fix: use LinkResolver fallback in build_context for flexible identifier matching (#582)

build_context now falls back to LinkResolver when an exact permalink lookup
returns empty results. This reuses the same resolution pipeline as read_note
(permalink candidates, title match, file path, FTS) so callers no longer
get empty results for valid note identifiers.

Also changes ensure_frontmatter_on_sync default to True — frontmatter is
now added during sync by default. Tests updated accordingly.

🔧 ContextService accepts optional LinkResolver, wired via DI in all 3 factory variants
✅ 2027 unit + 278 integration tests passing

Closes #582

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: phernandez <paul@basicmachines.co>

src/basic_memory/config.py

@@ -246,7 +246,7 @@ class BasicMemoryConfig(BaseSettings):
     )
 
     ensure_frontmatter_on_sync: bool = Field(
-        default=False,
+        default=True,
         description="Ensure markdown files have frontmatter during sync by adding derived title/type/permalink when missing. When combined with disable_permalinks=True, this setting takes precedence for missing-frontmatter files and still writes permalinks.",
     )
 

src/basic_memory/deps/services.py

@@ -309,11 +309,13 @@ async def get_context_service(
     search_repository: SearchRepositoryDep,
     entity_repository: EntityRepositoryDep,
     observation_repository: ObservationRepositoryDep,
+    link_resolver: LinkResolverDep,
 ) -> ContextService:
     return ContextService(
         search_repository=search_repository,
         entity_repository=entity_repository,
         observation_repository=observation_repository,
+        link_resolver=link_resolver,
     )
 
 
@@ -324,12 +326,14 @@ async def get_context_service_v2(  # pragma: no cover
     search_repository: SearchRepositoryV2Dep,
     entity_repository: EntityRepositoryV2Dep,
     observation_repository: ObservationRepositoryV2Dep,
+    link_resolver: LinkResolverV2Dep,
 ) -> ContextService:
     """Create ContextService for v2 API."""
     return ContextService(
         search_repository=search_repository,
         entity_repository=entity_repository,
         observation_repository=observation_repository,
+        link_resolver=link_resolver,
     )
 
 
@@ -340,12 +344,14 @@ async def get_context_service_v2_external(
     search_repository: SearchRepositoryV2ExternalDep,
     entity_repository: EntityRepositoryV2ExternalDep,
     observation_repository: ObservationRepositoryV2ExternalDep,
+    link_resolver: LinkResolverV2ExternalDep,
 ) -> ContextService:
     """Create ContextService for v2 API (uses external_id)."""
     return ContextService(
         search_repository=search_repository,
         entity_repository=entity_repository,
         observation_repository=observation_repository,
+        link_resolver=link_resolver,
     )
 
 

src/basic_memory/services/context_service.py

@@ -1,8 +1,10 @@
 """Service for building rich context from the knowledge graph."""
 
+from __future__ import annotations
+
 from dataclasses import dataclass, field
 from datetime import datetime, timezone
-from typing import List, Optional, Tuple
+from typing import List, Optional, Tuple, TYPE_CHECKING
 
 
 from loguru import logger
@@ -16,6 +18,9 @@ from basic_memory.schemas.memory import MemoryUrl, memory_url_path
 from basic_memory.schemas.search import SearchItemType
 from basic_memory.utils import generate_permalink
 
+if TYPE_CHECKING:
+    from basic_memory.services.link_resolver import LinkResolver
+
 
 @dataclass
 class ContextResultRow:
@@ -82,10 +87,12 @@ class ContextService:
         search_repository: SearchRepository,
         entity_repository: EntityRepository,
         observation_repository: ObservationRepository,
+        link_resolver: Optional[LinkResolver] = None,
     ):
         self.search_repository = search_repository
         self.entity_repository = entity_repository
         self.observation_repository = observation_repository
+        self.link_resolver = link_resolver
 
     async def build_context(
         self,
@@ -131,6 +138,24 @@ class ContextService:
                 primary = await self.search_repository.search(
                     permalink=normalized_path, limit=fetch_limit, offset=offset
                 )
+
+                # Trigger: exact permalink lookup returned no results
+                # Why: the identifier may be valid but not an exact permalink match
+                #      (e.g., missing project prefix, title instead of permalink)
+                # Outcome: use LinkResolver's multi-strategy resolution to find the entity,
+                #          then retry search with its actual permalink
+                if not primary and self.link_resolver:
+                    entity = await self.link_resolver.resolve_link(
+                        path, use_search=True, strict=False
+                    )
+                    if entity:
+                        logger.debug(
+                            f"LinkResolver resolved '{path}' to permalink '{entity.permalink}'"
+                        )
+                        normalized_path = entity.permalink
+                        primary = await self.search_repository.search(
+                            permalink=entity.permalink, limit=fetch_limit, offset=offset
+                        )
         else:
             logger.debug(f"Build context for '{types}'")
             primary = await self.search_repository.search(

test-int/mcp/test_build_context_underscore.py

@@ -99,7 +99,8 @@ async def test_build_context_underscore_normalization(mcp_server, app, test_proj
         assert "related-to" in response_text_related.lower()
 
         # Test 4: Test exact path (non-wildcard) with underscore
-        # Exact relation permalink would be child/relation/target
+        # Previously this returned empty (no exact permalink match). Now LinkResolver
+        # resolves to the child entity, so we get its relations back.
         result_exact = await client.call_tool(
             "build_context",
             {
@@ -110,7 +111,8 @@ async def test_build_context_underscore_normalization(mcp_server, app, test_proj
 
         response_text_exact = result_exact.content[0].text  # pyright: ignore
         assert '"results"' in response_text_exact
-        assert "part-of" in response_text_exact.lower()
+        # LinkResolver resolves to child-with-underscore entity; its relation_type is "part_of"
+        assert "part_of" in response_text_exact.lower()
 
 
 @pytest.mark.asyncio

test-int/test_disable_permalinks_integration.py

@@ -28,6 +28,7 @@ async def test_disable_permalinks_create_entity(tmp_path, engine_factory, app_co
 
     # Override app config to enable disable_permalinks
     app_config.disable_permalinks = True
+    app_config.ensure_frontmatter_on_sync = False
 
     # Setup repositories
     entity_repository = EntityRepository(session_maker, project_id=test_project.id)
@@ -88,6 +89,7 @@ async def test_disable_permalinks_sync_workflow(tmp_path, engine_factory, app_co
 
     # Override app config to enable disable_permalinks
     app_config.disable_permalinks = True
+    app_config.ensure_frontmatter_on_sync = False
 
     # Create a test markdown file without frontmatter
     test_file = tmp_path / "test_note.md"

tests/api/v2/test_prompt_router.py

@@ -9,9 +9,13 @@ from basic_memory.services.context_service import ContextService
 
 
 @pytest_asyncio.fixture
-async def context_service(entity_repository, search_service, observation_repository):
+async def context_service(
+    search_repository, entity_repository, observation_repository, link_resolver
+):
     """Create a real context service for testing."""
-    return ContextService(entity_repository, search_service, observation_repository)
+    return ContextService(
+        search_repository, entity_repository, observation_repository, link_resolver=link_resolver
+    )
 
 
 @pytest.mark.asyncio

tests/services/test_context_service.py

@@ -14,9 +14,13 @@ from basic_memory.models.project import Project
 
 
 @pytest_asyncio.fixture
-async def context_service(search_repository, entity_repository, observation_repository):
+async def context_service(
+    search_repository, entity_repository, observation_repository, link_resolver
+):
     """Create context service for testing."""
-    return ContextService(search_repository, entity_repository, observation_repository)
+    return ContextService(
+        search_repository, entity_repository, observation_repository, link_resolver=link_resolver
+    )
 
 
 @pytest.mark.asyncio
@@ -333,3 +337,49 @@ async def test_project_isolation_in_find_related(session_maker, app_config):
         assert entity1_p1.project_id == project1.id
         assert entity2_p1.project_id == project1.id
         assert entity1_p2.project_id == project2.id
+
+
+@pytest.mark.asyncio
+async def test_build_context_fallback_via_link_resolver(context_service, test_graph):
+    """Test that build_context falls back to LinkResolver when exact permalink fails.
+
+    The test_graph creates entities with permalinks like 'test-project/test/root'.
+    Looking up by title ('Root') won't match the exact permalink, but LinkResolver
+    can resolve it via title matching.
+    """
+    # This identifier is the entity title, not a permalink — exact lookup will fail
+    url = memory_url.validate_strings("memory://Root")
+    context_result = await context_service.build_context(url)
+
+    # LinkResolver should resolve 'Root' → entity with permalink 'test-project/test/root'
+    assert context_result.metadata.primary_count == 1
+    assert len(context_result.results) == 1
+    assert context_result.results[0].primary_result.id == test_graph["root"].id
+
+
+@pytest.mark.asyncio
+async def test_build_context_fallback_not_found(context_service):
+    """Test that build_context returns empty when both exact lookup and fallback fail."""
+    url = memory_url.validate_strings("memory://completely-nonexistent-note-xyz")
+    context_result = await context_service.build_context(url)
+
+    assert context_result.metadata.primary_count == 0
+    assert len(context_result.results) == 0
+
+
+@pytest.mark.asyncio
+async def test_build_context_without_link_resolver(
+    search_repository, entity_repository, observation_repository, test_graph
+):
+    """Test that build_context still works without a link_resolver (no fallback)."""
+    service = ContextService(search_repository, entity_repository, observation_repository)
+
+    # Exact permalink lookup should still work
+    url = memory_url.validate_strings("memory://test-project/test/root")
+    context_result = await service.build_context(url)
+    assert context_result.metadata.primary_count == 1
+
+    # Title-based lookup should return empty (no fallback available)
+    url = memory_url.validate_strings("memory://Root")
+    context_result = await service.build_context(url)
+    assert context_result.metadata.primary_count == 0

tests/sync/test_sync_service.py

@@ -1101,8 +1101,11 @@ async def test_sync_permalink_not_created_if_no_frontmatter(
     sync_service: SyncService,
     project_config: ProjectConfig,
     file_service: FileService,
+    app_config: BasicMemoryConfig,
 ):
-    """Test that sync resolves permalink conflicts on update."""
+    """Test that sync does not add frontmatter when ensure_frontmatter_on_sync is disabled."""
+    app_config.ensure_frontmatter_on_sync = False
+
     project_dir = project_config.home
 
     file = project_dir / "one.md"

tests/test_config.py

@@ -342,15 +342,15 @@ class TestConfigManager:
         assert config.disable_permalinks is True
 
     def test_ensure_frontmatter_on_sync_flag_default(self):
-        """Test that ensure_frontmatter_on_sync defaults to False."""
+        """Test that ensure_frontmatter_on_sync defaults to True."""
         config = BasicMemoryConfig()
-        assert config.ensure_frontmatter_on_sync is False
-
-    def test_ensure_frontmatter_on_sync_flag_can_be_enabled(self):
-        """Test that ensure_frontmatter_on_sync can be set to True."""
-        config = BasicMemoryConfig(ensure_frontmatter_on_sync=True)
         assert config.ensure_frontmatter_on_sync is True
 
+    def test_ensure_frontmatter_on_sync_flag_can_be_disabled(self):
+        """Test that ensure_frontmatter_on_sync can be set to False."""
+        config = BasicMemoryConfig(ensure_frontmatter_on_sync=False)
+        assert config.ensure_frontmatter_on_sync is False
+
     def test_permalinks_include_project_flag_default(self):
         """Test that permalinks_include_project defaults to True."""
         config = BasicMemoryConfig()