## What changed
- Pass goal objectives as untrusted `goal_objective` context instead of embedding them in continuation instructions. Direct the model to use `get_goal` if the objective is missing or truncated.
- Inject newly created objectives into their originating active turn without dropping unrelated client context. Render them as tool outputs when `UntrustedAsToolOutput` is enabled.
- Queue additional context together with automatic turn input so both reach the first model request.
## Testing
Extend app-server coverage to verify that model-written objectives appear as tool outputs at creation and continuation, without duplicating them in user messages. Update steering and Python SDK tests to check objective preservation and delivery alongside continuation instructions.
GitOrigin-RevId: 6f44f6d6c895bb4dc378c9cf84d6470ccc885c67
## Why
The Python SDK must treat the runtime's initial goal turn and its
continuations as one logical operation. That requires a private
lifecycle engine before the public API can return the existing turn
handle and result types.
## What
- start goals by composing the existing clear/set goal RPCs
- enforce persisted, idle threads and a bounded startup handshake
- coalesce continuation notifications under a stable logical turn ID
- aggregate items, usage, timing, and terminal status
- support rollover-aware steering, interruption, cancellation, and
cleanup
- provide equivalent sync and async internals
This is the second PR in the stack and intentionally adds no public API.
## Test plan
- online CI, including the Python SDK suite
- behavioral coverage is added in the following two stack PRs
Dylan Hurd