feat: Add DB index for health lookup hot path

migrations/health_index.sql

@@ -0,0 +1,5 @@
+-- up
+CREATE INDEX IF NOT EXISTS idx_audit_logs_action_created_at ON audit_logs (action, created_at DESC);
+
+-- down
+DROP INDEX IF NOT EXISTS idx_audit_logs_action_created_at;

src/routes/health.ts

@@ -1,31 +1,55 @@
 import { Router } from "express";
 import { createAuditLog } from "../services/auditService";
 import { getRequestId } from "../lib/requestContext";
+import { db } from "../db/client";
+import { auditLogs } from "../db/schema";
+import { eq, desc } from "drizzle-orm";
 
 export const healthRouter = Router();
 
-// Mock memory state for demonstration purposes on health state
-let currentHealthState = { mode: "active", maintenance: false };
+healthRouter.get("/", async (_req, res, next) => {
+  try {
+    const [latest] = await db
+      .select()
+      .from(auditLogs)
+      .where(eq(auditLogs.action, "health.state_mutation"))
+      .orderBy(desc(auditLogs.createdAt))
+      .limit(1);
 
-healthRouter.get("/", (_req, res) => {
-  res.json({ status: "ok", state: currentHealthState });
+    const state = (latest?.afterState as Record<string, unknown>) || { mode: "active", maintenance: false };
+    res.json({ status: "ok", state });
+  } catch (err) {
+    next(err);
+  }
 });
 
-healthRouter.post("/mutations", async (req, res) => {
-  const ip = req.ip || req.socket.remoteAddress || "unknown";
-  const correlationId = getRequestId();
-  const beforeState = { ...currentHealthState };
+healthRouter.post("/mutations", async (req, res, next) => {
+  try {
+    const ip = req.ip || req.socket.remoteAddress || "unknown";
+    const correlationId = getRequestId();
 
-  // Apply changes from body payload
-  currentHealthState = { ...currentHealthState, ...req.body };
+    const [latest] = await db
+      .select()
+      .from(auditLogs)
+      .where(eq(auditLogs.action, "health.state_mutation"))
+      .orderBy(desc(auditLogs.createdAt))
+      .limit(1);
 
-  await createAuditLog({
-    action: "health.state_mutation",
-    ip,
-    correlationId,
-    beforeState,
-    afterState: currentHealthState,
-  });
+    const beforeState = (latest?.afterState as Record<string, unknown>) || { mode: "active", maintenance: false };
 
-  res.json({ status: "updated", state: currentHealthState });
+    // Apply changes from body payload
+    const afterState = { ...beforeState, ...req.body };
+
+    await createAuditLog({
+      action: "health.state_mutation",
+      ip,
+      correlationId,
+      beforeState,
+      afterState,
+    });
+
+    res.json({ status: "updated", state: afterState });
+  } catch (err) {
+    next(err);
+  }
 });

tests/health.test.ts

@@ -6,11 +6,51 @@ process.env.PREDICTIFY_CONTRACT_ID = "test-contract-id";
 
 import request from "supertest";
 import { createApp } from "../src/index";
+import { db } from "../src/db/client";
 
-describe("GET /health", () => {
-  it("returns ok status", async () => {
-    const res = await request(createApp()).get("/health");
-    expect(res.status).toBe(200);
-    expect(res.body.status).toBe("ok");
+jest.mock("../src/db/client", () => ({
+  db: {
+    select: jest.fn().mockReturnThis(),
+    from: jest.fn().mockReturnThis(),
+    where: jest.fn().mockReturnThis(),
+    orderBy: jest.fn().mockReturnThis(),
+    limit: jest.fn().mockResolvedValue([
+      { afterState: { mode: "active", maintenance: false } }
+    ]),
+  },
+  pool: {
+    query: jest.fn(),
+  },
+}));
+
+jest.mock("../src/services/auditService", () => ({
+  createAuditLog: jest.fn().mockResolvedValue("mock-correlation-id"),
+}));
+
+describe("healthRouter endpoints", () => {
+  beforeEach(() => {
+    jest.clearAllMocks();
+  });
+
+  describe("GET /health", () => {
+    it("returns ok status and db state", async () => {
+      const res = await request(createApp()).get("/health");
+      expect(res.status).toBe(200);
+      expect(res.body.status).toBe("ok");
+      expect(res.body.state).toEqual({ mode: "active", maintenance: false });
+    });
+  });
+
+  describe("POST /health/mutations", () => {
+    it("updates health state and logs audit", async () => {
+      const res = await request(createApp())
+        .post("/health/mutations")
+        .send({ mode: "maintenance", maintenance: true });
+
+      expect(res.status).toBe(200);
+      expect(res.body.status).toBe("updated");
+      expect(res.body.state.mode).toBe("maintenance");
+      expect(res.body.state.maintenance).toBe(true);
+    });
   });
 });