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[DRAFT] chore: add experimental python 314 support #129

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[DRAFT] chore: add experimental python 314 support #129

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4 changes: 3 additions & 1 deletion packages/cli/src/pywrangler/metadata.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3,12 +3,14 @@


class PythonCompatVersion(NamedTuple):
version: Literal["3.12", "3.13"]
version: Literal["3.12", "3.13", "3.14"]
compat_flag: str
compat_date: datetime | None
experimental: bool = False


PYTHON_COMPAT_VERSIONS = [
PythonCompatVersion("3.14", "pythonWorkers20260610", None, experimental=True),
PythonCompatVersion(
"3.13", "python_workers_20250116", datetime.strptime("2025-09-29", "%Y-%m-%d")
),
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10 changes: 9 additions & 1 deletion packages/cli/src/pywrangler/utils.py
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Expand Up @@ -334,7 +334,7 @@ def _parse_wrangler_config() -> WranglerConfig:


@cache
def get_python_version() -> Literal["3.12", "3.13"]:
def get_python_version() -> Literal["3.12", "3.13", "3.14"]:
"""
Determine Python version from wrangler configuration.

Expand Down Expand Up @@ -372,6 +372,10 @@ def get_python_version() -> Literal["3.12", "3.13"]:
)

for py_version in sorted_versions:
# Skip experimental versions unless the experimental compat flag is enabled
if "experimental" not in compat_flags and py_version.experimental:
continue

# Check if the specific compat flag is present
if py_version.compat_flag in compat_flags:
return py_version.version
Expand All @@ -390,6 +394,8 @@ def get_uv_pyodide_interp_name() -> str:
v = "3.12.7"
case "3.13":
v = "3.13.2"
case "3.14":
v = "3.14.2"
return f"cpython-{v}-emscripten-wasm32-musl"


Expand All @@ -407,6 +413,8 @@ def get_pyodide_index() -> str:
v = "0.27.7"
case "3.13":
v = "0.28.3"
case "3.14":
v = "314.0.0"

@ask-bonk ask-bonk Bot Jun 18, 2026

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314.0.0 is clearly a placeholder. If someone enables the experimental flag today, pywrangler sync will silently try to fetch from a non-existent index URL. Consider adding a comment, or raising an explicit error until a real Pyodide build for 3.14 is available.

@ryanking13 ryanking13 Jun 18, 2026

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experimental flag will fail on publish for non-Cloudflare employees so it is safe.

return "https://index.pyodide.org/" + v


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12 changes: 12 additions & 0 deletions packages/cli/tests/test_py_version_detect.py
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Expand Up @@ -176,3 +176,15 @@ def test_main_get_python_version_integration(test_dir):

version = get_python_version()
assert version == "3.12"


def test_314_compat_flag_with_experimental(test_dir):
wrangler_toml = test_dir / "wrangler.toml"
wrangler_toml.write_text("""
name = "test-worker"
compatibility_flags = ["python_workers", "pythonWorkers20260610", "experimental"]
compatibility_date = "2026-06-10"
""")

version = get_python_version()
assert version == "3.14"

@ask-bonk ask-bonk Bot Jun 18, 2026

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This test covers the happy path, but there's no test for when pythonWorkers20260610 is present without the experimental flag. That's the key scenario the gating logic protects against — please add a negative test to verify it falls back to an earlier version.

Suggested change
assert version == "3.14"
version = get_python_version()
assert version == "3.14"
def test_314_compat_flag_without_experimental(test_dir):
"""Test that Python 3.14 is NOT selected without the experimental flag."""
wrangler_toml = test_dir / "wrangler.toml"
wrangler_toml.write_text("""
name = "test-worker"
compatibility_flags = ["python_workers", "pythonWorkers20260610"]
compatibility_date = "2026-06-10"
""")
version = get_python_version()
assert version == "3.12"

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