fix(mcp): route mixed local/cloud projects correctly

AGENTS.md

@@ -56,6 +56,15 @@ Run `just test-smoke` when you specifically need the MCP smoke flow.
 
 If testmon is “cold,” the first run may be long. Subsequent runs get much faster.
 
+### PR CI Gate
+
+Before opening or updating a PR, run the checks that mirror the common required CI failures:
+
+- Run `just typecheck` in addition to targeted `ruff` and `pytest` commands when tests were added or changed.
+- Sign commits with `git commit -s` so DCO passes. If a PR branch already has unsigned commits, rewrite the branch with signed-off commits before asking for review.
+- Use a semantic PR title accepted by `.github/workflows/pr-title.yml`: `type(scope): summary`.
+- Use one of the allowed scopes: `core`, `cli`, `api`, `mcp`, `sync`, `ui`, `deps`, `installer`.
+
 ### Test Structure
 
 - `tests/` - Unit tests for individual components (mocked, fast)

src/basic_memory/mcp/project_context.py

@@ -142,6 +142,15 @@ async def _set_cached_active_project(
         await context.set_state("default_project_name", active_project.name)
 
 
+async def _clear_cached_active_project(context: Optional[Context]) -> None:
+    """Clear cached project metadata that may no longer match the active route."""
+    if not context:
+        return
+
+    await context.set_state("active_project", None)
+    await context.set_state("default_project_name", None)
+
+
 async def _get_cached_active_workspace(context: Optional[Context]) -> Optional[WorkspaceInfo]:
     """Return the cached active workspace from context when available."""
     if not context:
@@ -167,8 +176,7 @@ async def _set_cached_active_workspace(
         # Why: project names are only unique inside one workspace, so a cached
         #   ProjectItem from the previous tenant can point at the wrong project
         # Outcome: force the next validation call to resolve within the new tenant
-        await context.set_state("active_project", None)
-        await context.set_state("default_project_name", None)
+        await _clear_cached_active_project(context)
 
     await context.set_state("active_workspace", active_workspace.model_dump())
 
@@ -525,6 +533,28 @@ def _cloud_workspace_discovery_available(config: BasicMemoryConfig) -> bool:
     )
 
 
+def _workspace_identifier_discovery_available(
+    identifier: str,
+    config: BasicMemoryConfig,
+) -> bool:
+    """Return True when an identifier is allowed to consult workspace discovery."""
+    if _cloud_workspace_discovery_available(config):
+        return True
+
+    from basic_memory.mcp.async_client import (
+        _explicit_routing,
+        _force_local_mode,
+    )
+
+    if _explicit_routing() and _force_local_mode():
+        return False
+
+    return (
+        has_cloud_credentials(config)
+        and _split_workspace_identifier_segments(identifier) is not None
+    )
+
+
 async def resolve_workspace_qualified_memory_url(
     identifier: str,
     context: Optional[Context] = None,
@@ -1326,11 +1356,23 @@ async def detect_project_from_identifier_prefix(
         # Outcome: keep unqualified search/title input on the active/default project route.
         return None
 
-    if _cloud_workspace_discovery_available(config):
-        workspace_resolution = await resolve_workspace_qualified_identifier(
-            identifier,
-            context=context,
+    if _workspace_identifier_discovery_available(identifier, config):
+        workspace_discovery_fallback_errors = (
+            "not found",
+            "no accessible workspaces",
+            "unable to discover",
         )
+        try:
+            workspace_resolution = await resolve_workspace_qualified_identifier(
+                identifier,
+                context=context,
+            )
+        except ValueError as exc:
+            message = str(exc).lower()
+            if any(error in message for error in workspace_discovery_fallback_errors):
+                return None
+            raise
+
         if workspace_resolution is not None:
             return workspace_resolution.project_identifier
 
@@ -1345,7 +1387,7 @@ async def detect_project_from_identifier_prefix(
             )
         except ValueError as exc:
             message = str(exc).lower()
-            if "not found" in message or "no accessible workspaces" in message:
+            if any(error in message for error in workspace_discovery_fallback_errors):
                 return None
             raise
 
@@ -1462,9 +1504,26 @@ async def get_project_client(
     if project_id and not cloud_available:
         project_mode = ProjectMode.LOCAL
 
+    if (
+        project_id
+        and config.projects
+        and not factory_mode
+        and not explicit_cloud_routing
+        and project_mode == ProjectMode.CLOUD
+    ):
+        try:
+            canonical_project_id = str(UUID(project_id))
+        except ValueError:
+            pass
+        else:
+            workspace_index = await _ensure_workspace_project_index(context=context)
+            if canonical_project_id not in workspace_index.entries_by_external_id:
+                project_mode = ProjectMode.LOCAL
+
     if factory_mode or project_mode == ProjectMode.CLOUD or explicit_cloud_routing:
         route_mode = "factory" if factory_mode else "cloud_proxy"
         active_ws: WorkspaceInfo | None = None
+        resolved_entry: WorkspaceProjectEntry | None = None
         workspace_id: str
         project_for_api = _unqualified_project_identifier(resolved_project)
 
@@ -1487,6 +1546,13 @@ async def get_project_client(
 
         if active_ws is not None:
             await _set_cached_active_workspace(context, active_ws)
+        if resolved_entry is not None:
+            cached_project = await _get_cached_active_project(context)
+            if (
+                cached_project is not None
+                and cached_project.external_id != resolved_entry.project.external_id
+            ):
+                await _clear_cached_active_project(context)
         with logfire.span(
             "routing.client_session",
             project_name=project_for_api,

src/basic_memory/mcp/tools/edit_note.py

@@ -9,7 +9,7 @@
 
 from basic_memory.config import ConfigManager
 from basic_memory.mcp.project_context import (
-    _cloud_workspace_discovery_available,
+    _workspace_identifier_discovery_available,
     detect_project_from_memory_url_prefix,
     get_project_client,
     add_project_metadata,
@@ -368,8 +368,9 @@ async def edit_note(
                 config,
                 context=context,
             )
-        elif _cloud_workspace_discovery_available(
-            config
+        elif _workspace_identifier_discovery_available(
+            identifier,
+            config,
         ) and is_workspace_qualified_plain_identifier(identifier):
             detected = await detect_project_from_workspace_identifier_prefix(
                 identifier,

src/basic_memory/services/link_resolver.py

@@ -40,17 +40,29 @@ async def detect_project_from_workspace_identifier_prefix(
         return None
 
     from basic_memory.mcp.project_context import (
-        _cloud_workspace_discovery_available,
+        _workspace_identifier_discovery_available,
         resolve_workspace_qualified_identifier,
     )
 
-    if not _cloud_workspace_discovery_available(config):
+    if not _workspace_identifier_discovery_available(identifier, config):
         return None
 
-    workspace_resolution = await resolve_workspace_qualified_identifier(
-        identifier,
-        context=context,
+    workspace_discovery_fallback_errors = (
+        "not found",
+        "no accessible workspaces",
+        "unable to discover",
     )
+    try:
+        workspace_resolution = await resolve_workspace_qualified_identifier(
+            identifier,
+            context=context,
+        )
+    except ValueError as exc:
+        message = str(exc).lower()
+        if any(error in message for error in workspace_discovery_fallback_errors):
+            return None
+        raise
+
     if workspace_resolution is None:
         return None
     return workspace_resolution.project_identifier

tests/mcp/conftest.py

@@ -20,6 +20,31 @@ def mcp() -> FastMCP:
     return cast(Any, mcp_server)
 
 
+class ContextState:
+    """Minimal FastMCP context-state stub for MCP tests."""
+
+    def __init__(self):
+        self._state: dict[str, object] = {}
+
+    async def get_state(self, key: str):
+        return self._state.get(key)
+
+    async def set_state(self, key: str, value: object, **kwargs) -> None:
+        self._state[key] = value
+
+    async def info(self, message: str) -> None:
+        self._state["info_message"] = message
+
+
+def ctx(context: ContextState) -> Any:
+    return cast(Any, context)
+
+
+@pytest.fixture
+def context_state() -> ContextState:
+    return ContextState()
+
+
 @pytest.fixture(scope="function")
 def app(
     app_config, project_config, engine_factory, config_manager