## What changed
Add the experimental `thread/sample/cancel` request with a `requestId` identifying a `thread/sample` request on the same connection. Cancellation returns an empty response, stops the matching sample with `sample canceled`, and cleans up its ephemeral fork. Repeated cancellation and unknown request IDs are harmless no-ops; other request types are unaffected.
## Testing
Add coverage for connection and request ID isolation, request type filtering, and repeated cancellation. Extend the sample integration test to verify cancellation keeps the parent responsive and reclaims the child thread.
GitOrigin-RevId: 92d12e5c0190e1d3b06cb482543615a3ec77bdc8
## What changed
Add `thread/sample` to collect one model response on an ephemeral fork that inherits a loaded thread's context and configuration. Return the source turn ID, response ID, assistant text, and available token usage without modifying the source conversation.
Require an idle, persistent root thread and an `expectedTurnId` matching its latest completed turn. Reject results if the source history changes during sampling. Keep the parent responsive while sampling, hide sample forks from `thread/loaded/list`, and reclaim them after completion or timeout.
Intercept responses before tool execution or Stop hooks can run, returning null text for tool calls or responses without text. Apply optional reasoning-effort updates only when the provider and model support cache-preserving updates.
## Testing
Add integration coverage for inherited context and reasoning effort, source preservation, tool and Stop hook suppression, invalid requests, stream errors, parent responsiveness, and timeout cleanup.
GitOrigin-RevId: 08f4867e53ec7f6c8f4428d5542eeea4e6dadd0b
liame-oai