fix: skip orphan .find-replace-* temp files during walks

file_handling.go

@@ -98,18 +98,33 @@ func (f *File) Write(content string) error {
 		return err
 	}
 
-	tempName := filepath.Join(f.Dir(), RandomString(20))
-	if err := os.WriteFile(tempName, []byte(content), mode); err != nil {
+	tempFile, err := os.CreateTemp(f.Dir(), ".find-replace-*")
+	if err != nil {
 		return fmt.Errorf("create tempfile in %v: %w", f.Dir(), err)
 	}
-	// Make sure the temp file is removed if the rename below fails. On
-	// success, the rename has already moved the file to f.Path so this is
-	// a no-op (we deliberately ignore the not-exist error).
-	defer os.Remove(tempName)
+	tempName := tempFile.Name()
+	removeTemp := true
+	defer func() {
+		if removeTemp {
+			_ = os.Remove(tempName)
+		}
+	}()
+	if err := tempFile.Chmod(mode); err != nil {
+		_ = tempFile.Close()
+		return fmt.Errorf("chmod temp file %v: %w", tempName, err)
+	}
+	if _, err := tempFile.WriteString(content); err != nil {
+		_ = tempFile.Close()
+		return fmt.Errorf("write temp file %v: %w", tempName, err)
+	}
+	if err := tempFile.Close(); err != nil {
+		return fmt.Errorf("close temp file %v: %w", tempName, err)
+	}
 
 	log.Printf("Rewriting %v", f.Path)
 	if err := os.Rename(tempName, f.Path); err != nil {
 		return fmt.Errorf("atomically move temp file %v to %v: %w", tempName, f.Path, err)
 	}
+	removeTemp = false
 	return nil
 }

file_handling_test.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"os"
 	"path/filepath"
 	"testing"
 )
@@ -77,3 +78,28 @@ func TestNewFile(t *testing.T) {
 		})
 	}
 }
+
+func TestWriteUsesCreateTempPrefix(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "target.txt")
+	if err := os.WriteFile(path, []byte("old"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	f, err := NewFile(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := f.Write("new"); err != nil {
+		t.Fatal(err)
+	}
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, e := range entries {
+		if e.Name() != "target.txt" {
+			t.Fatalf("unexpected leftover file %q", e.Name())
+		}
+	}
+}
+

find_replace.go

@@ -124,6 +124,9 @@ func (fr *findReplace) WalkDir(f *File) {
 	}
 
 	for _, file := range files {
+		if strings.HasPrefix(file.Name(), ".find-replace-") {
+			continue
+		}
 		childPath := filepath.Join(f.Path, file.Name())
 		childFile, err := NewFile(childPath)
 		if err != nil {
@@ -156,6 +159,10 @@ func (fr *findReplace) HandleFile(f *File) error {
 		return err
 	}
 
+	if strings.HasPrefix(f.Base(), ".find-replace-") {
+		return nil
+	}
+
 	// If file is a directory, recurse immediately (depth-first).
 	if info.IsDir() {
 		// Ignore certain directories

find_replace_test.go

@@ -684,3 +684,42 @@ func BenchmarkNova(b *testing.B) {
 		fr.WalkDir(d)
 	}
 }
+
+func TestSkipStaleTempFiles(t *testing.T) {
+	dir := t.TempDir()
+	if err := os.WriteFile(filepath.Join(dir, "keep.txt"), []byte("alpha"), 0644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(dir, ".find-replace-stale"), []byte("alpha"), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	orig, err := os.Getwd()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := os.Chdir(dir); err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() { _ = os.Chdir(orig) })
+
+	code := run([]string{"find-replace", "alpha", "beta"}, ioDiscard{t})
+	if code != 0 {
+		t.Fatalf("run exit = %d; want 0", code)
+	}
+
+	if _, err := os.Stat(filepath.Join(dir, ".find-replace-stale")); err != nil {
+		t.Fatalf("stale temp file should remain untouched: %v", err)
+	}
+	got, err := os.ReadFile(filepath.Join(dir, "keep.txt"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(got) != "beta" {
+		t.Fatalf("keep.txt = %q; want beta", got)
+	}
+}
+
+type ioDiscard struct{ t *testing.T }
+
+func (d ioDiscard) Write(p []byte) (int, error) { return len(p), nil }