fix(render): set and unset RUNEWIDTH_EASTASIAN in program lifetime

tea.go

@@ -20,6 +20,8 @@ import (
 	"sync"
 	"syscall"
 
+	"github.com/charmbracelet/log"
+
 	"github.com/containerd/console"
 	isatty "github.com/mattn/go-isatty"
 	"github.com/muesli/cancelreader"
@@ -169,6 +171,11 @@ type Program struct {
 	// fps is the frames per second we should set on the renderer, if
 	// applicable,
 	fps int
+
+	// We initialize RUNEWIDTH_EASTASIAN to resolve runewidth conflicts. This
+	// value will be hold the original value of the environment variable on
+	// startup, so we can reset it on program shutdown.
+	runewidthEastAsian string
 }
 
 // Quit is a special command that tells the Bubble Tea program to exit.
@@ -406,6 +413,10 @@ func (p *Program) eventLoop(model Model, cmds chan Cmd) (Model, error) {
 // terminated by either [Program.Quit], [Program.Kill], or its signal handler.
 // Returns the final model.
 func (p *Program) Run() (Model, error) {
+	p.runewidthEastAsian = os.Getenv("RUNEWIDTH_EASTASIAN")
+	if err := os.Setenv("RUNEWIDTH_EASTASIAN", "0"); err != nil {
+		log.Error("Unable to set RUNEWIDTH_EASTASIAN environment variable; it should be set to true for compatiblity purposes", "err", err)
+	}
 	handlers := handlers{}
 	cmds := make(chan Cmd)
 	p.errs = make(chan error)
@@ -596,13 +607,19 @@ func (p *Program) Send(msg Msg) {
 // If the program is not running this will be a no-op, so it's safe to call
 // if the program is unstarted or has already exited.
 func (p *Program) Quit() {
+	if err := os.Setenv("RUNEWIDTH_EASTASIAN", p.runewidthEastAsian); err != nil {
+		log.Error("Unable to unset RUNEWIDTH_EASTASIAN environment variable; it is set to true for compatiblity purposes", "err", err)
+	}
 	p.Send(Quit())
 }
 
 // Kill stops the program immediately and restores the former terminal state.
 // The final render that you would normally see when quitting will be skipped.
 // [program.Run] returns a [ErrProgramKilled] error.
 func (p *Program) Kill() {
+	if err := os.Setenv("RUNEWIDTH_EASTASIAN", p.runewidthEastAsian); err != nil {
+		log.Error("Unable to unset RUNEWIDTH_EASTASIAN environment variable; it is set to true for compatiblity purposes", "err", err)
+	}
 	p.cancel()
 }