Can't write to icechunk store

[tomwhite]

Here's a reproducible example.

# /// script
# requires-python = ">=3.12"
# dependencies = [
#     "icechunk>=2",
#     "numpy",
#     "zarrista==0.1.0",
# ]
# ///

import asyncio
import tempfile
from pathlib import Path

import icechunk
import numpy as np
from zarrista import ArrayBuilder, ChunkGrid, DataType, FillValue

async def main() -> None:
    
    root = Path(tempfile.mkdtemp()) / "repo"
    storage = icechunk.local_filesystem_storage(str(root))
    session = icechunk.Repository.create(storage).writable_session("main")

    data = np.arange(256 * 1024, dtype="int32").reshape(512, 512)

    builder = ArrayBuilder(
        ChunkGrid.regular(data.shape, chunk_shape=data.shape),
        DataType.from_string("int32"),
        FillValue(np.zeros((), dtype=data.dtype).tobytes()),
    )

    array = await builder.create_async(session, "/arr")
    await array.store_array_subset(Ellipsis, data)

    # following raises icechunk.SessionStateError
    session.commit("zarrista write")

asyncio.run(main())

Stacktrace is

Details

Traceback (most recent call last):
  File "/Users/tom/workspace/memray-array/examples/zarrista_icechunk_write_mre.py", line 38, in <module>
    asyncio.run(main())
    ~~~~~~~~~~~^^^^^^^^
  File "/Users/tom/.local/share/uv/python/cpython-3.14.2-macos-aarch64-none/lib/python3.14/asyncio/runners.py", line 204, in run
    return runner.run(main)
           ~~~~~~~~~~^^^^^^
  File "/Users/tom/.local/share/uv/python/cpython-3.14.2-macos-aarch64-none/lib/python3.14/asyncio/runners.py", line 127, in run
    return self._loop.run_until_complete(task)
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^
  File "/Users/tom/.local/share/uv/python/cpython-3.14.2-macos-aarch64-none/lib/python3.14/asyncio/base_events.py", line 719, in run_until_complete
    return future.result()
           ~~~~~~~~~~~~~^^
  File "/Users/tom/workspace/memray-array/examples/zarrista_icechunk_write_mre.py", line 36, in main
    session.commit("zarrista write")
    ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^
  File "/Users/tom/.cache/uv/environments-v2/zarrista-icechunk-write-mre-6d9278fab165d75f/lib/python3.14/site-packages/icechunk/session.py", line 452, in commit
    return self._session.commit(
           ~~~~~~~~~~~~~~~~~~~~^
        message,
        ^^^^^^^^
    ...<3 lines>...
        allow_empty=allow_empty,
        ^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
icechunk.SessionStateError: session error: cannot commit, no changes made to the session (use `allow_empty=true` to commit anyway)

context:
   0: icechunk::session::commit_inner
           with zarrista write max_concurrent_nodes=1 rewrite_manifests=false commit_method=NewCommit allow_empty=false
             at icechunk/src/session.rs:1699
  × session error: cannot commit, no changes made to the session (use `allow_empty=true` to commit anyway)
  │ 
  │ context:
  │    0: icechunk::session::commit_inner
  │            with zarrista write max_concurrent_nodes=1 rewrite_manifests=false commit_method=NewCommit allow_empty=false
  │              at icechunk/src/session.rs:1699
  │ 

[kylebarron]

Perhaps this is the answer to the question from #107