Merge branch 'feat/p3-editor-coverage' into feat/p3-remote-editor

# Conflicts:
#	CHANGELOG.md
#	CLAUDE.md
#	docs/design/range-reads.md

CLAUDE.md

@@ -152,12 +152,18 @@ Cargo workspace with 19 crates under `crates/` (plus `libaec-sys`, an internal F
   `MemorySource` for this bookkeeping is inferred from the caller-supplied
   `source_channel` string (a heuristic, not an authenticated trust boundary).
 - In-place modification: `clawhdf5::FileEditor` (`crates/clawhdf5/src/edit/`)
-  overwrites values, grows chunked datasets and sets attributes in existing
-  files (h5py- or clawhdf5-written) without rewriting them; anything it
-  cannot do safely is `Error::Unsupported` before any write (limits in
+  overwrites values, grows and shrinks chunked datasets (every chunk index,
+  version-2 B-trees included) and sets attributes (compact and dense
+  storage) in existing files (h5py- or clawhdf5-written) without rewriting
+  them, changing indexes and heaps as libhdf5 does (index shapes and heap
+  bookkeeping are compared with libhdf5's in the tests); space an edit
+  frees is reused by later edits of the same editor. Anything it cannot do
+  safely is `Error::Unsupported` before any write (limits in
   `docs/known-issues.md`). Test changes with
-  `cargo test -p clawhdf5-tools --test edit_interop` (h5py, h5dump,
-  `h5rs check`).
+  `cargo test -p clawhdf5-tools --test edit_interop --test
+  edit_coverage_interop` (h5py, h5dump, `h5rs check`, structure comparisons
+  with libhdf5; libhdf5 sources for the algorithms are at
+  github.com/HDFGroup/hdf5, tag `hdf5_1_14_6`).
 - Remote files (`clawhdf5-remote`, range-read milestone M3 of
   `docs/design/range-reads.md`): `open_url("http://…")` gives a
   `clawhdf5::File` over `File::open_storage`, read through `BlockCache`
@@ -166,8 +172,9 @@ Cargo workspace with 19 crates under `crates/` (plus `libaec-sys`, an internal F
   ETag/Last-Modified and length (a change is `RemoteError::FileChanged`),
   refuses servers that ignore `Range` unless a full download is allowed,
   and retries transient failures. `ObjectStoreStorage` (feature
-  `object-store`, pure Rust) blocks on a small owned tokio runtime and
-  refuses to run inside another runtime. Default build is plain HTTP with
+  `object-store`, pure Rust) runs each read on a small owned tokio
+  runtime and waits on a channel, so it works from any thread, including
+  inside `spawn_blocking` or another runtime. Default build is plain HTTP with
   no C; `https` (rustls + ring) and `s3`/`gcs`/`azure` (aws-lc-rs) are
   opt-in. Tests run a std-only HTTP server
   (`tests/common/server.rs`, also the `range_server` example);