feat(py): Implement reflection server v2#5186
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This pull request introduces the Reflection API v2, implementing a WebSocket-based JSON-RPC client (ReflectionServerV2) to facilitate communication with the Genkit Dev UI and CLI. Key features include support for listing actions and values, running actions with streaming support, and cancelling active actions. Additionally, the PR updates the action tracing mechanism to support asynchronous on_trace_start callbacks and fixes a registry key initialization bug. Feedback focuses on ensuring full compliance with the JSON-RPC 2.0 specification by correctly handling empty strings as valid request IDs across several handler methods.
huangjeff5
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Apr 27, 2026
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Implemented support for Reflection Server V2.
list_actionsas a stub because we're waiting for refactored code from feat(py): Add DAP helpers to registry + fix business logic in Registry.list_actions() #5073 to land before we wire that to the RPC method.stream_input_chunkfor now until SessionFlow stuff is ready.ai.flush_tracing()method. Cleaning that up here.