What changed

• merged the public stream execution modes down to single-process and local-workers
• kept the former actor-credit hot path as an internal local-workers accelerator instead of a separate public mode
• renamed explain/config surfaces to local-worker semantics and updated core docs and examples
• updated core regressions to validate the merged behavior, including the local_workers=1 guardrail

Why

The previous public model exposed actor-credit and auto as separate modes even though they overlapped with the local-workers data-parallel path. This made the execution contract harder to understand and left a bug where eligible local-workers queries could silently fan out to more workers than configured.

Impact

• users now choose between single-process and local-workers
• credit-based scheduling remains available only as an internal optimization for eligible local-workers queries
• local_workers=1 now stays truthful and no longer activates the credit accelerator

Validation

• bazel test //:stream_strategy_explain_test
• bazel test //:core_regression
• bazel build //:stream_benchmark