zarr-python

name	zarr-python
description	Use when ARIA-NBV work changes Zarr-Python API usage, chunking, codecs, stores, sharding, concurrency, or v2/v3 migration behavior in offline or rollout storage.
metadata	{"mode":"implementation","not_when":["ASE download, ATEK shard, manifest, split, or data smoke work with no Zarr API or storage-layout change","rollout reward, target, invalidity, or Q_H semantics with no Zarr API or storage-layout change","model training or scoring changes that only read an existing store"],"handoff_to":["dataset-cache-ops for ASE, ATEK, VIN offline store operation, manifests, splits, smoke checks, or rebuild decisions","counterfactual-rollout-planner for rollout reward, target, invalidity, or Q_H semantics","diagnose-aria for concrete Zarr tracebacks, stale stores, or failed validation commands","lrz-ai-systems for Slurm, DSS, remote filesystem, or container execution constraints"],"evidence_required":["local owner file and symbol for the touched offline or rollout Zarr path","official Zarr-Python or Context7 evidence for nontrivial API, codec, store, sharding, or migration behavior","round-trip validation or explicit blocker for changed arrays, chunks, codecs, stores, or readers"],"applies_to":["aria_nbv/aria_nbv/data_handling/**","aria_nbv/aria_nbv/rollouts/**","aria_nbv/tests/data_handling/**","aria_nbv/tests/rollouts/**",".configs/**"],"triggers":["Zarr","zarr-python","create_array","LocalStore","FsspecStore","chunking","codec","compressor","sharding","Zarr v3"],"must_read":["aria_nbv/AGENTS.md","aria_nbv/aria_nbv/data_handling/AGENTS.md","aria_nbv/aria_nbv/rollouts/AGENTS.md","aria_nbv/aria_nbv/data_handling/README.md"],"canonical_sources":["aria_nbv/AGENTS.md","aria_nbv/aria_nbv/data_handling/AGENTS.md","aria_nbv/aria_nbv/rollouts/AGENTS.md","aria_nbv/aria_nbv/data_handling/README.md","aria_nbv/pyproject.toml"],"context7_refs":["/zarr-developers/zarr-python"],"tool_refs":["mcp__MCP_DOCKER.get_library_docs","mcp__MCP_DOCKER.resolve_library_id","mcp__code_index.search_code_advanced"],"verification":["make scaffold-audit for skill guidance changes","cd aria_nbv && uv run pytest tests/data_handling/test_vin_offline_store.py tests/rollouts/test_zarr_store.py for storage behavior changes","cd aria_nbv && uv run nbv-rollouts-info --store ../.data/offline_cache/rollouts_v1_smoke.zarr --validate when rollout stores are touched"]}

Zarr Python

Use this skill when ARIA-NBV work changes Zarr-Python usage rather than merely operating an existing dataset or rollout artifact.

When To Use

• Zarr-Python 3 API changes such as create_array, open_group, LocalStore, FsspecStore, codec imports, or group/array creation behavior.
• Chunk shape, sharding, compression, selected-depth storage, or high-throughput rollout reader/writer changes.
• Zarr v2/v3 migration, metadata layout, cloud/object-store access, or concurrency assumptions that affect ARIA storage code.

Read First

1. aria_nbv/AGENTS.md
2. aria_nbv/aria_nbv/data_handling/AGENTS.md
3. aria_nbv/aria_nbv/rollouts/AGENTS.md
4. The implementation file being changed.
5. Context7 or official Zarr-Python docs for nontrivial API behavior.

Rules

• Treat aria_nbv/pyproject.toml as the local dependency source; do not copy upstream community install or Python-version claims into ARIA guidance.
• Keep VIN offline numeric blocks under aria_nbv.data_handling; keep rollout replay and q_h Zarr artifacts under aria_nbv.rollouts.
• Do not mutate VIN offline stores to carry rollout replay data.
• Do not hand-edit Zarr arrays, manifests, sample indexes, or split arrays to silence validation; fix the writer, reader, or generator.
• Prefer existing helpers such as VinOfflineShardWriter, VinOfflineStoreReader, write_rollout_zarr_store, and validate_rollout_zarr_store before adding new storage code.
• For chunking, codec, sharding, LocalStore, FsspecStore, concurrency, or migration behavior, confirm current Zarr-Python docs before implementation.

Workflow

1. Identify whether the owner is data handling, rollouts, or an adjacent skill.
2. Localize the existing writer/reader/helper with rg or code-index evidence.
3. Check official Zarr-Python guidance when API behavior is not trivial.
4. Change the smallest owner surface and keep ARIA storage responsibilities separate.
5. Prove the changed path with round-trip tests, validation CLIs, or an explicit blocker.

Verification

• Guidance-only edits: make scaffold-audit and make check-agent-memory.
• Offline-store behavior: cd aria_nbv && uv run pytest tests/data_handling/test_vin_offline_store.py tests/data_handling/test_public_api_contract.py.
• Rollout Zarr behavior: cd aria_nbv && uv run pytest tests/rollouts/test_zarr_store.py tests/rollouts/test_info_cli.py.
• CLI smoke when rollout stores are touched: cd aria_nbv && uv run nbv-rollouts-info --store ../.data/offline_cache/rollouts_v1_smoke.zarr --validate.