fix: FusedCodecPipeline falls back to async path for sharded arrays with async-only inner codecs#4179
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* fix: byte-order handling for structured dtypes in the bytes codec The bytes codec neither byte-swapped structured-dtype fields to its configured endian on encode (numpy reports byteorder '|' for void dtypes, so the top-level byteorder comparison never detected a mismatch) nor honored its endian when decoding, silently corrupting any structured data whose field byte order differed from the stored one (e.g. virtual references to external big-endian data). Encode now detects byte-order mismatches by comparing full dtypes via newbyteorder, and decode reinterprets raw bytes in the stored byte order before converting to the data type's declared byte order, so the stored layout (codec state) and the in-memory layout (array data type) are independent. Closes zarr-developers#4141 Assisted-by: ClaudeCode:claude-fable-5 * test: fold structured byte-order cases into existing bytes codec tests Extend test_endian's parametrization with structured dtypes and test_bytes_codec_sync_roundtrip with endian/dtype parametrization plus stored-layout and decoded-dtype assertions, instead of adding parallel test functions for the same properties. Assisted-by: ClaudeCode:claude-fable-5 * refactor: rename stored_dtype to view_dtype in BytesCodec decode The variable is the dtype used to view the raw chunk bytes (byte order from the codec's endian configuration), not a property of the stored data or of the returned buffer, which always carries the array's declared dtype. Assisted-by: ClaudeCode:claude-fable-5 * docs: note that the decode-side byte-order conversion copies the chunk Assisted-by: ClaudeCode:claude-fable-5
…async-only inner codecs Under the opt-in FusedCodecPipeline, a sharded array whose inner codec chain contained a codec implementing only the async interface (no SupportsSyncCodec) raised TypeError on both read and write: ShardingCodec structurally satisfies SupportsSyncCodec, so the pipeline built a top-level sync transform and took the sync fast path, which dove into the sharding codec's sync shard paths and crashed constructing the inner ChunkTransform. The default BatchedCodecPipeline handled the same configuration fine. Fix: sync capability is now a dynamic query (_codec_supports_sync) — structural SupportsSyncCodec membership plus an optional _sync_capable opt-out. ShardingCodec reports _sync_capable=False when its inner or index codec chain is not fully sync-capable (recursively, so nested sharding propagates). ChunkTransform consults the query, so its construction raises for such chains and the pipeline's existing top-level guard (evolve_from_array_spec -> sync_transform=None) now declines the sync fast path, routing reads through the async partial shard decode and writes through the async fallback — the same graceful degradation already used for async-only top-level codecs and non-sync stores. All-sync chains still build the sync transform and keep the fast path. Assisted-by: ClaudeCode:claude-fable-5
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Assisted-by: ClaudeCode:claude-fable-5
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Summary
This PR adds a private method to the sharding codec to allow it to report whether the members of its
codecsattributes support synchronous execution. I think this is an unfortunate move, and we should more formally approach the sync vs async nature of codecs. But that requires new codec classes, which is a lot of work. Until then, this change is sufficient to avoid a confusing error at chunk encode / decode time.closes #4178
The original PR by claude is here: d-v-b#237
For reviewers
[What would you most value a second look at? What are you already confident in? For a refactor, say whether behavior is meant to be unchanged.]
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TODO
docs/user-guide/*.mdchanges/