feat(tasks): Add task pool start/stop toggle

- Add task-pool-state.ts for shared pause/resume state
- Add /api/tasks/pool/status, pause, resume endpoints
- Add Start/Stop Pool toggle button to TasksDashboard
- Spinner stops when pool is closed
- Fix is_active column name in store-discovery.ts
- Fix missing active column in task-service.ts claimTask
- Auto-refresh every 15 seconds

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

backend/src/routes/tasks.ts

@@ -13,6 +13,12 @@ import {
   TaskFilter,
 } from '../tasks/task-service';
 import { pool } from '../db/pool';
+import {
+  isTaskPoolPaused,
+  pauseTaskPool,
+  resumeTaskPool,
+  getTaskPoolStatus,
+} from '../tasks/task-pool-state';
 
 const router = Router();
 
@@ -592,4 +598,42 @@ router.post('/migration/full-migrate', async (req: Request, res: Response) => {
   }
 });
 
+/**
+ * GET /api/tasks/pool/status
+ * Check if task pool is paused
+ */
+router.get('/pool/status', async (_req: Request, res: Response) => {
+  const status = getTaskPoolStatus();
+  res.json({
+    success: true,
+    ...status,
+  });
+});
+
+/**
+ * POST /api/tasks/pool/pause
+ * Pause the task pool - workers won't pick up new tasks
+ */
+router.post('/pool/pause', async (_req: Request, res: Response) => {
+  pauseTaskPool();
+  res.json({
+    success: true,
+    paused: true,
+    message: 'Task pool paused - workers will not pick up new tasks',
+  });
+});
+
+/**
+ * POST /api/tasks/pool/resume
+ * Resume the task pool - workers will pick up tasks again
+ */
+router.post('/pool/resume', async (_req: Request, res: Response) => {
+  resumeTaskPool();
+  res.json({
+    success: true,
+    paused: false,
+    message: 'Task pool resumed - workers will pick up new tasks',
+  });
+});
+
 export default router;

backend/src/tasks/handlers/store-discovery.ts

@@ -25,7 +25,7 @@ export async function handleStoreDiscovery(ctx: TaskContext): Promise<TaskResult
   try {
     // Get states to discover
     const statesResult = await pool.query(`
-      SELECT code FROM states WHERE active = true ORDER BY code
+      SELECT code FROM states WHERE is_active = true ORDER BY code
     `);
     const stateCodes = statesResult.rows.map(r => r.code);
 

backend/src/tasks/task-pool-state.ts

@@ -0,0 +1,35 @@
+/**
+ * Task Pool State
+ *
+ * Shared state for task pool pause/resume functionality.
+ * This is kept separate to avoid circular dependencies between
+ * task-service.ts and routes/tasks.ts.
+ *
+ * State is in-memory and resets on server restart.
+ * By default, the pool is OPEN (not paused).
+ */
+
+let taskPoolPaused = false;
+
+export function isTaskPoolPaused(): boolean {
+  return taskPoolPaused;
+}
+
+export function pauseTaskPool(): void {
+  taskPoolPaused = true;
+  console.log('[TaskPool] Task pool PAUSED - workers will not pick up new tasks');
+}
+
+export function resumeTaskPool(): void {
+  taskPoolPaused = false;
+  console.log('[TaskPool] Task pool RESUMED - workers can pick up tasks');
+}
+
+export function getTaskPoolStatus(): { paused: boolean; message: string } {
+  return {
+    paused: taskPoolPaused,
+    message: taskPoolPaused
+      ? 'Task pool is paused - workers will not pick up new tasks'
+      : 'Task pool is open - workers are picking up tasks',
+  };
+}

backend/src/tasks/task-service.ts

@@ -9,6 +9,7 @@
  */
 
 import { pool } from '../db/pool';
+import { isTaskPoolPaused } from './task-pool-state';
 
 // Helper to check if a table exists
 async function tableExists(tableName: string): Promise<boolean> {
@@ -149,8 +150,14 @@ class TaskService {
   /**
    * Claim a task atomically for a worker
    * If role is null, claims ANY available task (role-agnostic worker)
+   * Returns null if task pool is paused.
    */
   async claimTask(role: TaskRole | null, workerId: string): Promise<WorkerTask | null> {
+    // Check if task pool is paused - don't claim any tasks
+    if (isTaskPoolPaused()) {
+      return null;
+    }
+
     if (role) {
       // Role-specific claiming - use the SQL function
       const result = await pool.query(
@@ -170,7 +177,6 @@ class TaskService {
       WHERE id = (
         SELECT id FROM worker_tasks
         WHERE status = 'pending'
-          AND active = true
           AND (scheduled_for IS NULL OR scheduled_for <= NOW())
           -- Exclude stores that already have an active task
           AND (dispensary_id IS NULL OR dispensary_id NOT IN (