Use Unicode case folding for author search

go.mod

@@ -6,6 +6,7 @@ require (
 	github.com/charmbracelet/bubbles v0.20.0
 	github.com/charmbracelet/bubbletea v1.2.4
 	github.com/charmbracelet/lipgloss v1.0.0
+	golang.org/x/text v0.22.0
 )
 
 require (
@@ -24,5 +25,4 @@ require (
 	github.com/rivo/uniseg v0.4.7 // indirect
 	golang.org/x/sync v0.11.0 // indirect
 	golang.org/x/sys v0.30.0 // indirect
-	golang.org/x/text v0.22.0 // indirect
 )

tui.go

@@ -11,6 +11,7 @@ import (
 	"github.com/charmbracelet/bubbles/textinput"
 	tea "github.com/charmbracelet/bubbletea"
 	"github.com/charmbracelet/lipgloss"
+	"golang.org/x/text/cases"
 )
 
 const (
@@ -1246,6 +1247,8 @@ func stageAuthorReplacement(commits []CommitRecord, draftByHash map[string]Commi
 	if replacementEmail == "" {
 		return 0, errors.New("replacement author email is required")
 	}
+	fold := cases.Fold()
+	foldedQuery := fold.String(query)
 	matched := 0
 	for _, commit := range commits {
 		draft, ok := draftByHash[commit.Hash]
@@ -1255,9 +1258,8 @@ func stageAuthorReplacement(commits []CommitRecord, draftByHash map[string]Commi
 		nameMatches := strings.EqualFold(draft.AuthorName, query)
 		emailMatches := strings.EqualFold(draft.AuthorEmail, query)
 		if !exact {
-			lowerQuery := strings.ToLower(query)
-			nameMatches = strings.Contains(strings.ToLower(draft.AuthorName), lowerQuery)
-			emailMatches = strings.Contains(strings.ToLower(draft.AuthorEmail), lowerQuery)
+			nameMatches = strings.Contains(fold.String(draft.AuthorName), foldedQuery)
+			emailMatches = strings.Contains(fold.String(draft.AuthorEmail), foldedQuery)
 		}
 		if !nameMatches && !emailMatches {
 			continue

tui_test.go

@@ -90,6 +90,24 @@ func TestStageAuthorReplacementExactModeRequiresWholeFieldMatch(t *testing.T) {
 	}
 }
 
+func TestStageAuthorReplacementPartialModeUsesUnicodeCaseFolding(t *testing.T) {
+	commits := []CommitRecord{
+		{Hash: "greek", AuthorName: "Σωκράτης", AuthorEmail: "socrates@example.com"},
+	}
+	drafts := cloneMapByHash(commits)
+
+	matched, err := stageAuthorReplacement(commits, drafts, "ΣΩΚΡΆΤΗΣ", "Socrates", "new@example.com", false)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if matched != 1 {
+		t.Fatalf("expected Unicode case variants to match, got %d matches", matched)
+	}
+	if got := drafts["greek"]; got.AuthorName != "Socrates" || got.AuthorEmail != "new@example.com" {
+		t.Fatalf("expected Unicode author identity to be replaced, got %#v", got)
+	}
+}
+
 func TestStageAuthorReplacementRejectsBlankInputsWithoutChangingDrafts(t *testing.T) {
 	commits := []CommitRecord{{Hash: "one", AuthorName: "Foo Bar", AuthorEmail: "foo@bar.baz"}}
 	tests := []struct {