feat: Add delegation tracking MCP tools

Session 374: Task-MCP and Delegation System Integration (Phase 4 & 6)

- Add task_delegations tool: query delegations for a specific task
- Add task_delegation_query tool: query across all tasks by status/backend
- Enhance taskShow() to display recent delegation history
- New delegations.ts module with getRecentDelegations helper

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/index.ts

@@ -22,6 +22,7 @@ import { taskAdd, taskList, taskShow, taskClose, taskUpdate } from './tools/crud
 import { taskSimilar, taskContext } from './tools/search.js';
 import { taskLink, checklistAdd, checklistToggle, taskResolveDuplicate } from './tools/relations.js';
 import { epicAdd, epicList, epicShow, epicAssign } from './tools/epics.js';
+import { taskDelegations, taskDelegationQuery } from './tools/delegations.js';
 
 // Create MCP server
 const server = new Server(
@@ -147,6 +148,18 @@ server.setRequestHandler(CallToolRequestSchema, async (request) => {
         });
         break;
 
+      // Delegations
+      case 'task_delegations':
+        result = await taskDelegations({ task_id: a.task_id });
+        break;
+      case 'task_delegation_query':
+        result = await taskDelegationQuery({
+          status: a.status,
+          backend: a.backend,
+          limit: a.limit,
+        });
+        break;
+
       default:
         throw new Error(`Unknown tool: ${name}`);
     }

src/tools/crud.ts

@@ -3,6 +3,7 @@
 import { query, queryOne, execute, getNextTaskId, getProjectKey } from '../db.js';
 import { getEmbedding, formatEmbedding } from '../embeddings.js';
 import type { Task, ChecklistItem, TaskLink } from '../types.js';
+import { getRecentDelegations } from './delegations.js';
 
 interface TaskAddArgs {
   title: string;
@@ -225,6 +226,12 @@ export async function taskShow(id: string): Promise<string> {
     }
   }
 
+  // Get recent delegations
+  const delegationHistory = await getRecentDelegations(id);
+  if (delegationHistory) {
+    output += delegationHistory;
+  }
+
   return output;
 }
 

src/tools/delegations.ts

@@ -0,0 +1,163 @@
+// Delegation tracking tools for task-mcp
+// Session 374: Task-MCP and Delegation System Integration
+
+import { query } from '../db.js';
+
+interface TaskDelegation {
+  delegation_id: string;
+  backend: string;
+  quality_score: number | null;
+  status: string;
+  input_tokens: number;
+  output_tokens: number;
+  cost_usd: number;
+  started_at: string;
+  completed_at: string | null;
+  error_message: string | null;
+}
+
+interface TaskDelegationWithTask extends TaskDelegation {
+  task_id: string;
+  title: string;
+}
+
+interface DelegationListArgs {
+  task_id: string;
+}
+
+interface DelegationQueryArgs {
+  status?: string;
+  backend?: string;
+  limit?: number;
+}
+
+/**
+ * List delegations for a specific task
+ */
+export async function taskDelegations(args: DelegationListArgs): Promise<string> {
+  const { task_id } = args;
+
+  const delegations = await query<TaskDelegation>(
+    `SELECT delegation_id, backend, quality_score, status,
+            input_tokens, output_tokens, cost_usd,
+            to_char(started_at, 'YYYY-MM-DD HH24:MI') as started_at,
+            to_char(completed_at, 'YYYY-MM-DD HH24:MI') as completed_at,
+            error_message
+     FROM task_delegations
+     WHERE task_id = $1
+     ORDER BY started_at DESC
+     LIMIT 20`,
+    [task_id]
+  );
+
+  if (delegations.length === 0) {
+    return `No delegations found for ${task_id}`;
+  }
+
+  let output = `Delegations for ${task_id}:\n\n`;
+
+  for (const d of delegations) {
+    const icon = d.status === 'success' ? '✓' : d.status === 'failed' ? '✗' : '○';
+    const quality = d.quality_score !== null ? `Q:${d.quality_score}` : 'Q:-';
+    const tokens = d.input_tokens + d.output_tokens;
+    const cost = d.cost_usd > 0 ? ` $${d.cost_usd.toFixed(4)}` : '';
+
+    output += `  ${icon} ${d.delegation_id.substring(0, 8)} [${d.backend}] ${quality} (${d.started_at})`;
+    if (tokens > 0) output += ` ${tokens}tok`;
+    output += cost;
+    output += '\n';
+
+    if (d.error_message) {
+      output += `     Error: ${d.error_message.substring(0, 60)}\n`;
+    }
+  }
+
+  return output;
+}
+
+/**
+ * Query delegations across all tasks with filters
+ */
+export async function taskDelegationQuery(args: DelegationQueryArgs): Promise<string> {
+  const { status, backend, limit = 20 } = args;
+
+  let whereClause = 'WHERE 1=1';
+  const params: unknown[] = [];
+  let paramIndex = 1;
+
+  if (status) {
+    whereClause += ` AND d.status = $${paramIndex++}`;
+    params.push(status);
+  }
+  if (backend) {
+    whereClause += ` AND d.backend = $${paramIndex++}`;
+    params.push(backend);
+  }
+
+  params.push(limit);
+
+  const delegations = await query<TaskDelegationWithTask>(
+    `SELECT d.delegation_id, d.task_id, t.title, d.backend,
+            d.quality_score, d.status,
+            d.input_tokens, d.output_tokens, d.cost_usd,
+            to_char(d.started_at, 'YYYY-MM-DD HH24:MI') as started_at,
+            d.error_message
+     FROM task_delegations d
+     JOIN tasks t ON t.id = d.task_id
+     ${whereClause}
+     ORDER BY d.started_at DESC
+     LIMIT $${paramIndex}`,
+    params
+  );
+
+  if (delegations.length === 0) {
+    return `No delegations found${status ? ` with status '${status}'` : ''}${backend ? ` for backend '${backend}'` : ''}`;
+  }
+
+  let output = `Delegations${status ? ` (${status})` : ''}${backend ? ` [${backend}]` : ''}:\n\n`;
+
+  for (const d of delegations) {
+    const icon = d.status === 'success' ? '✓' : d.status === 'failed' ? '✗' : '○';
+    const quality = d.quality_score !== null ? `Q:${d.quality_score}` : 'Q:-';
+    const titleShort = d.title.length > 30 ? d.title.substring(0, 27) + '...' : d.title;
+
+    output += `${icon} ${d.task_id}: ${titleShort}\n`;
+    output += `   ${d.delegation_id.substring(0, 8)} [${d.backend}] ${quality} (${d.started_at})\n`;
+
+    if (d.error_message) {
+      output += `   Error: ${d.error_message.substring(0, 50)}\n`;
+    }
+  }
+
+  return output;
+}
+
+/**
+ * Get recent delegations for a task (for embedding in taskShow)
+ * Returns formatted string or empty string if no delegations
+ */
+export async function getRecentDelegations(taskId: string): Promise<string> {
+  const delegations = await query<TaskDelegation>(
+    `SELECT delegation_id, backend, quality_score, status,
+            to_char(started_at, 'YYYY-MM-DD HH24:MI') as started_at
+     FROM task_delegations
+     WHERE task_id = $1
+     ORDER BY started_at DESC
+     LIMIT 5`,
+    [taskId]
+  );
+
+  if (delegations.length === 0) {
+    return '';
+  }
+
+  let output = '\n**Recent Delegations:**\n';
+
+  for (const d of delegations) {
+    const icon = d.status === 'success' ? '✓' : d.status === 'failed' ? '✗' : '○';
+    const quality = d.quality_score !== null ? `Q:${d.quality_score}` : 'Q:-';
+    output += `  ${icon} ${d.delegation_id.substring(0, 8)} [${d.backend}] ${quality} (${d.started_at})\n`;
+  }
+
+  return output;
+}

src/tools/index.ts

@@ -197,4 +197,29 @@ export const toolDefinitions = [
       required: ['task_id', 'epic_id'],
     },
   },
+
+  // Delegation Tools
+  {
+    name: 'task_delegations',
+    description: 'List delegations for a specific task (quality scores, backends, status)',
+    inputSchema: {
+      type: 'object',
+      properties: {
+        task_id: { type: 'string', description: 'Task ID (e.g., ST-123)' },
+      },
+      required: ['task_id'],
+    },
+  },
+  {
+    name: 'task_delegation_query',
+    description: 'Query delegations across tasks (filter by status, backend)',
+    inputSchema: {
+      type: 'object',
+      properties: {
+        status: { type: 'string', enum: ['pending', 'success', 'failed', 'partial'], description: 'Filter by delegation status' },
+        backend: { type: 'string', description: 'Filter by backend (e.g., grok, haiku)' },
+        limit: { type: 'number', description: 'Max results (default: 20)' },
+      },
+    },
+  },
 ];