write-product-spec Write a spec for a significant feature in Warp. Overview The product spec should make the desired behavior unambiguous enough that an agent can implement it correctly and avoid regressions. Describe the feature purely from the user's perspective — what the user sees, does, and experiences, and the invariants that must hold for them. Do not include implementation details (internal types, state layout, module boundaries, data flow, algorithms). "User" is not limited to the end user of the Warp app. It means whoever consumes the surface being designed: - For UI / UX features:…