fix(diff): compare normalized lines so CRLF-only differences are skipped (#11)

cmd/promptctl/main.go

@@ -23,6 +23,7 @@ import (
 	"os"
 	"path/filepath"
 	"regexp"
+	"slices"
 	"sort"
 	"strings"
 	"time"
@@ -136,17 +137,16 @@ func runDiff(r *git.Repository, ref string, w io.Writer) []fileVerdict {
 
 	var out []fileVerdict
 	for _, p := range promptUnion(tree) {
-		old := blobContent(tree, p)
-		neu := diskContent(p)
-		if old == neu {
+		a, b, differs := changedLines(blobContent(tree, p), diskContent(p))
+		if !differs {
 			continue
 		}
 		if _, err := tree.File(p); err != nil { // added since ref: nothing to diff against
 			fmt.Fprintf(w, "## %s\nnew prompt (not in %s)\n  => new\n\n", p, ref)
 			out = append(out, fileVerdict{p, "new"})
 			continue
 		}
-		res, err := semdiff.Analyze(emb, splitLines(old), splitLines(neu))
+		res, err := semdiff.Analyze(emb, a, b)
 		if err != nil {
 			log.Fatal(err)
 		}
@@ -549,3 +549,11 @@ func firstLine(s string) string {
 func splitLines(s string) []string {
 	return strings.Split(strings.ReplaceAll(s, "\r\n", "\n"), "\n")
 }
+
+// changedLines splits both versions into lines and reports whether they differ.
+// The comparison runs after splitLines normalises line endings, so a CRLF-only
+// difference (core.autocrlf on Windows) is not a change.
+func changedLines(old, neu string) (a, b []string, changed bool) {
+	a, b = splitLines(old), splitLines(neu)
+	return a, b, !slices.Equal(a, b)
+}

cmd/promptctl/main_test.go

@@ -12,6 +12,29 @@ func TestPathToURI(t *testing.T) {
 	}
 }
 
+func TestChangedLines(t *testing.T) {
+	cases := []struct {
+		name, old, neu string
+		want           bool
+	}{
+		{"identical", "a\nb\n", "a\nb\n", false},
+		{"crlf vs lf", "a\r\nb\r\n", "a\nb\n", false},
+		{"lf vs crlf", "a\nb\n", "a\r\nb\r\n", false},
+		{"mixed endings", "a\r\nb\n", "a\nb\r\n", false},
+		{"text change", "a\r\nb\r\n", "a\nc\n", true},
+		{"trailing newline added", "a\nb", "a\r\nb\r\n", true},
+	}
+	for _, c := range cases {
+		a, b, changed := changedLines(c.old, c.neu)
+		if changed != c.want {
+			t.Errorf("%s: changed = %v, want %v", c.name, changed, c.want)
+		}
+		if !reflect.DeepEqual(a, splitLines(c.old)) || !reflect.DeepEqual(b, splitLines(c.neu)) {
+			t.Errorf("%s: lines = %q, %q, want normalised split of inputs", c.name, a, b)
+		}
+	}
+}
+
 func TestDeriveSlots(t *testing.T) {
 	got := deriveSlots("Hi {name}, welcome to {org}. Bye {name}.")
 	if want := []string{"name", "org"}; !reflect.DeepEqual(got, want) { // deduped, in order