Add scraper indexes and switch to validation collection names

Add createScraperIndexes() to create indexes on the scraper_runs
collection: a compound index on status+startedAt for active job queries
and a descending index on startedAt for recent run lookups.

Change default collection names from production tables
(units_migration_test, unit_prices_migration_test) to dedicated
validation collections (units_scraper, unit_prices_scraper). This
enables the Node.js scraper to run in parallel with the existing Python
scraper during validation without interfering with production data.

Update all scraper test files to reference the new default collection
names.

__tests__/scraper/insertPrices.test.js

@@ -22,7 +22,7 @@ let mongoServer;
 let client;
 let db;
 
-const PRICES_COLLECTION = 'unit_prices_migration_test';
+const PRICES_COLLECTION = 'unit_prices_scraper';
 
 // Mock logger for capturing log calls
 function createMockLogger() {

__tests__/scraper/markStaleUnits.test.js

@@ -21,7 +21,7 @@ let mongoServer;
 let client;
 let db;
 
-const UNITS_COLLECTION = 'units_migration_test';
+const UNITS_COLLECTION = 'units_scraper';
 
 // Mock logger for capturing log calls
 function createMockLogger() {

__tests__/scraper/scraperConfig.test.js

@@ -142,14 +142,14 @@ describe('config/scraper', () => {
 
   describe('COLLECTIONS', () => {
     describe('default values', () => {
-      test('UNITS should default to "units_migration_test"', () => {
+      test('UNITS should default to "units_scraper"', () => {
         const config = require('../../config/scraper');
-        expect(config.COLLECTIONS.UNITS).toBe('units_migration_test');
+        expect(config.COLLECTIONS.UNITS).toBe('units_scraper');
       });
 
-      test('PRICES should default to "unit_prices_migration_test"', () => {
+      test('PRICES should default to "unit_prices_scraper"', () => {
         const config = require('../../config/scraper');
-        expect(config.COLLECTIONS.PRICES).toBe('unit_prices_migration_test');
+        expect(config.COLLECTIONS.PRICES).toBe('unit_prices_scraper');
       });
 
       test('DAILY_SUMMARIES should default to "daily_summaries"', () => {

__tests__/scraper/scraperRoutes.test.js

@@ -118,8 +118,8 @@ jest.mock('../../config/scraper', () => ({
   RETRY_CONFIG: { maxRetries: 3, baseDelay: 1000, timeout: 30000 },
   SHUTDOWN_TIMEOUT: 30000,
   COLLECTIONS: {
-    UNITS: 'units_migration_test',
-    PRICES: 'unit_prices_migration_test',
+    UNITS: 'units_scraper',
+    PRICES: 'unit_prices_scraper',
     DAILY_SUMMARIES: 'daily_summaries',
     SCRAPER_RUNS: 'scraper_runs'
   }

__tests__/scraper/scraperService.test.js

@@ -20,9 +20,10 @@ let mongoServer;
 let client;
 let db;
 
-// We will require runScrape and recordScraperRun after implementation
+// We will require runScrape, recordScraperRun, and createScraperIndexes after implementation
 let runScrape;
 let recordScraperRun;
+let createScraperIndexes;
 
 // Store original module references so we can mock individual functions
 let scraperService;
@@ -36,7 +37,7 @@ beforeAll(async () => {
 
   // Dynamically require to pick up implementation
   scraperService = require('../../services/scraperService');
-  ({ runScrape, recordScraperRun } = scraperService);
+  ({ runScrape, recordScraperRun, createScraperIndexes } = scraperService);
 });
 
 afterAll(async () => {
@@ -219,11 +220,11 @@ describe('runScrape', () => {
     expect(result.staleUnitsCount).toBe(0);
 
     // Verify no units were written to the units collection
-    const unitsCount = await db.collection('units_migration_test').countDocuments();
+    const unitsCount = await db.collection('units_scraper').countDocuments();
     expect(unitsCount).toBe(0);
 
     // Verify no prices were written
-    const pricesCount = await db.collection('unit_prices_migration_test').countDocuments();
+    const pricesCount = await db.collection('unit_prices_scraper').countDocuments();
     expect(pricesCount).toBe(0);
   });
 
@@ -277,7 +278,7 @@ describe('runScrape', () => {
     const faultyDb = {
       collection: (name) => {
         const realCollection = db.collection(name);
-        if (name === 'units_migration_test') {
+        if (name === 'units_scraper') {
           return new Proxy(realCollection, {
             get(target, prop) {
               if (prop === 'bulkWrite') {
@@ -343,7 +344,7 @@ describe('runScrape', () => {
     const faultyDb = {
       collection: (name) => {
         const realCollection = db.collection(name);
-        if (name === 'unit_prices_migration_test') {
+        if (name === 'unit_prices_scraper') {
           return new Proxy(realCollection, {
             get(target, prop) {
               if (prop === 'bulkWrite') {
@@ -388,7 +389,7 @@ describe('runScrape', () => {
     const yesterdayStr = yesterday.toISOString().split('T')[0];
 
     // Yesterday had units: OLD-A, OLD-B, OLD-C
-    await db.collection('unit_prices_migration_test').insertMany([
+    await db.collection('unit_prices_scraper').insertMany([
       { unit_code: 'OLD-A', date_checked: yesterdayStr, price: 1000 },
       { unit_code: 'OLD-B', date_checked: yesterdayStr, price: 1100 },
       { unit_code: 'OLD-C', date_checked: yesterdayStr, price: 1200 }
@@ -631,7 +632,7 @@ describe('sanitizeError', () => {
       const faultyDb = {
         collection: (name) => {
           const realCollection = db.collection(name);
-          if (name === 'units_migration_test') {
+          if (name === 'units_scraper') {
             return new Proxy(realCollection, {
               get(target, prop) {
                 if (prop === 'bulkWrite') {
@@ -674,3 +675,51 @@ describe('sanitizeError', () => {
     });
   });
 });
+
+// ============================================================
+// Test: createScraperIndexes
+// ============================================================
+describe('createScraperIndexes', () => {
+  it('should create the status_startedAt compound index', async () => {
+    await createScraperIndexes(db);
+
+    const indexes = await db.collection('scraper_runs').indexes();
+    const statusIndex = indexes.find(idx => idx.name === 'status_startedAt');
+    expect(statusIndex).toBeTruthy();
+    expect(statusIndex.key).toEqual({ status: 1, startedAt: -1 });
+  });
+
+  it('should create the startedAt_desc index', async () => {
+    await createScraperIndexes(db);
+
+    const indexes = await db.collection('scraper_runs').indexes();
+    const startedAtIndex = indexes.find(idx => idx.name === 'startedAt_desc');
+    expect(startedAtIndex).toBeTruthy();
+    expect(startedAtIndex.key).toEqual({ startedAt: -1 });
+  });
+
+  it('should be idempotent (no error on second call)', async () => {
+    await createScraperIndexes(db);
+
+    // Calling again should not throw
+    await expect(createScraperIndexes(db)).resolves.not.toThrow();
+
+    // Indexes should still exist
+    const indexes = await db.collection('scraper_runs').indexes();
+    const statusIndex = indexes.find(idx => idx.name === 'status_startedAt');
+    const startedAtIndex = indexes.find(idx => idx.name === 'startedAt_desc');
+    expect(statusIndex).toBeTruthy();
+    expect(startedAtIndex).toBeTruthy();
+  });
+
+  it('should handle database errors gracefully', async () => {
+    // Pass an object that will throw when collection() is called
+    const faultyDb = {
+      collection: () => {
+        throw new Error('Connection lost');
+      }
+    };
+
+    await expect(createScraperIndexes(faultyDb)).rejects.toThrow('Connection lost');
+  });
+});

__tests__/scraper/upsertUnits.test.js

@@ -56,7 +56,7 @@ beforeEach(async () => {
 });
 
 describe('upsertUnits', () => {
-  const UNITS_COLLECTION = 'units_migration_test';
+  const UNITS_COLLECTION = 'units_scraper';
 
   // ---------------------------------------------------------------
   // 1. bulkWrite is called with correct updateOne operations