content-addressed blob storage: blob_storage.py, memory, local, and S3 adapters

tests/cmis/test_cmis_runtime_browser_binding.py

@@ -164,6 +164,11 @@ def test_runtime_cmis_governed_authoring_allows_selected_mutations(cmis_runtime)
         {"content": "# Authored\n\nUpdated stream.", "media_type": "text/markdown"},
         context,
     )
+    stream_bytes = runtime.cmis_content_stream_bytes(
+        "governed-authoring",
+        "cmis:asset:asset-authored",
+        context,
+    )
     deleted = runtime.cmis_delete_object(
         "governed-authoring",
         "cmis:asset:asset-authored",
@@ -174,6 +179,8 @@ def test_runtime_cmis_governed_authoring_allows_selected_mutations(cmis_runtime)
     assert created["object_id"] == "cmis:asset:asset-authored"
     assert updated["properties"]["kontextual:metadata:reviewer"] == "codex"
     assert streamed["content_stream"]["mime_type"] == "text/markdown"
+    assert b"".join(stream_bytes.chunks) == b"# Authored\n\nUpdated stream."
+    assert stream_bytes.representation.storage_ref.startswith("blob://memory/")
     assert deleted["deleted"] is False
     assert deleted["lifecycle"] == "delete_requested"