Workaround for pyright bug on ccflow.BaseModel subclasses#222
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…defaults v0.8.4 introduced a runtime-conditional metaclass on ccflow.BaseModel (`metaclass=_BASE_MODEL_METACLASS`) so that the SerializeAsAny annotation rewriting could be bypassed on pydantic >= 2.13, which now supports runtime polymorphic serialization natively. Pyright cannot statically resolve a metaclass whose value is selected at runtime, and falls back to a treatment that disables pydantic's __init__ synthesis. As a result, every ccflow.BaseModel subclass has its field defaults treated as required, e.g. `ccflow.FlowOptions()` is reported as missing arguments for log_level, verbose, validate_result, volatile, cacheable, and evaluator. Restore the static `metaclass=_SerializeAsAnyMeta` declaration and instead gate the annotation-rewriting body of `_SerializeAsAnyMeta.__new__` on `_USE_RUNTIME_POLYMORPHIC_SERIALIZATION`. Runtime behavior is preserved on both pydantic < 2.13 and pydantic >= 2.13, while pyright once again recognizes the metaclass as a pydantic ModelMetaclass and synthesizes __init__ with field defaults. Signed-off-by: Pascal Tomecek <pascal.tomecek@cubistsystematic.com>
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## main #222 +/- ##
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timkpaine
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timkpaine
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Jun 3, 2026
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A user reported that on v0.8.4, running pyright over
fails with:
even though all those fields have defaults. v0.8.3 was clean.
The cause is the conditional metaclass introduced in #215 for pydantic 2.13 compat:
Pyright can't resolve a metaclass picked at runtime, so it stops synthesizing the pydantic
__init__and every field with a default ends up looking required. This affects everyccflow.BaseModelsubclass, not justFlowOptions.Fix: keep the metaclass statically declared as
_SerializeAsAnyMetaand move the_USE_RUNTIME_POLYMORPHIC_SERIALIZATIONgate one level inward, into the body of_SerializeAsAnyMeta.__new__. On pydantic ≥ 2.13 the metaclass is now a thin pass-through overModelMetaclass; on older pydantic the annotation rewrite still runs as before.Verified:
python -m pyright repro.py→ 0 errorspytest ccflow/tests/test_base_serialize.py ccflow/tests/test_base_cloudpickle.py→ all pass