Fullstack Software Engineer

Full Stack Software Engineer

When to Use

• Implement a vertical feature (UI + API + persistence)
• Design or change an API consumed by the frontend
• Fix bugs spanning client and server
• Add auth, validation, pagination, or file upload flows
• Write or extend unit, integration, and critical-path e2e tests

When NOT to Use

• Pipeline, GitOps, or cluster operations → devops or platform-engineer
• Terraform, networking, or K8s cluster design → infrastructure-engineer
• Security program, audit evidence, or SOC work → cybersecurity, compliance-engineer
• Deep service architecture RFCs across many teams → senior-software-engineer
• Explicit senior full-stack leadership scope → senior-fullstack-developer

Related skills

Core Workflows

1. Vertical feature delivery

1. Confirm acceptance criteria and edge cases (empty, error, permissions) 2. Define API contract and UI states 3. Implement server: validation, authz, persistence, migrations 4. Implement client against typed contract 5. Test: unit (logic), integration (API), e2e (happy path) 6. Add logging/metrics on new paths; feature flag if risky

See `references/feature_delivery.md` for checklist.

2. API and database

See `references/api_and_database.md` for pagination and migrations.

3. Frontend integration

• Match loading/error/empty states to design
• Prefer server fetch for read-heavy pages when using Next.js App Router
• Client components only for interactivity
• Accessible forms (labels, focus, keyboard)

See `references/frontend_integration.md` for forms and caching.

4. Testing and PR hygiene

• Lint and typecheck clean
• Tests cover changed behavior, not only happy path
• No secrets in repo; env via configuration
• Small PRs; describe rollout and rollback

See `references/testing_debugging.md` for test pyramid.

5. Production debugging

1. Reproduce with correlation ID or request ID 2. Check deploys, flags, and recent config changes 3. Trace: logs → metrics → DB slow queries 4. Fix with regression test; hotfix or rollback per severity

See `references/testing_debugging.md` for common failures.

When to load references

• Feature flow → references/feature_delivery.md
• APIs and DB → references/api_and_database.md
• UI integration → references/frontend_integration.md
• Tests and prod issues → references/testing_debugging.md

API and database

Table of contents

1. REST defaults 2. Pagination 3. Migrations

REST defaults

• POST create, GET read, PATCH partial update, DELETE remove
• Validate body and query params at entry
• Return consistent error shape: { code, message, details? }

Pagination

Prefer cursor-based for large lists:

GET /items?cursor=abc&limit=20
→ { items: [], next_cursor: "def" }

Migrations

• One logical change per migration
• Backfill in batches for large tables
• Test rollback on staging
• Never drop column until code no longer reads it (expand-contract)

Feature delivery

Table of contents

1. Slice checklist 2. PR description

Slice checklist

• [ ] Acceptance criteria met including error paths
• [ ] API contract documented or types shared
• [ ] Authz tested for allowed and denied roles
• [ ] Migration reviewed (up/down, backfill plan)
• [ ] UI states: loading, empty, error
• [ ] Metrics or logs for new operations
• [ ] Feature flag or safe rollout noted if needed

PR description

• What — user-visible change
• How — approach in one paragraph
• Test — how verified
• Risk — rollout/rollback

Frontend integration

Table of contents

1. Data fetching 2. Forms 3. Performance

Data fetching

• Server Components: fetch on server for read-heavy pages (Next.js)
• Client: useQuery or equivalent with stale-time for interactive views
• Invalidate cache after mutations

Forms

• Client validation for UX; server validation for security
• Disable submit while pending; show field-level errors
• Optimistic UI only when rollback is trivial

Performance

• Code-split large routes
• Optimize images; avoid layout shift
• Debounce search inputs

Testing and debugging

Table of contents

1. Test pyramid 2. Common prod failures

Test pyramid

Common prod failures