From 417e61da004c2fd080f30b994030d15372af5d1b Mon Sep 17 00:00:00 2001
From: Nils Stinnesbeck <git@stinnesbeck.com>
Date: Wed, 21 Oct 2026 11:38:04 +0200
Subject: [PATCH] Kitty graphics probe that works on macOS

Go cannot set a read deadline on a terminal device on macOS (kqueue does
not support them), so the probe failed at once and Ghostty and kitty got
block posters there. Wait for the answer with select(2) instead.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019reK4DUGYqDUjniWYJvwUW
---
 go.mod                    |  2 +-
 internal/ui/probe_unix.go | 37 ++++++++++++++++++++++++++++++-------
 2 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/go.mod b/go.mod
index 10ed047..7faf8e4 100644
--- a/go.mod
+++ b/go.mod
@@ -6,6 +6,7 @@ require (
 	github.com/gdamore/tcell/v2 v2.13.10
 	github.com/rivo/tview v0.42.0
 	golang.org/x/image v0.47.0
+	golang.org/x/sys v0.49.0
 	golang.org/x/term v0.37.0
 )
 
@@ -13,6 +14,5 @@ require (
 	github.com/gdamore/encoding v1.0.1 // indirect
 	github.com/lucasb-eyer/go-colorful v1.3.0 // indirect
 	github.com/rivo/uniseg v0.4.7 // indirect
-	golang.org/x/sys v0.49.0 // indirect
 	golang.org/x/text v0.43.0 // indirect
 )
diff --git a/internal/ui/probe_unix.go b/internal/ui/probe_unix.go
index a412352..56dff2e 100644
--- a/internal/ui/probe_unix.go
+++ b/internal/ui/probe_unix.go
@@ -4,9 +4,11 @@ package ui
 
 import (
 	"bytes"
+	"errors"
 	"os"
 	"time"
 
+	"golang.org/x/sys/unix"
 	"golang.org/x/term"
 )
 
@@ -36,13 +38,37 @@ func probeKittyGraphics(timeout time.Duration) bool {
 	// A terminal that does not know APC sequences may print the query; erase it.
 	defer tty.WriteString("\r\x1b[2K")
 
-	if err := tty.SetReadDeadline(time.Now().Add(timeout)); err != nil {
-		return false
-	}
+	// The wait uses select(2): a read deadline does not work on a terminal
+	// device on macOS (kqueue does not support them), which made the probe
+	// give up at once there.
+	deadline := time.Now().Add(timeout)
 	var got []byte
 	buf := make([]byte, 256)
 	for {
-		n, err := tty.Read(buf)
+		left := time.Until(deadline)
+		if left <= 0 {
+			return false // no answer in time: assume no support
+		}
+		var fds unix.FdSet
+		fds.Set(fd)
+		tv := unix.NsecToTimeval(left.Nanoseconds())
+		n, err := unix.Select(fd+1, &fds, nil, nil, &tv)
+		if errors.Is(err, unix.EINTR) {
+			continue
+		}
+		if err != nil {
+			return false
+		}
+		if n == 0 {
+			continue // timed out; the loop ends above
+		}
+		n, err = unix.Read(fd, buf)
+		if errors.Is(err, unix.EINTR) || errors.Is(err, unix.EAGAIN) {
+			continue
+		}
+		if err != nil || n <= 0 {
+			return false
+		}
 		got = append(got, buf[:n]...)
 		if bytes.Contains(got, []byte("_Gi=31;OK")) {
 			return true
@@ -50,8 +76,5 @@ func probeKittyGraphics(timeout time.Duration) bool {
 		if da := bytes.Index(got, []byte("\x1b[?")); da >= 0 && bytes.IndexByte(got[da:], 'c') >= 0 {
 			return false // device attributes answered, graphics query not
 		}
-		if err != nil {
-			return false // timeout or error: assume no support
-		}
 	}
 }