Multiple improvements for April 2025

* Improve refresh token handling in the background.

Resolves issue when user opens the website, allows the access token to expire, but continues browsing.
The background requests are failing with CORS errors to OIDC provider.

* fixup! Improve refresh token handling in the background.

* Abstract the token blacklisting.

metadata_cache.go

@@ -34,6 +34,7 @@ func (c *MetadataCache) Cleanup() {
 		c.metadata = nil
 	}
 }
+
 func (c *MetadataCache) isCacheValid() bool {
 	return c.metadata != nil && time.Now().Before(c.expiresAt)
 }
@@ -67,15 +68,9 @@ func (c *MetadataCache) GetMetadata(providerURL string, httpClient *http.Client,
 	}
 
 	c.metadata = metadata
-	// Calculate expiration time based on usage patterns
-	usageCount := 0 // This should be replaced with actual usage tracking logic
-	if usageCount < 10 {
-		c.expiresAt = time.Now().Add(30 * time.Minute)
-	} else if usageCount < 50 {
-		c.expiresAt = time.Now().Add(1 * time.Hour)
-	} else {
-		c.expiresAt = time.Now().Add(2 * time.Hour)
-	}
+	// Set a fixed cache lifetime (e.g., 1 hour)
+	// TODO: Consider making this configurable or respecting HTTP cache headers
+	c.expiresAt = time.Now().Add(1 * time.Hour)
 
 	// End of GetMetadata
 	return metadata, nil