diff --git a/src/basic_memory/mcp/async_client.py b/src/basic_memory/mcp/async_client.py
index 76580f05..421e658b 100644
--- a/src/basic_memory/mcp/async_client.py
+++ b/src/basic_memory/mcp/async_client.py
@@ -128,11 +128,14 @@ async def get_cloud_control_plane_client(
         yield client
 
 
-# Optional factory override for dependency injection
-_client_factory: Optional[Callable[[], AbstractAsyncContextManager[AsyncClient]]] = None
+# Optional factory override for dependency injection.
+# The factory accepts an optional workspace keyword argument so that MCP tools
+# can route individual requests to a different workspace than the one set at
+# connection time.  See basic-memory-cloud main.py tenant_asgi_client_factory.
+_client_factory: Optional[Callable[..., AbstractAsyncContextManager[AsyncClient]]] = None
 
 
-def set_client_factory(factory: Callable[[], AbstractAsyncContextManager[AsyncClient]]) -> None:
+def set_client_factory(factory: Callable[..., AbstractAsyncContextManager[AsyncClient]]) -> None:
     """Override the default client factory (for cloud app, testing, etc)."""
     global _client_factory
     _client_factory = factory
@@ -173,7 +176,7 @@ async def get_client(
     4. Local ASGI transport by default.
     """
     if _client_factory:
-        async with _client_factory() as client:
+        async with _client_factory(workspace=workspace) as client:
             yield client
         return
 
diff --git a/src/basic_memory/mcp/project_context.py b/src/basic_memory/mcp/project_context.py
index c29fc152..2c2f58df 100644
--- a/src/basic_memory/mcp/project_context.py
+++ b/src/basic_memory/mcp/project_context.py
@@ -622,10 +622,10 @@ async def get_project_client(
 
     # Step 1b: Factory injection (in-process cloud server)
     # Trigger: set_client_factory() was called (e.g., by cloud MCP server)
-    # Why: the transport layer already resolved workspace and tenant context;
-    #   attempting cloud workspace resolution here would call the production
-    #   control-plane API with no valid credentials and fail with 401
-    # Outcome: use the factory client directly, skip workspace resolution
+    # Why: the factory's transport layer handles auth and tenant resolution;
+    #   we pass workspace through so the transport can route to the correct
+    #   workspace when the tool specifies one different from the connection default
+    # Outcome: factory client with optional workspace override via inner request headers
     if is_factory_mode():
         route_mode = "factory"
         with telemetry.scope(
@@ -635,7 +635,7 @@ async def get_project_client(
             workspace_id=workspace,
         ):
             logger.debug("Using injected client factory for project routing")
-            async with get_client() as client:
+            async with get_client(workspace=workspace) as client:
                 active_project = await get_active_project(client, resolved_project, context)
                 yield client, active_project
         return
diff --git a/tests/mcp/test_async_client_modes.py b/tests/mcp/test_async_client_modes.py
index 5a0d65f9..ba63f5ba 100644
--- a/tests/mcp/test_async_client_modes.py
+++ b/tests/mcp/test_async_client_modes.py
@@ -28,7 +28,7 @@ async def test_get_client_uses_injected_factory(monkeypatch):
     seen = {"used": False}
 
     @asynccontextmanager
-    async def factory():
+    async def factory(workspace=None):
         seen["used"] = True
         async with httpx.AsyncClient(base_url="https://example.test") as client:
             yield client
@@ -185,7 +185,7 @@ async def test_get_client_factory_overrides_per_project_routing(config_manager):
     config_manager.save_config(cfg)
 
     @asynccontextmanager
-    async def factory():
+    async def factory(workspace=None):
         async with httpx.AsyncClient(base_url="https://factory.test") as client:
             yield client
 
diff --git a/tests/mcp/test_project_context.py b/tests/mcp/test_project_context.py
index 15c1dac1..94a5c94f 100644
--- a/tests/mcp/test_project_context.py
+++ b/tests/mcp/test_project_context.py
@@ -709,7 +709,7 @@ async def test_factory_mode_skips_workspace_resolution(self, config_manager, mon
 
         # Set up a factory (simulates what cloud MCP server does)
         @asynccontextmanager
-        async def fake_factory():
+        async def fake_factory(workspace=None):
             from httpx import ASGITransport, AsyncClient
             from basic_memory.api.app import app as fastapi_app