Credman Helper by wickedcube · Pull Request #115 · android/games-samples

wickedcube · 2026-06-08T11:04:40Z

Credman implementation in Java to support migration from PGS v1 to v2

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Code Review

This pull request replaces the legacy Google Sign-In V2 implementation with a new Credential Manager (CredMan) integration via a Java bridge (CredManBridge.java), updating AuthManager.cs to handle silent and interactive sign-in flows and manage session caching. The review feedback highlights several critical issues: a shadowed webClientId variable in AuthManager.cs that will fail authentication, an unhandled SilentFailed error that causes a soft-lock, invalid '#' comments and a non-existent hasResolution() method in the Java bridge that will cause compilation failures, and potential thread leaks from creating new executors on every sign-in call.

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gemini-code-assist · 2026-06-08T11:06:13Z

+        string webClientId = "";
+        AndroidJavaClass unityPlayer = new AndroidJavaClass("com.unity3d.player.UnityPlayer");
+        AndroidJavaObject currentActivity = unityPlayer.GetStatic<AndroidJavaObject>("currentActivity");
+        AndroidJavaClass bridge = new AndroidJavaClass("com.gamesamples.trivialkartunity.CredManBridge");

-        googleTaskComplete = true;
+        string methodName = interactive ? "signInInteractive" : "signInSilent";
+        bridge.CallStatic(methodName, currentActivity, webClientId);


The local variable webClientId is declared as an empty string "", which shadows the class field webClientId (defined at line 61). This causes an empty client ID to be passed to the Java bridge, which will fail to authenticate or retrieve the server auth code. We should remove the local declaration and use the class field this.webClientId.

AndroidJavaClass unityPlayer = new AndroidJavaClass("com.unity3d.player.UnityPlayer"); AndroidJavaObject currentActivity = unityPlayer.GetStatic<AndroidJavaObject>("currentActivity"); AndroidJavaClass bridge = new AndroidJavaClass("com.gamesamples.trivialkartunity.CredManBridge"); string methodName = interactive ? "signInInteractive" : "signInSilent"; bridge.CallStatic(methodName, currentActivity, this.webClientId);

gemini-code-assist · 2026-06-08T11:06:13Z

+            if (!string.IsNullOrEmpty(credManError))
            {
-                // --- Success case ---
-                Debug.Log($"Google Sign-In successful for: {this.googleUser.Email}");
-                Debug.Log($"Retrieved Server Auth Code. Sending to backend...");
-                statusText.text = "Connecting to game server...";
-                StartCoroutine(ExchangeAuthcodeAndLink(authCodeToExchange));
+                Debug.LogError("CredMan Error: " + credManError);
+                statusText.text = "Sign-in Failed.";
+                ShowStartPanel();
            }


If silent sign-in fails, OnSignInError is called with "SilentFailed". Currently, this error is ignored and does not trigger the main thread dispatcher to show the start panel. As a result, the game will soft-lock on the loading screen. We should handle "SilentFailed" gracefully by showing the start panel and updating the status text to "Please sign in.".

if (!string.IsNullOrEmpty(credManError)) { Debug.LogError("CredMan Error: " + credManError); statusText.text = credManError == "SilentFailed" ? "Please sign in." : "Sign-in Failed."; ShowStartPanel(); }

gemini-code-assist · 2026-06-08T11:06:13Z

+    public void OnSignInError(string error) 
+    { 
+        if (error == "SilentFailed") { Debug.Log("Silent failed. Idle."); return; }
+        credManError = error; googleTaskComplete = true; 
    }


Returning early when error == "SilentFailed" prevents the main thread from being notified of the failure, leading to a soft-lock. We should set credManError and googleTaskComplete for all errors so the main thread can handle them and show the appropriate UI.

public void OnSignInError(string error) { credManError = error; googleTaskComplete = true; }

gemini-code-assist · 2026-06-08T11:06:13Z

+public class CredManBridge {
+
+    // --- MODE 1: SILENT SIGN-IN (Called on Awake) ---
+    // Tries to auto-select an authorized account. If it fails, it does NOT show UI.
+    public static void signInSilent(Context context, String webClientId) {
+        CredentialManager credentialManager = CredentialManager.create(context);
+        CancellationSignal cancellationSignal = new CancellationSignal();
+        Executor executor = Executors.newSingleThreadExecutor();


Creating a new single-thread executor on every call to signInSilent (and signInInteractive) is inefficient and can lead to thread leaks since these executors are never shut down. We should define a single static Executor at the class level and reuse it.

public class CredManBridge { private static final Executor executor = Executors.newSingleThreadExecutor(); // --- MODE 1: SILENT SIGN-IN (Called on Awake) --- // Tries to auto-select an authorized account. If it fails, it does NOT show UI. public static void signInSilent(Context context, String webClientId) { CredentialManager credentialManager = CredentialManager.create(context); CancellationSignal cancellationSignal = new CancellationSignal();

gemini-code-assist · 2026-06-08T11:06:14Z

+    public static void signInInteractive(Context context, String webClientId) {
+        CredentialManager credentialManager = CredentialManager.create(context);
+        CancellationSignal cancellationSignal = new CancellationSignal();
+        Executor executor = Executors.newSingleThreadExecutor();


Since we introduced a shared static executor at the class level, we should remove the local executor instantiation here to avoid shadowing and reuse the shared one.

// Using the shared static executor

borisf · 2026-06-08T11:47:31Z

+import java.util.concurrent.Executors;
+
+
+# [START google_signin_credman_example]


We need to follow up with the DAC team, as this code will not compile

Can do a multiline comment (look below) , or a custom doclet (not 100% sure)

/*

[END google_signin_credman_example]

*/

This was requested by our tech writing team for linking to DAC

The code isn't compiling with the #'s , should it be // (for java comments instead of Python)

borisf · 2026-06-08T11:50:42Z

+
+            Account account = new Account(email, "com.google");
+            // Requesting GAMES_LITE scope to check for pre-existing V1 grants
+            List<Scope> requestedScopes = Collections.singletonList(new Scope("https://www.googleapis.com/auth/games_lite"));


Let's make it a constant

Same, let's make this a constant

borisf · 2026-06-08T11:55:06Z

-    private GoogleSignInUser googleUser;
-
-    // --- NEW VARIABLES for main-thread dispatching ---
+    // V2 (CredMan) Specific Variables


PGS v2 + link

borisf · 2026-06-08T11:55:32Z

 #endif
    }

    private void Update()
    {
 #if PGS_V2
+        // V2 Main Thread Dispatcher


borisf · 2026-06-08T11:56:34Z

@@ -422,8 +432,6 @@ private IEnumerator ExchangeAuthcodeAndLink(string serverAuthCode)
            Debug.LogError($"Backend Error: {request.error}");
            Debug.LogError($"Response: {request.downloadHandler.text}");
            statusText.text = "Failed to link account. Server error.";
-
-            GoogleSignIn.DefaultInstance.SignOut(); 
            ShowStartPanel();
        }


Not sure about this, mismatched braces?

patm1987 · 2026-06-09T17:44:18Z

+import android.util.Log;
+import android.os.CancellationSignal;
+
+import androidx.credentials.CredentialManager;


Dependencies are missing for credential manager.

You can add a Dependencies.xml with the missing bits in an Editor folder or modify gradle directly. I think you need

implementation("androidx.credentials:credentials:1.6.0") implementation("androidx.credentials:credentials-play-services-auth:1.6.0") implementation("com.google.android.libraries.identity.googleid:googleid:1.2.0")

patm1987

I wasn't able to build as is, I think it's some small things I called out

borisf · 2026-07-02T09:27:15Z

+            interactiveRequest,
+            cancellationSignal,
+            executor,
+            new androidx.credentials.CredentialManagerCallback<GetCredentialResponse, GetCredentialException>() {


Lets' do an import for androidx.credentials to get the following

CredentialManagerCallback<GetCredentialResponse, GetCredentialException>() { ...

borisf · 2026-07-02T09:34:14Z

+
+public class CredManBridge {
+
+    private static final Executor executor = Executors.newSingleThreadExecutor();


Who is closing the executor

ExecutorService executor = Executors.newSingleThreadExecutor();
try {
executor.submit(() -> System.out.println("Processing task..."));
} finally {
executor.shutdown(); // Stops accepting new tasks, lets current ones finish
}

borisf

Thanks

…idge

borisf

Thanks

borisf

Thanks

patm1987 · 2026-07-13T19:30:37Z

Running in Editor, I'm getting warnings for both FriendsPage and LeaderboardPage, that scripts are missing. Double check me that I don't just have a stale client, but I think this was left over from commit 209221d when FriendsPageController.cs was deleted and you can probably delete these nodes in the scene.

I tried doing that in a commit, but that added a lot of changes in TrivialKartScene.unity and I want to make sure I don't move that scene to a different Unity version than you're using.

wickedcube · 2026-07-15T21:15:20Z

LGTM from Boris and Patrick

Credman Helper

10860a2

wickedcube requested review from borisf, natetrost and stmazoni June 8, 2026 11:04

gemini-code-assist Bot reviewed Jun 8, 2026

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Removed empty webclientID

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borisf reviewed Jun 8, 2026

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Comment thread trivialkart/trivialkart-unity/Assets/Scripts/Utils/CredManBridge.java

borisf reviewed Jun 8, 2026

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Update CredManBridge.java

9ea1e9e

borisf reviewed Jun 8, 2026

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Comment thread trivialkart/trivialkart-unity/Assets/Scripts/Utils/CredManBridge.java

borisf reviewed Jun 8, 2026

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wickedcube requested a review from patm1987 June 9, 2026 08:54

patm1987 reviewed Jun 9, 2026

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Dependencies for credman bridge

a644580

wickedcube requested review from borisf and patm1987 June 30, 2026 17:38

borisf reviewed Jul 2, 2026

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Add CredMan callback import and executor lifecycle fixes in CredManBr…

7d96d8f

…idge

wickedcube requested a review from borisf July 12, 2026 11:23

borisf reviewed Jul 12, 2026

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Update CredManBridge.java

c9b1c56

wickedcube requested a review from borisf July 12, 2026 15:53

borisf reviewed Jul 13, 2026

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wickedcube merged commit c06fcc3 into main Jul 15, 2026
7 checks passed

wickedcube deleted the PGS-migration-helper-credman branch July 15, 2026 21:15

		import java.util.concurrent.Executors;


		# [START google_signin_credman_example]


		public class CredManBridge {

		private static final Executor executor = Executors.newSingleThreadExecutor();

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[END google_signin_credman_example]

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patm1987 commented Jul 13, 2026

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borisf Jun 8, 2026 •

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