add ai feature

tests/contract/ai_command_preview_test.go

@@ -0,0 +1,48 @@
+package contract
+
+import (
+	"bytes"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/rogeecn/renamer/cmd"
+)
+
+func TestAICommandPreviewTable(t *testing.T) {
+	t.Setenv("RENAMER_AI_KEY", "test-key")
+
+	tmp := t.TempDir()
+	createFile(t, filepath.Join(tmp, "IMG_0001.jpg"))
+	createFile(t, filepath.Join(tmp, "trip-notes.txt"))
+
+	root := cmd.NewRootCommand()
+	root.SetArgs([]string{"ai", "--path", tmp, "--prompt", "Travel Memories", "--dry-run"})
+
+	var buf bytes.Buffer
+	root.SetIn(strings.NewReader("\n"))
+	root.SetOut(&buf)
+	root.SetErr(&buf)
+
+	if err := root.Execute(); err != nil {
+		t.Fatalf("ai command returned error: %v\noutput: %s", err, buf.String())
+	}
+
+	output := buf.String()
+
+	if !strings.Contains(output, "IMG_0001.jpg") {
+		t.Fatalf("expected original filename in preview, got: %s", output)
+	}
+
+	if !strings.Contains(output, "trip-notes.txt") {
+		t.Fatalf("expected secondary filename in preview, got: %s", output)
+	}
+
+	if !strings.Contains(output, "01.travel-memories-img-0001.jpg") {
+		t.Fatalf("expected deterministic suggestion in preview, got: %s", output)
+	}
+
+	if !strings.Contains(output, "02.travel-memories-trip-notes.txt") {
+		t.Fatalf("expected sequential suggestion for second file, got: %s", output)
+	}
+}