diff --git a/crates/gpui_windows/src/platform.rs b/crates/gpui_windows/src/platform.rs
index 871da413e3..9ba94563a4 100644
--- a/crates/gpui_windows/src/platform.rs
+++ b/crates/gpui_windows/src/platform.rs
@@ -741,6 +741,15 @@ impl Platform for WindowsPlatform {
     }
 
     fn write_credentials(&self, url: &str, username: &str, password: &[u8]) -> Task<Result<()>> {
+        // CredWriteW rejects larger blobs with the opaque RPC error
+        // 0x800706F7 "The stub received bad data", so fail with a clear
+        // message instead.
+        if password.len() > CRED_MAX_CREDENTIAL_BLOB_SIZE as usize {
+            return Task::ready(Err(anyhow!(
+                "credential for {url} is {} bytes, which exceeds the Windows Credential Manager limit of {CRED_MAX_CREDENTIAL_BLOB_SIZE} bytes",
+                password.len()
+            )));
+        }
         let password = password.to_vec();
         let mut username = username.encode_utf16().chain(Some(0)).collect_vec();
         let mut target_name = windows_credentials_target_name(url)
diff --git a/crates/language_models/src/provider/openai_subscribed.rs b/crates/language_models/src/provider/openai_subscribed.rs
index 20038e6123..e3ec95859a 100644
--- a/crates/language_models/src/provider/openai_subscribed.rs
+++ b/crates/language_models/src/provider/openai_subscribed.rs
@@ -760,10 +760,12 @@ async fn do_oauth_flow(
         .query_pairs_mut()
         .append_pair("client_id", CLIENT_ID)
         .append_pair("redirect_uri", &redirect_uri)
-        .append_pair(
-            "scope",
-            "openid profile email offline_access api.connectors.read api.connectors.invoke",
-        )
+        // Deliberately excludes `api.connectors.read api.connectors.invoke`
+        // (which Codex CLI requests): extra scopes inflate the
+        // access-token JWT, and the serialized credentials must fit within
+        // Windows Credential Manager's 2560-byte blob limit
+        // (CRED_MAX_CREDENTIAL_BLOB_SIZE). See #58541.
+        .append_pair("scope", "openid profile email offline_access")
         .append_pair("response_type", "code")
         .append_pair("code_challenge", &challenge)
         .append_pair("code_challenge_method", "S256")