diff --git a/DECISIONS.md b/DECISIONS.md
index 6ab80f7..150b42d 100644
--- a/DECISIONS.md
+++ b/DECISIONS.md
@@ -207,3 +207,8 @@ Implementation decisions not spelled out in `memory-bank/implementation-plan.md`
 - **Config** comes from env vars validated with Zod in `loadConfig`, which reports every problem at once. `NODE_ENV`, `PORT` and `LOG_LEVEL` have defaults (development, 3000, info). The entry point loads the repo-root `.env` with `process.loadEnvFile` when the file exists; deployments set real env vars.
 - **The health endpoint is `GET /api/health`**, under `/api` so it is reachable through the same-domain proxy (decision 0.5.20). It is infrastructure, so it is not in the route catalog.
 - **`buildApp(config)` does not listen,** so tests start it on port 0. Logs are pino JSON; tests use `LOG_LEVEL=silent`.
+
+## Step 5.2
+
+- **The injectable clock arrives now, not in Step 7.2.** `buildApp(config, { clock })` takes a `Clock` (`() => RealTime`) and defaults to `Date.now`. Every endpoint will read "now" through it (decision 0.5.18). Step 7.2 still adds the test-only clock-offset endpoint.
+- **Game time uses the default `content.config`**, via sim `realToGame`.
diff --git a/apps/server/src/app.ts b/apps/server/src/app.ts
index dd5addb..7b9ff39 100644
--- a/apps/server/src/app.ts
+++ b/apps/server/src/app.ts
@@ -1,8 +1,17 @@
+import { content } from "@deadhead/content";
+import { routes, type ServerTime } from "@deadhead/schema";
+import { realToGame } from "@deadhead/sim";
 import Fastify, { type FastifyInstance } from "fastify";
+import { type Clock, systemClock } from "./clock";
 import type { ServerConfig } from "./config";
 
+export interface AppDeps {
+  clock?: Clock;
+}
+
 /** Builds the Fastify app without listening, so tests can start it on any port. */
-export function buildApp(config: ServerConfig): FastifyInstance {
+export function buildApp(config: ServerConfig, deps: AppDeps = {}): FastifyInstance {
+  const clock = deps.clock ?? systemClock;
   const app = Fastify({
     // Structured JSON logs (pino); silenced in tests unless LOG_LEVEL says otherwise.
     logger: { level: config.logLevel },
@@ -11,5 +20,10 @@ export function buildApp(config: ServerConfig): FastifyInstance {
   // Under /api so it is reachable through the same-domain proxy (decision 0.5.20).
   app.get("/api/health", async () => ({ status: "ok" }));
 
+  app.get(routes.getServerTime.path, async (): Promise<ServerTime> => {
+    const realTime = clock();
+    return { realTime, gameTime: realToGame(realTime, content.config) };
+  });
+
   return app;
 }
diff --git a/apps/server/src/clock.ts b/apps/server/src/clock.ts
new file mode 100644
index 0000000..40d3df8
--- /dev/null
+++ b/apps/server/src/clock.ts
@@ -0,0 +1,6 @@
+import type { RealTime } from "@deadhead/sim";
+
+/** The server's only source of "now" (decision 0.5.18), so tests can control time. */
+export type Clock = () => RealTime;
+
+export const systemClock: Clock = () => Date.now();
diff --git a/apps/server/src/index.ts b/apps/server/src/index.ts
index 4424b84..b5971c7 100644
--- a/apps/server/src/index.ts
+++ b/apps/server/src/index.ts
@@ -1,2 +1,3 @@
-export { buildApp } from "./app";
+export { buildApp, type AppDeps } from "./app";
+export { systemClock, type Clock } from "./clock";
 export { loadConfig, type ServerConfig } from "./config";
diff --git a/apps/server/test/time.test.ts b/apps/server/test/time.test.ts
new file mode 100644
index 0000000..fa4dc8d
--- /dev/null
+++ b/apps/server/test/time.test.ts
@@ -0,0 +1,27 @@
+import { content } from "@deadhead/content";
+import { serverTimeSchema } from "@deadhead/schema";
+import { realToGame } from "@deadhead/sim";
+import { afterAll, describe, expect, it } from "vitest";
+import { buildApp } from "../src/app";
+import { testConfig } from "./helpers";
+
+describe("server time endpoint", () => {
+  const app = buildApp(testConfig());
+  afterAll(() => app.close());
+
+  it("returns the current real time and the matching game time", async () => {
+    const response = await app.inject({ method: "GET", url: "/api/time" });
+    expect(response.statusCode).toBe(200);
+    const body = serverTimeSchema.parse(response.json());
+    expect(Math.abs(body.realTime - Date.now())).toBeLessThan(2000);
+    expect(body.gameTime).toBe(realToGame(body.realTime, content.config));
+  });
+
+  it("reads time from the injected clock", async () => {
+    const fixed = Date.parse("2100-06-01T12:00:00Z");
+    const fixedApp = buildApp(testConfig(), { clock: () => fixed });
+    const body = (await fixedApp.inject({ method: "GET", url: "/api/time" })).json();
+    expect(body).toEqual({ realTime: fixed, gameTime: realToGame(fixed, content.config) });
+    await fixedApp.close();
+  });
+});
diff --git a/memory-bank/progress.md b/memory-bank/progress.md
index a8a6493..89884ff 100644
--- a/memory-bank/progress.md
+++ b/memory-bank/progress.md
@@ -46,7 +46,7 @@
 ## Phase 5 — Server Foundation
 
 - [x] **Step 5.1 — Fastify skeleton.** `apps/server`: Zod-validated env config (`src/config.ts`), `buildApp` with pino JSON logging and `GET /api/health` (`src/app.ts`), entry point `src/main.ts` (loads repo-root `.env` if present). `pnpm --filter @deadhead/server dev|start` run it with tsx. Integration test starts the app on an ephemeral port and calls health over HTTP.
-- [ ] Step 5.2 — Server time endpoint
+- [x] **Step 5.2 — Server time endpoint.** `GET /api/time` returns `{ realTime, gameTime }` from an injectable `Clock` (`src/clock.ts`, passed via `buildApp(config, { clock })`).
 - [ ] Step 5.3 — Database schema and migrations
 - [ ] Step 5.4 — Test database harness
 - [ ] Step 5.5 — Guest accounts