Fix concurrent token initialization

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

extensions/connector-namespaces/auth.mjs

@@ -231,31 +231,35 @@ export class InteractiveAuthBroker {
         if (hasUsableToken(this.accessToken, this.now())) return this.accessToken.token;
         if (this.tokenInFlight) return this.tokenInFlight;
 
-        let credential = this.credential;
-        if (!credential) {
-            try {
-                const authenticationRecord = await this.loadAuthRecord();
-                credential = this.createInteractiveCredential(authenticationRecord);
-                this.credential = credential;
-            } catch (error) {
-                if (isAuthenticationRequiredError(error)) {
-                    throw new ConnectorAuthenticationRequiredError(
-                        "Sign in to Azure to continue.",
-                        { cause: error },
-                    );
+        const request = (async () => {
+            let credential = this.credential;
+            if (!credential) {
+                try {
+                    const authenticationRecord = await this.loadAuthRecord();
+                    if (hasUsableToken(this.accessToken, this.now())) return this.accessToken.token;
+                    credential = this.credential;
+                    if (!credential) {
+                        credential = this.createInteractiveCredential(authenticationRecord);
+                        this.credential = credential;
+                    }
+                } catch (error) {
+                    if (isAuthenticationRequiredError(error)) {
+                        throw new ConnectorAuthenticationRequiredError(
+                            "Sign in to Azure to continue.",
+                            { cause: error },
+                        );
+                    }
+                    throw error;
                 }
-                throw error;
             }
-        }
-        const request = credential.getToken(this.scope)
-            .then((accessToken) => {
+            try {
+                const accessToken = await credential.getToken(this.scope);
                 if (!accessToken?.token || !Number.isFinite(accessToken.expiresOnTimestamp)) {
                     throw new Error("Azure identity returned an incomplete ARM access token.");
                 }
                 this.accessToken = accessToken;
                 return accessToken.token;
-            })
-            .catch((error) => {
+            } catch (error) {
                 if (!isAuthenticationRequiredError(error)) throw error;
                 if (this.credential === credential) {
                     this.credential = null;
@@ -265,12 +269,14 @@ export class InteractiveAuthBroker {
                     "Sign in to Azure to continue.",
                     { cause: error },
                 );
-            })
-            .finally(() => {
-                if (this.tokenInFlight === request) this.tokenInFlight = null;
-            });
+            }
+        })();
         this.tokenInFlight = request;
-        return request;
+        try {
+            return await request;
+        } finally {
+            if (this.tokenInFlight === request) this.tokenInFlight = null;
+        }
     }
 }
 

extensions/connector-namespaces/auth.test.mjs

@@ -162,6 +162,47 @@ test("a new broker restores the persisted credential without reopening the brows
     assert.equal(authenticateCalls, 1);
 });
 
+test("concurrent first-time token requests share credential initialization and acquisition", async () => {
+    let releaseAuthenticationRecord;
+    const authenticationRecordReady = new Promise((resolve) => {
+        releaseAuthenticationRecord = resolve;
+    });
+    let loadAuthRecordCalls = 0;
+    let createCredentialCalls = 0;
+    let tokenCalls = 0;
+    const broker = new InteractiveAuthBroker({
+        async loadAuthRecord() {
+            loadAuthRecordCalls++;
+            await authenticationRecordReady;
+            return authenticationRecord();
+        },
+        createCredential: () => {
+            createCredentialCalls++;
+            return {
+                async getToken() {
+                    tokenCalls++;
+                    return accessToken("shared-token");
+                },
+            };
+        },
+    });
+
+    const firstRequest = broker.getToken();
+    const secondRequest = broker.getToken();
+    await new Promise((resolve) => setImmediate(resolve));
+    const loadsBeforeRelease = loadAuthRecordCalls;
+    releaseAuthenticationRecord();
+
+    assert.deepEqual(
+        await Promise.all([firstRequest, secondRequest]),
+        ["shared-token", "shared-token"],
+    );
+    assert.equal(loadsBeforeRelease, 1);
+    assert.equal(loadAuthRecordCalls, 1);
+    assert.equal(createCredentialCalls, 1);
+    assert.equal(tokenCalls, 1);
+});
+
 test("cancelling sign-in aborts the credential request", async () => {
     let abortSignal;
     const credential = {