zarr-developers · d-v-b · Sep 16, 2026 · Sep 16, 2026 · Sep 16, 2026 · Sep 16, 2026
diff --git a/packages/zarr-metadata/changes/4365.bugfix.md b/packages/zarr-metadata/changes/4365.bugfix.md
@@ -0,0 +1 @@
+The v2 array validator follows the spec on two points it was stricter than: members outside the `.zarray` definition are tolerated and dropped (the spec says other keys ["SHOULD NOT be present ... and SHOULD be ignored"](https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v2/v2.0.rst#L91-L92), unlike `.zgroup`'s ["MUST NOT"](https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v2/v2.0.rst#L313)), and `filters: []` is accepted (["a list of JSON objects providing codec configurations, or null"](https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v2/v2.0.rst#L76-L79) sets no minimum). The Pydantic schema follows: `ZarrV2ArrayMetadataJSON` is open and the filter pipeline has no minimum length.
diff --git a/packages/zarr-metadata/src/zarr_metadata/_pydantic_schema.py b/packages/zarr-metadata/src/zarr_metadata/_pydantic_schema.py
@@ -38,7 +38,7 @@ class ZarrV3MandatoryNamedConfigJSON(TypedDict, closed=True):
 ZarrV3MetadataFieldJSON = str | ZarrV3NamedConfigJSON
 ZarrV3MandatoryMetadataFieldJSON = str | ZarrV3MandatoryNamedConfigJSON
 ZarrV3CodecPipelineJSON = Annotated[tuple[ZarrV3MetadataFieldJSON, ...], Field(min_length=1)]
-ZarrV2FilterPipelineJSON = Annotated[tuple[ZarrV2CodecMetadata, ...], Field(min_length=1)]
+ZarrV2FilterPipelineJSON = tuple[ZarrV2CodecMetadata, ...]
 
 
 class ZarrV3ArrayMetadataJSON(TypedDict, extra_items=JSONValue):
@@ -74,8 +74,14 @@ class ZarrV3GroupMetadataJSON(TypedDict, extra_items=JSONValue):
     consolidated_metadata: NotRequired[ZarrV3ConsolidatedMetadataJSON | None]
 
 
-class ZarrV2ArrayMetadataJSON(TypedDict, closed=True):
-    """Schema input for the closed, merged v2 array representation."""
+class ZarrV2ArrayMetadataJSON(TypedDict, extra_items=JSONValue):
+    """Schema input for the merged v2 array representation.
+
+    Open, like the runtime validator: the v2 spec says other keys "SHOULD NOT
+    be present ... and SHOULD be ignored by implementations"
+    (https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v2/v2.0.rst#L91-L92); the group document's "MUST NOT" (https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v2/v2.0.rst#L313) keeps
+    `ZarrV2GroupMetadataJSON` closed.
+    """
 
     zarr_format: Literal[2]
     shape: tuple[NonNegativeInt, ...]

diff --git a/packages/zarr-metadata/src/zarr_metadata/model/_array.py b/packages/zarr-metadata/src/zarr_metadata/model/_array.py
@@ -51,7 +51,7 @@ class ZarrV3NamedConfig:
 
     Bare names and missing configurations normalize to an empty configuration.
     Bare names and missing `must_understand` members normalize to the spec's
-    implicit `True` value.
+    implicit `True` value (https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v3/core/index.rst#L1571-L1573).
     """
 
     name: str
@@ -107,8 +107,8 @@ def must_understand_subset(
 ) -> dict[str, ZarrV3ExtensionField]:
     """The subset of `extra_fields` the reader is obligated to understand.
 
-    Per the v3 spec, an extension field is implicitly `must_understand: True`
-    unless it explicitly says otherwise, and an implementation MUST fail to
+    Per the v3 spec (https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v3/core/index.rst#L1571-L1578), an extension field is implicitly `must_understand:
+    True` unless it explicitly says otherwise, and an implementation MUST fail to
     open a group or array carrying fields it does not recognize that are not
     explicitly `must_understand: false`. A non-mapping field value cannot
     carry the explicit waiver, so it always requires understanding (the
@@ -310,7 +310,7 @@ def must_understand_fields(self) -> dict[str, ZarrV3ExtensionField]:
         """Extra fields the reader is obligated to understand.
 
         Everything in `extra_fields` not explicitly waived with
-        `must_understand: false` (the spec's implicit-true rule). A compliant
+        `must_understand: false` (the spec's implicit-true rule, https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v3/core/index.rst#L1571-L1578). A compliant
         reader MUST fail to open the array if this contains any field it does
         not recognize; the model layer only partitions by obligation, since
         recognition is reader-specific.
@@ -428,7 +428,8 @@ def to_json(self) -> ZarrV2ArrayMetadataJSON:
         `attributes` is included when set (even empty). This is not the
         on-disk `.zarray` content: a conforming `.zarray` must exclude
         `attributes` (they live in the sibling `.zattrs` file). Use
-        `to_key_value` to produce the spec-conforming split for storage.
+        `to_key_value` to produce the spec-conforming split for storage
+        (https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v2/v2.0.rst#L323-L330).
         """
         # to_json output shares no mutable state with the model: every value
         # that can hold a mutable container is deep-copied.

diff --git a/packages/zarr-metadata/src/zarr_metadata/model/_group.py b/packages/zarr-metadata/src/zarr_metadata/model/_group.py
@@ -168,7 +168,7 @@ def must_understand_fields(self) -> dict[str, ZarrV3ExtensionField]:
         """Extra fields the reader is obligated to understand.
 
         Everything in `extra_fields` not explicitly waived with
-        `must_understand: false` (the spec's implicit-true rule). A compliant
+        `must_understand: false` (the spec's implicit-true rule, https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v3/core/index.rst#L1571-L1578). A compliant
         reader MUST fail to open the group if this contains any field it does
         not recognize; the model layer only partitions by obligation, since
         recognition is reader-specific.
@@ -299,7 +299,8 @@ def to_json(self) -> ZarrV2GroupMetadataJSON:
         `attributes` is included when set (even empty). This is not the
         on-disk `.zgroup` content: a conforming `.zgroup` must exclude
         `attributes` (they live in the sibling `.zattrs` file). Use
-        `to_key_value` to produce the spec-conforming split for storage.
+        `to_key_value` to produce the spec-conforming split for storage
+        (https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v2/v2.0.rst#L313; https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v2/v2.0.rst#L323-L330).
         """
         # to_json output shares no mutable state with the model.
         out: ZarrV2GroupMetadataJSON = {"zarr_format": self.zarr_format}

diff --git a/packages/zarr-metadata/src/zarr_metadata/model/_validation.py b/packages/zarr-metadata/src/zarr_metadata/model/_validation.py
@@ -584,10 +584,12 @@ def validate_array_metadata_v2(value: object) -> list[ValidationProblem]:
     if not isinstance(value, Mapping):
         return [ValidationProblem((), "expected a mapping", "invalid_type")]
     doc = cast("Mapping[str, object]", value)
+    # Unlike the group document ("Other keys MUST NOT be present",
+    # https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v2/v2.0.rst#L313), the v2 array document is open: other keys "SHOULD NOT be
+    # present within the metadata object and SHOULD be ignored by
+    # implementations" (https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v2/v2.0.rst#L91-L92), so members outside
+    # ARRAY_METADATA_STANDARD_KEYS_V2 are not problems.
     problems: list[ValidationProblem] = _missing_keys(ARRAY_METADATA_REQUIRED_KEYS_V2, doc)
-    problems.extend(
-        _unexpected_keys(ARRAY_METADATA_STANDARD_KEYS_V2, cast("Mapping[object, object]", value))
-    )
     problems.extend(_check_literal(doc, "zarr_format", 2))
     shape_problems = _validate_dim_sequence(doc, "shape")
     chunks_problems = _validate_dim_sequence(doc, "chunks")
@@ -642,10 +644,8 @@ def validate_array_metadata_v2(value: object) -> list[ValidationProblem]:
                 )
             )
         elif filters is not None:
-            if len(cast("Sequence[object]", filters)) == 0:
-                problems.append(
-                    ValidationProblem(("filters",), "expected at least one filter", "invalid_value")
-                )
+            # "A list of JSON objects providing codec configurations, or
+            # null" (https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v2/v2.0.rst#L76-L79): an empty list is a list.
             for index, item in enumerate(cast("Sequence[object]", filters)):
                 problems.extend(_prefix("filters", _prefix(index, validate_json(item))))
     if "dimension_separator" in doc and doc["dimension_separator"] not in (".", "/"):

diff --git a/packages/zarr-metadata/src/zarr_metadata/v2/array.py b/packages/zarr-metadata/src/zarr_metadata/v2/array.py
@@ -81,8 +81,8 @@ class ZarrV2ArrayMetadataJSON(TypedDict):
     """
     Zarr v2 array metadata document, in-memory merged form.
 
-    Models the union of `.zarray` (the spec-defined fields) and `.zattrs`
-    (user attributes). On disk, attributes live in a sibling `.zattrs` file
+    Models the union of `.zarray` (the spec-defined fields, https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v2/v2.0.rst#L51-L92)
+    and `.zattrs` (user attributes, https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v2/v2.0.rst#L323-L330). On disk, attributes live in a sibling `.zattrs` file
     and are not part of `.zarray`; this type folds them in as the
     `attributes` field so a single TypedDict represents the complete
     in-memory state of a v2 array node. Consumers that read or write a
@@ -126,8 +126,10 @@ class ZarrV2ArrayMetadataJSONPartial(TypedDict, total=False):
     `tests/test_partial_equivalence.py` passes without special-casing those
     fields (PEP 655 explicitly permits `NotRequired` inside `total=False`).
 
-    Note: v2 array metadata has no `extra_items` setting (the v2 spec has no
-    extension-field concept), so this partial inherits the same closed shape.
+    Note: v2 array metadata has no `extra_items` setting: the v2 spec has no
+    extension-field concept, and other `.zarray` keys "SHOULD be ignored by
+    implementations" (https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v2/v2.0.rst#L91-L92), so nothing beyond the spec-defined
+    fields is modeled.
 
     Drift between this type and `ZarrV2ArrayMetadataJSON` is prevented by
     `tests/test_partial_equivalence.py`.

diff --git a/packages/zarr-metadata/src/zarr_metadata/v2/attributes.py b/packages/zarr-metadata/src/zarr_metadata/v2/attributes.py
@@ -15,6 +15,7 @@
 Spec-defined keys for arrays / groups live in sibling `.zarray` / `.zgroup`
 files (modeled by `ZarrV2ZArrayJSON` / `ZarrV2ZGroupJSON`). This type does not
 constrain the keys or values of the attributes mapping.
+  https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v2/v2.0.rst#L323-L330
 """
 
 

diff --git a/packages/zarr-metadata/src/zarr_metadata/v2/group.py b/packages/zarr-metadata/src/zarr_metadata/v2/group.py
@@ -16,9 +16,10 @@ class ZarrV2ZGroupJSON(TypedDict):
     On-disk `.zgroup` file content.
 
     Strict shape of the JSON document persisted at `<path>/.zgroup` for
-    a v2 group. The spec defines exactly one field. User attributes live
-    in a sibling `.zattrs` file and are NOT part of this type; see
-    `ZarrV2ZAttrsJSON`.
+    a v2 group. The spec defines exactly one field and forbids others. User
+    attributes live in a sibling `.zattrs` file and are NOT part of this
+    type; see `ZarrV2ZAttrsJSON`.
+      https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v2/v2.0.rst#L306-L313
 
     See https://zarr-specs.readthedocs.io/en/latest/v2/v2.0.html
     """
@@ -30,8 +31,8 @@ class ZarrV2GroupMetadataJSON(TypedDict):
     """
     Zarr v2 group metadata document, in-memory merged form.
 
-    Models the union of `.zgroup` (the spec-defined `zarr_format` field)
-    and `.zattrs` (user attributes). On disk these are persisted as two
+    Models the union of `.zgroup` (the spec-defined `zarr_format` field,
+    https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v2/v2.0.rst#L306-L313) and `.zattrs` (user attributes, https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v2/v2.0.rst#L323-L330). On disk these are persisted as two
     separate files; this type folds them so a single TypedDict represents
     the complete in-memory state of a v2 group node. Consumers that read
     or write the real on-disk files should use `ZarrV2ZGroupJSON` (strict
@@ -64,7 +65,8 @@ class ZarrV2GroupMetadataJSONPartial(TypedDict, total=False):
     `total=False`).
 
     Note: v2 group metadata has no `extra_items` setting (the v2 spec has no
-    extension-field concept), so this partial inherits the same closed shape.
+    extension-field concept, and `.zgroup` forbids other keys outright:
+    https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v2/v2.0.rst#L313), so this partial inherits the same closed shape.
 
     Drift between this type and `ZarrV2GroupMetadataJSON` is prevented by
     `tests/test_partial_equivalence.py`.

diff --git a/packages/zarr-metadata/src/zarr_metadata/v3/chunk_grid/rectilinear.py b/packages/zarr-metadata/src/zarr_metadata/v3/chunk_grid/rectilinear.py
@@ -1,7 +1,7 @@
 """
 Rectilinear chunk grid (zarr-extensions).
 
-See https://github.com/zarr-developers/zarr-extensions/tree/main/chunk-grids/rectilinear
+See https://github.com/zarr-developers/zarr-extensions/blob/4da7b37a84f76e660902f6d3de3eaef0e0febae6/chunk-grids/rectilinear/README.md
 """
 
 from typing import Final, Literal
@@ -42,6 +42,8 @@ class RectilinearChunkGridObject(TypedDict):
 
 `kind` and `chunk_shapes` are required, so only the object form is valid;
 the short-hand-name form is not permitted by the spec for this grid.
+  https://github.com/zarr-developers/zarr-extensions/blob/4da7b37a84f76e660902f6d3de3eaef0e0febae6/chunk-grids/rectilinear/README.md#L59-L62
+  https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v3/core/index.rst#L1562-L1564
 """
 
 __all__ = [

diff --git a/packages/zarr-metadata/src/zarr_metadata/v3/chunk_grid/regular.py b/packages/zarr-metadata/src/zarr_metadata/v3/chunk_grid/regular.py
@@ -33,6 +33,8 @@ class RegularChunkGridObject(TypedDict):
 
 `chunk_shape` is required and has no default, so only the object form is
 valid; the short-hand-name form is not permitted by the spec for this grid.
+  https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v3/core/index.rst#L528-L537 ("must be an object with the names name and configuration")
+  https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v3/core/index.rst#L1562-L1564
 """
 
 __all__ = [

diff --git a/packages/zarr-metadata/src/zarr_metadata/v3/chunk_key_encoding/__init__.py b/packages/zarr-metadata/src/zarr_metadata/v3/chunk_key_encoding/__init__.py
@@ -6,7 +6,9 @@
 - `default` -- v3 default encoding (`/`-separated)
 - `v2`      -- v2-compatibility encoding (`.`-separated by default)
 
-Both are defined by the v3 core spec.
+Both are defined by the v3 core spec:
+  https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v3/chunk-key-encodings/default/index.rst
+  https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v3/chunk-key-encodings/v2/index.rst
 
 The `<X>ChunkKeyEncodingMetadata` aliases re-exported here are the canonical
 type for each encoding's permitted JSON shapes. For the underlying

diff --git a/packages/zarr-metadata/src/zarr_metadata/v3/chunk_key_encoding/default.py b/packages/zarr-metadata/src/zarr_metadata/v3/chunk_key_encoding/default.py
@@ -31,6 +31,7 @@ class DefaultChunkKeyEncodingConfiguration(TypedDict):
     """Configuration for the default chunk key encoding.
 
     `separator` is optional and defaults to `"/"` per spec.
+      https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v3/chunk-key-encodings/default/index.rst#L27-L29
     """
 
     separator: NotRequired[DefaultChunkKeyEncodingSeparator]

diff --git a/packages/zarr-metadata/src/zarr_metadata/v3/chunk_key_encoding/v2.py b/packages/zarr-metadata/src/zarr_metadata/v3/chunk_key_encoding/v2.py
@@ -37,6 +37,7 @@ class V2ChunkKeyEncodingConfiguration(TypedDict):
     """Configuration for the v2 chunk key encoding.
 
     `separator` is optional and defaults to `"."` per spec.
+      https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v3/chunk-key-encodings/v2/index.rst#L27-L29
     """
 
     separator: NotRequired[V2ChunkKeyEncodingSeparator]

diff --git a/packages/zarr-metadata/src/zarr_metadata/v3/codec/blosc.py b/packages/zarr-metadata/src/zarr_metadata/v3/codec/blosc.py
@@ -50,6 +50,8 @@ class BloscCodecObject(TypedDict):
 The configuration has multiple required keys (`cname`, `clevel`, `shuffle`,
 `blocksize`), so only the object form is valid; the short-hand-name form
 is not permitted by the spec for this codec.
+  https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v3/codecs/blosc/index.rst#L57-L98 (configuration parameters)
+  https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v3/core/index.rst#L1562-L1564 (short-hand names only "if no configuration metadata is required")
 """
 
 __all__ = [

diff --git a/packages/zarr-metadata/src/zarr_metadata/v3/codec/bytes.py b/packages/zarr-metadata/src/zarr_metadata/v3/codec/bytes.py
@@ -51,6 +51,8 @@ class BytesCodecObject(TypedDict):
 at runtime based on data type), so the spec's short-hand-name form is
 permitted in addition to the object form, and the object form may itself
 omit `configuration` entirely.
+  https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v3/codecs/bytes/index.rst#L64-L69 ("endian: Required for data types for which endianness is applicable")
+  https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v3/core/index.rst#L1562-L1564
 """
 
 __all__ = [

diff --git a/packages/zarr-metadata/src/zarr_metadata/v3/codec/cast_value.py b/packages/zarr-metadata/src/zarr_metadata/v3/codec/cast_value.py
@@ -1,7 +1,7 @@
 """
 Cast-value codec types.
 
-See https://github.com/zarr-developers/zarr-extensions/tree/main/codecs/cast_value
+See https://github.com/zarr-developers/zarr-extensions/blob/4da7b37a84f76e660902f6d3de3eaef0e0febae6/codecs/cast_value/README.md
 """
 
 from typing import Final, Literal, NotRequired
@@ -89,6 +89,8 @@ class CastValueCodecObject(TypedDict):
 
 `configuration.data_type` is required, so only the object form is valid;
 the short-hand-name form is not permitted by the spec for this codec.
+  https://github.com/zarr-developers/zarr-extensions/blob/4da7b37a84f76e660902f6d3de3eaef0e0febae6/codecs/cast_value/README.md#L33-L36 and #L46-L48 (required fields)
+  https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v3/core/index.rst#L1562-L1564 (short-hand names only "if no configuration metadata is required")
 """
 
 

diff --git a/packages/zarr-metadata/src/zarr_metadata/v3/codec/crc32c.py b/packages/zarr-metadata/src/zarr_metadata/v3/codec/crc32c.py
@@ -27,6 +27,7 @@ class Crc32cCodecObject(TypedDict):
 
     Per spec the codec has no configuration fields. `configuration` is
     optional and, if present, should be an empty mapping.
+      https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v3/codecs/crc32c/index.rst#L63-L66
     """
 
     name: Crc32cCodecName
@@ -39,6 +40,7 @@ class Crc32cCodecObject(TypedDict):
 The spec's Extension definition allows extensions with no required
 configuration to be encoded as a bare short-hand name. CRC32C has no
 configuration, so both forms are valid.
+  https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v3/core/index.rst#L1562-L1564
 """
 
 

diff --git a/packages/zarr-metadata/src/zarr_metadata/v3/codec/gzip.py b/packages/zarr-metadata/src/zarr_metadata/v3/codec/gzip.py
@@ -26,6 +26,7 @@ class GzipCodecConfiguration(TypedDict):
     is required for the metadata to fulfill its reproducibility role,
     even though the spec text does not mark it required with RFC 2119
     keywords.
+      https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v3/codecs/gzip/index.rst#L57-L66
     """
 
     level: int

diff --git a/packages/zarr-metadata/src/zarr_metadata/v3/codec/scale_offset.py b/packages/zarr-metadata/src/zarr_metadata/v3/codec/scale_offset.py
@@ -1,7 +1,7 @@
 """
 Scale-offset codec types.
 
-See https://github.com/zarr-developers/zarr-extensions/tree/main/codecs/scale_offset
+See https://github.com/zarr-developers/zarr-extensions/blob/4da7b37a84f76e660902f6d3de3eaef0e0febae6/codecs/scale_offset/README.md
 """
 
 from typing import Final, Literal, NotRequired
@@ -38,6 +38,7 @@ class ScaleOffsetCodecObject(TypedDict):
     `configuration` is itself optional per spec — when both `offset` and
     `scale` are at their identity defaults, the codec is a no-op and the
     entire `configuration` field may be omitted.
+      https://github.com/zarr-developers/zarr-extensions/blob/4da7b37a84f76e660902f6d3de3eaef0e0febae6/codecs/scale_offset/README.md#L18 and #L35
     """
 
     name: ScaleOffsetCodecName
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		The v2 array validator follows the spec on two points it was stricter than: members outside the `.zarray` definition are tolerated and dropped (the spec says other keys ["SHOULD NOT be present ... and SHOULD be ignored"](https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v2/v2.0.rst#L91-L92), unlike `.zgroup`'s ["MUST NOT"](https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v2/v2.0.rst#L313)), and `filters: []` is accepted (["a list of JSON objects providing codec configurations, or null"](https://github.com/zarr-developers/zarr-specs/blob/fc7dd9c9beb5a50b87f9b08b00bf50fc0048482f/docs/v2/v2.0.rst#L76-L79) sets no minimum). The Pydantic schema follows: `ZarrV2ArrayMetadataJSON` is open and the filter pipeline has no minimum length.