## Why
`thread/sample` previously required the source's latest turn to finish before it could be sampled.
## What changed
Add `allowInProgressTurn`, defaulting to `false`, to sample a snapshot of the latest turn while the source continues running. The requested turn must still be the latest, but source history changes during sampling no longer invalidate the result when this option is enabled.
For an in-progress snapshot, include a context note explaining that the source was not stopped and pending tool calls may appear as `aborted` in the copy. Suppress the copy's default interruption message.
## Testing
Add coverage for sampling running turns in legacy and paginated history modes, including pending tool calls and mid-turn compaction. Verify that the source continues independently and that finished-turn samples retain their existing context.
GitOrigin-RevId: 771b979bf677e4ff0686476bfaf21aff92f7e7ac
Keyan Zhang
c37fd5665f