feat(api): add unauthenticated health endpoints

Add GET /api/v1/health/live and GET /api/v1/health/ready per ADR 0044.

- live returns a fixed 200 {"status":"live"} whenever the process serves.
- ready returns 200 {"status":"ready"} only when module startup has
  completed (and shutdown has not begun) and a database ping succeeds
  within 2s; otherwise a fixed 503 {"code":"NOT_READY"}.
- The ping runs on the shared pool as one simple-protocol message with
  a transaction-local statement_timeout, so PostgreSQL cancels a stalled
  statement; the pool discards the connection on failure.
- At most one ping is ever unsettled: probes share its outcome and, once
  its deadline passes, answer 503 immediately until it settles.
- Both routes set Cache-Control: no-store, accept GET only (405 with
  Allow: GET otherwise, HEAD included), never resolve a principal, and
  are mounted in app.ts beside, never inside, /api/v1/modules/.
- createApiApp gains a required `health` option; startApi supplies it
  and clears module readiness when shutdown begins.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

apps/api/src/app.ts

@@ -31,6 +31,7 @@ import { createDashboardRoutes } from "./dashboard-routes.js";
 import { createDeviceRoutes } from "./device-routes.js";
 import type { DisplayHostAssets } from "./display-host-assets.js";
 import { createGrantsRoutes } from "./grants-routes.js";
+import { type ApiHealthOptions, createHealthRoutes } from "./health-routes.js";
 import { createModuleConfigurationRoutes } from "./module-configuration-routes.js";
 import { mountModuleDisplayRoutes } from "./module-display-routes.js";
 import { canonicalizeVaryHeader, mountModuleHttpRoutes } from "./module-http-routes.js";
@@ -137,6 +138,13 @@ export interface CreateApiAppOptions {
    * presentation only — nothing reachable through this store influences discovery, dependency
    * ordering, module startup, or any authorization decision. */
   readonly dashboard: DashboardStore;
+  /**
+   * The readiness inputs behind the unauthenticated health routes (ADR 0044). Required rather than
+   * defaulted, like every other dependency here: a composition that cannot reach a database says so
+   * with a check that rejects, never falls through to an implicitly healthy one. `checkDatabase` is
+   * the bare query; the routes themselves bound and serialize it. See `./health-routes.js`.
+   */
+  readonly health: ApiHealthOptions;
   readonly runtime: EkklesiaIdentityRuntime;
   /** Exact allowed browser origins. Never a wildcard; combined with `credentials: true`, only an
    * exact, reflected match is ever returned in `Access-Control-Allow-Origin`. Also the trusted set
@@ -341,6 +349,11 @@ export function createApiApp(options: CreateApiAppOptions): Hono {
     }
   });
 
+  // Unauthenticated liveness/readiness under a platform-owned sibling prefix: like every route below,
+  // it is mounted before module routes and never inside `/api/v1/modules/`, which installed modules
+  // own entirely. See `./health-routes.js`.
+  app.route("/", createHealthRoutes(options.health));
+
   app.route(
     "/",
     createGrantsRoutes({

apps/api/src/database.ts

@@ -26,11 +26,31 @@ export interface ApiDatabaseHandle {
   readonly module: ModuleDatabase;
   readonly moduleConfiguration: ModuleConfigurationDrizzleDatabase;
   readonly moduleLifecycle: ModuleLifecycleDrizzleDatabase;
+  /**
+   * One trivial round trip on the shared pool, for readiness (`./health-routes.js`). The `SELECT 1`
+   * runs in a read-only transaction carrying its own `SET LOCAL statement_timeout`, so PostgreSQL
+   * cancels a stalled statement itself rather than the caller merely abandoning it; the pool's
+   * session-wide `statement_timeout`/`query_timeout` remain the outer bound. The four statements
+   * travel as one simple-protocol message, so the check costs a single round trip. On any failure
+   * the pool discards that connection instead of returning it, so a transaction left open by a
+   * cancelled statement never reaches another caller. Rejects with whatever the driver raised; no
+   * caller may surface it.
+   */
+  readonly ping: (statementTimeoutMs: number) => Promise<void>;
   /** Closes the one shared pool exactly once, regardless of how many typed views were created
    * over it. Safe to call from both a startup-failure cleanup path and normal shutdown. */
   readonly close: () => Promise<void>;
 }
 
+function pingStatement(statementTimeoutMs: number): string {
+  // Interpolated rather than bound: neither SET nor a multi-statement simple query accepts
+  // parameters. Only a positive safe integer can ever reach the SQL text.
+  if (!Number.isSafeInteger(statementTimeoutMs) || statementTimeoutMs <= 0) {
+    throw new RangeError("The ping statement timeout must be a positive integer.");
+  }
+  return `BEGIN READ ONLY; SET LOCAL statement_timeout = ${statementTimeoutMs}; SELECT 1; COMMIT`;
+}
+
 /**
  * Composes the one physical PostgreSQL pool this process uses for Core's identity and
  * authorization schemas plus the module database facade: one validated, timeout-bounded
@@ -58,5 +78,8 @@ export function createApiDatabase(
     module: createModuleDatabaseView(pool),
     moduleConfiguration: createModuleConfigurationView(pool),
     moduleLifecycle: createModuleLifecycleView(pool),
+    ping: async (statementTimeoutMs: number) => {
+      await pool.query(pingStatement(statementTimeoutMs));
+    },
   });
 }

apps/api/src/health-routes.ts

@@ -0,0 +1,121 @@
+import { Hono } from "hono";
+
+/**
+ * The longest a readiness probe waits on the database before answering `503` (ADR 0044). Short
+ * enough for a Compose health check or an external monitor to treat a stall as "not ready" rather
+ * than as a hung probe, and well inside the shared pool's own 10s connection and operation
+ * timeouts, which bound the underlying query independently.
+ */
+export const READINESS_DATABASE_TIMEOUT_MS = 2_000;
+
+export const HEALTH_LIVE_PATH = "/api/v1/health/live";
+export const HEALTH_READY_PATH = "/api/v1/health/ready";
+
+export interface ApiHealthOptions {
+  /**
+   * One trivial database round trip. Resolves when the database answered; rejects on any failure.
+   * The rejection is never read — not its message, code, or cause — so nothing a driver says can
+   * reach a response. The route bounds the wait and never overlaps two calls; this function only
+   * has to perform the query.
+   */
+  readonly checkDatabase: () => Promise<void>;
+  /** Whether module startup has completed. `false` again from the moment shutdown begins, so a
+   * draining instance stops reporting ready while it finishes in-flight requests. */
+  readonly isModuleStartupComplete: () => boolean;
+}
+
+const LIVE_BODY = Object.freeze({ status: "live" });
+const READY_BODY = Object.freeze({ status: "ready" });
+const NOT_READY_BODY = Object.freeze({ code: "NOT_READY" });
+
+/**
+ * Wraps `checkDatabase` so at most one call is ever unsettled, and no probe waits longer than
+ * `timeoutMs`.
+ *
+ * Every probe arriving while a check is unsettled shares that check's outcome, including after its
+ * deadline has passed: the deadline resolves the shared outcome to `false`, so those later probes
+ * answer immediately. A new check starts only once the previous call has actually settled. A timed-
+ * out query still occupies a pool connection until the database or the pool's own timeouts end it,
+ * so starting a fresh query on every probe would let a stalled database drain the pool one health
+ * check at a time.
+ */
+function createBoundedDatabaseCheck(
+  checkDatabase: () => Promise<void>,
+  timeoutMs: number,
+): () => Promise<boolean> {
+  let inFlight: Promise<boolean> | undefined;
+
+  return () => {
+    if (inFlight !== undefined) {
+      return inFlight;
+    }
+    let timer: ReturnType<typeof setTimeout> | undefined;
+    // The executor runs `checkDatabase` synchronously, so a synchronous throw is a rejection like
+    // any other rather than an exception escaping the route.
+    const settled = new Promise<void>((resolve) => resolve(checkDatabase())).then(
+      () => true,
+      () => false,
+    );
+    const outcome = Promise.race([
+      settled,
+      new Promise<false>((resolve) => {
+        timer = setTimeout(() => resolve(false), timeoutMs);
+      }),
+    ]);
+    inFlight = outcome;
+    void settled.then(() => {
+      clearTimeout(timer);
+      inFlight = undefined;
+    });
+    return outcome;
+  };
+}
+
+/** The same fixed refusal `./module-realtime-routes.js` uses: Hono lets a GET handler answer HEAD,
+ * and these routes accept GET alone. */
+function methodNotAllowed(): Response {
+  return new Response(null, {
+    headers: { Allow: "GET", "Cache-Control": "no-store" },
+    status: 405,
+  });
+}
+
+/**
+ * Unauthenticated liveness and readiness (ADR 0044), for Compose health checks and external
+ * monitoring. Neither route resolves a principal or reads a cookie, and both return fixed bodies
+ * that name no module, version, error, or connection detail; `pnpm doctor` remains the detailed
+ * operator report. They live under `/api/v1/health/`, a sibling of the `/api/v1/modules/` prefix that
+ * installed modules own entirely, so no module route can shadow them.
+ */
+export function createHealthRoutes(options: ApiHealthOptions): Hono {
+  const checkDatabase = createBoundedDatabaseCheck(
+    options.checkDatabase,
+    READINESS_DATABASE_TIMEOUT_MS,
+  );
+  const routes = new Hono();
+
+  routes.all(HEALTH_LIVE_PATH, (c) => {
+    if (c.req.method !== "GET") {
+      return methodNotAllowed();
+    }
+    c.header("Cache-Control", "no-store");
+    return c.json(LIVE_BODY, 200);
+  });
+
+  routes.all(HEALTH_READY_PATH, async (c) => {
+    if (c.req.method !== "GET") {
+      return methodNotAllowed();
+    }
+    c.header("Cache-Control", "no-store");
+    if (!options.isModuleStartupComplete()) {
+      return c.json(NOT_READY_BODY, 503);
+    }
+    const databaseReady = await checkDatabase();
+    // Checked again afterwards: shutdown may have begun while the query was in flight.
+    return databaseReady && options.isModuleStartupComplete()
+      ? c.json(READY_BODY, 200)
+      : c.json(NOT_READY_BODY, 503);
+  });
+
+  return routes;
+}

apps/api/src/server.ts

@@ -48,6 +48,7 @@ import { type ApiRuntimeConfig, createApiRuntimeConfig } from "./config.js";
 import { type ApiDatabaseHandle, createApiDatabase } from "./database.js";
 import { withDevicePrincipals } from "./device-principal.js";
 import { loadDisplayHostAssets } from "./display-host-assets.js";
+import { READINESS_DATABASE_TIMEOUT_MS } from "./health-routes.js";
 import { prepareStartupModuleInventory } from "./platform-permissions.js";
 
 const connectionTimeoutMs = 10_000;
@@ -576,6 +577,10 @@ export async function startApi(
     throw error;
   }
 
+  // Set by the first `shutdown()` call, before anything is drained or stopped, so readiness turns
+  // `503` while the instance still finishes in-flight requests.
+  let shuttingDown = false;
+
   let app: Hono;
   try {
     app = createApiApp({
@@ -620,6 +625,12 @@ export async function startApi(
       },
       // A typed view over the same single pool as identity, authorization, and the module facade.
       dashboard: createDashboardStore(databaseHandle.dashboard),
+      // The app is only composed after `startDiscoveredModuleRuntime` resolved, so module startup
+      // has completed whenever it can answer; it stops counting as complete once shutdown begins.
+      health: {
+        checkDatabase: () => databaseHandle.ping(READINESS_DATABASE_TIMEOUT_MS),
+        isModuleStartupComplete: () => !shuttingDown,
+      },
       devices: {
         // `Secure` follows the deployment's own scheme, read from the already-validated identity
         // base URL rather than from any request. Production is https by configuration policy, so a
@@ -677,6 +688,7 @@ export async function startApi(
   let shutdownPromise: Promise<void> | undefined;
   const shutdown = (): Promise<void> => {
     if (!shutdownPromise) {
+      shuttingDown = true;
       shutdownPromise = (async () => {
         // Close long-lived streams so HTTP can drain, but leave publishers active until the drain
         // completes: an in-flight module command may still commit and publish its resulting state.