/{cmd,docs,internal,website}: make dolt backend explicitly single process

cmd/bd/daemon_guard.go

@@ -0,0 +1,66 @@
+package main
+
+import (
+	"fmt"
+	"path/filepath"
+	"strings"
+
+	"github.com/spf13/cobra"
+	"github.com/steveyegge/beads/internal/beads"
+	"github.com/steveyegge/beads/internal/configfile"
+)
+
+func singleProcessBackendHelp(backend string) string {
+	b := strings.TrimSpace(backend)
+	if b == "" {
+		b = "unknown"
+	}
+	// Keep this short; Cobra will prefix with "Error:".
+	return fmt.Sprintf("daemon mode is not supported with the %q backend (single-process only). To use daemon mode, initialize with %q (e.g. `bd init --backend sqlite`). Otherwise run commands in direct mode (default for dolt)", b, configfile.BackendSQLite)
+}
+
+// guardDaemonUnsupportedForDolt blocks all daemon-related commands when the current
+// workspace backend is Dolt.
+//
+// Rationale: embedded Dolt is effectively single-writer at the OS-process level. The
+// daemon architecture relies on multiple processes (CLI + daemon + helper spawns),
+// which can trigger lock contention and transient "read-only" failures.
+//
+// We still allow help output so users can discover the command surface.
+func guardDaemonUnsupportedForDolt(cmd *cobra.Command, _ []string) error {
+	// Allow `--help` for any daemon subcommand.
+	if helpFlag := cmd.Flags().Lookup("help"); helpFlag != nil {
+		if help, _ := cmd.Flags().GetBool("help"); help {
+			return nil
+		}
+	}
+
+	// Best-effort determine the active workspace backend. If we can't determine it,
+	// don't block (the command will likely fail later anyway).
+	beadsDir := beads.FindBeadsDir()
+	if beadsDir == "" {
+		// Fall back to configured dbPath if set; daemon commands often run from workspace root,
+		// but tests may set BEADS_DB explicitly.
+		if dbPath != "" {
+			beadsDir = filepath.Dir(dbPath)
+		} else if found := beads.FindDatabasePath(); found != "" {
+			beadsDir = filepath.Dir(found)
+		}
+	}
+	if beadsDir == "" {
+		return nil
+	}
+
+	cfg, err := configfile.Load(beadsDir)
+	if err != nil || cfg == nil {
+		return nil
+	}
+
+	backend := cfg.GetBackend()
+	if configfile.CapabilitiesForBackend(backend).SingleProcessOnly {
+		return fmt.Errorf("%s", singleProcessBackendHelp(backend))
+	}
+
+	return nil
+}
+