feat(schema/enums): define TypeBox categorical enum schemas and type aliases

tasks/implementation/schema/enums.md

@@ -1,7 +1,7 @@
 ---
 id: schema/enums
 name: Define TypeBox categorical enum schemas and type aliases
-status: pending
+status: completed
 depends_on:
   - setup/project-init
 scope: narrow
@@ -18,17 +18,17 @@ The six enums: `TaskScopeEnum`, `TaskRiskEnum`, `TaskImpactEnum`, `TaskLevelEnum
 
 ## Acceptance Criteria
 
-- [ ] `src/schema/enums.ts` exports all six enum schemas and their type aliases
-- [ ] Each enum uses `Type.Union([Type.Literal("value"), ...])` pattern per [typebox-patterns.md](../../../docs/research/typebox-patterns.md)
-- [ ] `TaskScopeEnum`: `"single" | "narrow" | "moderate" | "broad" | "system"`
-- [ ] `TaskRiskEnum`: `"trivial" | "low" | "medium" | "high" | "critical"`
-- [ ] `TaskImpactEnum`: `"isolated" | "component" | "phase" | "project"`
-- [ ] `TaskLevelEnum`: `"planning" | "decomposition" | "implementation" | "review" | "research"`
-- [ ] `TaskPriorityEnum`: `"low" | "medium" | "high" | "critical"`
-- [ ] `TaskStatusEnum`: `"pending" | "in-progress" | "completed" | "failed" | "blocked"`
-- [ ] Type aliases derived via `Static<typeof>`: `TaskScope`, `TaskRisk`, `TaskImpact`, `TaskLevel`, `TaskPriority`, `TaskStatus`
-- [ ] Naming convention matches spec: `Enum` suffix on schema constants only, never on type aliases
-- [ ] `src/schema/index.ts` re-exports all schemas and types
+- [x] `src/schema/enums.ts` exports all six enum schemas and their type aliases
+- [x] Each enum uses `Type.Union([Type.Literal("value"), ...])` pattern per [typebox-patterns.md](../../../docs/research/typebox-patterns.md)
+- [x] `TaskScopeEnum`: `"single" | "narrow" | "moderate" | "broad" | "system"`
+- [x] `TaskRiskEnum`: `"trivial" | "low" | "medium" | "high" | "critical"`
+- [x] `TaskImpactEnum`: `"isolated" | "component" | "phase" | "project"`
+- [x] `TaskLevelEnum`: `"planning" | "decomposition" | "implementation" | "review" | "research"`
+- [x] `TaskPriorityEnum`: `"low" | "medium" | "high" | "critical"`
+- [x] `TaskStatusEnum`: `"pending" | "in-progress" | "completed" | "failed" | "blocked"`
+- [x] Type aliases derived via `Static<typeof>`: `TaskScope`, `TaskRisk`, `TaskImpact`, `TaskLevel`, `TaskPriority`, `TaskStatus`
+- [x] Naming convention matches spec: `Enum` suffix on schema constants only, never on type aliases
+- [x] `src/schema/index.ts` re-exports all schemas and types
 
 ## References
 
@@ -37,8 +37,11 @@ The six enums: `TaskScopeEnum`, `TaskRiskEnum`, `TaskImpactEnum`, `TaskLevelEnum
 
 ## Notes
 
-> To be filled by implementation agent
+Also exported the `Nullable` helper generic (used by downstream schemas) and added JSDoc comments on each type alias.
 
 ## Summary
 
-> To be filled on completion
+Implemented all six categorical enum schemas using `Type.Union([Type.Literal(...)])` pattern with `Static<typeof>` type aliases.
+- Created: `src/schema/enums.ts` (6 enum schemas + 6 type aliases + Nullable helper)
+- Modified: `test/schema.test.ts` (21 enum-specific tests: Value.Check validation, Nullable helper, compile-time type alias verification)
+- Tests: 21 enum tests + 4 placeholders, all passing; `tsc --noEmit` clean