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refactor: use lower-level metadata models in zarr-python#4129

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refactor: use lower-level metadata models in zarr-python#4129
d-v-b wants to merge 59 commits into
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d-v-b:claude/zarr-metadata-integration-06b0d6

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@d-v-b d-v-b commented Jul 8, 2026

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Summary

This PR builds on the changes outlined in #4119 by adding the low-level metadata classes defined in zarr-metadata as load-bearing members of zarr-python's array and group classes. This doesn't replace the .metadata attribute. That would take place over a few more transitional PRs. It is the first of several PRs that would refactor our metadata classes to be more future-proof.

Author attestation

  • I am a human, these are my changes, and I have reviewed and understood every change and can explain why each is correct.

AI coding assistance is welcome, but a human must be the author and is responsible for the contents of the PR. The description and any review responses must be in your own words. Please read AI-assisted contributions before opening.

TODO

  • Add unit tests and/or doctests in docstrings
  • Add docstrings and API docs for any new/modified user-facing classes and functions
  • New/modified features documented in docs/user-guide/*.md
  • Changes documented as a new file in changes/
  • GitHub Actions have all passed
  • Test coverage is 100% (Codecov passes)

dependabot Bot and others added 30 commits May 31, 2026 19:28
…#176)

Bumps the actions group with 8 updates in the / directory:

| Package | From | To |
| --- | --- | --- |
| [prefix-dev/setup-pixi](https://github.com/prefix-dev/setup-pixi) | `0.9.5` | `0.9.6` |
| [codecov/codecov-action](https://github.com/codecov/codecov-action) | `6.0.0` | `6.0.1` |
| [github/issue-metrics](https://github.com/github/issue-metrics) | `4.2.2` | `4.2.7` |
| [j178/prek-action](https://github.com/j178/prek-action) | `2.0.3` | `2.0.4` |
| [actions/upload-artifact](https://github.com/actions/upload-artifact) | `7.0.0` | `7.0.1` |
| [actions/download-artifact](https://github.com/actions/download-artifact) | `7.0.0` | `8.0.1` |
| [pypa/gh-action-pypi-publish](https://github.com/pypa/gh-action-pypi-publish) | `1.13.0` | `1.14.0` |
| [zizmorcore/zizmor-action](https://github.com/zizmorcore/zizmor-action) | `0.5.3` | `0.5.6` |



Updates `prefix-dev/setup-pixi` from 0.9.5 to 0.9.6
- [Release notes](https://github.com/prefix-dev/setup-pixi/releases)
- [Commits](prefix-dev/setup-pixi@1b2de7f...5185adf)

Updates `codecov/codecov-action` from 6.0.0 to 6.0.1
- [Release notes](https://github.com/codecov/codecov-action/releases)
- [Changelog](https://github.com/codecov/codecov-action/blob/main/CHANGELOG.md)
- [Commits](codecov/codecov-action@57e3a13...e79a696)

Updates `github/issue-metrics` from 4.2.2 to 4.2.7
- [Release notes](https://github.com/github/issue-metrics/releases)
- [Commits](github-community-projects/issue-metrics@c9e9838...1e38d5e)

Updates `j178/prek-action` from 2.0.3 to 2.0.4
- [Release notes](https://github.com/j178/prek-action/releases)
- [Commits](j178/prek-action@6ad8027...bdca6f1)

Updates `actions/upload-artifact` from 7.0.0 to 7.0.1
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v7...043fb46)

Updates `actions/download-artifact` from 7.0.0 to 8.0.1
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v7...3e5f45b)

Updates `pypa/gh-action-pypi-publish` from 1.13.0 to 1.14.0
- [Release notes](https://github.com/pypa/gh-action-pypi-publish/releases)
- [Commits](pypa/gh-action-pypi-publish@v1.13.0...cef2210)

Updates `zizmorcore/zizmor-action` from 0.5.3 to 0.5.6
- [Release notes](https://github.com/zizmorcore/zizmor-action/releases)
- [Commits](zizmorcore/zizmor-action@b1d7e1f...5f14fd0)

---
updated-dependencies:
- dependency-name: prefix-dev/setup-pixi
  dependency-version: 0.9.6
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: actions
- dependency-name: codecov/codecov-action
  dependency-version: 6.0.1
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: actions
- dependency-name: github/issue-metrics
  dependency-version: 4.2.7
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: actions
- dependency-name: j178/prek-action
  dependency-version: 2.0.4
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: actions
- dependency-name: actions/upload-artifact
  dependency-version: 7.0.1
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: actions
- dependency-name: actions/download-artifact
  dependency-version: 8.0.1
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: actions
- dependency-name: pypa/gh-action-pypi-publish
  dependency-version: 1.14.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: actions
- dependency-name: zizmorcore/zizmor-action
  dependency-version: 0.5.6
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: actions
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Assisted-by: ClaudeCode:claude-fable-5
Assisted-by: ClaudeCode:claude-fable-5
Assisted-by: ClaudeCode:claude-fable-5
Assisted-by: ClaudeCode:claude-fable-5
Findings from an API-ergonomics exercise (a fresh agent consuming
defective metadata documents):

- ValidationProblem gains a machine-readable kind (missing_key /
  invalid_type / invalid_value / invalid_json), ending message
  string-matching in consumers.
- The v2 array validator now enforces what its types declare (dtype,
  order, compressor, filters, dimension_separator), and all four
  document validators check the fixed zarr_format / node_type literals.
- All ingestion failures surface as MetadataValidationError: missing
  store keys and undecodable bytes in from_key_value (previously
  KeyError / JSONDecodeError) and constructor invariants (previously
  bare ValueError).
- ZarrMetadataV3 is renamed NamedConfigModelV3: it models a name +
  configuration pair, and the old name read as a whole-document type.
- Discoverability: the validate_*/is_*/parse_* contract is documented
  on zarr_metadata.model itself; update() documents that it does not
  re-validate; the v2 to_json/to_key_value attributes split is
  documented on both.

Assisted-by: ClaudeCode:claude-fable-5
…aFieldModelV3

Model fields and consumer signatures should convey the logical meaning
of the type (a metadata-document field), not the form it takes when
JSON-serialized (a named configuration). MetadataFieldModelV3 is today
exactly NamedConfigModelV3; if a future spec revision adds a field form
that cannot normalize to name + configuration, the alias widens to a
union and annotation sites do not move. Mirrors the raw-layer split
between NamedConfigV3 (shape) and MetadataV3 (field union).

Assisted-by: ClaudeCode:claude-fable-5
test_v3_to_json_includes_required_fields hand-enumerated keys with
chained asserts, restating what ARRAY_METADATA_REQUIRED_KEYS_V3 already
defines. Now: one coverage assert driven by the constant (tracks the
TypedDict automatically) and one whole-document equality for the values.

Assisted-by: ClaudeCode:claude-fable-5
The subset assert against ARRAY_METADATA_REQUIRED_KEYS_V3 was redundant:
equality with a literal that spells out the full document already covers
every required key. One dict, one assert.

Assisted-by: ClaudeCode:claude-fable-5
Invalid documents that previously passed validation:

- shape/chunks containing JSON booleans (bool is an int subclass in
  Python but not an integer in a metadata document) or negative values
- dimension_names whose length does not match shape
- attributes and configuration values that are not JSON-serializable —
  now checked recursively like fill_value, so an int-keyed dict cannot
  be silently rewritten by json.dumps on round-trip and a set() cannot
  escape as a TypeError from to_key_value
- consolidated_metadata envelopes: the group validator now deep-validates
  the envelope and its entries via the shared
  validate_consolidated_metadata_v3, which ConsolidatedMetadataModelV3
  .from_json also uses, so is_group_metadata_v3 never vouches for a
  document the model constructor would reject

Three pre-existing test fixtures paired dimension_names=('x',) with the
default scalar shape () and were themselves spec-invalid; they now use a
matching 1-d shape.

Deliberately unchanged, pending a design decision: unknown extension
fields with must_understand: true still pass (which layer owns the
spec's refusal duty), and empty v2 dtype records / empty codec names
still pass (domain territory).

Assisted-by: ClaudeCode:claude-fable-5
The v3 core spec: 'An implementation MUST fail to open Zarr groups or
arrays if any metadata fields are present which (a) the implementation
does not recognize and (b) are not explicitly set to
"must_understand": false' — and fields are implicitly must-understand
unless waived.

The model layer cannot discharge this itself: recognition is
reader-specific (consolidated_metadata is itself an extension field one
reader understands and another does not), and a document carrying a
must-understand extension is still a valid document. So the models
partition by obligation: must_understand_fields is the subset of
extra_fields not explicitly waived, and a compliant reader fails to
open when must_understand_fields.keys() - recognized is non-empty.
The design spec pins that duty on the part-2 resolve layer, matching
what zarr-python's parse_extra_fields enforces today.

Assisted-by: ClaudeCode:claude-fable-5
Delegate wholesale rather than letting pydantic introspect the dataclass:
InstanceOf (is-instance core schema) + BeforeValidator(from_json) +
PlainSerializer(to_json, return_type=dict). Field-by-field validation is
impossible anyway (the models' annotation-only imports live behind
TYPE_CHECKING, so pydantic raises class-not-fully-defined) and would
diverge from the library's structural validation via coercion if it
weren't. MetadataValidationError subclasses ValueError, so failed parses
surface as pydantic ValidationError with the loc-annotated messages.

pydantic is already in the package's test dependency group.

Assisted-by: ClaudeCode:claude-fable-5
…y not

Correcting the previous commit's too-strong claim: pydantic CAN
introspect the model dataclass — TypeAdapter(...).rebuild() with the
TYPE_CHECKING-only names supplied as _types_namespace resolves the
schema, and __post_init__ invariants still run. A new test exercises
that path and pins why it is not the recommended integration: it
validates the model shape, not the document (bare-string data_type
rejected — no from_json normalization), and pydantic's lax coercion
silently re-opens holes the library validators close (shape=[True, -5]
coerces to (1, -5); a wrong dimension_names count passes).

Assisted-by: ClaudeCode:claude-fable-5
…ic-zarr pattern)

For consumers that want a first-class BaseModel — JSON schema generation
and generics for typed attributes, as in pydantic-zarr's ArraySpec — the
example adds a third pattern: pydantic-native fields as the user-facing
surface, with the library as the engine. A mode='before' validator
canonicalizes every input via from_json(...).to_json(), so structural
validation and normalization run before pydantic parses fields (the
[True, -5] coercion divergence cannot occur), and to_metadata_model /
to_document bridge both ways through the document form. One translation
noted at the bridge: the document spells 'no dimension names' as key
absence, the pydantic side as None.

Assisted-by: ClaudeCode:claude-fable-5
Spec: 'If specified, must be an array of strings or null objects...
If dimension_names is not specified, all dimensions are unnamed.' The
null object is a permitted element (an unnamed dimension), never the
field value; key absence is the only spelling of 'not specified'. Pins
the validator's existing rejection so it is not later 'fixed' to accept
null-as-absence, and documents that in-memory None maps to key absence
on serialization.

Assisted-by: ClaudeCode:claude-fable-5
d-v-b and others added 29 commits July 5, 2026 18:34
…ydantic

Gamed out three shapes with prototypes before choosing:
- dunders on the core classes (works, verified pydantic 2.0-2.13, but
  puts a framework protocol in the dependency-free layer);
- pydantic-aware SUBCLASSES in a namespace (rejected on empirical
  failures: identity split breaks equality, core instances are rejected
  by subclass-typed fields, and nested construction produces core-class
  children unless every cross-reference is overridden);
- Annotated field types over the CORE classes in an opt-in module
  (chosen): instances are the core classes so interop is free, pydantic
  imports eagerly at the module (loud failure when absent), core stays
  framework-free, and pydantic-protocol risk is quarantined to one
  clearly-labeled module.

The module exports one field type per model. Validation delegates to
from_json (structural validation and normalization cannot be bypassed by
pydantic coercion), instances pass through, serialization emits the
canonical document, and WithJsonSchema describes the accepted document
form so model_json_schema works. Tests cover all seven field types,
core-instance interop, error quality, JSON schema, roundtrip, and that
importing zarr_metadata does not import pydantic.

Assisted-by: ClaudeCode:claude-fable-5
create_default(shape=(100, 100)) silently kept the scalar default's 0-d
chunk grid (chunk_shape: ()), producing a structurally-valid but
semantically inconsistent document — a footgun for every test fixture
built on it. When shape is overridden and the grid is not, the default
is now one regular chunk covering the array (v3 chunk_shape == shape,
v2 chunks == shape); an explicit chunk_grid/chunks override still wins.
update() stays a dumb dataclasses.replace, per its documented contract.

One existing whole-document test literal carried exactly this
inconsistency (shape (10,) with chunk_shape ()) and was updated.

Assisted-by: ClaudeCode:claude-fable-5
…unk grid

The spec's constraint is conditional ('non-zero when the corresponding
dimensions of the arrays have non-zero length'), so chunk_shape == shape
is sound for every shape, including empty dimensions.

Assisted-by: ClaudeCode:claude-fable-5
…-way

Overriding shape without a grid derives the grid; the reverse does not
hold. A user-supplied chunk_grid is an extension point taken verbatim —
deriving shape from it would require interpreting grid configurations,
which the model layer never does and cannot do for unrecognized grid
names. Pinned by test so the asymmetry reads as a decision, not an
oversight; the v2 model documents the same one-way rule for chunks for
cross-version consistency.

Assisted-by: ClaudeCode:claude-fable-5
Audited all 24 (15 src, 9 tests); each was either obsolete, replaceable
by a sound cast, or avoidable by better-typed code:

- Two fill_value arg-type ignores were factually obsolete: their
  justifying comment said 'fill_value: object in upstream TypedDict',
  but 0.3.0 narrowed it to JSONValue.
- Eight pre-existing call-arg/reportInvalidTypeForm ignores on the PEP
  728 TypedDicts and the recursive JSONValue alias were mypy-dialect
  suppressions that the checker of record (pyright strict with
  enableExperimentalFeatures) never needed; mypy has never checked this
  package.
- The two extra_fields comprehensions are a genuine checker limitation
  (a key filter cannot narrow a PEP 728 TypedDict's item-value union),
  now expressed as casts whose comments state the soundness claim
  instead of suppressing the diagnostic.
- pydantic.py's generic coercer factory takes the parse callable
  explicitly instead of calling from_json through type[_M].
- NamedConfigModelV3.from_json casts the validated configuration (sound
  since configuration values are now deep-validated as JSON).
- Tests: _build_v2/_build_v3 gained real Unpack[...Partial] signatures;
  raw-document pydantic inputs go through model_validate (the idiomatic
  entry point for untyped data) instead of ignoring constructor
  signatures; the frozen-dataclass test uses setattr for its
  intentional runtime error.

src and tests/model now carry zero type-ignore comments.

Assisted-by: ClaudeCode:claude-fable-5
roborev job 426 (branch review) found that ArrayMetadataModelV2
normalized an ABSENT dimension_separator key to '/', inherited verbatim
from the zng prototype. The v2 convention's default is '.': a consumer
deriving chunk keys from the model against a real-world v2 array
written with the default separator would have looked for '0/0' instead
of '0.0'. No test caught it because every fixture started from
create_default(), which always carries an explicit separator.

Absence is normalized to an explicit '.' -- a semantics-preserving
spelling normalization consistent with the model's existing canonical
forms (bare-string metadata fields, missing configuration). The field
is deliberately NOT modeled as Optional: the document grammar has no
null spelling for this key, and a None in the model invites writing
'dimension_separator': null into documents. Pinned by three tests,
including explicit-null rejection.

Assisted-by: ClaudeCode:claude-fable-5
Establishes the models' None/absence invariant: None in a model always
corresponds to a JSON null in the document (a v2 compressor/filters
value, an unnamed dimension inside dimension_names), and UNSET always
means the key is absent. The two are never interchangeable.

Applied to the two fields that used None as an absence marker:
dimension_names (ArrayMetadataModelV3) and consolidated_metadata
(GroupMetadataModelV3). For dimension_names this also preserves a
semantic distinction d-v-b identified: an absent field ("there are no
dimension names") and an explicit all-null array ("every dimension has
a name, which is null") are different documents; both spellings now
round-trip faithfully and compare unequal.

Normalizing absence to the all-null form was considered and rejected:
the spellings' interpretations coincide but interpretation-equivalence
is the resolve layer's business, and collapsing document-level
distinctions on that basis is the layer violation this package exists
to avoid. Verified that current zarr-python never writes
"consolidated_metadata": null (GroupMetadata.to_dict pops the key), so
None there was purely an absence marker, not a document spelling.

UnsetType is a single-member enum (identity-checkable, repr "UNSET",
deliberately truthy so `if not x` cannot silently treat it as absent);
UNSET and UnsetType are exported from zarr_metadata.model and the
package front door.

Assisted-by: ClaudeCode:claude-fable-5
…a null

Historical zarr-python versions wrote "consolidated_metadata": null into
group documents for groups without consolidated metadata, so real stores
contain the spelling; the validator was rejecting those documents
("expected a mapping"). Per the None/UNSET invariant, the field is now
honestly three-state: UNSET (key absent), None (the document's literal
null, preserved on round-trip), or a ConsolidatedMetadataModelV3.
Interpreting null as absence is the consumer's call, not a document
rewrite by this layer.

Also records an implementation constraint on the sentinel itself:
typing_extensions.Sentinel (PEP 661) is the intended spelling, but
pyright 1.1.411 degrades a Sentinel to Unknown in dataclass FIELD
annotations (function signatures work), verified by probe both with and
without enableExperimentalFeatures. Using it would reintroduce
suppressions at every use site under the strict gate, so UNSET stays a
single-member enum, with the Sentinel switch documented in
_sentinel.py for when pyright catches up.

Assisted-by: ClaudeCode:claude-fable-5
… preserve it

d-v-b: the bugged spelling should not be preserved or honored. The
three-state field reverts to two states (model | UNSET): a document
carrying "consolidated_metadata": null — written by a historical
zarr-python bug — remains readable (the validator accepts it so real
stores open), but the spelling gets no model representation: it is read
as absence and never written back. This is the one deliberate exception
to faithful round-tripping, pinned as such: from_json(null_doc) equals
from_json(absent_doc), and to_json omits the key.

Assisted-by: ClaudeCode:claude-fable-5
…11115

Investigated: the Unknown-degradation of typing_extensions.Sentinel is a
confirmed upstream pyright regression, not by-design. Introduced in
1.1.405 (verified: 1.1.404 is clean on the same probe, 1.1.411 fails),
affects reads of any class-body attribute annotation (dataclass or
plain class), does not affect function signatures or module variables,
and Final on the sentinel does not help. Tracked as
microsoft/pyright#11115 (open, bug+regression); #11467 closed as its
duplicate. The enum sentinel stays until the fix lands.

Assisted-by: ClaudeCode:claude-fable-5
… pyright

Pinning a working pyright (<= 1.1.404) in CI was considered and does
not suffice: the pin controls one of four checker surfaces. Contributor
IDEs (Pylance bundles current pyright) and downstream consumers'
pyright read the py.typed inline annotations with their own versions,
and decisively, mypy 2.1.0 has no PEP 661 support at all — a sentinel
in type position is a hard [valid-type] error, which would degrade
these fields to Any for mypy consumers, including zarr-python itself.
The enum is currently the only spelling with exact types on every
surface; switch when pyright#11115 is fixed AND mypy implements PEP 661.

Assisted-by: ClaudeCode:claude-fable-5
Corrects the sentinel implementation note: PEP 661 was accepted
2026-04-23 and ships as stdlib sentinel in Python 3.15. The two checker
gaps blocking the Sentinel spelling (pyright regression #11115, mypy
not yet implementing the PEP) are therefore temporary gaps against a
Final standard, and the enum is a stopgap with a defined end state.

Assisted-by: ClaudeCode:claude-fable-5
…are the laggards

ty 0.0.56 types the Sentinel spelling perfectly in dataclass fields:
exact T | UNSET unions, both-direction is/is-not narrowing, and
wrong-typed constructor arguments rejected (verified with reveal_type,
so it is real inference, not silent Any). The checker matrix for
sentinel-in-type-position is therefore ty full / pyright regressed
(#11115) / mypy not implemented — recorded so the switch decision has
current calibration.

Assisted-by: ClaudeCode:claude-fable-5
d-v-b's call: PEP 661 is Final, ty already types the sentinel spelling
exactly, mypy support is in review (python/mypy#21647) and treated as
imminent, and pyright has a known-good version — so use the standard
sentinel today rather than carrying the enum stopgap.

- UNSET is now typing_extensions.Sentinel("UNSET"), used directly in
  type expressions (tuple[str | None, ...] | UNSET); the UnsetType
  companion enum is gone from the API.
- typing_extensions floor bumped to 4.14 (where Sentinel arrived).
- CI pins pyright==1.1.404, the last version before the class-attribute
  sentinel regression (microsoft/pyright#11115); pyproject documents the
  same pin for local runs. 0 errors on the pin; ty checks the sentinel
  fields clean (its 2 remaining diagnostics are its incomplete PEP 728
  extra_items write support, unrelated).
- Known short-term cost, accepted deliberately: mypy-checked consumers
  need cast/type-ignore at narrowing sites until mypy#21647 merges, and
  contributors' Pylance may show phantom Unknowns until the pyright fix
  ships. Recorded in _sentinel.py and the changelog.
- The pydantic native-introspection test reverts to documenting that
  introspection is unsupported (pydantic 2.13 cannot schema a Sentinel);
  the delegation patterns are unaffected.

Assisted-by: ClaudeCode:claude-fable-5
…ifact

Resolves the last flagged round-trip question from the initial port:
to_key_value on the v2 models always emitted a .zattrs key, so a store
that never had one gained a file on round-trip. Per d-v-b's ruling,
attributes on ArrayMetadataModelV2/GroupMetadataModelV2 is now
`dict[str, JSONValue] | UNSET`: UNSET means no .zattrs file (and no
attributes key in the merged document form) and emits nothing, while
any dict — including an explicit empty {} — means the file exists and
is emitted. The two spellings stay distinct through round-trips, per
the None/UNSET invariant; create_default defaults to UNSET (a fresh
minimal node has no .zattrs).

Assisted-by: ClaudeCode:claude-fable-5
…by reference

Models hold the UNSET sentinel as field values (dimension_names,
attributes), so any object graph containing a model must survive pickling
and deep-copying. A sentinel's contract is identity — state-based pickling
would produce impostor objects that fail every `is UNSET` check — which is
why typing_extensions <= 4.15 refused to pickle sentinels at all.

typing_extensions 4.16 implements Sentinel.__reduce__ as pickling by
reference (a lookup of the sentinel's name on its defining module), the same
mechanism enum members use, so the singleton identity survives the round
trip. Bump the floor and pin the behavior with tests: identity across
pickle/copy/deepcopy, models holding UNSET round-tripping, and a guard that
a non-importable sentinel still fails loudly rather than pickling by state.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
…mary, JSON suffix for documents

Applies the naming decisions from the PR discussion: ZarrV2/ZarrV3 moves to
the front of every type name so a format version cannot be misread as a
class revision, and the model dataclasses take the bare entity names
(ZarrV3ArrayMetadata, ZarrV3GroupMetadata, ZarrV3ConsolidatedMetadata,
ZarrV3NamedConfig, role alias ZarrV3MetadataField) while the TypedDict
document forms carry a JSON suffix (ZarrV3ArrayMetadataJSON, ...,
ZarrV3MetadataFieldJSON, ZarrV3NamedConfigJSON).

The zarr_metadata.pydantic field types take the bare entity names, matching
the model classes they validate into; the module now references the model
module qualified to keep those names free. Raw-layer names released in 0.3.0
are renamed without aliases (pre-1.0), documented in changes/4119.removal.md.
Validation problem messages name documents in plain English instead of type
names. snake_case function names (validate_array_metadata_v3, ...) and
SCREAMING_SNAKE constants are deliberately untouched: the revision ambiguity
the rename fixes does not arise for them, and renaming them is a separate
decision.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
zarr now declares a runtime dependency on zarr-metadata (>=0.4.0, the first
release that will contain the metadata model layer). Within a checkout the
dependency resolves to packages/zarr-metadata via a uv workspace source, so
CI and dev environments always test against the in-tree package.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
…data models

Adds zarr.core.metadata.model with array_metadata_to_model/from_model and
group_metadata_to_model/from_model, bridging zarr-python's interpreted
metadata classes (ZDType, codec instances, cast fill values) and the pure
JSON-shaped model dataclasses in zarr_metadata.model.

runtime -> model round-trips through the JSON document form and is total;
model -> runtime behaves exactly like reading the equivalent document from a
store, including rejection of uninterpretable extension points.

Also teaches DataTypeRegistry.match_json to accept the v3-spec-equivalent
{"name": X, "configuration": {}} spelling of configuration-free data types:
the model layer (and other zarr implementations) normalize bare names to that
form, which the per-dtype from_json methods previously rejected.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
AsyncArray, Array, AsyncGroup, and Group gain a _future_metadata property
exposing the node's metadata as a zarr_metadata document model
(ArrayMetadataModelV2 | ArrayMetadataModelV3 for arrays,
GroupMetadataModelV2 | GroupMetadataModelV3 for groups). This is the planned
future type of the public .metadata attribute; per-format group metadata
classes arrive with it.

The model is derived lazily from the runtime metadata and cached, keyed on
the identity of the metadata object. To make that sound, the two remaining
in-place metadata mutations (array _update_attributes and
AsyncGroup.update_attributes) now swap in a new metadata object instead of
mutating attributes in place.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Migrates the reads where the document model already carries exactly the
value internals need: array shape/ndim/size, indexer shapes, resize/append
shape checks, and group zarr_format dispatches. Interpreted reads (dtype,
codecs, fill value, chunk key encoding) stay on the runtime metadata until
the model becomes the stored source of truth.

The zarr_format == 2 dispatches inside AsyncArray property bodies
deliberately stay on self.metadata: they type-check via Literal narrowing of
the constrained metadata TypeVar, and they gate access to interpreted fields
that have no model equivalent yet.

Arrays and groups also drop the _future_metadata cache from pickled state:
the model holds PEP 661 sentinels (zarr_metadata.model.UNSET), which are
process-local by design and refuse to pickle.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Reading Array.metadata or Group.metadata now emits
ZarrPendingDeprecationWarning (a PendingDeprecationWarning, so ignored by
default) announcing that the attribute's type will change to the
zarr-metadata document model classes. _future_metadata previews the new
interface.

Internal consumers of the sync properties (the Attributes wrapper,
migrate_v3, the testing strategies) move to a private no-warning _metadata
accessor so zarr never warns on its own operation. The test suite ignores
the warning class globally for now (asserted explicitly in
tests/test_future_metadata.py); that filter comes out when the tests
themselves migrate.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
zarr-metadata now requires typing_extensions>=4.16, whose Sentinel pickles
by reference with singleton identity preserved, so the _future_metadata
cache no longer *has* to be excluded from pickled node state — it still is,
because it is derived state and the wire format should not couple to the
cache layout. Comments updated accordingly, the lockfile picks up 4.16, and
the pickle tests now round-trip whole nodes parametrized over the states
sensitive to serialization (absent vs present optional keys, both formats).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Follows the naming decision applied in the zarr-metadata model layer:
format version at the front, dataclasses take the bare entity names. All
references (conversion layer, _future_metadata annotations and docstrings,
warning messages, tests, changelog) move from ArrayMetadataModelV2/V3,
GroupMetadataModelV2/V3, ConsolidatedMetadataModelV3, NamedConfigModelV3 to
ZarrV2ArrayMetadata / ZarrV3ArrayMetadata, ZarrV2GroupMetadata /
ZarrV3GroupMetadata, ZarrV3ConsolidatedMetadata, ZarrV3NamedConfig.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The zarr-metadata model layer that zarr now depends on is unreleased, and
the previous wiring only covered uv project flows, breaking everything else:

- The floor 'zarr-metadata>=0.4.0' is unresolvable from PyPI (only <0.4.0
  exists), failing every hatch env (test matrix, doctests, benchmarks,
  hypothesis, min_deps, upstream) and the readthedocs build. The floor now
  names the newest release (>=0.3) with a TODO to bump at release time, and
  each non-uv flow installs the in-tree package explicitly: hatch envs get a
  '{root:uri}/packages/zarr-metadata' direct reference (repeated per env,
  since hatch replaces extra-dependencies on inheritance), readthedocs gets
  an extra pip install step.

- uv workspace membership made 'uv sync' inside packages/zarr-metadata
  resolve the whole workspace, dragging zarr's requires-python (>=3.12) into
  the subpackage's own CI, which tests down to 3.11. The workspace is now a
  plain editable path source, restoring the subpackage's independence.

- min_deps pins typing_extensions==4.16.* (was 4.14.*): 4.16 is the
  effective minimum because zarr-metadata requires it for sentinel pickling.

Also fixes the Lint (mypy) findings in the new tests — a bare generic Array
annotation, stale type-ignores, and two sentinel comparisons mypy cannot
narrow (python/mypy#21647) — and renames the changelog entries to the PR
number (4129) required by the changelog check.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
CI builds from shallow clones, where hatch-vcs cannot see the
zarr_metadata-v* tags and derives 0.1.devN for the in-tree package — so the
'>=0.3' floor rejected the very package CI installs (uv reported the
URL-pinned candidate as 'only zarr-metadata<0.3 is available'). No floor can
be satisfied by both PyPI and tag-less in-tree builds until 0.4.0 ships, so
the requirement carries no version until then; the TODO(release) comment
marks where the real floor lands. Verified against a shallow clone: both the
hatch env and the frozen root uv sync now build and import.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
@codecov

codecov Bot commented Jul 8, 2026

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Codecov Report

❌ Patch coverage is 97.45763% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.69%. Comparing base (6876120) to head (919ae77).

Files with missing lines Patch % Lines
src/zarr/testing/stateful.py 0.00% 2 Missing ⚠️
src/zarr/core/attributes.py 85.71% 1 Missing ⚠️
Additional details and impacted files
@@            Coverage Diff             @@
##             main    #4129      +/-   ##
==========================================
+ Coverage   93.62%   93.69%   +0.06%     
==========================================
  Files          90       91       +1     
  Lines       11936    12019      +83     
==========================================
+ Hits        11175    11261      +86     
+ Misses        761      758       -3     
Files with missing lines Coverage Δ
src/zarr/core/array.py 97.88% <100.00%> (+0.04%) ⬆️
src/zarr/core/dtype/registry.py 94.00% <100.00%> (+0.81%) ⬆️
src/zarr/core/group.py 95.40% <100.00%> (+0.20%) ⬆️
src/zarr/core/metadata/model.py 100.00% <100.00%> (ø)
src/zarr/errors.py 100.00% <100.00%> (ø)
src/zarr/metadata/migrate_v3.py 98.36% <100.00%> (ø)
src/zarr/testing/strategies.py 95.39% <100.00%> (ø)
src/zarr/core/attributes.py 96.15% <85.71%> (ø)
src/zarr/testing/stateful.py 35.57% <0.00%> (ø)

... and 2 files with indirect coverage changes

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