## What changed
Enable `instant_interrupt` by default so new user input can preempt responses and yield foreground code-mode observations. Keep the feature marked as under development and update feature-policy tests to allow this exception.
Explicitly disable instant interrupts in core, TUI, and Python SDK tests that depend on responses completing before steering or processing subsequent input.
GitOrigin-RevId: a8cab2d6c445bfdbd10b0b2abcf7893d32ee8595