Add unit tests for nodb.go and daemon/discovery.go

- Added tests for extractIssuePrefix, loadIssuesFromJSONL, detectPrefix, writeIssuesToJSONL
- Added tests for walkWithDepth depth limiting and hidden directory skipping
- Added tests for DiscoverDaemons registry and legacy discovery paths
- Improved test coverage for cmd/bd and internal/daemon

internal/daemon/discovery_test.go

@@ -115,3 +115,146 @@ func TestCleanupStaleSockets(t *testing.T) {
 		t.Error("stale socket still exists")
 	}
 }
+
+func TestWalkWithDepth(t *testing.T) {
+	tmpDir := t.TempDir()
+
+	// Create test directory structure
+	// tmpDir/
+	//   file1.txt
+	//   dir1/
+	//     file2.txt
+	//     dir2/
+	//       file3.txt
+	//       dir3/
+	//         file4.txt
+
+	os.WriteFile(filepath.Join(tmpDir, "file1.txt"), []byte("test"), 0644)
+	os.MkdirAll(filepath.Join(tmpDir, "dir1", "dir2", "dir3"), 0755)
+	os.WriteFile(filepath.Join(tmpDir, "dir1", "file2.txt"), []byte("test"), 0644)
+	os.WriteFile(filepath.Join(tmpDir, "dir1", "dir2", "file3.txt"), []byte("test"), 0644)
+	os.WriteFile(filepath.Join(tmpDir, "dir1", "dir2", "dir3", "file4.txt"), []byte("test"), 0644)
+
+	tests := []struct {
+		name      string
+		maxDepth  int
+		wantFiles int
+	}{
+		{"depth 0", 0, 1},        // Only file1.txt
+		{"depth 1", 1, 2},        // file1.txt, file2.txt
+		{"depth 2", 2, 3},        // file1.txt, file2.txt, file3.txt
+		{"depth 3", 3, 4},        // All files
+		{"depth 10", 10, 4},      // All files (max depth not reached)
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var foundFiles []string
+			fn := func(path string, info os.FileInfo) error {
+				if !info.IsDir() {
+					foundFiles = append(foundFiles, path)
+				}
+				return nil
+			}
+
+			err := walkWithDepth(tmpDir, 0, tt.maxDepth, fn)
+			if err != nil {
+				t.Fatalf("walkWithDepth failed: %v", err)
+			}
+
+			if len(foundFiles) != tt.wantFiles {
+				t.Errorf("Expected %d files, got %d: %v", tt.wantFiles, len(foundFiles), foundFiles)
+			}
+		})
+	}
+}
+
+func TestWalkWithDepth_SkipsHiddenDirs(t *testing.T) {
+	tmpDir := t.TempDir()
+
+	// Create hidden directories (should skip)
+	os.MkdirAll(filepath.Join(tmpDir, ".git"), 0755)
+	os.MkdirAll(filepath.Join(tmpDir, ".hidden"), 0755)
+	os.MkdirAll(filepath.Join(tmpDir, "node_modules"), 0755)
+	os.MkdirAll(filepath.Join(tmpDir, "vendor"), 0755)
+
+	// Create .beads directory (should NOT skip)
+	os.MkdirAll(filepath.Join(tmpDir, ".beads"), 0755)
+
+	// Add files
+	os.WriteFile(filepath.Join(tmpDir, ".git", "config"), []byte("test"), 0644)
+	os.WriteFile(filepath.Join(tmpDir, ".hidden", "secret"), []byte("test"), 0644)
+	os.WriteFile(filepath.Join(tmpDir, "node_modules", "package.json"), []byte("test"), 0644)
+	os.WriteFile(filepath.Join(tmpDir, ".beads", "beads.db"), []byte("test"), 0644)
+
+	var foundFiles []string
+	fn := func(path string, info os.FileInfo) error {
+		if !info.IsDir() {
+			foundFiles = append(foundFiles, filepath.Base(path))
+		}
+		return nil
+	}
+
+	err := walkWithDepth(tmpDir, 0, 5, fn)
+	if err != nil {
+		t.Fatalf("walkWithDepth failed: %v", err)
+	}
+
+	// Should only find beads.db from .beads directory
+	if len(foundFiles) != 1 || foundFiles[0] != "beads.db" {
+		t.Errorf("Expected only beads.db, got: %v", foundFiles)
+	}
+}
+
+func TestDiscoverDaemons_Registry(t *testing.T) {
+	// Test registry-based discovery (no search roots)
+	daemons, err := DiscoverDaemons(nil)
+	if err != nil {
+		t.Fatalf("DiscoverDaemons failed: %v", err)
+	}
+
+	// Should return empty list (no daemons running in test environment)
+	// Just verify it doesn't error
+	_ = daemons
+}
+
+func TestDiscoverDaemons_Legacy(t *testing.T) {
+	tmpDir := t.TempDir()
+	beadsDir := filepath.Join(tmpDir, ".beads")
+	os.MkdirAll(beadsDir, 0755)
+
+	// Start a test daemon
+	dbPath := filepath.Join(beadsDir, "test.db")
+	socketPath := filepath.Join(beadsDir, "bd.sock")
+	store, err := sqlite.New(dbPath)
+	if err != nil {
+		t.Fatalf("failed to create storage: %v", err)
+	}
+	defer store.Close()
+
+	server := rpc.NewServer(socketPath, store, tmpDir, dbPath)
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	go server.Start(ctx)
+	<-server.WaitReady()
+	defer server.Stop()
+
+	// Test legacy discovery with explicit search roots
+	daemons, err := DiscoverDaemons([]string{tmpDir})
+	if err != nil {
+		t.Fatalf("DiscoverDaemons failed: %v", err)
+	}
+
+	if len(daemons) != 1 {
+		t.Fatalf("Expected 1 daemon, got %d", len(daemons))
+	}
+
+	daemon := daemons[0]
+	if !daemon.Alive {
+		t.Errorf("Daemon not alive: %s", daemon.Error)
+	}
+	if daemon.WorkspacePath != tmpDir {
+		t.Errorf("Wrong workspace path: expected %s, got %s", tmpDir, daemon.WorkspacePath)
+	}
+}