feat(12-04): add Plan tRPC procedures

- Import PlanRepository type
- Add requirePlanRepository helper
- Add createPlan procedure (auto-assigns number if not provided)
- Add listPlans procedure (returns plans ordered by number)
- Add getPlan procedure (throws NOT_FOUND if not found)
- Add updatePlan procedure (name, description, status)

src/trpc/router.ts

@@ -13,9 +13,10 @@ import type { TaskRepository } from '../db/repositories/task-repository.js';
 import type { MessageRepository } from '../db/repositories/message-repository.js';
 import type { InitiativeRepository } from '../db/repositories/initiative-repository.js';
 import type { PhaseRepository } from '../db/repositories/phase-repository.js';
+import type { PlanRepository } from '../db/repositories/plan-repository.js';
 import type { DispatchManager } from '../dispatch/types.js';
 import type { CoordinationManager } from '../coordination/types.js';
-import type { Phase } from '../db/schema.js';
+import type { Phase, Plan } from '../db/schema.js';
 import { buildDiscussPrompt, buildBreakdownPrompt } from '../agent/prompts.js';
 
 /**
@@ -264,6 +265,19 @@ function requirePhaseRepository(ctx: TRPCContext): PhaseRepository {
   return ctx.phaseRepository;
 }
 
+/**
+ * Helper to ensure planRepository is available in context.
+ */
+function requirePlanRepository(ctx: TRPCContext): PlanRepository {
+  if (!ctx.planRepository) {
+    throw new TRPCError({
+      code: 'INTERNAL_SERVER_ERROR',
+      message: 'Plan repository not available',
+    });
+  }
+  return ctx.planRepository;
+}
+
 // =============================================================================
 // Application Router with Procedures
 // =============================================================================
@@ -841,6 +855,79 @@ export const appRouter = router({
       return created;
     }),
 
+  // ===========================================================================
+  // Plan Procedures
+  // ===========================================================================
+
+  /**
+   * Create a new plan for a phase.
+   * Auto-assigns the next plan number if not provided.
+   */
+  createPlan: publicProcedure
+    .input(z.object({
+      phaseId: z.string().min(1),
+      number: z.number().int().positive().optional(),
+      name: z.string().min(1),
+      description: z.string().optional(),
+    }))
+    .mutation(async ({ ctx, input }) => {
+      const repo = requirePlanRepository(ctx);
+      const number = input.number ?? await repo.getNextNumber(input.phaseId);
+      return repo.create({
+        phaseId: input.phaseId,
+        number,
+        name: input.name,
+        description: input.description ?? null,
+        status: 'pending',
+      });
+    }),
+
+  /**
+   * List plans for a phase.
+   * Returns plans ordered by number.
+   */
+  listPlans: publicProcedure
+    .input(z.object({ phaseId: z.string().min(1) }))
+    .query(async ({ ctx, input }) => {
+      const repo = requirePlanRepository(ctx);
+      return repo.findByPhaseId(input.phaseId);
+    }),
+
+  /**
+   * Get a plan by ID.
+   * Throws NOT_FOUND if plan doesn't exist.
+   */
+  getPlan: publicProcedure
+    .input(z.object({ id: z.string().min(1) }))
+    .query(async ({ ctx, input }) => {
+      const repo = requirePlanRepository(ctx);
+      const plan = await repo.findById(input.id);
+      if (!plan) {
+        throw new TRPCError({
+          code: 'NOT_FOUND',
+          message: `Plan '${input.id}' not found`,
+        });
+      }
+      return plan;
+    }),
+
+  /**
+   * Update a plan.
+   * Returns the updated plan.
+   */
+  updatePlan: publicProcedure
+    .input(z.object({
+      id: z.string().min(1),
+      name: z.string().min(1).optional(),
+      description: z.string().optional(),
+      status: z.enum(['pending', 'in_progress', 'completed']).optional(),
+    }))
+    .mutation(async ({ ctx, input }) => {
+      const repo = requirePlanRepository(ctx);
+      const { id, ...data } = input;
+      return repo.update(id, data);
+    }),
+
   // ===========================================================================
   // Architect Spawn Procedures
   // ===========================================================================