pydantic-core has no usable wheels in Pyodide — all versions fail

[seanai1996]

Description

Since approximately May 30, 2026, deploying Python Workers that depend on pydantic fails with the error that ALL versions of pydantic-core have no usable wheels. This was previously working fine.

Error Output

× No solution found when resolving dependencies: ╰─▶ Because pydantic-core==2.0.1 has no usable wheels and pydantic==2.0 depends on pydantic-core==2.0.1, we can conclude that pydantic==2.0 cannot be used.

Because pydantic-core==2.4.0 has no usable wheels and
pydantic>=2.1.0,<=2.1.1 depends on pydantic-core==2.4.0, we can
conclude that pydantic>=2.1.0,<=2.1.1 cannot be used.

... (all pydantic-core versions have no usable wheels)

your requirements are unsatisfiable.

Environment

• workers-py version: 1.9.3
• compatibility_date: 2026-04-23 (also tried 2026-06-01, same result)
• pydantic version tried: >=2.0,<2.10, ==2.9.2, various — all fail
• Last successful deployment: May 30, 2026

Steps to Reproduce

1. Create a Python Worker with pydantic>=2.0 in pyproject.toml
2. Run uv run pywrangler deploy
3. Observe: all pydantic-core versions report "no usable wheels"

Additional Context

• Locking pydantic to <2.10 does NOT fix the issue — ALL pydantic-core versions are affected
• Updating compatibility_date does NOT fix the issue
• This appears to be a regression — the same project deployed successfully before May 30