency: update latency, transaction counts
• Developer experience: onboarding minutes, LOC per component, event bindings per component
• Bundle and Lighthouse scores: budgets and category thresholds

Data Shape

Schema: scripts/metrics.schema.json
Output file: test-results/metrics.json

Collecting Metrics (CI Placeholder)

• Command: npm run metrics:collect
• Environment variables consumed (optional):
  • BD_BUNDLE_TOTAL_KB, BD_BUNDLE_VENDOR_KB
  • BD_LH_PERF, BD_LH_A11Y, BD_LH_BP, BD_LH_SEO
  • BD_DOM_CYCLES, BD_DOM_DIFF_MS, BD_DOM_REFLOWS
  • BD_STATE_LAT_MS, BD_STATE_TX
  • BD_DX_ONBOARD_M, BD_DX_LOC, BD_DX_EVT

CI uploads test-results/metrics.json as an artifact named engineering-metrics.

Future Harness

• PerformanceObserver sampling in E2E to populate DOM metrics
• Parsing Lighthouse JSON to fill category scores
• Bundle analyzer parsing to emit vendor/core split sizes
• Telemetry during local dev to populate DX signals (opt-in)