feat: compose executable frontend runtime

src/adapters/auth/external-session-adapter.js

@@ -4,6 +4,9 @@
  *
  * @param {{
  *   readState(): import("../../application/ports/auth-session-port.js").SessionState,
+ *   subscribe(listener: () => void): () => void,
+ *   beginSignIn(returnTo?: string): Promise<void>,
+ *   signOut(): Promise<void>,
  *   attachCredential(request: Request): Promise<Request>,
  *   recoverSession(): Promise<"restored" | "no-session">,
  *   notifyUnauthenticated(): void
@@ -15,6 +18,16 @@ export function createExternalAuthSessionAdapter(owner) {
     getState() {
       return owner.readState();
     },
+    subscribe(listener) {
+      return owner.subscribe(listener);
+    },
+    async beginSignIn(returnTo) {
+      await owner.beginSignIn(returnTo);
+    },
+    async signOut() {
+      await owner.signOut();
+    },
+    /** @param {Request} request */
     async attach(request) {
       const attached = await owner.attachCredential(request);
       if (!(attached instanceof Request)) {
@@ -38,8 +51,74 @@ export function createExternalAuthSessionAdapter(owner) {
 export function createAnonymousSessionAdapter() {
   return createExternalAuthSessionAdapter({
     readState: () => "unauthenticated",
+    subscribe: () => () => {},
+    beginSignIn: async () => {},
+    signOut: async () => {},
     attachCredential: async (request) => request,
     recoverSession: async () => "no-session",
     notifyUnauthenticated: () => {},
   });
 }
+
+/**
+ * Local/test-only session seam. It never creates or stores credentials.
+ *
+ * @param {import("../../application/ports/auth-session-port.js").SessionState} [initialState]
+ */
+export function createDemoSessionAdapter(initialState = "unauthenticated") {
+  let state = initialState;
+  const listeners = new Set();
+
+  function notify() {
+    for (const listener of listeners) listener();
+  }
+
+  /** @param {import("../../application/ports/auth-session-port.js").SessionState} next */
+  function setState(next) {
+    state = next;
+    notify();
+  }
+
+  return Object.freeze({
+    getState: () => state,
+    /** @param {() => void} listener */
+    subscribe(listener) {
+      listeners.add(listener);
+      return () => listeners.delete(listener);
+    },
+    async beginSignIn() {
+      setState("authenticated");
+    },
+    async signOut() {
+      setState("unauthenticated");
+    },
+    /** @param {Request} request */
+    async attach(request) {
+      return request;
+    },
+    async recover() {
+      if (state === "recovery-pending") {
+        setState("authenticated");
+        return /** @type {const} */ ("restored");
+      }
+      return /** @type {const} */ ("no-session");
+    },
+    onUnauthenticated() {
+      setState("unauthenticated");
+    },
+    setState,
+  });
+}
+
+export function createUnavailableSessionAdapter() {
+  return Object.freeze({
+    getState: () => /** @type {const} */ ("integration-failed"),
+    subscribe: () => () => {},
+    beginSignIn: async () => {},
+    signOut: async () => {},
+    /** @param {Request} request */
+    attach: async (request) => request,
+    recover: async () => /** @type {const} */ ("no-session"),
+    onUnauthenticated: () => {},
+  });
+}