feat: compose executable frontend runtime

tests/unit/auth-session-adapter.test.js

@@ -2,6 +2,7 @@ import { describe, expect, it, vi } from "vitest";
 
 import {
   createAnonymousSessionAdapter,
+  createDemoSessionAdapter,
   createExternalAuthSessionAdapter,
 } from "../../src/adapters/auth/external-session-adapter.js";
 
@@ -9,6 +10,9 @@ describe("external AuthSessionPort adapter", () => {
   it("attaches opaque credentials without exposing a token-shaped session", async () => {
     const adapter = createExternalAuthSessionAdapter({
       readState: () => "authenticated",
+      subscribe: () => () => {},
+      beginSignIn: async () => {},
+      signOut: async () => {},
       attachCredential: async (request) => {
         const headers = new Headers(request.headers);
         headers.set("X-Session-Attached", "true");
@@ -28,6 +32,9 @@ describe("external AuthSessionPort adapter", () => {
   it("fails invalid recovery states closed", async () => {
     const adapter = createExternalAuthSessionAdapter({
       readState: () => "authenticated",
+      subscribe: () => () => {},
+      beginSignIn: async () => {},
+      signOut: async () => {},
       attachCredential: async (request) => request,
       recoverSession: async () => "unexpected",
       notifyUnauthenticated: vi.fn(),
@@ -41,4 +48,20 @@ describe("external AuthSessionPort adapter", () => {
     expect(adapter.getState()).toBe("unauthenticated");
     await expect(adapter.recover()).resolves.toBe("no-session");
   });
+
+  it("provides a reactive credential-free demo seam", async () => {
+    const adapter = createDemoSessionAdapter();
+    let notifications = 0;
+    const unsubscribe = adapter.subscribe(() => {
+      notifications += 1;
+    });
+
+    expect(adapter.getState()).toBe("unauthenticated");
+    await adapter.beginSignIn("/");
+    expect(adapter.getState()).toBe("authenticated");
+    await adapter.signOut();
+    expect(adapter.getState()).toBe("unauthenticated");
+    expect(notifications).toBe(2);
+    unsubscribe();
+  });
 });

tests/unit/runtime-adapters.test.js

@@ -0,0 +1,57 @@
+import { describe, expect, it } from "vitest";
+
+import { createRuntimeAdapters } from "../../src/bootstrap/runtime-adapters.js";
+
+const runtime = {
+  config: {
+    APP_ENV: "local",
+    API_BASE_URL: "http://localhost:8080",
+    TELEMETRY_ENABLED: false,
+    AUTH_MODE: "demo",
+  },
+};
+const release = {
+  schemaVersion: 1,
+  appVersion: "0.1.0",
+  buildId: "build-a",
+  commitSha: "abc123",
+  configSchemaVersion: "1",
+  apiContractVersion: "1",
+  assetManifestHash: "hash-a",
+  releaseId: "release-a",
+  builtAt: "2026-07-25T00:00:00Z",
+};
+
+describe("runtime adapter composition", () => {
+  it("constructs the local demo seam and infrastructure adapters", async () => {
+    const adapters = await createRuntimeAdapters({
+      runtime:
+        /** @type {Parameters<typeof createRuntimeAdapters>[0]["runtime"]} */ (
+          runtime
+        ),
+      release,
+      host: {},
+    });
+
+    expect(adapters.authSession.getState()).toBe("unauthenticated");
+    expect(adapters.cache.read(["missing"])).toEqual({
+      ok: true,
+      value: undefined,
+    });
+    await expect(adapters.releaseInfo.getCurrent()).resolves.toMatchObject({
+      releaseId: "release-a",
+    });
+  });
+
+  it("fails closed when an external auth owner was not installed", async () => {
+    const adapters = await createRuntimeAdapters({
+      runtime:
+        /** @type {Parameters<typeof createRuntimeAdapters>[0]["runtime"]} */ ({
+          config: { ...runtime.config, AUTH_MODE: "external" },
+        }),
+      release,
+      host: {},
+    });
+    expect(adapters.authSession.getState()).toBe("integration-failed");
+  });
+});