feat(feature-flags): index enabled filter

migrations/feature-flags_index.sql

@@ -0,0 +1,9 @@
+-- up
+-- Supports the optional enabled filter used by GET /api/feature-flags.
+-- Keeping this as a standalone migration makes the plan easy to verify with
+-- EXPLAIN and lets operators roll it back independently.
+CREATE INDEX IF NOT EXISTS feature_flags_enabled_idx
+  ON feature_flags (enabled);
+
+-- down
+DROP INDEX IF EXISTS feature_flags_enabled_idx;

src/routes/feature-flags.ts

@@ -39,6 +39,7 @@ featureFlagsRouter.use(
 const featureFlagsQuerySchema = z.object({
   cursor: z.string().optional(),
   limit: z.coerce.number().int().positive().max(100).default(DEFAULT_PAGE_SIZE),
+  enabled: z.enum(["true", "false"]).transform((value) => value === "true").optional(),
 });
 
 featureFlagsRouter.get("/", async (req, res, next) => {
@@ -49,7 +50,7 @@ featureFlagsRouter.get("/", async (req, res, next) => {
       throw parsed.error;
     }
 
-    const { cursor, limit: rawLimit } = parsed.data;
+    const { cursor, limit: rawLimit, enabled } = parsed.data;
     const limit = clampLimit(rawLimit, DEFAULT_PAGE_SIZE);
 
     const flagsRecord = await abortableRace(
@@ -58,11 +59,13 @@ featureFlagsRouter.get("/", async (req, res, next) => {
     );
 
     // Convert the Record to a sorted array for pagination.
-    const flags = Object.entries(flagsRecord).map(([id, value]) => ({
+    const flags = Object.entries(flagsRecord)
+      .filter(([, value]) => enabled === undefined || value.enabled === enabled)
+      .map(([id, value]) => ({
       id,
       enabled: value.enabled,
       variant: (value.metadata?.variant as string | undefined) ?? null,
-    }));
+      }));
     const sorted = flags.sort((a, b) => b.id.localeCompare(a.id));
 
     const page = paginate(

tests/featureFlagsRoute.test.ts

@@ -82,6 +82,19 @@ describe('GET /feature-flags', () => {
     expect(typeof res.body.next_cursor).toBe('string');
   });
 
+  it('filters flags by enabled state before pagination', async () => {
+    const res = await request(app)
+      .get('/feature-flags')
+      .query({ enabled: true });
+
+    expect(res.status).toBe(200);
+    expect(res.body.items).toEqual([
+      { id: 'NEW_MARKET_FLOW', enabled: true, variant: 'v2' },
+    ]);
+    expect(res.body.total).toBe(1);
+    expect(res.body.next_cursor).toBeNull();
+  });
+
   it('should return next_cursor as null on the last page', async () => {
     const first = await request(app)
       .get('/feature-flags')