Migrating KuzuGraphStore from kuzu to ladybug¶

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What Changed¶

The KuzuGraphStore class moved from amplihack.memory.kuzu_store to amplihack.memory.ladybug_store. The underlying graph engine changed from kuzu to ladybug, Kùzu's next-generation embedded graph database.

The class name (KuzuGraphStore) and its public API are unchanged.

Why ladybug?¶

Ladybug is the successor to kuzu. It ships the same Cypher query engine with improvements to concurrent access, string handling, and packaging. The amplihack upgrade adds fcntl.flock serialization so multiple processes (e.g., parallel agent workstreams) can safely share a single database directory.

Who Needs to Migrate¶

You are…	Action required
Using `amplihack memory tree` / `export` / `import` CLI	None — transparent
Importing `from amplihack.memory import KuzuGraphStore`	None — still works
Importing `from amplihack.memory.kuzu_store import …`	Update import path
Running tests that mock `kuzu_store` internals	Update mock paths
Calling `KuzuGraphStore(db_path=…)`	None — API unchanged

Migration Steps¶

1. Update direct imports¶

# Before
from amplihack.memory.kuzu_store import KuzuGraphStore

# After
from amplihack.memory.ladybug_store import KuzuGraphStore

The package-level import still works without changes:

from amplihack.memory import KuzuGraphStore  # no change needed

2. Install ladybug¶

uv add ladybug
# or
pip install ladybug

A graceful fallback to import kuzu exists during the transition period. If neither package is installed, the import raises ImportError.

3. Update mock/patch targets in tests¶

# Before
@mock.patch("amplihack.memory.kuzu_store.ladybug.Database")

# After
@mock.patch("amplihack.memory.ladybug_store.ladybug.Database")

4. Verify¶

# Quick smoke test
python3 -c "from amplihack.memory.ladybug_store import KuzuGraphStore; print('OK')"

# Run graph store tests
pytest tests/test_graph_store.py -q

New Features¶

Read-only mode¶

Open a database for read-only access with a shared lock:

store = KuzuGraphStore(db_path="~/.amplihack/memory.db", read_only=True)
nodes = store.query_nodes("Session", filters={"status": "completed"})
store.close()

Read-only mode acquires LOCK_SH (shared) instead of LOCK_EX (exclusive), allowing concurrent readers.

flock serialization¶

All Database() creation is now serialized through fcntl.flock on a sidecar .lock file next to the database directory. This prevents corruption when multiple agent processes access the same graph store.

Scenario	Lock type	Concurrent access
Normal open	`LOCK_EX` (exclusive)	One writer at a time
`read_only=True`	`LOCK_SH` (shared)	Multiple readers
Lock timeout (30s)	Raises `TimeoutError`	Caller retries or fails

The lock is released when close() is called or the process exits.

Cypher identifier validation¶

All table names, relationship types, and property keys interpolated into Cypher queries are validated against ^[a-zA-Z_][a-zA-Z0-9_]*$. Invalid identifiers raise ValueError immediately, preventing Cypher injection.

Unchanged Behavior¶

KuzuGraphStore class name
Constructor signature: db_path, buffer_pool_size, max_db_size
All public methods: create_node, get_node, update_node, delete_node, query_nodes, search_nodes, create_edge, get_edges, delete_edge, ensure_table, ensure_rel_table, export_nodes, export_edges, import_nodes, import_edges, get_all_node_ids, close
Thread safety via threading.RLock
In-memory mode (db_path=None)

Files Changed¶

File	Change
`src/amplihack/memory/ladybug_store.py`	New — replaces `kuzu_store.py`
`src/amplihack/memory/kuzu_store.py`	Deleted
`src/amplihack/memory/__init__.py`	Import path updated
`src/amplihack/memory/facade.py`	2 lazy imports updated
`src/amplihack/memory/distributed_store.py`	1 lazy import updated
`src/amplihack/memory/cli_visualize.py`	2 docstring references updated
`tests/test_graph_store.py`	Import path updated
`tests/memory/test_cli_visualize.py`	Import path updated
`tests/memory/test_code_context_injection.py`	Import path updated

Out of Scope¶

These modules still use kuzu directly and are not affected:

src/amplihack/memory/kuzu/ — Code-graph indexing subsystem
src/amplihack/memory/backends/kuzu_backend.py — Separate backend for the 5-type memory system