feat: add kitty keyboard uniform key layout support

This uses kitty keyboard protocol "Report alternate keys" and "Report
all keys as escape codes" to report key events as though they were on a
PC-101 layout. This is useful for uniform key event reporting across
different keyboard layouts.

keyboard.go

@@ -50,6 +50,17 @@ func WithKeyReleases(k *keyboardEnhancements) {
 	k.kittyFlags |= ansi.KittyReportEventTypes
 }
 
+// WithUniformKeyLayout enables support for reporting key events as though they
+// were on a PC-101 layout. This is useful for uniform key event reporting
+// across different keyboard layouts. This is equivalent to the Kitty keyboard
+// protocol "Report alternate keys" and "Report all keys as escape codes"
+// progressive enhancement features.
+//
+// Note that not all terminals support this feature.
+func WithUniformKeyLayout(k *keyboardEnhancements) {
+	k.kittyFlags |= ansi.KittyReportAlternateKeys | ansi.KittyReportAllKeysAsEscapeCodes
+}
+
 // withKeyDisambiguation enables support for disambiguating keyboard escape
 // codes. This is useful for terminals that support the Kitty keyboard protocol
 // "Disambiguate escape codes" progressive enhancement feature or the XTerm
@@ -102,3 +113,16 @@ func (k KeyboardEnhancementsMsg) SupportsKeyReleases() bool {
 	}
 	return k.kittyFlags&ansi.KittyReportEventTypes != 0
 }
+
+// SupportsKeyBaseLayout returns whether the terminal supports reporting key
+// events as though they were on a PC-101 layout.
+func (k KeyboardEnhancementsMsg) SupportsUniformKeyLayout() bool {
+	if runtime.GOOS == "windows" {
+		// We use Windows Console API which supports reporting key events as
+		// though they were on a PC-101 layout.
+		return true
+	}
+	return k.SupportsKeyDisambiguation() &&
+		k.kittyFlags&ansi.KittyReportAlternateKeys != 0 &&
+		k.kittyFlags&ansi.KittyReportAllKeysAsEscapeCodes != 0
+}

kitty.go

@@ -181,7 +181,7 @@ func fromKittyMod(mod int) KeyMod {
 //	CSI unicode-key-code:alternate-key-codes ; modifiers:event-type ; text-as-codepoints u
 //
 // See https://sw.kovidgoyal.net/kitty/keyboard-protocol/
-func parseKittyKeyboard(csi *ansi.CsiSequence) Msg {
+func parseKittyKeyboard(csi *ansi.CsiSequence) (msg Msg) {
 	var isRelease bool
 	key := Key{}
 
@@ -253,6 +253,12 @@ func parseKittyKeyboard(csi *ansi.CsiSequence) Msg {
 		}
 	}
 
+	if key.Mod == ModShift && key.ShiftedCode == 0 {
+		if unicode.IsLower(key.Code) {
+			key.ShiftedCode = unicode.ToUpper(key.Code)
+		}
+	}
+
 	noneOrShifted := key.Mod <= ModShift && key.Code != KeyLeftShift && key.Code != KeyRightShift
 	if len(key.Text) == 0 && noneOrShifted {
 		if key.ShiftedCode != 0 && unicode.IsPrint(key.ShiftedCode) {

tea.go

@@ -17,6 +17,7 @@ import (
 	"io"
 	"os"
 	"os/signal"
+	"runtime"
 	"runtime/debug"
 	"sync"
 	"sync/atomic"
@@ -476,6 +477,12 @@ func (p *Program) eventLoop(model Model, cmds chan Cmd) (Model, error) {
 				}
 
 			case enableKeyboardEnhancementsMsg:
+				if runtime.GOOS == "windows" {
+					// We use the Windows Console API which supports keyboard
+					// enhancements.
+					break
+				}
+
 				var ke keyboardEnhancements
 				for _, e := range msg {
 					e(&ke)
@@ -494,6 +501,12 @@ func (p *Program) eventLoop(model Model, cmds chan Cmd) (Model, error) {
 				}
 
 			case disableKeyboardEnhancementsMsg:
+				if runtime.GOOS == "windows" {
+					// We use the Windows Console API which supports keyboard
+					// enhancements.
+					break
+				}
+
 				if p.keyboard.modifyOtherKeys > 0 {
 					p.execute(ansi.DisableModifyOtherKeys)
 					p.keyboard.modifyOtherKeys = 0
@@ -706,7 +719,10 @@ func (p *Program) Run() (Model, error) {
 		p.execute(ansi.EnableReportFocus)
 		p.modes[ansi.ReportFocusMode] = true
 	}
-	if p.startupOptions&withKeyboardEnhancements != 0 {
+	if p.startupOptions&withKeyboardEnhancements != 0 && runtime.GOOS != "windows" {
+		// We use the Windows Console API which supports keyboard
+		// enhancements.
+
 		if p.keyboard.modifyOtherKeys > 0 {
 			p.execute(ansi.ModifyOtherKeys(p.keyboard.modifyOtherKeys))
 			p.execute(ansi.RequestModifyOtherKeys)