PR #5406's launcher contract withheld chat_only because the diagnostic dict gated it behind a valid bearer. The SPA's first-load router needs chat_only *before* any bearer is available (to decide whether /studio and /export redirect to /chat); the Windows + Linux UI smokes' chat_only inference fallback was incorrectly classifying non-chat-only Studios as chat-only when the bearered probe came back without the field (post-bootstrap tokens still carry must_change_password=True).
chat_only is a hardware-shape capability bit (training vs inference-only) -- the same category as supports_desktop_auth and desktop_manageability_version which already ship unauth -- so promoting it is consistent with the existing contract. The truly sensitive diagnostic stays gated: version, studio_version, device_type, native_path_leases_supported, desktop_owner. Tests + the playwright_extra_ui chat_only probe updated to match the new contract.
c7cbc39ff5