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/api_data_patterns.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/api_data_patterns.md
- React/Next UI →
references/frontend_patterns.md
- Testing and review →
references/testing_quality.md
- Prod debugging →
references/debugging_ops.md
1---2name: senior-fullstack-developer3description: Guides senior full-stack delivery across TypeScript/React/Next.js frontends, Node or Python APIs, relational databases, authentication, testing, performance, and pragmatic system design for product features. Use when implementing end-to-end features, designing REST/GraphQL contracts, refactoring UI and backend, debugging production issues in app code, or reviewing PRs for maintainability—not for standard full-stack IC delivery without senior scope (fullstack-software-engineer), CI/CD platform work (devops), security program design (cybersecurity), ML modeling (data-scientist), or LLM prompt/agent design (ai-engineer, prompt-engineer).4---56# Senior Fullstack Developer78## When to Use910- Senior-owned vertical features with higher design bar11- PR review for authz, data layer, and frontend architecture12- Production debugging across app layers with mentorship-level guidance1314## When NOT to Use1516- Routine full-stack feature work at standard IC bar → `fullstack-software-engineer`17- Cross-team RFCs and service boundaries → `senior-software-engineer`18- Infrastructure or pipelines → `infrastructure-engineer`, `devops`1920## Related skills2122| Need | Skill |23|---|---|24| General full-stack IC delivery | `fullstack-software-engineer` |25| Pipelines, deploy, SLOs | `devops` |26| SAST, dependency, pipeline security | `devsecops` |27| Requirements and BRDs | `business-analyst` |28| RAG, agents, LLM APIs | `ai-engineer` |29| Docs and API reference publishing | `tech-writer-researcher` |30| RFCs, service design, senior code review | `senior-software-engineer` |31| Front-end-only senior work | `senior-frontend-software-engineer` |32| Web platform security and auth patterns | `web-application-developer` |3334## Core Workflows3536### 1. Feature delivery (vertical slice)37381. Clarify acceptance criteria and non-goals392. Sketch API contract + UI states (loading, empty, error)403. Implement backend with validation and authz checks first414. Implement UI against contract; use typed client425. Add tests: unit for logic, integration for API, e2e for critical path436. Instrument logs/metrics for new endpoints447. Ship behind flag if risky; document rollout and rollback4546**See `references/feature_delivery.md` for slice checklist and PR template.**4748### 2. API and data layer design4950| Concern | Default |51|---|---|52| Style | REST with OpenAPI or tRPC for TS monoliths |53| Auth | Session or JWT; validate on every mutating route |54| Validation | Schema at boundary (Zod, Pydantic) |55| DB | Migrations versioned; indexes for query paths |56| Errors | Stable error codes; no stack traces to clients |5758**See `references/api_data_patterns.md` for pagination, idempotency, and transaction patterns.**5960### 3. Frontend architecture6162- Prefer server components where data is read-heavy (Next.js App Router)63- Colocate state: server for fetch, client only for interaction64- Accessible components (labels, focus, contrast)65- Avoid premature abstraction; extract after second use6667**See `references/frontend_patterns.md` for forms, caching, and performance.**6869### 4. Quality and review7071**PR review focus:** correctness, authz, input validation, N+1 queries, error paths, test coverage on changed lines.7273**Before merge:** lint, typecheck, tests green; no secrets; migration plan if schema changed.7475**See `references/testing_quality.md` for test pyramid and flaky test handling.**7677### 5. Production debugging78791. Reproduce with correlation ID802. Check recent deploys and feature flags813. Trace logs → metrics → DB slow queries824. Fix forward or rollback; add regression test8384**See `references/debugging_ops.md` for common failure modes.**8586## When to load references8788- **End-to-end feature flow** → `references/feature_delivery.md`89- **APIs and databases** → `references/api_data_patterns.md`90- **React/Next UI** → `references/frontend_patterns.md`91- **Testing and review** → `references/testing_quality.md`92- **Prod debugging** → `references/debugging_ops.md`
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