Get App Chat
The chat the caller should edit this app through.
For an EDITOR this is their DEFAULT branch's chat, auto-forked from main's on first use (Phase 2) — that fork is what stops two editors sharing one transcript and one SDK session. For a VIEWER it is main's chat, read-only: creating a branch is an editing act, so a viewer opening the page must not silently spawn one.
"Default" is exact and not a hedge: an editor can hold several open work branches, and this route takes no branch id, so it answers "which chat do I open first", not "the caller's chat". A client that has a specific branch in hand already holds its chat_id from GET /branches and should use that. Unlike regenerate, guessing here costs a wrong default view rather than a run dispatched onto the wrong branch, so it stays a default.
Path parameters
Response
Successful Response