Single-source requirement and traceability enums across backend, frontend, and MCP

[Brad-Edwards]

Raised from the 2026-03-28 full-codebase architecture and code-quality review.

Problem

Backend enums, MCP enums, and frontend enums are not single-sourced. The frontend currently exposes unsupported values for requirement type, artifact type, and link type.

Evidence

Backend/MCP agree:

• backend/src/main/java/com/keplerops/groundcontrol/domain/requirements/state/RequirementType.java
• backend/src/main/java/com/keplerops/groundcontrol/domain/requirements/state/ArtifactType.java
• backend/src/main/java/com/keplerops/groundcontrol/domain/requirements/state/LinkType.java
• mcp/ground-control/lib.js

Frontend drift:

• frontend/src/types/api.ts
• frontend/src/components/requirement-form.tsx
• frontend/src/components/traceability-form.tsx
• frontend/src/pages/analysis.tsx
• frontend/src/pages/requirements.tsx
• frontend/src/components/ui/badge.tsx

Why this matters

The UI currently offers impossible states like PERFORMANCE, SECURITY, DATA, GITHUB_PR, TRACES_TO, and DERIVED_FROM. This causes avoidable runtime failures and guarantees contract drift will recur.

Definition of done

• Establish one source of truth for API enums and request contracts.
• Remove unsupported enum values from the frontend.
• Align create/edit form validation with backend-required fields.
• Add a contract check so backend/frontend/MCP enum drift fails fast in CI.
• Add a regression test covering the current mismatch class.