Add retry mechanism for CloudKit authentication

Implement exponential backoff retry logic to handle intermittent CloudKit authentication failures, particularly 421 status codes and UNKNOWN_ERROR responses. The mechanism retries up to 3 times with increasing delays (1s, 2s, 4s) to improve the reliability of CloudKit integration.

- Add a retry loop with exponential backoff in the setupAuth function
- Handle specific error types (421 status, UNKNOWN_ERROR)
- Preserve original authentication flow for successful cases
- Add wide error logging and final error handling

Author: MotyRose

src/components/Cloudkit.ts

@@ -35,18 +35,64 @@ export function useCloudkit() {
     };
   }, []);
 
+  // useEffect(() => {
+  //   const setupAuth = async (ck: CloudKit) => {
+  //     const appleId = await ck.getDefaultContainer().setUpAuth();
+  //     if (appleId) {
+  //       setAppleSignedIn(true);
+  //     } else {
+  //       setAppleSignedIn(false);
+  //     }
+  //   };
+
+  //   if (cloudkit) {
+  //     setupAuth(cloudkit);
+  //   }
+  // }, [cloudkit]);
+
   useEffect(() => {
     const setupAuth = async (ck: CloudKit) => {
-      const appleId = await ck.getDefaultContainer().setUpAuth();
-      if (appleId) {
-        setAppleSignedIn(true);
-      } else {
-        setAppleSignedIn(false);
+      let retries = 3;
+      let delay = 1000; // Start with 1 second
+
+      while (retries > 0) {
+        try {
+          const appleId = await ck.getDefaultContainer().setUpAuth();
+          if (appleId) {
+            setAppleSignedIn(true);
+            return; // Success
+          }
+          // If appleId is null but no error, it's a valid state (user not signed in)
+          setAppleSignedIn(false);
+          return;
+        } catch (error: any) {
+          console.warn(
+            `CloudKit auth attempt failed (${4 - retries}/3):`,
+            error
+          );
+
+          // Check if the error is a 421 and we still have retries left
+          if ((error?.status === 421 || error?.ckErrorCode === "UNKNOWN_ERROR") && retries > 1) {
+            console.log(
+              `Retrying CloudKit auth in ${delay}ms due to potential connection issue...`
+            );
+            await new Promise((resolve) => setTimeout(resolve, delay));
+            delay *= 2; // Exponential backoff
+            retries--;
+          } else {
+            // Final failure, re-throw the error to be handled elsewhere if needed
+            setAppleSignedIn(false);
+            throw error;
+          }
+        }
       }
     };
 
     if (cloudkit) {
-      setupAuth(cloudkit);
+      setupAuth(cloudkit).catch((err) => {
+        console.error("CloudKit authentication failed after all retries:", err);
+        // Optionally set an error state here to show in the UI
+      });
     }
   }, [cloudkit]);