From d1faccdd1ce9fffb53f877215729a521f6748a1c Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Sun, 1 Jun 2025 12:51:59 +0530
Subject: [PATCH] Loop API print proper stack traces for panics in go routines

---
 kittens/choose_files/scan.go |  1 +
 kittens/diff/ui.go           |  5 +++++
 tools/tui/loop/api.go        | 18 ++++++++++++++----
 tools/tui/loop/run.go        |  3 +++
 4 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/kittens/choose_files/scan.go b/kittens/choose_files/scan.go
index aeedafd4e..fb4a22c47 100644
--- a/kittens/choose_files/scan.go
+++ b/kittens/choose_files/scan.go
@@ -229,6 +229,7 @@ func (h *Handler) get_results() (ans []*ResultItem, in_progress bool) {
 	sc.search_text = st
 	sp := h.state.ScorePatterns()
 	go func() {
+		defer h.lp.RecoverFromPanicInGoRoutine()
 		results := sc.scan(cd, st, sp)
 		sc.mutex.Lock()
 		defer sc.mutex.Unlock()
diff --git a/kittens/diff/ui.go b/kittens/diff/ui.go
index a5737958b..4c0738c4e 100644
--- a/kittens/diff/ui.go
+++ b/kittens/diff/ui.go
@@ -171,6 +171,7 @@ func (self *Handler) initialize() {
 	self.original_context_count = self.current_context_count
 	self.async_results = make(chan AsyncResult, 32)
 	go func() {
+		self.lp.RecoverFromPanicInGoRoutine()
 		r := AsyncResult{}
 		r.collection, r.err = create_collection(self.left, self.right)
 		self.async_results <- r
@@ -191,6 +192,7 @@ func (self *Handler) generate_diff() {
 		return nil
 	})
 	go func() {
+		self.lp.RecoverFromPanicInGoRoutine()
 		r := AsyncResult{rtype: DIFF}
 		r.diff_map, r.err = diff(jobs, self.current_context_count)
 		self.async_results <- r
@@ -230,6 +232,7 @@ func (self *Handler) highlight_all() {
 	}
 	text_files := utils.Filter(self.collection.paths_to_highlight.AsSlice(), is_path_text)
 	go func() {
+		self.lp.RecoverFromPanicInGoRoutine()
 		r := AsyncResult{rtype: HIGHLIGHT}
 		highlight_all(text_files, use_light_colors)
 		self.async_results <- r
@@ -252,6 +255,7 @@ func (self *Handler) load_all_images() {
 	if self.image_count > 0 {
 		image_collection.Initialize(self.lp)
 		go func() {
+			self.lp.RecoverFromPanicInGoRoutine()
 			r := AsyncResult{rtype: IMAGE_LOAD}
 			image_collection.LoadAll()
 			self.async_results <- r
@@ -273,6 +277,7 @@ func (self *Handler) resize_all_images_if_needed() {
 	}
 	if sz != self.images_resized_to && self.image_count > 0 {
 		go func() {
+			self.lp.RecoverFromPanicInGoRoutine()
 			image_collection.ResizeForPageSize(sz.Width, sz.Height)
 			r := AsyncResult{rtype: IMAGE_RESIZE, page_size: sz}
 			self.async_results <- r
diff --git a/tools/tui/loop/api.go b/tools/tui/loop/api.go
index 7c83dbc4b..7c4136d9c 100644
--- a/tools/tui/loop/api.go
+++ b/tools/tui/loop/api.go
@@ -49,6 +49,7 @@ type Loop struct {
 	timers, timers_temp                    []*timer
 	timer_id_counter, write_msg_id_counter IdType
 	wakeup_channel                         chan byte
+	panic_channel                          chan any
 	pending_writes                         []write_msg
 	tty_write_channel                      chan write_msg
 	pending_mouse_events                   *utils.RingBuffer[MouseEvent]
@@ -328,11 +329,14 @@ func (self *Loop) Run() (err error) {
 				lines = append(lines, fmt.Sprintf("%s\r\n\t%s:%d\r\n", frame.Function, frame.File, frame.Line))
 			}
 			text := strings.Join(lines, "")
-			os.Stderr.WriteString(text)
 			tty.DebugPrintln(strings.TrimSpace(text))
-			if self.terminal_options.Alternate_screen {
-				term, err := tty.OpenControllingTerm(tty.SetRaw)
-				if err == nil {
+			is_terminal := tty.IsTerminal(os.Stderr.Fd())
+			if is_terminal {
+				os.Stderr.WriteString("\x1b]\x1b\\\x1bc\x1b[H\x1b[2J") // reset terminal
+			}
+			os.Stderr.WriteString(text)
+			if is_terminal {
+				if term, err := tty.OpenControllingTerm(tty.SetRaw); err == nil {
 					defer term.RestoreAndClose()
 					fmt.Println("Press any key to exit.\r")
 					buf := make([]byte, 16)
@@ -588,6 +592,12 @@ type SizedText struct {
 	Width                                           int
 }
 
+func (self *Loop) RecoverFromPanicInGoRoutine() {
+	if r := recover(); r != nil {
+		self.panic_channel <- r
+	}
+}
+
 func (self *Loop) DrawSizedText(text string, spec SizedText) {
 	b := strings.Builder{}
 	b.Grow(len(text) + 24)
diff --git a/tools/tui/loop/run.go b/tools/tui/loop/run.go
index 76aaca346..8f8b2d3db 100644
--- a/tools/tui/loop/run.go
+++ b/tools/tui/loop/run.go
@@ -394,6 +394,7 @@ func (self *Loop) run() (err error) {
 	self.write_msg_id_counter = 0
 	write_done_channel := make(chan IdType)
 	self.wakeup_channel = make(chan byte, 256)
+	self.panic_channel = make(chan any)
 	self.pending_writes = make([]write_msg, 0, 256)
 	err_channel := make(chan error, 8)
 	self.death_signal = SIGNULL
@@ -563,6 +564,8 @@ func (self *Loop) run() (err error) {
 		}
 		select {
 		case <-timeout_chan:
+		case p := <-self.panic_channel:
+			panic(p)
 		case <-self.wakeup_channel:
 			for len(self.wakeup_channel) > 0 {
 				<-self.wakeup_channel