Fix bd-8zf2: MCP server auto-detects workspace from CWD

- Add _find_beads_db_in_tree() to walk up looking for .beads/*.db
- Update _get_client() to auto-detect when workspace not set
- Matches CLI behavior (no manual set_context needed after restart)
- Add 8 comprehensive tests for auto-detection
- Update existing tests to mock auto-detection in error cases

Fixes silent failures after Amp restart.

Amp-Thread-ID: https://ampcode.com/threads/T-c47f524d-c101-40d5-839a-659f52b9be48
Co-authored-by: Amp <amp@ampcode.com>

integrations/beads-mcp/src/beads_mcp/tools.py

@@ -63,6 +63,50 @@ def _register_client_for_cleanup(client: BdClientBase) -> None:
         pass
 
 
+def _find_beads_db_in_tree(start_dir: str | None = None) -> str | None:
+    """Walk up directory tree looking for .beads/*.db (matches Go CLI behavior).
+    
+    Args:
+        start_dir: Starting directory (default: current working directory)
+        
+    Returns:
+        Absolute path to workspace root containing .beads/*.db, or None if not found
+    """
+    import glob
+    
+    try:
+        current = os.path.abspath(start_dir or os.getcwd())
+        
+        # Resolve symlinks like Go CLI does
+        try:
+            current = os.path.realpath(current)
+        except Exception:
+            pass
+        
+        # Walk up directory tree
+        while True:
+            beads_dir = os.path.join(current, ".beads")
+            if os.path.isdir(beads_dir):
+                # Find any .db file in .beads/ (excluding backups)
+                db_files = glob.glob(os.path.join(beads_dir, "*.db"))
+                valid_dbs = [f for f in db_files if ".backup" not in os.path.basename(f)]
+                
+                if valid_dbs:
+                    # Return workspace root (parent of .beads), not the db path
+                    return current
+            
+            parent = os.path.dirname(current)
+            if parent == current:  # Reached filesystem root
+                break
+            current = parent
+        
+        return None
+        
+    except Exception as e:
+        logger.debug(f"Failed to search for .beads in tree: {e}")
+        return None
+
+
 def _resolve_workspace_root(path: str) -> str:
     """Resolve workspace root to git repo root if inside a git repo.
     
@@ -181,8 +225,11 @@ async def _get_client() -> BdClientBase:
     """Get a BdClient instance for the current workspace.
     
     Uses connection pool to manage per-project daemon sockets.
-    Workspace is determined by current_workspace ContextVar or BEADS_WORKING_DIR env.
-
+    Workspace is auto-detected using the same logic as CLI:
+    1. current_workspace ContextVar (from workspace_root parameter)
+    2. BEADS_WORKING_DIR environment variable
+    3. Walk up from CWD looking for .beads/*.db
+    
     Performs health check before returning cached client.
     On failure, drops from pool and attempts reconnection with exponential backoff.
     
@@ -193,13 +240,23 @@ async def _get_client() -> BdClientBase:
         Configured BdClientBase instance for the current workspace
 
     Raises:
-        BdError: If no workspace is set, or bd is not installed, or version is incompatible
+        BdError: If no workspace found, or bd is not installed, or version is incompatible
     """
-    # Determine workspace from ContextVar or environment
+    # Determine workspace using standard search order (matches Go CLI)
     workspace = current_workspace.get() or os.environ.get("BEADS_WORKING_DIR")
+    
+    # Auto-detect from CWD if not explicitly set (NEW!)
+    if not workspace:
+        workspace = _find_beads_db_in_tree()
+        if workspace:
+            logger.debug(f"Auto-detected workspace from CWD: {workspace}")
+    
     if not workspace:
         raise BdError(
-            "No workspace set. Either provide workspace_root parameter or call set_context() first."
+            "No beads workspace found. Either:\n"
+            "  1. Call set_context(workspace_root=\"/path/to/project\"), OR\n"
+            "  2. Run from a directory containing .beads/, OR\n"
+            "  3. Set BEADS_WORKING_DIR environment variable"
         )
     
     # Canonicalize path to handle symlinks and deduplicate connections

integrations/beads-mcp/tests/test_daemon_health_check.py

@@ -299,5 +299,7 @@ async def test_get_client_no_workspace_error():
     tools.current_workspace.set(None)
     
     with patch.dict('os.environ', {}, clear=True):
-        with pytest.raises(BdError, match="No workspace set"):
-            await _get_client()
+        # Mock auto-detection to fail
+        with patch("beads_mcp.tools._find_beads_db_in_tree", return_value=None):
+            with pytest.raises(BdError, match="No beads workspace found"):
+                await _get_client()

integrations/beads-mcp/tests/test_multi_project_switching.py

@@ -430,16 +430,18 @@ class TestEdgeCases:
     async def test_no_workspace_raises_error(self):
         """Test calling without workspace raises helpful error."""
         import os
+        from beads_mcp import tools
         
-        # Clear env
+        # Clear context and env
+        tools.current_workspace.set(None)
         os.environ.pop("BEADS_WORKING_DIR", None)
         
-        # No ContextVar set, no env var
+        # No ContextVar set, no env var, and auto-detect fails
         with pytest.raises(Exception) as exc_info:
-            with patch("beads_mcp.tools.create_bd_client") as mock_create:
+            with patch("beads_mcp.tools._find_beads_db_in_tree", return_value=None):
                 await beads_ready_work()
         
-        assert "No workspace set" in str(exc_info.value)
+        assert "No beads workspace found" in str(exc_info.value)
     
     def test_canonicalize_path_cached(self, temp_projects):
         """Test path canonicalization is cached for performance."""

integrations/beads-mcp/tests/test_workspace_auto_detect.py

@@ -0,0 +1,156 @@
+"""Test workspace auto-detection from CWD (bd-8zf2)."""
+
+import os
+import pytest
+import tempfile
+from pathlib import Path
+from unittest.mock import AsyncMock, patch
+
+from beads_mcp.tools import _find_beads_db_in_tree, _get_client, current_workspace
+from beads_mcp.bd_client import BdError
+
+
+def test_find_beads_db_in_tree_direct():
+    """Test finding .beads in current directory."""
+    with tempfile.TemporaryDirectory() as tmpdir:
+        # Create .beads/beads.db
+        beads_dir = Path(tmpdir) / ".beads"
+        beads_dir.mkdir()
+        (beads_dir / "beads.db").touch()
+        
+        # Should find workspace root (use realpath for macOS symlink resolution)
+        result = _find_beads_db_in_tree(tmpdir)
+        assert result == os.path.realpath(tmpdir)
+
+
+def test_find_beads_db_in_tree_parent():
+    """Test finding .beads in parent directory."""
+    with tempfile.TemporaryDirectory() as tmpdir:
+        # Create .beads/beads.db in root
+        beads_dir = Path(tmpdir) / ".beads"
+        beads_dir.mkdir()
+        (beads_dir / "beads.db").touch()
+        
+        # Create subdirectory
+        subdir = Path(tmpdir) / "subdir" / "deep"
+        subdir.mkdir(parents=True)
+        
+        # Should find workspace root (walks up from subdir)
+        result = _find_beads_db_in_tree(str(subdir))
+        assert result == os.path.realpath(tmpdir)
+
+
+def test_find_beads_db_in_tree_not_found():
+    """Test when no .beads directory exists."""
+    with tempfile.TemporaryDirectory() as tmpdir:
+        # No .beads directory
+        result = _find_beads_db_in_tree(tmpdir)
+        assert result is None
+
+
+def test_find_beads_db_excludes_backups():
+    """Test that backup .db files are ignored."""
+    with tempfile.TemporaryDirectory() as tmpdir:
+        beads_dir = Path(tmpdir) / ".beads"
+        beads_dir.mkdir()
+        
+        # Only backup file exists
+        (beads_dir / "beads.db.backup").touch()
+        
+        result = _find_beads_db_in_tree(tmpdir)
+        assert result is None  # Should not find backup files
+        
+        # Add valid db file
+        (beads_dir / "beads.db").touch()
+        result = _find_beads_db_in_tree(tmpdir)
+        assert result == os.path.realpath(tmpdir)
+
+
+@pytest.mark.asyncio
+async def test_get_client_auto_detect_from_cwd():
+    """Test that _get_client() auto-detects workspace from CWD."""
+    with tempfile.TemporaryDirectory() as tmpdir:
+        # Create .beads/beads.db
+        beads_dir = Path(tmpdir) / ".beads"
+        beads_dir.mkdir()
+        (beads_dir / "beads.db").touch()
+        
+        # Reset ContextVar for this test
+        token = current_workspace.set(None)
+        try:
+            with patch.dict(os.environ, {}, clear=True):
+                # Mock _find_beads_db_in_tree to return our tmpdir
+                with patch("beads_mcp.tools._find_beads_db_in_tree", return_value=tmpdir):
+                    # Mock create_bd_client to avoid actual connection
+                    mock_client = AsyncMock()
+                    mock_client.ping = AsyncMock(return_value=None)
+                    
+                    with patch("beads_mcp.tools.create_bd_client", return_value=mock_client):
+                        # Should auto-detect and not raise error
+                        client = await _get_client()
+                        assert client is not None
+        finally:
+            current_workspace.reset(token)
+
+
+@pytest.mark.asyncio
+async def test_get_client_no_workspace_found():
+    """Test that _get_client() raises helpful error when no workspace found."""
+    # Reset ContextVar for this test
+    token = current_workspace.set(None)
+    try:
+        with patch.dict(os.environ, {}, clear=True):
+            with patch("beads_mcp.tools._find_beads_db_in_tree", return_value=None):
+                with pytest.raises(BdError) as exc_info:
+                    await _get_client()
+                
+                # Verify error message is helpful
+                error_msg = str(exc_info.value)
+                assert "No beads workspace found" in error_msg
+                assert "set_context" in error_msg
+                assert ".beads/" in error_msg
+    finally:
+        current_workspace.reset(token)
+
+
+@pytest.mark.asyncio
+async def test_get_client_prefers_context_var_over_auto_detect():
+    """Test that explicit workspace_root parameter takes precedence."""
+    explicit_workspace = "/explicit/path"
+    
+    token = current_workspace.set(explicit_workspace)
+    try:
+        with patch("beads_mcp.tools._canonicalize_path", return_value=explicit_workspace):
+            mock_client = AsyncMock()
+            mock_client.ping = AsyncMock(return_value=None)
+            
+            with patch("beads_mcp.tools.create_bd_client", return_value=mock_client) as mock_create:
+                client = await _get_client()
+                
+                # Should use explicit workspace, not auto-detect
+                mock_create.assert_called_once()
+                # The working_dir parameter should be the canonicalized explicit path
+                assert mock_create.call_args[1]["working_dir"] == explicit_workspace
+    finally:
+        current_workspace.reset(token)
+
+
+@pytest.mark.asyncio  
+async def test_get_client_env_var_over_auto_detect():
+    """Test that BEADS_WORKING_DIR env var takes precedence over auto-detect."""
+    env_workspace = "/env/path"
+    
+    token = current_workspace.set(None)
+    try:
+        with patch.dict(os.environ, {"BEADS_WORKING_DIR": env_workspace}):
+            with patch("beads_mcp.tools._canonicalize_path", return_value=env_workspace):
+                mock_client = AsyncMock()
+                mock_client.ping = AsyncMock(return_value=None)
+                
+                with patch("beads_mcp.tools.create_bd_client", return_value=mock_client):
+                    client = await _get_client()
+                    
+                    # Should use env var, not call auto-detect
+                    assert client is not None
+    finally:
+        current_workspace.reset(token)