feat(11-05): add spawnArchitect tRPC procedures

- Add spawnArchitectDiscuss for context-gathering mode
- Add spawnArchitectBreakdown for phase decomposition mode
- Both procedures validate initiative exists before spawning
- Use comprehensive prompts from agent/prompts module

src/trpc/router.ts

@@ -16,6 +16,7 @@ import type { PhaseRepository } from '../db/repositories/phase-repository.js';
 import type { DispatchManager } from '../dispatch/types.js';
 import type { CoordinationManager } from '../coordination/types.js';
 import type { Phase } from '../db/schema.js';
+import { buildDiscussPrompt, buildBreakdownPrompt } from '../agent/prompts.js';
 
 /**
  * Initialize tRPC with our context type.
@@ -839,6 +840,74 @@ export const appRouter = router({
       }
       return created;
     }),
+
+  // ===========================================================================
+  // Architect Spawn Procedures
+  // ===========================================================================
+
+  /**
+   * Spawn architect in discuss mode.
+   * Uses comprehensive discuss prompt to gather context from user.
+   */
+  spawnArchitectDiscuss: publicProcedure
+    .input(z.object({
+      name: z.string().min(1),
+      initiativeId: z.string().min(1),
+      context: z.string().optional(),
+    }))
+    .mutation(async ({ ctx, input }) => {
+      const agentManager = requireAgentManager(ctx);
+      const initiativeRepo = requireInitiativeRepository(ctx);
+
+      const initiative = await initiativeRepo.findById(input.initiativeId);
+      if (!initiative) {
+        throw new TRPCError({
+          code: 'NOT_FOUND',
+          message: `Initiative '${input.initiativeId}' not found`,
+        });
+      }
+
+      const prompt = buildDiscussPrompt(initiative, input.context);
+
+      return agentManager.spawn({
+        name: input.name,
+        taskId: input.initiativeId,
+        prompt,
+        mode: 'discuss',
+      });
+    }),
+
+  /**
+   * Spawn architect in breakdown mode.
+   * Uses comprehensive breakdown prompt to decompose initiative into phases.
+   */
+  spawnArchitectBreakdown: publicProcedure
+    .input(z.object({
+      name: z.string().min(1),
+      initiativeId: z.string().min(1),
+      contextSummary: z.string().optional(),
+    }))
+    .mutation(async ({ ctx, input }) => {
+      const agentManager = requireAgentManager(ctx);
+      const initiativeRepo = requireInitiativeRepository(ctx);
+
+      const initiative = await initiativeRepo.findById(input.initiativeId);
+      if (!initiative) {
+        throw new TRPCError({
+          code: 'NOT_FOUND',
+          message: `Initiative '${input.initiativeId}' not found`,
+        });
+      }
+
+      const prompt = buildBreakdownPrompt(initiative, input.contextSummary);
+
+      return agentManager.spawn({
+        name: input.name,
+        taskId: input.initiativeId,
+        prompt,
+        mode: 'breakdown',
+      });
+    }),
 });
 
 /**