make pydantic optional - #6786

Merging this PR will not alter performance

✅ 26 untouched benchmarks
⏩ 8 skipped benchmarks¹

_{Comparing benedikt-bartscher:make-pydantic-optional (02f7152) with main (7ba00b4)}

Greptile Summary

This PR makes pydantic an optional dependency of both reflex and reflex-base. The hot-path pydantic check in base_state_processor.py is moved from per-call find_spec to a single module-level probe (with the result cached as BaseModelV2 = None when absent), which is a good performance improvement. A new subprocess-based test verifies that core import, state, component render, and serializer functionality all work without pydantic present.

• packages/reflex-base/pyproject.toml: pydantic removed from hard deps, added as [project.optional-dependencies] pydantic.
• pyproject.toml: new pydantic = ["reflex-base[pydantic]"] extra; db extra retains a direct pydantic pin.
• tests/units/test_optional_pydantic.py: subprocess test with sys.meta_path filter + sys.modules purge to simulate a pydantic-free environment.

Confidence Score: 5/5

• This PR is safe to merge — the changes are narrowly scoped to dependency declarations and a single import-time guard, with no functional regressions for users who have pydantic installed.
• The pydantic guard is moved from per-call to module-level with a clear null sentinel, the test simulates a pydantic-free environment correctly (including the sys.modules purge that was previously missing), and the breaking change is documented. No defects were found in the changed paths.
• No files require special attention.

_{Reviews (8): Last reviewed commit: "Resolve pydantic presence once instead o..." | Re-trigger Greptile}

interesting; i thought we had pydantic as optional for some time now, but i guess not...

I remember reading some git commits or changelogs which mentioned this as well - however somehow it currently isn't optional.

I guess this is ready for review now.

Validated this end to end in a real app: installed the branch's packages into a clean venv (confirmed nothing pulls pydantic transitively — 40 packages, no pydantic), ran a counter app, and exercised state events in the browser — compile, hydration, and event round-trips all work without pydantic. Also confirmed the [pydantic] extra resolves and re-activates model serialization / MUTABLE_TYPES / ObjectVar support.

One perf issue surfaced and is fixed in 02f7152: _transform_event_arg called find_spec("pydantic") per dict-payload event argument. That was harmless while pydantic was a hard dep (sys.modules hit, ~125ns), but with pydantic absent every call did a full sys.path scan — measured 85.3µs per argument, and 0.64µs after hoisting the check to import time like the other guarded sites.