fix(core): preserve an existing database default when repairing a missing config default

src/basic_memory/services/project_service.py

@@ -261,14 +261,36 @@ async def add_project(self, name: str, path: str, set_default: bool = False) ->
             if config_default is not None:
                 db_default_project = await self.repository.get_by_name(config_default)
                 if db_default_project is None:
-                    await self.repository.set_as_default(created_project.id)
-                    self.config_manager.set_default_project(name)
-                    logger.info(
-                        "Promoted project '%s' to default because configured default '%s' "
-                        "is missing from database",
-                        name,
-                        config_default,
-                    )
+                    # Trigger: config names a default project that has no database row
+                    #      (the fresh-config wedge from issue #974).
+                    # Why: synchronize_projects treats an existing database default as
+                    #      authoritative, so a surviving default must win over promoting
+                    #      the just-added project. set_default_project raises for names
+                    #      absent from config — and reconciliation deletes such rows —
+                    #      so a database default unknown to config cannot be repointed to.
+                    # Outcome: config is repointed at a usable database default when one
+                    #      exists; otherwise the added project becomes the default.
+                    db_default = await self.repository.get_default_project()
+                    if (
+                        db_default is not None
+                        and self.config_manager.get_project(db_default.name)[0] is not None
+                    ):
+                        self.config_manager.set_default_project(db_default.name)
+                        logger.info(
+                            "Repointed config default from missing '%s' at existing "
+                            "database default '%s'",
+                            config_default,
+                            db_default.name,
+                        )
+                    else:
+                        await self.repository.set_as_default(created_project.id)
+                        self.config_manager.set_default_project(name)
+                        logger.info(
+                            "Promoted project '%s' to default because configured default '%s' "
+                            "is missing from database",
+                            name,
+                            config_default,
+                        )
 
         logger.info(f"Project '{name}' added at {resolved_path}")
 

tests/services/test_project_service.py

@@ -440,7 +440,7 @@ async def test_add_project_promotes_when_config_default_missing_from_db(
 ):
     """Regression #974: config default exists only in config, not DB — promote on add."""
     from basic_memory import config as config_module
-    from basic_memory.config import ProjectConfig, ProjectEntry
+    from basic_memory.config import ProjectEntry
     from basic_memory.markdown.entity_parser import EntityParser
     from basic_memory.markdown.markdown_processor import MarkdownProcessor
     from basic_memory.repository.project_repository import ProjectRepository
@@ -480,6 +480,52 @@ async def test_add_project_promotes_when_config_default_missing_from_db(
     assert await repo.get_by_name("main") is None
 
 
+@pytest.mark.asyncio
+async def test_add_project_preserves_existing_db_default(
+    project_service: ProjectService, config_manager: ConfigManager, test_project
+):
+    """The #974 repair must not steal an existing database default.
+
+    Drift state: config's default_project names a project with no database row,
+    but the database still holds a valid default of its own. synchronize_projects
+    resolves this by trusting the database default, so add_project's repair must
+    repoint config at it rather than promoting the just-added project.
+    """
+    config_default = config_manager.default_project
+    assert config_default is not None
+
+    surviving_name = f"test-surviving-default-{os.urandom(4).hex()}"
+    added_name = f"test-no-steal-{os.urandom(4).hex()}"
+    with tempfile.TemporaryDirectory() as temp_dir:
+        surviving_path = str(Path(temp_dir) / "surviving")
+        os.makedirs(surviving_path, exist_ok=True)
+
+        # A normally-added project that then becomes the database default,
+        # while config's default_project still names the fixture project.
+        await project_service.add_project(surviving_name, surviving_path)
+        surviving = await project_service.repository.get_by_name(surviving_name)
+        assert surviving is not None
+        await project_service.repository.set_as_default(surviving.id)
+
+        # Wedge config: its named default loses its database row.
+        await project_service.repository.delete(test_project.id)
+        assert await project_service.get_project(config_default) is None
+
+        added_path = str(Path(temp_dir) / "added")
+        os.makedirs(added_path, exist_ok=True)
+        await project_service.add_project(added_name, added_path)
+
+        # The surviving database default wins: config is repointed at it and
+        # the newly added project is not promoted.
+        assert config_manager.default_project == surviving_name
+        db_default = await project_service.repository.get_default_project()
+        assert db_default is not None
+        assert db_default.name == surviving_name
+        added = await project_service.repository.get_by_name(added_name)
+        assert added is not None
+        assert added.is_default is not True
+
+
 @pytest.mark.asyncio
 async def test_add_project_default_parameter_omitted(project_service: ProjectService):
     """Test adding a project without set_default parameter defaults to False behavior."""