SKILL.md
Senior Fullstack Developer
When to Use
- Senior-owned vertical features with higher design bar
- PR review for authz, data layer, and frontend architecture
- Production debugging across app layers with mentorship-level guidance
When NOT to Use
- Routine full-stack feature work at standard IC bar →
fullstack-software-engineer - Cross-team RFCs and service boundaries →
senior-software-engineer - Infrastructure or pipelines →
infrastructure-engineer,devops
Related skills
| Need | Skill |
|---|---|
| General full-stack IC delivery | fullstack-software-engineer |
| Pipelines, deploy, SLOs | devops |
| SAST, dependency, pipeline security | devsecops |
| Requirements and BRDs | business-analyst |
| RAG, agents, LLM APIs | ai-engineer |
| Docs and API reference publishing | tech-writer-researcher |
| RFCs, service design, senior code review | senior-software-engineer |
| Front-end-only senior work | senior-frontend-software-engineer |
| Web platform security and auth patterns | web-application-developer |
Core Workflows
1. Feature delivery (vertical slice)
- Clarify acceptance criteria and non-goals
- Sketch API contract + UI states (loading, empty, error)
- Implement backend with validation and authz checks first
- Implement UI against contract; use typed client
- Add tests: unit for logic, integration for API, e2e for critical path
- Instrument logs/metrics for new endpoints
- Ship behind flag if risky; document rollout and rollback
See references/feature_delivery.md for slice checklist and PR template.
2. API and data layer design
| Concern | Default |
|---|---|
| Style | REST with OpenAPI or tRPC for TS monoliths |
| Auth | Session or JWT; validate on every mutating route |
| Validation | Schema at boundary (Zod, Pydantic) |
| DB | Migrations versioned; indexes for query paths |
| Errors | Stable error codes; no stack traces to clients |
See references/apidatapatterns.md for pagination, idempotency, and transaction patterns.
3. Frontend architecture
- Prefer server components where data is read-heavy (Next.js App Router)
- Colocate state: server for fetch, client only for interaction
- Accessible components (labels, focus, contrast)
- Avoid premature abstraction; extract after second use
See references/frontend_patterns.md for forms, caching, and performance.
4. Quality and review
PR review focus: correctness, authz, input validation, N+1 queries, error paths, test coverage on changed lines.
Before merge: lint, typecheck, tests green; no secrets; migration plan if schema changed.
See references/testing_quality.md for test pyramid and flaky test handling.
5. Production debugging
- Reproduce with correlation ID
- Check recent deploys and feature flags
- Trace logs → metrics → DB slow queries
- Fix forward or rollback; add regression test
See references/debugging_ops.md for common failure modes.
When to load references
- End-to-end feature flow →
references/feature_delivery.md - APIs and databases →
references/apidatapatterns.md - React/Next UI →
references/frontend_patterns.md - Testing and review →
references/testing_quality.md - Prod debugging →
references/debugging_ops.md