chore: include complete dc refactor implementation and audits

internal/executor/edit_test.go

@@ -0,0 +1,52 @@
+package executor
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestEditBlockUniqueAndAtomic(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "config.txt")
+	if err := os.WriteFile(path, []byte("a\nTARGET\nz\n"), 0640); err != nil {
+		t.Fatal(err)
+	}
+	res, err := EditBlock(path, "TARGET", "CHANGED")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if res.BytesWritten != int64(len("a\nCHANGED\nz\n")) {
+		t.Fatalf("bytes=%d", res.BytesWritten)
+	}
+	got, _ := os.ReadFile(path)
+	if string(got) != "a\nCHANGED\nz\n" {
+		t.Fatalf("content=%q", got)
+	}
+	info, _ := os.Stat(path)
+	if info.Mode().Perm() != 0640 {
+		t.Fatalf("mode=%o, want 0640", info.Mode().Perm())
+	}
+}
+
+func TestEditBlockRejectsZeroAndMultipleMatchesWithoutMutation(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "config.txt")
+	original := "TARGET\nother\nTARGET\n"
+	if err := os.WriteFile(path, []byte(original), 0644); err != nil {
+		t.Fatal(err)
+	}
+	_, err := EditBlock(path, "MISSING", "x")
+	if !errors.Is(err, ErrBlockNotUnique) {
+		t.Fatalf("missing match error=%v", err)
+	}
+	_, err = EditBlock(path, "TARGET", "x")
+	if !errors.Is(err, ErrBlockNotUnique) {
+		t.Fatalf("multiple match error=%v", err)
+	}
+	got, _ := os.ReadFile(path)
+	if string(got) != original {
+		t.Fatalf("file mutated after rejected edit: %q", got)
+	}
+}