Contractor‑Ready Microfeature Spec: One Page Template + Acceptance Tests

Contractors succeed when ambiguity is removed. The spec should be a single page that answers: what the UX must look like (pixel‑accurate targets), what the API contract is, which acceptance tests must pass, which telemetry matters for billing and reliability, and how to rollback or kill the feature quickly.

Keep each section rigidly scoped to the microfeature. For example: define the exact Figma frame(s) to implement, list OpenAPI endpoints with example requests/responses, include Playwright test cases (happy and key unhappy paths), map telemetry events and billing counters to database fields or metrics, and provide a one‑step rollback recipe (feature flag + metric gate).

Use this exact structure in a single page README.md that lives in the feature branch. Top section: Title, short description, owner, estimated hours, and a single sentence acceptance criteria. Next: Links — Figma Dev Mode link (exact frame), OpenAPI file path or inline YAML, and the test file path.

Include short, runnable examples instead of vague notes. Paste the OpenAPI paths you expect the contractor to implement (2–4 examples), and a Playwright test file with selectors derived from Figma node names. Below that, a telemetry map table showing event name, payload fields, billing counter, and the target metric to watch during rollout.

Example A — New billing toggle (metered usage): Figma shows the billing screen slice, OpenAPI POST /subscriptions/{id}/meter with sample 200 and 402 responses, Playwright test asserts that usage increments and invoice preview updates, telemetry includes event billing.usage.increment and billing.counter.{feature}. The rollback path: flip feature_flag.billing_preview to off and run a DB compensation script if partial charges occurred.

Example B — Lightweight settings page toggle: Figma frame with toggle states, OpenAPI PATCH /users/{id}/settings, Playwright validates UI state, localStorage persistence, and server response. Rollback: feature flag + canary rollout at 1% for 24 hours; gate uses error-rate and p95 latency thresholds.

Example C — Email confirmation flow: include Figma email flow mock, OpenAPI POST /auth/send-confirm, test that clicking the deep link changes user state, telemetry for email.sent and confirmation.success. Rollback: disable outbound email service for that flow and display fallback UI; circuit breaker metric is email bounce rate > X%.

Acceptance tests must be deterministic and map to UI artifacts in Figma. Use data-testid values that match Figma node names or frame IDs so selectors never drift. Provide the contractor with a Playwright example that runs against a dev mock server generated from your OpenAPI stubs.

Keep tests focused: one end‑to‑end happy path (user flow end to end), and 2–3 focused unhappy/edge cases (API 400/401/500 responses, missing assets). Include CI instructions to run tests against the stub server and the staging environment; require green tests before merge.

Treat rollback as part of the spec, not an afterthought. Include an explicit kill switch (feature flag name) and step‑by‑step rollback steps: flip flag, revert traffic via canary/blue‑green, run compensation jobs, and notify on‑call with a prefilled incident template. Define metric gates (error rate, p95 latency, billing counter delta) and the exact thresholds that trigger manual or automated rollback.

For billing‑sensitive microfeatures add a metric that captures 'net billed amount delta' and a runbook entry that explains how to stop further billing and refund or reconcile. If you use canary deployments or feature flags, point to the exact canary percentages and monitoring windows the contractor should test against during QA.