fix: make lancedb an optional dependency to fix Windows installation (#5045)

lancedb >=0.30 dropped Windows (win_amd64) wheels, causing 'crewai install'
to fail on Windows with:
  Distribution lancedb==0.30.1 can't be installed because it doesn't have a
  source distribution or wheel for the current platform

Changes:
- Move lancedb from core dependencies to [project.optional-dependencies]
  under a new 'memory-storage' extra
- Guard the top-level 'import lancedb' in lancedb_storage.py with
  try/except ImportError, raising a clear install hint
- Guard the lazy import in Memory.model_post_init with a helpful
  ImportError message pointing to 'pip install crewai[memory-storage]'
- Add 3 tests verifying graceful handling when lancedb is absent

Co-Authored-By: João <joao@crewai.com>

lib/crewai/pyproject.toml

@@ -43,7 +43,6 @@ dependencies = [
     "uv~=0.9.13",
     "aiosqlite~=0.21.0",
     "pyyaml~=6.0",
-    "lancedb>=0.29.2",
 ]
 
 [project.urls]
@@ -103,6 +102,9 @@ a2a = [
      "httpx-sse~=0.4.0",
      "aiocache[redis,memcached]~=0.12.3",
 ]
+memory-storage = [
+    "lancedb>=0.29.2",
+]
 file-processing = [
     "crewai-files",
 ]

lib/crewai/src/crewai/memory/storage/lancedb_storage.py

@@ -12,12 +12,28 @@ import threading
 import time
 from typing import Any
 
-import lancedb  # type: ignore[import-untyped]
+
+try:
+    import lancedb  # type: ignore[import-untyped]
+except ImportError:
+    lancedb = None  # type: ignore[assignment]
 
 from crewai.memory.types import MemoryRecord, ScopeInfo
 from crewai.utilities.lock_store import lock as store_lock
 
 
+_INSTALL_HINT = (
+    "lancedb is required for the default memory storage backend but is not installed.\n\n"
+    "Install it with:\n"
+    "  pip install crewai[memory-storage]   # or: pip install lancedb\n\n"
+    "If lancedb does not provide wheels for your platform (e.g. Windows with "
+    "lancedb >=0.30), pin an older version:\n"
+    "  pip install 'lancedb>=0.29.2,<0.30'\n\n"
+    "Alternatively, supply a custom StorageBackend to Memory(storage=...) to "
+    "bypass lancedb entirely."
+)
+
+
 _logger = logging.getLogger(__name__)
 
 # Default embedding vector dimensionality (matches OpenAI text-embedding-3-small).
@@ -63,6 +79,8 @@ class LanceDBStorage:
                   fragment file; compaction merges them, keeping query
                   performance consistent.  Set to 0 to disable.
         """
+        if lancedb is None:
+            raise ImportError(_INSTALL_HINT)
         if path is None:
             storage_dir = os.environ.get("CREWAI_STORAGE_DIR")
             if storage_dir:

lib/crewai/src/crewai/memory/unified_memory.py

@@ -173,7 +173,20 @@ class Memory(BaseModel):
         )
 
         if isinstance(self.storage, str):
-            from crewai.memory.storage.lancedb_storage import LanceDBStorage
+            try:
+                from crewai.memory.storage.lancedb_storage import LanceDBStorage
+            except ImportError as exc:
+                raise ImportError(
+                    "lancedb is required for the default memory storage backend "
+                    "but is not installed.\n\n"
+                    "Install it with:\n"
+                    "  pip install crewai[memory-storage]   # or: pip install lancedb\n\n"
+                    "If lancedb does not provide wheels for your platform "
+                    "(e.g. Windows with lancedb >=0.30), pin an older version:\n"
+                    "  pip install 'lancedb>=0.29.2,<0.30'\n\n"
+                    "Alternatively, supply a custom StorageBackend instance to "
+                    "Memory(storage=my_backend) to bypass lancedb entirely."
+                ) from exc
 
             self._storage = (
                 LanceDBStorage()

lib/crewai/tests/memory/test_unified_memory.py

@@ -999,3 +999,62 @@ def test_close_drains_and_shuts_down(tmp_path: Path, mock_embedder: MagicMock) -
     mem.close()
     # After close, records should be persisted
     assert mem._storage.count() == 1
+
+
+# --- lancedb optional dependency ---
+
+
+def test_lancedb_storage_import_error_when_missing(monkeypatch: pytest.MonkeyPatch) -> None:
+    """LanceDBStorage.__init__ raises ImportError with install hint when lancedb is absent."""
+    import crewai.memory.storage.lancedb_storage as mod
+
+    # Simulate lancedb not being installed
+    monkeypatch.setattr(mod, "lancedb", None)
+    with pytest.raises(ImportError, match="pip install crewai\\[memory-storage\\]"):
+        mod.LanceDBStorage(path="/tmp/fake")
+
+
+def test_memory_raises_import_error_when_lancedb_missing(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    """Memory(storage='lancedb') raises ImportError with install hint when lancedb is absent."""
+    import importlib
+
+    # Make the import of lancedb_storage raise ImportError
+    original_import = importlib.import_module
+
+    def _patched_import(name: str, *args, **kwargs):  # type: ignore[no-untyped-def]
+        if name == "crewai.memory.storage.lancedb_storage":
+            raise ImportError("No module named 'lancedb'")
+        return original_import(name, *args, **kwargs)
+
+    monkeypatch.setattr(importlib, "import_module", _patched_import)
+
+    # Also patch the direct import that model_post_init uses
+    import builtins
+
+    original_builtins_import = builtins.__import__
+
+    def _patched_builtins_import(name, *args, **kwargs):  # type: ignore[no-untyped-def]
+        if "lancedb_storage" in name:
+            raise ImportError("No module named 'lancedb'")
+        return original_builtins_import(name, *args, **kwargs)
+
+    monkeypatch.setattr(builtins, "__import__", _patched_builtins_import)
+
+    from crewai.memory.unified_memory import Memory
+
+    with pytest.raises(ImportError, match="pip install crewai\\[memory-storage\\]"):
+        Memory(storage="lancedb", llm=MagicMock(), embedder=MagicMock())
+
+
+def test_memory_works_with_custom_storage_when_lancedb_missing(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    """Memory accepts a custom StorageBackend even when lancedb is not installed."""
+    from crewai.memory.unified_memory import Memory
+
+    mock_storage = MagicMock()
+    # Should not raise even if lancedb is missing — custom storage bypasses it
+    mem = Memory(storage=mock_storage, llm=MagicMock(), embedder=MagicMock())
+    assert mem._storage is mock_storage