deps: address required missing key in zarr upgrade

py_hamt/encryption_hamt_store.py

@@ -180,3 +180,23 @@ async def set(self, key: str, value: zarr.core.buffer.Buffer) -> None:
         # Encrypt it
         encrypted_bytes = self._encrypt(raw_bytes)
         await self.hamt.set(key, encrypted_bytes)
+
+    # we only need to override because we have extra ctor args
+    def with_read_only(self, read_only: bool = False) -> "SimpleEncryptedZarrHAMTStore":  # noqa: D401
+        if read_only == self.read_only:
+            return self
+
+        new_hamt = HAMT(
+            cas=self.hamt.cas,
+            root_node_id=self.hamt.root_node_id,
+            read_only=read_only,
+            values_are_bytes=self.hamt.values_are_bytes,
+            max_bucket_size=self.hamt.max_bucket_size,
+            hash_fn=self.hamt.hash_fn,
+        )
+        return type(self)(
+            new_hamt,
+            read_only,
+            encryption_key=self.encryption_key,
+            header=self.header,
+        )

py_hamt/zarr_hamt_store.py

@@ -83,6 +83,33 @@ def read_only(self) -> bool:
         """@private"""
         return self.hamt.read_only
 
+    def with_read_only(self, read_only: bool = False) -> "ZarrHAMTStore":  # noqa: D401
+        """
+        Return *this* store or a lightweight clone with the requested
+        ``read_only`` flag.
+
+        The clone shares the same HAMT *content*: we rebuild a **new**
+        :class:`~py_hamt.hamt.HAMT` instance that
+        *points to the same root CID* but is initialised in the desired
+        mode.  This involves **no I/O** – merely instantiating a Python
+        object – and therefore keeps the helper strictly synchronous,
+        exactly as expected by Zarr.
+        """
+        # Fast‑path: nothing to do
+        if read_only == self.read_only:
+            return self
+
+        # Re‑use all immutable HAMT knobs so that behaviour is identical
+        new_hamt = HAMT(
+            cas=self.hamt.cas,
+            root_node_id=self.hamt.root_node_id,
+            read_only=read_only,
+            values_are_bytes=self.hamt.values_are_bytes,
+            max_bucket_size=self.hamt.max_bucket_size,
+            hash_fn=self.hamt.hash_fn,
+        )
+        return type(self)(new_hamt, read_only=read_only)
+
     def __eq__(self, other: object) -> bool:
         """@private"""
         if not isinstance(other, ZarrHAMTStore):

pyproject.toml

@@ -9,7 +9,7 @@ dependencies = [
     "dag-cbor>=0.3.3",
     "msgspec>=0.18.6",
     "multiformats[full]>=0.3.1.post4",
-    "zarr>=3.0.8",
+    "zarr==3.0.9",
     "pycryptodome>=3.21.0",
 ]
 

tests/test_with_read_only.py

@@ -0,0 +1,19 @@
+import pytest
+
+from py_hamt import HAMT, InMemoryCAS, ZarrHAMTStore
+
+
+@pytest.mark.asyncio
+async def test_with_read_only_roundtrip():
+    cas = InMemoryCAS()
+    hamt_rw = await HAMT.build(cas=cas, values_are_bytes=True)
+    store_rw = ZarrHAMTStore(hamt_rw, read_only=False)
+
+    # clone → RO
+    store_ro = store_rw.with_read_only(True)
+    assert store_ro.read_only is True
+    assert store_ro is not store_rw
+    # clone back → RW
+    store_rw2 = store_ro.with_read_only(False)
+    assert store_rw2.read_only is False
+    assert store_rw2.hamt.root_node_id == store_rw.hamt.root_node_id