## What changed
Add `experimentalDisablePredictionMcp` to `thread/fork` and `disableMcp` to `thread/sample`. Disable MCP servers when requested and the inherited history contains incremental tools on Responses Lite. The fork option requires `experimentalPredictionMode: true`.
Apply disablement through a thread-local policy that excludes configured MCP servers and runtime contributions, including after MCP refresh. Preserve the inherited history prefix and append tool-removal instructions without changing the parent's tools.
## Testing
Add coverage for prediction forks with legacy and paginated history, flag validation, conditional disablement, MCP refresh, and sample/fork request parity. Add a request-history snapshot covering preserved history, tool removal across child turns, and unchanged parent tools.
GitOrigin-RevId: e31d602480e6550ed130d8152f538b8668280fa0
## 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
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