Add configurable sequence numbering command

tests/integration/sequence_flow_test.go

@@ -0,0 +1,70 @@
+package integration
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/rogeecn/renamer/internal/history"
+	"github.com/rogeecn/renamer/internal/sequence"
+)
+
+func TestSequenceApplyAndUndo(t *testing.T) {
+	tmp := t.TempDir()
+
+	createIntegrationFile(t, filepath.Join(tmp, "draft.txt"))
+	createIntegrationFile(t, filepath.Join(tmp, "notes.txt"))
+
+	opts := sequence.DefaultOptions()
+	opts.WorkingDir = tmp
+
+	plan, err := sequence.Preview(context.Background(), opts, nil)
+	if err != nil {
+		t.Fatalf("preview error: %v", err)
+	}
+
+	if plan.Summary.RenamedCount != 2 {
+		t.Fatalf("expected 2 planned renames, got %d", plan.Summary.RenamedCount)
+	}
+
+	entry, err := sequence.Apply(context.Background(), opts, plan)
+	if err != nil {
+		t.Fatalf("apply error: %v", err)
+	}
+
+	if len(entry.Operations) != 2 {
+		t.Fatalf("expected 2 recorded operations, got %d", len(entry.Operations))
+	}
+	if entry.Command != "sequence" {
+		t.Fatalf("expected ledger command 'sequence', got %s", entry.Command)
+	}
+
+	if _, err := os.Stat(filepath.Join(tmp, "001_draft.txt")); err != nil {
+		t.Fatalf("expected renamed file exists: %v", err)
+	}
+	if _, err := os.Stat(filepath.Join(tmp, "002_notes.txt")); err != nil {
+		t.Fatalf("expected renamed file exists: %v", err)
+	}
+
+	if _, err := history.Undo(tmp); err != nil {
+		t.Fatalf("undo error: %v", err)
+	}
+
+	if _, err := os.Stat(filepath.Join(tmp, "draft.txt")); err != nil {
+		t.Fatalf("expected original file after undo: %v", err)
+	}
+	if _, err := os.Stat(filepath.Join(tmp, "notes.txt")); err != nil {
+		t.Fatalf("expected original file after undo: %v", err)
+	}
+}
+
+func createIntegrationFile(t *testing.T, path string) {
+	t.Helper()
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		t.Fatalf("mkdir %s: %v", path, err)
+	}
+	if err := os.WriteFile(path, []byte("data"), 0o644); err != nil {
+		t.Fatalf("write file %s: %v", path, err)
+	}
+}