Reported by @ember hawk
On macOS 15 (Sequoia), ensure iCloud Keychain is enabled under System Settings → Passwords.
Install and sign into 1Password v8 for Mac.
Open ChatGPT Atlas v1.2025.295.4.
Visit any site with a login form.
Attempt to autofill credentials using 1Password.
Atlas should recognise the user’s preferred password-manager provider (1Password) and allow autofill to function normally even if iCloud Keychain remains active.
No autofill occurs. iCloud Keychain silently intercepts autofill focus events, preventing 1Password from activating. Disabling iCloud Keychain restores 1Password’s behaviour, but it cannot be selectively disabled for Atlas without affecting the rest of the system. This suggests Atlas is calling the macOS system autofill API directly rather than allowing third-party credential providers.
macOS 26.0.1 (Taho) ChatGPT Atlas v1.2025.295.4 (stable) 1Password for Mac 8.11.16 (81116035) iCloud Keychain enabled No browser extensions available in Atlas