fix: make set_default_project also activate project for current session to fix #37

This change makes the 'basic-memory project default <name>' command both:
1. Set the default project for future invocations (persistent change)
2. Activate the project for the current session (immediate change)

Added tests to verify this behavior, which resolves issue #37 where the
project name and path weren't changing properly when the default project
was changed.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/basic_memory/cli/commands/project.py

@@ -92,12 +92,22 @@ def remove_project(
 def set_default_project(
     name: str = typer.Argument(..., help="Name of the project to set as default"),
 ) -> None:
-    """Set the default project."""
+    """Set the default project and activate it for the current session."""
     config_manager = ConfigManager()
 
     try:
+        # Set the default project
         config_manager.set_default_project(name)
-        console.print(f"[green]Project '{name}' set as default[/green]")
+        
+        # Also activate it for the current session by setting the environment variable
+        os.environ["BASIC_MEMORY_PROJECT"] = name
+        
+        # Reload configuration to apply the change
+        from importlib import reload
+        from basic_memory import config as config_module
+        reload(config_module)
+        
+        console.print(f"[green]Project '{name}' set as default and activated[/green]")
     except ValueError as e:  # pragma: no cover
         console.print(f"[red]Error: {e}[/red]")
         raise typer.Exit(1)

tests/cli/test_project_commands.py

@@ -15,6 +15,13 @@ from basic_memory.config import ConfigManager, DATA_DIR_NAME, CONFIG_FILE_NAME
 @pytest.fixture
 def temp_home(monkeypatch):
     """Create a temporary directory for testing."""
+    # Save the original environment variable if it exists
+    original_env = os.environ.get("BASIC_MEMORY_PROJECT")
+    
+    # Clear environment variable for clean test
+    if "BASIC_MEMORY_PROJECT" in os.environ:
+        del os.environ["BASIC_MEMORY_PROJECT"]
+    
     with TemporaryDirectory() as tempdir:
         temp_home = Path(tempdir)
         monkeypatch.setattr(Path, "home", lambda: temp_home)
@@ -24,6 +31,12 @@ def temp_home(monkeypatch):
         config_dir.mkdir(parents=True, exist_ok=True)
 
         yield temp_home
+        
+        # Cleanup: restore original environment variable if it existed
+        if original_env is not None:
+            os.environ["BASIC_MEMORY_PROJECT"] = original_env
+        elif "BASIC_MEMORY_PROJECT" in os.environ:
+            del os.environ["BASIC_MEMORY_PROJECT"]
 
 
 @pytest.fixture
@@ -123,17 +136,33 @@ def test_project_default(cli_runner, temp_home):
     # Set as default
     result = cli_runner.invoke(app, ["project", "default", "test"])
     assert result.exit_code == 0
-    assert "Project 'test' set as default" in result.stdout
+    assert "Project 'test' set as default and activated" in result.stdout
 
     # Verify default was set
     config_manager = ConfigManager()
     assert config_manager.default_project == "test"
+    
+    # Extra verification: check if the environment variable was set
+    assert os.environ.get("BASIC_MEMORY_PROJECT") == "test"
 
 
 def test_project_current(cli_runner, temp_home):
     """Test showing the current project."""
+    # Create a bare-bones config.json with main as the default project
+    config_file = temp_home / DATA_DIR_NAME / CONFIG_FILE_NAME
+    config_data = {
+        "projects": {
+            "main": str(temp_home / "basic-memory"),
+        },
+        "default_project": "main",
+    }
+    config_file.write_text(json.dumps(config_data))
+    
+    # Create the main project directory
+    main_dir = temp_home / "basic-memory"
+    main_dir.mkdir(parents=True, exist_ok=True)
 
-    # Set as default
+    # Now check the current project
     result = cli_runner.invoke(app, ["project", "current"])
     assert result.exit_code == 0
     assert "Current project: main" in result.stdout
@@ -156,3 +185,24 @@ def test_project_option(cli_runner, temp_home, monkeypatch):
 
     # Verify environment variable was set
     assert env_vars.get("BASIC_MEMORY_PROJECT") == "test"
+
+
+def test_project_default_activates_project(cli_runner, temp_home, monkeypatch):
+    """Test that setting the default project also activates it in the current session."""
+    # Create a test environment
+    env = {}
+    monkeypatch.setattr(os, "environ", env)
+    
+    # Create two test projects
+    config_manager = ConfigManager()
+    config_manager.add_project("project1", str(temp_home / "project1"))
+    
+    # Set project1 as default using the CLI command
+    result = cli_runner.invoke(app, ["project", "default", "project1"])
+    assert result.exit_code == 0
+    assert "Project 'project1' set as default and activated" in result.stdout
+    
+    # Verify the environment variable was set
+    # This is the core of our fix - the set_default_project command now also sets
+    # the BASIC_MEMORY_PROJECT environment variable to activate the project
+    assert env.get("BASIC_MEMORY_PROJECT") == "project1"