## What changed
- Add callback lifetimes to extension `ToolCall`, `ToolEnvironment`, turn-input context, and skill-read request types.
- Require extension tool executors to handle calls for any invocation lifetime and tie their returned futures to that lifetime.
- Update built-in extensions, adapters, and tests to use the lifetime-scoped APIs without retaining host-owned environment capabilities.
GitOrigin-RevId: aca9ce3a1b6870df550bc84ec9308cc65533f161
## Why
Short continuation prompts such as `continue` do not contain enough context for
skill selection on their own.
## What changed
- Add the `task_context_fusion_v1` shadow selector, combining the current request
with up to two prior substantive requests and recently relevant skills.
- Record explicit skill intent and successful skill invocations for future turns,
while excluding same-turn observations from predictions.
- Bound retained requests, augmented queries, and skill history, including safe
truncation at UTF-8 character boundaries.
## Testing
Add unit and extension tests for continuation prompts, explicit intent, turn
isolation, cold thread state, bounded history, and unchanged control selectors.
GitOrigin-RevId: 72eca3f0d64620a0d24e95d5675f126ac982f8c7
Adam Perry @ OpenAI