docs(12): create phase plan

Phase 12: Phase-Task Decomposition
- 8 plans in 4 waves
- 4 parallel, 4 sequential
- Ready for execution

.planning/phases/12-phase-task-decomposition/12-02-PLAN.md

@@ -0,0 +1,112 @@
+---
+phase: 12-phase-task-decomposition
+plan: 02
+type: execute
+wave: 1
+depends_on: []
+files_modified:
+  - src/db/repositories/plan-repository.ts
+  - src/db/repositories/drizzle/drizzle-plan-repository.ts
+  - src/db/repositories/index.ts
+autonomous: true
+---
+
+<objective>
+Extend PlanRepository with methods needed for task decomposition workflow.
+
+Purpose: Enable creating plans from architect output and querying plans by phase. The decompose agent needs to know what plans exist in a phase to break them into tasks.
+
+Output: PlanRepository with findByPhaseId, getNextNumber, bulk creation methods.
+</objective>
+
+<execution_context>
+@~/.claude/get-shit-done/workflows/execute-plan.md
+@~/.claude/get-shit-done/templates/summary.md
+</execution_context>
+
+<context>
+@.planning/PROJECT.md
+@.planning/ROADMAP.md
+@.planning/STATE.md
+
+# Pattern reference from Phase 11 (repository extensions)
+@.planning/phases/11-architect-agent/11-02-SUMMARY.md
+
+# Source files to modify
+@src/db/repositories/plan-repository.ts
+@src/db/repositories/drizzle/drizzle-plan-repository.ts
+@src/db/repositories/phase-repository.ts
+</context>
+
+<tasks>
+
+<task type="auto">
+  <name>Task 1: Extend PlanRepository port interface</name>
+  <files>src/db/repositories/plan-repository.ts</files>
+  <action>
+Add the following methods to PlanRepository interface (following pattern from PhaseRepository):
+
+1. `findByPhaseId(phaseId: string): Promise<Plan[]>` - Get all plans for a phase, ordered by number
+2. `getNextNumber(phaseId: string): Promise<number>` - Get next available plan number (MAX+1 or 1 if none)
+  </action>
+  <verify>npm run build passes (no implementation yet)</verify>
+  <done>PlanRepository interface extended with new methods</done>
+</task>
+
+<task type="auto">
+  <name>Task 2: Implement methods in DrizzlePlanRepository</name>
+  <files>src/db/repositories/drizzle/drizzle-plan-repository.ts</files>
+  <action>
+Implement the new methods in DrizzlePlanRepository adapter:
+
+1. `findByPhaseId(phaseId)`:
+   - Query plans table where phase_id = phaseId
+   - Order by number ascending
+   - Return array (empty if none)
+
+2. `getNextNumber(phaseId)`:
+   - Query MAX(number) where phase_id = phaseId
+   - Return max + 1, or 1 if no plans exist
+
+Follow the pattern from DrizzlePhaseRepository.getNextNumber.
+  </action>
+  <verify>npm run build passes, npm test passes</verify>
+  <done>DrizzlePlanRepository implements findByPhaseId and getNextNumber</done>
+</task>
+
+<task type="auto">
+  <name>Task 3: Export types from repositories index</name>
+  <files>src/db/repositories/index.ts</files>
+  <action>
+Verify PlanRepository and its types are properly exported. If not already exported:
+- Export PlanRepository interface
+- Export CreatePlanData type
+- Export UpdatePlanData type
+
+Check existing exports and add if missing.
+  </action>
+  <verify>npm run build passes, types importable from src/db/repositories</verify>
+  <done>All PlanRepository types properly exported</done>
+</task>
+
+</tasks>
+
+<verification>
+Before declaring plan complete:
+- [ ] npm run build succeeds
+- [ ] npm test passes all tests
+- [ ] PlanRepository.findByPhaseId exists and works
+- [ ] PlanRepository.getNextNumber exists and works
+- [ ] Types exported from index
+</verification>
+
+<success_criteria>
+- All tasks completed
+- All verification checks pass
+- No errors or warnings introduced
+- PlanRepository ready for tRPC procedures
+</success_criteria>
+
+<output>
+After completion, create `.planning/phases/12-phase-task-decomposition/12-02-SUMMARY.md`
+</output>