What are you trying to achieve?

The specification changes in #4166 are considered breaking. Discussed in the 7/22/2025 Specification SIG: while we see this change as modifying an existing unspecified behavior, users may observe broken traces in certain scenarios leading us to decide to create a new sampler and deprecate the original one.

What did you expect to see?

Proposed: Create a new "ProbabilitySampler" to replace the "TraceIdRatioBased" sampler. The new will have exactly the same inputs and configuration as the old for compatibility, just new sampling decision logic.

Additional context.

See #4162.

We will modify and improve the discussion of this problem in our guidelines: https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/tracestate-probability-sampling.md#migration-to-consistent-probability-samplers.