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

gemini-code-assist

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

+                        Log.i("CredMan", "PGS v1: Existing grant found. Returning user detected. Auth Code retrieved.");
+                        UnityPlayer.UnitySendMessage("AuthManager", "OnSignInSuccess", authorizationResult.getServerAuthCode());
+                    } 
+                    else if (authorizationResult.hasResolution()) {


The AuthorizationResult class does not have a hasResolution() method. To check if a resolution is available, you should check if getPendingIntent() is not null. Using hasResolution() will cause a compilation error.

else if (authorizationResult.getPendingIntent() != null) {

https://developers.google.com/android/reference/com/google/android/gms/auth/api/identity/AuthorizationResult#hasResolution()

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

borisf · 2026-06-08T11:50:23Z

+            String email = credential.getId();
+
+            Account account = new Account(email, "com.google");
+            // Requesting GAMES_LITE scope to check for pre-existing V1 grants


Update the line to "pre-existing PGS V1 grants" + possible link

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

borisf · 2026-06-08T11:51:52Z

+                        Log.i("CredMan", "PGS v1: Existing grant found. Returning user detected. Auth Code retrieved.");
+                        UnityPlayer.UnitySendMessage("AuthManager", "OnSignInSuccess", authorizationResult.getServerAuthCode());
+                    } 
+                    else if (authorizationResult.hasResolution()) {


https://developers.google.com/android/reference/com/google/android/gms/auth/api/identity/AuthorizationResult#hasResolution()

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

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


borisf · 2026-06-08T11:56:34Z

-
-            GoogleSignIn.DefaultInstance.SignOut(); 
            ShowStartPanel();
        }


Not sure about this, mismatched braces?

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

c5248a2

borisf reviewed Jun 8, 2026

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

borisf reviewed Jun 8, 2026

View reviewed changes

Update CredManBridge.java

9ea1e9e

borisf reviewed Jun 8, 2026

View reviewed changes

		import java.util.concurrent.Executors;


		# [START google_signin_credman_example]

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borisf Jun 8, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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[END google_signin_credman_example]

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borisf Jun 8, 2026 •

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