Blosc · FrancescAlted · Sep 11, 2026 · Sep 3, 2026 · Sep 3, 2026 · Sep 3, 2026
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
@@ -88,15 +88,45 @@ jobs:
 
     - name: Test (Windows)
       if: runner.os == 'Windows'
-      run: python -m pytest -m "not heavy and not network" --durations=25
-#      env:
+      run: python -m pytest -m "not heavy and not network and not tui" --durations=25
+      env:
+        # A test over this many seconds is a deadlock, not a slow test (the
+        # slowest is ~7 s): dump stacks and kill the worker so xdist names it
+        # instead of the job hanging until the 6-hour cap.  The session budget
+        # catches the same hang in teardown or interpreter exit, where no test
+        # is running to be named.
+        PYTEST_DEADMAN_SECONDS: "300"
+        PYTEST_DEADMAN_SESSION_SECONDS: "1500"
 #        BLOSC_NTHREADS: "1"
 #        NUMEXPR_NUM_THREADS: "1"
 #        OMP_NUM_THREADS: "1"
 
     - name: Test (non-Windows)
       if: runner.os != 'Windows'
-      run: python -m pytest -m "not heavy and not network" --durations=25
+      run: python -m pytest -m "not heavy and not network and not tui" --durations=25
+      env:
+        PYTEST_DEADMAN_SECONDS: "300"
+        PYTEST_DEADMAN_SESSION_SECONDS: "1500"
+
+    # TUIs are timing-sensitive and only boot a headless terminal: one OS is
+    # enough, and a flake here is feedback, not a release blocker.
+    - name: Test TUI (non-blocking)
+      if: matrix.os == 'ubuntu-latest' && matrix.python-version == '3.12' && !matrix.numpy-version
+      continue-on-error: true
+      run: python -m pytest -m "tui and not heavy and not network" -n 4 --dist loadfile --durations=10
+      env:
+        PYTEST_DEADMAN_SECONDS: "300"
+        PYTEST_DEADMAN_SESSION_SECONDS: "900"
+
+    - name: Deadlock stacks, if a worker had to be killed
+      if: always()
+      shell: bash
+      run: |
+        if [ -s deadman-stacks.log ]; then
+          echo "::group::Deadlock stacks"
+          cat deadman-stacks.log
+          echo "::endgroup::"
+        fi
 
     # The network tests talk to a live Caterva2 server and were 24 of the 25
     # slowest tests in *both* the Windows and Linux jobs, with near-identical

diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
@@ -21,6 +21,9 @@ repos:
       - id: ruff-check
         args: ["--fix", "--show-fixes"]
       - id: ruff-format
+        # Ruff 0.16+ can claim Markdown code blocks; blacken-docs owns those
+        # blocks here, so keep Ruff on Python sources and notebooks.
+        types_or: [python, pyi, jupyter]
         exclude: ^bench/
 
   - repo: https://github.com/adamchainz/blacken-docs

diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -16,8 +16,8 @@ project(python-blosc2)
 
 # Update to the latest minimum C-Blosc2 version, and to the actual bundled one
 set(BLOSC2_MIN_VERSION 3.3.0)
-set(BLOSC2_BUNDLED_VERSION v3.3.3)
-# set(BLOSC2_BUNDLED_VERSION a7f9a5be3527e87a7cbce1c16977835361d27033)
+set(BLOSC2_BUNDLED_VERSION v3.3.4)
+#set(BLOSC2_BUNDLED_VERSION a54e259aeb1c0e62d6bbea28934369d4831e4046)
 
 if(WIN32 AND NOT CMAKE_C_COMPILER_ID STREQUAL "Clang")
     message(FATAL_ERROR "Windows builds require clang-cl. Set CC/CXX to clang-cl or configure CMake with -T ClangCL.")

diff --git a/RELEASE_NOTES.md b/RELEASE_NOTES.md
@@ -2,7 +2,24 @@
 
 ## Changes from 4.12.0 to 4.13.0
 
-XXX version-specific blurb XXX
+This release adds portable remote array references, bounded caches, and remote
+hierarchy browsing for B2Z, Zarr, and HDF5 containers.
+
+* `blosc2.open(..., lazy=True)` now returns a `RemoteArray` with a bounded
+  memory cache by default. `CachePolicy.NONE` disables retention; `cache_dir`
+  or `cache_path` selects persistent disk caching. `cache_storage` is deprecated
+  in favor of `cache_dir`.
+* `RemoteStore` discovers remote hierarchies and shares a cache budget across
+  their arrays. Stores and arrays can export portable references with optional
+  cached data. `b2view` supports browsing these remote sources.
+* New `ZarrNDSource`, `HDF5NDSource`, and `B2ZNDSource` adapters read immutable
+  arrays on demand. The `b2nd-to-zarr` command converts local NDArrays to Zarr.
+
+* Use `.attrs` as the recommended interface for user-defined metadata. Arrays,
+  containers and proxy sources now expose it as an alias for `.vlmeta`, preserving
+  existing storage and access rules. `C2Array.attrs` continues to select the
+  server's user attributes while `C2Array.vlmeta` retains protocol metadata.
+  `.vlmeta` remains supported and is not deprecated.
 
 ## Changes from 4.11.0 to 4.12.0
 

diff --git a/bench/remote_array_traffic.jsonl b/bench/remote_array_traffic.jsonl
@@ -0,0 +1,18 @@
+{"backend": "b2z", "transport": "s3", "url": "s3://blosc2/hierarchy.b2z", "dataset": "d0/a3", "shape": [10, 1000, 1000], "dtype": "int32", "chunks": [2, 500, 500], "blocks": [1, 50, 500], "slice": "[0, :100, :100]", "result_bytes": 40000, "cache_bytes": 15598, "blosc2_version": "4.13.0.dev0", "phases": {"open": {"seconds": 1.2488116670865566, "requests": 3, "methods": {"GET": 2, "HEAD": 1}, "connections": 1, "body_bytes": 24576, "traffic_requests": 2, "traffic_bytes": 24576}, "cold_slice": {"seconds": 0.49289220792707056, "requests": 2, "methods": {"GET": 2}, "connections": 0, "body_bytes": 16241, "traffic_requests": 2, "traffic_bytes": 16241}, "warm_slice": {"seconds": 0.0009889589855447412, "requests": 0, "methods": {}, "connections": 0, "body_bytes": 0, "traffic_requests": 0, "traffic_bytes": 0}}, "repetition": 1}
+{"backend": "b2z", "transport": "https", "url": "https://f001.backblazeb2.com/file/blosc2/hierarchy.b2z", "dataset": "d0/a3", "shape": [10, 1000, 1000], "dtype": "int32", "chunks": [2, 500, 500], "blocks": [1, 50, 500], "slice": "[0, :100, :100]", "result_bytes": 40000, "cache_bytes": 15598, "blosc2_version": "4.13.0.dev0", "phases": {"open": {"seconds": 1.043098833062686, "requests": 3, "methods": {"GET": 2, "HEAD": 1}, "connections": 1, "body_bytes": 24576, "traffic_requests": 2, "traffic_bytes": 24576}, "cold_slice": {"seconds": 0.48495695809833705, "requests": 2, "methods": {"GET": 2}, "connections": 0, "body_bytes": 16241, "traffic_requests": 2, "traffic_bytes": 16241}, "warm_slice": {"seconds": 0.0010930829448625445, "requests": 0, "methods": {}, "connections": 0, "body_bytes": 0, "traffic_requests": 0, "traffic_bytes": 0}}, "repetition": 1}
+{"backend": "zarr", "transport": "s3", "url": "s3://blosc2/hierarchy.zarr/d0/a3", "dataset": "d0/a3", "shape": [10, 1000, 1000], "dtype": "int32", "chunks": [2, 500, 500], "blocks": [1, 50, 500], "slice": "[0, :100, :100]", "result_bytes": 40000, "cache_bytes": 15598, "blosc2_version": "4.13.0.dev0", "phases": {"open": {"seconds": 7.477702042087913, "requests": 6, "methods": {"GET": 3, "HEAD": 3}, "connections": 5, "body_bytes": 1788, "traffic_requests": 1, "traffic_bytes": 1042}, "cold_slice": {"seconds": 0.4852743750670925, "requests": 2, "methods": {"GET": 1, "HEAD": 1}, "connections": 0, "body_bytes": 11645, "traffic_requests": 1, "traffic_bytes": 11645}, "warm_slice": {"seconds": 0.00036441697739064693, "requests": 0, "methods": {}, "connections": 0, "body_bytes": 0, "traffic_requests": 0, "traffic_bytes": 0}}, "repetition": 1}
+{"backend": "zarr", "transport": "https", "url": "https://f001.backblazeb2.com/file/blosc2/hierarchy.zarr/d0/a3", "dataset": "d0/a3", "shape": [10, 1000, 1000], "dtype": "int32", "chunks": [2, 500, 500], "blocks": [1, 50, 500], "slice": "[0, :100, :100]", "result_bytes": 40000, "cache_bytes": 15598, "blosc2_version": "4.13.0.dev0", "phases": {"open": {"seconds": 0.6389846670208499, "requests": 3, "methods": {"GET": 3}, "connections": 3, "body_bytes": 1230, "traffic_requests": 1, "traffic_bytes": 1042}, "cold_slice": {"seconds": 0.265499584027566, "requests": 1, "methods": {"GET": 1}, "connections": 0, "body_bytes": 11645, "traffic_requests": 1, "traffic_bytes": 11645}, "warm_slice": {"seconds": 0.00035462493542581797, "requests": 0, "methods": {}, "connections": 0, "body_bytes": 0, "traffic_requests": 0, "traffic_bytes": 0}}, "repetition": 1}
+{"backend": "h5", "transport": "s3", "url": "s3://blosc2/hierarchy.h5", "dataset": "d0/a3", "shape": [10, 1000, 1000], "dtype": "int32", "chunks": [2, 500, 500], "blocks": [1, 50, 500], "slice": "[0, :100, :100]", "result_bytes": 40000, "cache_bytes": 15598, "blosc2_version": "4.13.0.dev0", "phases": {"open": {"seconds": 11.35246516589541, "requests": 57, "methods": {"GET": 56, "HEAD": 1}, "connections": 1, "body_bytes": 47332, "traffic_requests": 2, "traffic_bytes": 392}, "cold_slice": {"seconds": 0.2362309170421213, "requests": 1, "methods": {"GET": 1}, "connections": 0, "body_bytes": 13399, "traffic_requests": 1, "traffic_bytes": 13399}, "warm_slice": {"seconds": 0.0005953341023996472, "requests": 0, "methods": {}, "connections": 0, "body_bytes": 0, "traffic_requests": 0, "traffic_bytes": 0}}, "repetition": 1}
+{"backend": "h5", "transport": "https", "url": "https://f001.backblazeb2.com/file/blosc2/hierarchy.h5", "dataset": "d0/a3", "shape": [10, 1000, 1000], "dtype": "int32", "chunks": [2, 500, 500], "blocks": [1, 50, 500], "slice": "[0, :100, :100]", "result_bytes": 40000, "cache_bytes": 15598, "blosc2_version": "4.13.0.dev0", "phases": {"open": {"seconds": 11.591361916973256, "requests": 57, "methods": {"GET": 56, "HEAD": 1}, "connections": 1, "body_bytes": 47332, "traffic_requests": 2, "traffic_bytes": 392}, "cold_slice": {"seconds": 0.2375075420131907, "requests": 1, "methods": {"GET": 1}, "connections": 0, "body_bytes": 13399, "traffic_requests": 1, "traffic_bytes": 13399}, "warm_slice": {"seconds": 0.0005853750044479966, "requests": 0, "methods": {}, "connections": 0, "body_bytes": 0, "traffic_requests": 0, "traffic_bytes": 0}}, "repetition": 1}
+{"backend": "b2z", "transport": "s3", "url": "s3://blosc2/hierarchy.b2z", "dataset": "d0/a3", "shape": [10, 1000, 1000], "dtype": "int32", "chunks": [2, 500, 500], "blocks": [1, 50, 500], "slice": "[0, :100, :100]", "result_bytes": 40000, "cache_bytes": 15598, "blosc2_version": "4.13.0.dev0", "phases": {"open": {"seconds": 1.2223038750234991, "requests": 3, "methods": {"GET": 2, "HEAD": 1}, "connections": 1, "body_bytes": 24576, "traffic_requests": 2, "traffic_bytes": 24576}, "cold_slice": {"seconds": 0.4608378750272095, "requests": 2, "methods": {"GET": 2}, "connections": 0, "body_bytes": 16241, "traffic_requests": 2, "traffic_bytes": 16241}, "warm_slice": {"seconds": 0.0009959590388461947, "requests": 0, "methods": {}, "connections": 0, "body_bytes": 0, "traffic_requests": 0, "traffic_bytes": 0}}, "repetition": 2}
+{"backend": "b2z", "transport": "https", "url": "https://f001.backblazeb2.com/file/blosc2/hierarchy.b2z", "dataset": "d0/a3", "shape": [10, 1000, 1000], "dtype": "int32", "chunks": [2, 500, 500], "blocks": [1, 50, 500], "slice": "[0, :100, :100]", "result_bytes": 40000, "cache_bytes": 15598, "blosc2_version": "4.13.0.dev0", "phases": {"open": {"seconds": 1.0011600840371102, "requests": 3, "methods": {"GET": 2, "HEAD": 1}, "connections": 1, "body_bytes": 24576, "traffic_requests": 2, "traffic_bytes": 24576}, "cold_slice": {"seconds": 0.4179259999655187, "requests": 2, "methods": {"GET": 2}, "connections": 0, "body_bytes": 16241, "traffic_requests": 2, "traffic_bytes": 16241}, "warm_slice": {"seconds": 0.0010035419836640358, "requests": 0, "methods": {}, "connections": 0, "body_bytes": 0, "traffic_requests": 0, "traffic_bytes": 0}}, "repetition": 2}
+{"backend": "zarr", "transport": "s3", "url": "s3://blosc2/hierarchy.zarr/d0/a3", "dataset": "d0/a3", "shape": [10, 1000, 1000], "dtype": "int32", "chunks": [2, 500, 500], "blocks": [1, 50, 500], "slice": "[0, :100, :100]", "result_bytes": 40000, "cache_bytes": 15598, "blosc2_version": "4.13.0.dev0", "phases": {"open": {"seconds": 1.3998966669896618, "requests": 6, "methods": {"GET": 3, "HEAD": 3}, "connections": 5, "body_bytes": 1788, "traffic_requests": 1, "traffic_bytes": 1042}, "cold_slice": {"seconds": 0.4981873750220984, "requests": 2, "methods": {"GET": 1, "HEAD": 1}, "connections": 0, "body_bytes": 11645, "traffic_requests": 1, "traffic_bytes": 11645}, "warm_slice": {"seconds": 0.00038591690827161074, "requests": 0, "methods": {}, "connections": 0, "body_bytes": 0, "traffic_requests": 0, "traffic_bytes": 0}}, "repetition": 2}
+{"backend": "zarr", "transport": "https", "url": "https://f001.backblazeb2.com/file/blosc2/hierarchy.zarr/d0/a3", "dataset": "d0/a3", "shape": [10, 1000, 1000], "dtype": "int32", "chunks": [2, 500, 500], "blocks": [1, 50, 500], "slice": "[0, :100, :100]", "result_bytes": 40000, "cache_bytes": 15598, "blosc2_version": "4.13.0.dev0", "phases": {"open": {"seconds": 0.6370132910087705, "requests": 3, "methods": {"GET": 3}, "connections": 3, "body_bytes": 1230, "traffic_requests": 1, "traffic_bytes": 1042}, "cold_slice": {"seconds": 0.2670587080065161, "requests": 1, "methods": {"GET": 1}, "connections": 0, "body_bytes": 11645, "traffic_requests": 1, "traffic_bytes": 11645}, "warm_slice": {"seconds": 0.0004256248939782381, "requests": 0, "methods": {}, "connections": 0, "body_bytes": 0, "traffic_requests": 0, "traffic_bytes": 0}}, "repetition": 2}
+{"backend": "h5", "transport": "s3", "url": "s3://blosc2/hierarchy.h5", "dataset": "d0/a3", "shape": [10, 1000, 1000], "dtype": "int32", "chunks": [2, 500, 500], "blocks": [1, 50, 500], "slice": "[0, :100, :100]", "result_bytes": 40000, "cache_bytes": 15598, "blosc2_version": "4.13.0.dev0", "phases": {"open": {"seconds": 11.579921333002858, "requests": 57, "methods": {"GET": 56, "HEAD": 1}, "connections": 1, "body_bytes": 47332, "traffic_requests": 2, "traffic_bytes": 392}, "cold_slice": {"seconds": 0.25883508403785527, "requests": 1, "methods": {"GET": 1}, "connections": 0, "body_bytes": 13399, "traffic_requests": 1, "traffic_bytes": 13399}, "warm_slice": {"seconds": 0.0006202919175848365, "requests": 0, "methods": {}, "connections": 0, "body_bytes": 0, "traffic_requests": 0, "traffic_bytes": 0}}, "repetition": 2}
+{"backend": "h5", "transport": "https", "url": "https://f001.backblazeb2.com/file/blosc2/hierarchy.h5", "dataset": "d0/a3", "shape": [10, 1000, 1000], "dtype": "int32", "chunks": [2, 500, 500], "blocks": [1, 50, 500], "slice": "[0, :100, :100]", "result_bytes": 40000, "cache_bytes": 15598, "blosc2_version": "4.13.0.dev0", "phases": {"open": {"seconds": 11.457834250060841, "requests": 57, "methods": {"GET": 56, "HEAD": 1}, "connections": 1, "body_bytes": 47332, "traffic_requests": 2, "traffic_bytes": 392}, "cold_slice": {"seconds": 0.2313700410304591, "requests": 1, "methods": {"GET": 1}, "connections": 0, "body_bytes": 13399, "traffic_requests": 1, "traffic_bytes": 13399}, "warm_slice": {"seconds": 0.0005405419506132603, "requests": 0, "methods": {}, "connections": 0, "body_bytes": 0, "traffic_requests": 0, "traffic_bytes": 0}}, "repetition": 2}
+{"backend": "b2z", "transport": "s3", "url": "s3://blosc2/hierarchy.b2z", "dataset": "d0/a3", "shape": [10, 1000, 1000], "dtype": "int32", "chunks": [2, 500, 500], "blocks": [1, 50, 500], "slice": "[0, :100, :100]", "result_bytes": 40000, "cache_bytes": 15598, "blosc2_version": "4.13.0.dev0", "phases": {"open": {"seconds": 1.2231810830999166, "requests": 3, "methods": {"GET": 2, "HEAD": 1}, "connections": 1, "body_bytes": 24576, "traffic_requests": 2, "traffic_bytes": 24576}, "cold_slice": {"seconds": 0.4398518749512732, "requests": 2, "methods": {"GET": 2}, "connections": 0, "body_bytes": 16241, "traffic_requests": 2, "traffic_bytes": 16241}, "warm_slice": {"seconds": 0.0009655829053372145, "requests": 0, "methods": {}, "connections": 0, "body_bytes": 0, "traffic_requests": 0, "traffic_bytes": 0}}, "repetition": 3}
+{"backend": "b2z", "transport": "https", "url": "https://f001.backblazeb2.com/file/blosc2/hierarchy.b2z", "dataset": "d0/a3", "shape": [10, 1000, 1000], "dtype": "int32", "chunks": [2, 500, 500], "blocks": [1, 50, 500], "slice": "[0, :100, :100]", "result_bytes": 40000, "cache_bytes": 15598, "blosc2_version": "4.13.0.dev0", "phases": {"open": {"seconds": 1.0051324159139767, "requests": 3, "methods": {"GET": 2, "HEAD": 1}, "connections": 1, "body_bytes": 24576, "traffic_requests": 2, "traffic_bytes": 24576}, "cold_slice": {"seconds": 0.41061416699085385, "requests": 2, "methods": {"GET": 2}, "connections": 0, "body_bytes": 16241, "traffic_requests": 2, "traffic_bytes": 16241}, "warm_slice": {"seconds": 0.0004735830007120967, "requests": 0, "methods": {}, "connections": 0, "body_bytes": 0, "traffic_requests": 0, "traffic_bytes": 0}}, "repetition": 3}
+{"backend": "zarr", "transport": "s3", "url": "s3://blosc2/hierarchy.zarr/d0/a3", "dataset": "d0/a3", "shape": [10, 1000, 1000], "dtype": "int32", "chunks": [2, 500, 500], "blocks": [1, 50, 500], "slice": "[0, :100, :100]", "result_bytes": 40000, "cache_bytes": 15598, "blosc2_version": "4.13.0.dev0", "phases": {"open": {"seconds": 1.4775527090532705, "requests": 6, "methods": {"GET": 3, "HEAD": 3}, "connections": 5, "body_bytes": 1788, "traffic_requests": 1, "traffic_bytes": 1042}, "cold_slice": {"seconds": 0.4406578750349581, "requests": 2, "methods": {"GET": 1, "HEAD": 1}, "connections": 0, "body_bytes": 11645, "traffic_requests": 1, "traffic_bytes": 11645}, "warm_slice": {"seconds": 0.00023274996783584356, "requests": 0, "methods": {}, "connections": 0, "body_bytes": 0, "traffic_requests": 0, "traffic_bytes": 0}}, "repetition": 3}
+{"backend": "zarr", "transport": "https", "url": "https://f001.backblazeb2.com/file/blosc2/hierarchy.zarr/d0/a3", "dataset": "d0/a3", "shape": [10, 1000, 1000], "dtype": "int32", "chunks": [2, 500, 500], "blocks": [1, 50, 500], "slice": "[0, :100, :100]", "result_bytes": 40000, "cache_bytes": 15598, "blosc2_version": "4.13.0.dev0", "phases": {"open": {"seconds": 6.490244832937606, "requests": 3, "methods": {"GET": 3}, "connections": 3, "body_bytes": 1230, "traffic_requests": 1, "traffic_bytes": 1042}, "cold_slice": {"seconds": 0.34011666697915643, "requests": 2, "methods": {"GET": 2}, "connections": 0, "body_bytes": 11645, "traffic_requests": 1, "traffic_bytes": 11645}, "warm_slice": {"seconds": 0.00039166701026260853, "requests": 0, "methods": {}, "connections": 0, "body_bytes": 0, "traffic_requests": 0, "traffic_bytes": 0}}, "repetition": 3}
+{"backend": "h5", "transport": "s3", "url": "s3://blosc2/hierarchy.h5", "dataset": "d0/a3", "shape": [10, 1000, 1000], "dtype": "int32", "chunks": [2, 500, 500], "blocks": [1, 50, 500], "slice": "[0, :100, :100]", "result_bytes": 40000, "cache_bytes": 15598, "blosc2_version": "4.13.0.dev0", "phases": {"open": {"seconds": 11.601201582932845, "requests": 57, "methods": {"GET": 56, "HEAD": 1}, "connections": 1, "body_bytes": 47332, "traffic_requests": 2, "traffic_bytes": 392}, "cold_slice": {"seconds": 0.2506593340076506, "requests": 1, "methods": {"GET": 1}, "connections": 0, "body_bytes": 13399, "traffic_requests": 1, "traffic_bytes": 13399}, "warm_slice": {"seconds": 0.0004546659765765071, "requests": 0, "methods": {}, "connections": 0, "body_bytes": 0, "traffic_requests": 0, "traffic_bytes": 0}}, "repetition": 3}
+{"backend": "h5", "transport": "https", "url": "https://f001.backblazeb2.com/file/blosc2/hierarchy.h5", "dataset": "d0/a3", "shape": [10, 1000, 1000], "dtype": "int32", "chunks": [2, 500, 500], "blocks": [1, 50, 500], "slice": "[0, :100, :100]", "result_bytes": 40000, "cache_bytes": 15598, "blosc2_version": "4.13.0.dev0", "phases": {"open": {"seconds": 13.41276800003834, "requests": 57, "methods": {"GET": 56, "HEAD": 1}, "connections": 1, "body_bytes": 47332, "traffic_requests": 2, "traffic_bytes": 392}, "cold_slice": {"seconds": 0.23232333292253315, "requests": 1, "methods": {"GET": 1}, "connections": 0, "body_bytes": 13399, "traffic_requests": 1, "traffic_bytes": 13399}, "warm_slice": {"seconds": 0.0005118330009281635, "requests": 0, "methods": {}, "connections": 0, "body_bytes": 0, "traffic_requests": 0, "traffic_bytes": 0}}, "repetition": 3}