fix(zarr-metadata): make JSONValue's array arm covariant - #295
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* deps: bump cast-value.rs to >= 0.4.2 * deps: update uv.lock for cast-value-rs >= 0.4.2 The pyproject floor alone left uv.lock pinning 0.4.0, so any lock-honoring install (uv sync --locked/--frozen) kept the version that silently transposes non-row-major input. Assisted-by: ClaudeCode:claude-fable-5 * fix(cast_value): enforce the cast-value-rs floor at runtime The pyproject floor only binds installs that go through the zarr[cast-value-rs] extra. An environment that already has an older cast-value-rs installed kept silently corrupting non-row-major input after upgrading zarr, which is the failure this floor exists to stop. Check the installed version at import and raise from _do_cast, so the error surfaces when the codec is used rather than breaking `import zarr` for everyone else. A backend without distribution metadata (a `maturin develop` build) has no version to compare and is left alone. Assisted-by: ClaudeCode:claude-fable-5 * test(cast_value): cover cast_value next to the transpose codec Regression test for zarr-developers#4237: a cast_value codec on either side of a transpose codec must round-trip, because transpose hands the next codec a non-row-major view. Imported unchanged from zarr-developers#4238, where this test was written. The np.ascontiguousarray workaround that accompanied it there is deliberately left out: cast-value-rs 0.4.2 normalizes layout itself, and the workaround promotes 0-d arrays to shape (1,), breaking 0-d arrays. Co-authored-by: Raphael Jolivet <raphael.jolivet@minesparis.psl.eu> Assisted-by: ClaudeCode:claude-fable-5 --------- Co-authored-by: Raphael Jolivet <contact@raphael-jolivet.name> Co-authored-by: Raphael Jolivet <raphael.jolivet@minesparis.psl.eu>
`list["JSONValue"] | tuple["JSONValue", ...]` is invariant in the element type, so a value typed with any narrower element -- a `list[str]` field on a TypedDict, a `Sequence[float]` -- was not assignable to `JSONValue`, and a TypedDict carrying such fields was not assignable to `Mapping[str, JSONValue]`. pyright's diagnostic for the failure suggests the fix verbatim: "Consider switching from list to Sequence which is covariant." The array arm is now `Sequence["JSONValue"]`. The docstring records the deliberate type-level cost (`Sequence` admits `str`/`bytes`; runtime narrowing must exclude them regardless of the alias's spelling). Found while aliasing zarr-cm's JsonValue to this type: the two aliases are structurally identical except for this arm, and with it changed, pyright unifies them across the package boundary. Assisted-by: ClaudeCode:claude-opus-5
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The problem
JSONValue's array arm islist["JSONValue"] | tuple["JSONValue", ...], andlist/tupleare invariant in their element type. So a value typed with any narrower element does not count as a JSON value:By extension, any TypedDict whose fields carry precise types (
Sequence[str],list[int], ...) is not assignable toMapping[str, JSONValue]— which is exactly the shape downstream packages want: zarr-cm's convention TypedDicts hit all three failure modes, andtyagrees with pyright on every one of them.The fix
The array arm becomes
Sequence["JSONValue"].Sequenceis covariant, solist[str],tuple[int, ...], andSequence[float]are all JSON values, and precisely-typed TypedDicts flow intoMapping[str, JSONValue].The docstring records the deliberate type-level cost:
Sequencesays nothing about the concrete container and admitsstr/bytes(strwas already a union arm); runtime code narrowing a JSON array must excludestr/bytes/bytearrayregardless of how the alias is spelled.Motivation
Found while unifying zarr-cm's
JsonValuewith this alias — the two are structurally identical except for this arm (zarr-cm choseSequencefor exactly the covariance reasons above). With this change, pyright unifies the two recursive aliases across the package boundary with zero errors, and zarr-cm can delete its own definition and alias this one.Verification
From
packages/zarr-metadata:just test(595 passed),just typecheck(0 errors),just lintclean. Probes exercising all three failure modes go from 3 errors to 0 against the patched package, under both pyright and ty.