Changes in version 0.2.0 (2026-04-20)                  

Two-tier distribution

  - CRAN ships pure R (no Rust compilation). r-universe ships pre-built
    binaries with the zarrs Rust backend compiled in. No Rust toolchain
    needed for end users on either tier.
  - New functions: is_zarrs_available(), pizzarr_compiled_features(),
    pizzarr_upgrade().
  - tools/cran-build.sh produces a CRAN tarball with src/ stripped out.

zarrs Rust backend (r-universe tier)

  - Added zarrs Rust backend via extendr for parallel decompression,
    codec execution, and store abstraction. 9 #[extendr] functions, 13
    Rust source files.
  - Transparent dispatch: ZarrArray$get_item() and $set_item()
    automatically use the zarrs fast path when eligible (contiguous
    slices, supported dtype, filesystem or HTTP store). Unsupported
    selections fall through to the R-native path silently.
  - Read path: two-step dtype dispatch retrieves data at stored
    precision, then widens to R-compatible types (f32→f64, i16→i32,
    etc.) in Rust before crossing the FFI boundary.
  - Write path: symmetric narrowing with range checks (R double→f32, R
    integer→i16, etc.). Out-of-range values produce errors, not silent
    truncation.
  - Array creation via zarrs: zarr_create() dispatches to the zarrs
    backend when available. Supports V2 and V3 formats with four codec
    presets (none, gzip, blosc, zstd).
  - C↔F order transpose moved from R (aperm) to Rust, eliminating two
    full-array copies per read and up to five per write. Cache-blocked
    tiling for 2D, output-order iteration for nD.
  - HTTP/HTTPS reads via zarrs_http crate. HttpStore-backed arrays use
    zarrs for parallel chunk decode on remote data. R-native crul-based
    path remains as fallback.
  - S3 reads via object_store crate. New S3Store R6 class for s3://
    URLs. Public buckets work without credentials (unsigned requests).
    Authenticated access uses standard AWS environment variables.
  - GCS reads via object_store crate. New GcsStore R6 class for gs://
    URLs (requires credentials). Public GCS data accessible via HTTPS
    endpoint without credentials.
  - Process-global store handle cache with explicit lifecycle management
    via zarrs_close_store().

Configuration

  - New pizzarr_config() function for viewing and setting concurrency
    options. Three settings: nthreads (rayon thread pool size),
    concurrent_target (codec concurrency level), and
    http_batch_range_requests (multipart range toggle for HTTP stores).
    All three backed by environment variables (PIZZARR_NTHREADS,
    PIZZARR_CONCURRENT_TARGET, PIZZARR_HTTP_BATCH_RANGE_REQUESTS).
  - zarrs_runtime_info() now includes nthreads (rayon thread pool size).

Breaking changes

  - Removed R-native parallel chunk I/O infrastructure. The
    pizzarr.parallel_backend, pizzarr.parallel_write_enabled, and
    pizzarr.progress_bar options are no longer used. On r-universe
    builds, zarrs handles parallelism internally via its Rust thread
    pool. On CRAN (pure R), chunk I/O is sequential.
  - Dropped pbapply, parallel, future, and future.apply from Suggests.
  - Removed vignettes/parallel.Rmd. Replaced by
    vignettes/zarrs-backend.Rmd.
  - Minimum R version raised from 4.1.0 to 4.2.

Other changes

  - New vignettes/zarrs-backend.Rmd documenting the zarrs backend,
    dispatch behavior, store types, concurrency tuning, and cloud
    access.
  - R-native chunk loop simplified from parallel dispatch infrastructure
    to sequential for loop.

                        Changes in version 0.1.3                        

  - Added set_dimension_names() / get_dimension_names() methods to
    ZarrArray (#170).
  - pkgdown site and documentation improvements (#171).

                 Changes in version 0.1.2 (2026-04-06)                  

  - Added get_dimension_names() method to ZarrArray for V3 dimension
    names support.
  - OME-NGFF vignettes now use base R rasterImage() instead of the
    raster package (#161).

                 Changes in version 0.1.1 (2026-03-25)                  

Fixes a flaky test failing on CRAN -- no functional changes.

                 Changes in version 0.1.0 (2026-03-24)                  

This is the first release of pizzarr to CRAN. The package has
significant testing and validation but has not been vetted by a large
and diverse user community. As a result, bugs and undesirable behavior
may be found. If you find issues please report them at:

https://github.com/zarr-developers/pizzarr/issues

  - Initial release of pizzarr.
  - Read and write Zarr V2 and Zarr V3 stores.
  - Storage backends: DirectoryStore, MemoryStore, HttpStore.
  - Compression codecs: Zstd, LZ4, Blosc, zlib, gzip, bzip2, LZMA.
  - VLenUTF8 object codec for variable-length strings.
  - Parallel read/write support via pbapply, parallel, and future.
  - R-like one-based and Python-like zero-based slicing.