A heap ID's type is in bits 4-5 of its first byte (H5HF_ID_TYPE_MASK
0x30); bits 6-7 are the ID version. The reader took the type from bits
6-7, so every huge object ID (0x10) was decoded as a managed one and
failed — and since dense attributes are read all at once, one attribute
over the heap's 4 KiB managed limit made every attribute on its object
unreadable (netcdf4-python's issue671.nc / issue672.nc).
- Huge objects (type 1): located directly from the ID when address and
length fit in it, otherwise through the huge-object v2 B-tree (record
types 1 and 2); filtered huge objects are decoded with the heap's
pipeline and their filter mask.
- Tiny objects (type 2): read from the ID itself.
- Filtered heaps: the header's pipeline is parsed (it was skipped short,
so the header checksum was read from the wrong place), indirect-block
entries for direct blocks carry their filtered size and mask, and
direct blocks are decoded before objects are read from them.
- An unknown ID version is an error.
FractalHeapHeader gains huge_btree_address, filter_pipeline,
root_direct_block_filtered_size, root_direct_block_filter_mask,
offset_size and length_size; read_managed_object now accepts any ID type.
Regression tests (h5py-written, compared with h5py):
dense_attribute_stored_as_a_huge_heap_object, dense_group_with_a_huge_link,
dense_group_with_a_filtered_link_heap; unit tests
tiny_object_is_read_from_the_id, huge_object_with_a_direct_id,
unknown_heap_id_version_is_refused.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Any maxshape forced chunked storage, even one equal to the shape, which
cannot grow. h5py and the library store such a dataset contiguously; we
now do too unless chunks (or a filter) are requested.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
FileWriter writes the root group plus one level of groups; it has no way
to create intermediate groups. create_group("a/b") therefore stored a
single link literally named "a/b", which no HDF5 reader can resolve
(h5py: "component not found"). Nesting would mean restructuring the
writer's layout around a group tree, so for now finish() rejects any
group, dataset or external-link name that is empty, "." or contains '/'.
Attribute names may still contain '/'.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
The writer indexed chunks by their position in the current shape, the
same mistake the reader had. With a finite maxshape larger than the shape
the Fixed Array was sized for the shape, so libhdf5 looked up chunks past
its end ("addr overflow"); with the unlimited dimension anywhere but first,
e.g. maxshape (20, None), libhdf5 swizzles that dimension to the slowest
position and read our Extensible Array scrambled. Two unlimited dimensions
produced a file libhdf5 refused to open ("already found unlimited
dimension").
Chunks are now placed with the shared chunk_grid linearisation: Fixed
Array slots cover every chunk of the maximum extent (unwritten ones
undefined), Extensible Array indexes are swizzled, Single Chunk is only
used when the maximum extent is one chunk, and a maxshape that is smaller
than the shape, has more than one unlimited dimension, or would need an
absurd Fixed Array is an error instead of a bad file.
build_chunked_data_from_precompressed now returns a Result.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
FillTime::to_byte had the fill-time field rotated against libhdf5
(H5D_FILL_TIME_ALLOC = 0, NEVER = 1, IFSET = 2): Never was written as
ALLOC, Alloc as IFSET and IfSet as NEVER, as h5py reported. The flags
byte is now late allocation plus the right code, and FillTime::from_byte
decodes it.
The default becomes IfSet, which is libhdf5's default and exactly the
byte (0x0a) every dataset was already written with, so default output
does not change; `Alloc` was documented as the C library's default but
never was. DatasetCreateProps follows.
DatasetBuilder::with_fill_value sets a user-defined fill value (one
element's stored bytes, checked against the datatype size), written as a
defined value in the fill value message. h5py reports it, and extending
the dataset in h5py fills the new elements with it.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
FileWriter::with_page_size wrote a "version 4" superblock with an extra
page-size field. HDF5 has no superblock version 4, so libhdf5 refused
every such file ("bad superblock version number").
A paged file is now what libhdf5 itself writes for fs_strategy="page":
a v3 superblock whose extension object header holds a File Space Info
message (strategy PAGE, the page size, free space not persisted; same
bytes and flags as HDF5 2.0), with the file padded to a whole page.
h5py opens it, reports the strategy and page size, and can modify it in
r+ mode. Page sizes outside libhdf5's 512 B..1 GiB are an error.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Datatype::serialize returned an empty message for these four classes, so
any dataset or attribute of them (including a Raw attribute copied from
another file) was unreadable by libhdf5 ("ran off end of input buffer
while decoding"). They now encode exactly as libhdf5 does: legacy object
and region references as datatype version 1, H5T_STD_REF kinds as version
4 with their encoding version, opaque tags NUL-padded to 8 bytes.
Parsing an opaque tag now stops at its first NUL, so libhdf5's padding
no longer becomes part of the tag. Datatype::check_encodable rejects
what has no encoding (an opaque tag over 248 bytes); FileWriter::finish
calls it for every dataset and attribute type.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
A v2 object header message has a 2-byte size field. The writer truncated
larger sizes to 16 bits, so an attribute over ~64 KiB (or a compact
dataset of 65532-65535 bytes, whose layout message adds 4 bytes) produced
a file libhdf5 rejects ("message of unshareable class flagged as
shareable", "bad flag combination").
ObjectHeaderWriter::serialize now returns a Result and fails on any message
over MAX_MESSAGE_SIZE; FileWriter::finish propagates it. Compact storage
falls back to contiguous above 65531 bytes, the real limit. Dense storage
for large attributes remains future work.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Two write-side bugs, both present in every release (the first at least
since v2.1.0), made libhdf5 refuse files written by clawhdf5. Our own
reader ignores both fields, and the interop suites only ever wrote f64
from our side, so nothing here caught them.
- Every f32 dataset: "sign bit position out of bounds". The float
datatype encoder hard-coded the sign bit's position (bits 8-15 of the
class bit field) to 63, which is right only for f64. It is now derived
from the type: bit_offset + bit_precision - 1. This covered every
agent store's embeddings, norms and activation weights.
- Every empty dataset: "invalid dataset size, likely file corruption".
It was written with a real address and size 0, which trips libhdf5's
`addr + size <= addr` overflow check. An empty contiguous dataset now
gets the undefined address, as libhdf5 writes it. This covered every
agent store without sessions or a knowledge graph.
Agent stores are rewritten in full at each checkpoint, so they become
readable at their next checkpoint on a fixed build; other files with f32
or empty datasets need rewriting. Both are recorded in
docs/known-issues.md.
Tests: the sign position byte for f32/f64, and h5py reading our f32
datasets (plain and chunked + deflate) bit for bit.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Requesting a filter without chunk dimensions made the whole dataset a single
chunk. Any read, even one row, then decompresses everything, and a large
dataset cannot be decoded in parallel — which also made the new partial reads
pointless for such files.
auto_chunk_dims keeps datasets up to 1 MiB as one chunk (unchanged behaviour)
and splits larger ones by halving the dimensions in turn, so chunks keep
roughly the dataset's proportions, until a chunk is at most 1 MiB — h5py's
approach. An empty (unlimited, unwritten) dimension is treated as 1024. The
writer passes the element size through resolve_chunk_dims_for; the old
resolve_chunk_dims assumes 8-byte elements. Explicit with_chunks always wins.
Interop test: h5py reads an auto-chunked 13 MB deflate dataset, sees chunks
between 128 KiB and 1 MiB, and a small dataset still has one chunk.
Co-Authored-By: Claude Fable 5.1 <[email protected]>
- Add .gitea/workflows/ci.yml running scripts/ci-test.sh (fmt, clippy,
test, no_std check) on push/PR to main.
- Fix stale rustyhdf5-py/rustyhdf5-format package names in
ci-test.sh/check-nostd.sh, which had been silently no-op'ing those
checks (cargo warns but doesn't fail on an unknown --exclude/-p
target).
- With those checks actually running, fix the real issues they surface:
- clippy: useless_conversion in chunked_write.rs, byte_char_slices in
global_heap.rs/object_header.rs.
- cargo fmt: apply formatting across the workspace (whitespace only).
- no_std (thumbv7em-none-eabihf) build errors in clawhdf5-format:
core::sync::atomic::AtomicU64 doesn't exist on that target (no
native 64-bit atomics) — switch profiling.rs's counters to
portable-atomic, which falls back to a CAS-based emulation there
and is a no-op wrapper elsewhere. Add missing alloc imports for
Box (filters.rs), Vec (filters_szip.rs), and format! (dict_encoding.rs)
on no_std paths. Replace f64::powi (std/libm-only) with a small
local exponentiation-by-squaring helper in the scale-offset filter.
- Remove clawhdf5-types (empty 1-line stub crate; type defs already live in
clawhdf5-format). Update workspace Cargo.toml and CLAUDE.md accordingly.
- Implement HDF5 superblock v4 (page-buffer mode) read and write support in
clawhdf5-format: Superblock::parse_v4, page_size field, v4 serialize
branch, and FileWriter::with_page_size. This was the one task left
unimplemented from docs/superpowers/plans/2026-06-29-format-write-extensions.md.
- Reconcile the three docs/superpowers/plans/*.md docs (filter codecs,
format write extensions, MPI-IO VOL) against actual shipped code: they
were pre-work plans for d6c4d4f (2026-06-30) committed to git late on
2026-08-03 with all checkboxes still unchecked. Mark completed tasks done
and add a status note so they read as historical records, not open work.
- Refresh ROADMAP.md's "What's Next" section against current repo state.
Co-Authored-By: Claude Sonnet 5 <[email protected]>
Four independent write-path improvements:
1. Cache compressed chunks between Pass 1 and Pass 2 (chunked_write.rs,
file_writer.rs): the two-pass layout writer previously called
build_chunked_data_at_ext() twice per chunked dataset — once in Pass 1
to get blob sizes and once in Pass 2 with real addresses. Add
PrecompressedChunks / precompress_chunks() / build_chunked_data_from_
precompressed() to compress once in Pass 1, cache the result, and only
rebuild the address-dependent index structures in Pass 2. Expected
~2× speedup for chunked+deflate writes (512×512 deflate: 3.33ms → ~1.7ms).
2. SIMD-vectorisable shuffle filter (filters.rs): replace the naïve O(N·S)
nested loop with an unrolled u32-load path for 4-byte elements (f32) and
a cache-blocked tile loop for all other sizes. LLVM auto-vectorises the
4-byte path into SSE2/AVX2/NEON byte-deinterleave sequences.
3. Zstd benchmark variant (h5bench_write.rs): add write_2d_chunked_zstd
group measuring Zstd level 3 vs deflate level 6 side-by-side. Also fix
the existing write_2d_chunked benchmark — the clawhdf5 path was missing
.with_deflate(6), making the comparison apples-to-oranges. Add arXiv-
backed doc recommendation on DatasetBuilder::with_zstd().
4. Zero-copy HNSW save (hnsw.rs, clawhdf5-io/lib.rs): add
FileWriter::write_bytes_owned(Vec<u8>) that takes ownership to avoid the
full-file clone in write_all_bytes(&[u8]). HNSW::save_to_hdf5 uses it.
Co-Authored-By: Claude Sonnet 4.6 <[email protected]>
Critical fixes from whole-branch code review:
- libaec-sys: fix flag constants to match <libaec.h> exactly
(PREPROCESS=8, MSB=4, RESTRICTED=16; drop non-existent AEC_ALLOW_K13)
and add aec_buffer_encode FFI declaration
- filters_szip: fix cd index for bits_per_sample (cd[2] per H5Z_SZIP_PARM_BPP,
not cd[4]); fix option-mask mapping (NN=0x20, MSB unconditional); add two
real encode→decode roundtrip tests (no-NN and NN) that exercise libaec end-to-end
- file_writer: fix serialize_vds_mappings to delegate to data_layout_write
(eliminates the buggy duplicate that always emitted version=1 even for
external-file mappings); retains trailing Jenkins checksum
Co-Authored-By: Claude Sonnet 4.6 <[email protected]>
Add `virtual_sources: Option<Vec<VdsMapping>>` field and `with_virtual_sources()` method to `DatasetBuilder`. In `FileWriter::finish()`, VDS datasets skip raw-data storage and instead serialize their source mappings into a global heap collection (version-1 same-file encoding) referenced by an HDF5 v4 layout-class-3 message. The two-pass address-computation loop handles VDS in both passes: pass 1 computes the fixed-size OH and pre-builds the heap blob; pass 2 places the blob at the correct file offset and rebuilds the OH with the real global heap address. Three new tests verify: (a) same-file two-source round-trip with mapping verification, (b) external-file source encoding, and (c) empty mapping list.
Co-Authored-By: Claude Sonnet 4.6 <[email protected]>
Dense attribute and dense link storage capped at a single fractal-heap direct
block (~64 KiB of heap data — a few thousand objects); beyond that the writer
produced an invalid oversized block. Lift the cap with a root indirect block.
When the serialized objects don't fit in one direct block, build a root
indirect block (FHIB) over multiple direct blocks sized by the doubling table
(start 512, width 4, doubling per row up to 64 KiB). Objects are packed
row-major across blocks, each block carries its logical block offset, and heap
IDs encode each object's heap offset (block offset + position). The FRHP points
root -> FHIB with the row count; unused slots in the current rows are undefined.
The fractal-heap builder is unified: FractalHeapBlock now carries the full heap
blob, and a shared write_frhp helper serializes the header for both the
single-block and multi-block paths. The single-block path is unchanged
(byte-identical), so existing dense attrs/links stay valid.
Validated end-to-end: a 2,500-attribute object and a 2,500-link group round-trip
through our reader and are read correctly by h5py. Objects still may not span a
block (no huge-object path).
Tests: facade round-trips for multi-block dense attrs and dense links, plus an
h5py-gated interop test (verified against the real h5py environment).
Co-Authored-By: Claude Opus 4.8 <[email protected]>
A group with more than 8 links (libhdf5's compact max_compact default) is now
written densely instead of as inline Link messages: the links live in a
single-direct-block fractal heap indexed by a v2 B-tree of type 5 (link-name
index), referenced from the group's LinkInfo message. This matches libhdf5's
compact->dense switchover and keeps large groups out of the object header.
- Extract the byte-identical fractal-heap builder shared by dense attributes
and dense links, parameterized by heap_id_length / max_heap_size. Attributes
keep 8 / 40; links use 7 / 32 to match libhdf5 (reverse-engineered: an
h5py-written dense group uses heap_id_length 7, max_heap_size 32, type-5
record = hash(4) + heap_id(7) = 11 bytes). This was the cause of an initial
"object overruns end of direct block" error from h5py.
- build_group_oh gained an optional dense LinkInfo (omitting inline Link
messages); the two-pass file assembly allocates each group's link blob after
its object header and rebuilds it with real target addresses in the final
pass (link-message size is address-independent, so layout is stable).
Validated end-to-end: our reader round-trips dense groups, h5py reads the
groups we write, and dense attributes remain byte-identical (still h5py-valid).
The agent's 9-dataset memory group now writes densely and round-trips. Single
direct block only (~a couple thousand links); indirect blocks remain a TODO.
Tests: facade round-trip (20-link dense group + compact sibling) and an
h5py-gated interop test confirming libhdf5 reads our dense groups.
Co-Authored-By: Claude Opus 4.8 <[email protected]>
