DSPy 3.4.0 Beta 1 DSPy 3.4.0b1 is the first beta of 3.4. It moves language-model execution to a shared engine interface, adds a local CPython interpreter for trusted code, and brings async execution to ReActV2. It also adds custom Flex code proposals in GEPA and fixes evaluation, streaming, and demonstration-sampling bugs. This is a prerelease, not the stable 3.4.0 release. APIs and behavior may change before stable. We especially welcome feedback on native versus LiteLLM compatibility, tool calling and streaming, custom LM migration, saved programs, and multi-answer latency and costs. Please include your engine selection and a minimal reproduction when reporting issues.

Install this beta explicitly: ```bash pip install --upgrade "dspy==3.4.0b1" ``` 3.4 is the LM transition release; 3.5 is the migration deadline. Ordinary DSPy programs and list-returning prompt calls remain supported, but the experimental LM types introduced in 3.3 are replaced in this release. Review the compatibility notes if you use those types, implement a custom LM, pass OpenAI-style messages directly to an LM, or request multiple answers with `n`. Highlights Native LM Engines and a New Custom-Backend…