Deadlock fix: no channel sends during frame rendering while mutex is locked.

cmd/pad/main.go

@@ -29,13 +29,16 @@ func main() {
 }
 
 func run(w *app.Window) error {
+	log.Printf("run: starting")
 	var ops op.Ops
 	shaper := text.NewShaper(text.WithCollection(gofont.Collection()))
 	logic := editor.NewLogic()
 	renderer := ui.New(ui.Theme{FontSize: 14}, shaper, logic.State())
 	var mu sync.Mutex
 	var elems []ui.Element
+	log.Printf("run: starting frameReceiver")
 	go frameReceiver(w, &mu, &elems, logic.FrameChan())
+	log.Printf("run: starting logic.Run")
 	go logic.Run()
 
 	for {
@@ -49,34 +52,43 @@ func run(w *app.Window) error {
 				PixelHeight: e.Config.Size.Y,
 			}
 		case app.FrameEvent:
+			log.Printf("run: FrameEvent")
 			gtx := app.NewContext(&ops, e)
 			newScale := gtx.Metric.PxPerDp
 			curScale := logic.State().Scale()
 			if newScale != curScale {
 				logic.ConfigChan() <- editor.ScaleEvent{newScale}
 			}
+			// Deadlock risk: ensure no channel sends while lock is held
 			mu.Lock()
 			currentElems := elems
 			renderer.Draw(gtx, currentElems)
-			logic.DisplayLineChan() <- int(renderer.LastLineY())
+			lastLineY := int(renderer.LastLineY())
 			// Send search query update to the logic goroutine when it changes.
 			// The logic goroutine handles filtering and triggers a new frame.
 			newQuery := logic.State().Browser.SearchEditor.Text()
+			sendQuery := false
 			if newQuery != logic.State().Browser.Query {
-				logic.SearchQueryChan() <- newQuery
+				sendQuery = true
 			}
 			if events := renderer.CheckGestures(e.Source, gtx.Metric); len(events) > 0 {
 				logic.InputChan() <- events
 			}
 			e.Frame(&ops)
 			mu.Unlock()
+			if sendQuery {
+				logic.SearchQueryChan() <- newQuery
+			}
+			logic.DisplayLineChan() <- lastLineY
 		}
 	}
 }
 
 func frameReceiver(w *app.Window, mu *sync.Mutex, elems *[]ui.Element, frameChan <-chan []ui.Element) {
+	log.Printf("frameReceiver: loop starting")
 	for {
 		frame := <-frameChan
+		log.Printf("frameReceiver: received frame")
 		mu.Lock()
 		*elems = frame
 		w.Invalidate()

internal/editor/logic.go

@@ -1,6 +1,7 @@
 package editor
 
 import (
+	"log"
 	"sync"
 
 	"pad/internal/browser"
@@ -136,6 +137,7 @@ func (l *Logic) Scale() float32 {
 // Run runs the logic goroutine loop.
 func (l *Logic) Run() {
 	// Dispatch initial directory index build on startup
+	log.Printf("Logic: Dispatching BuildIndexTask")
 	l.workerPool.Dispatch(pool.NewBuildIndexTask(l.state.Browser.CurrentPath, l.mockFS))
 
 	for {
@@ -143,6 +145,7 @@ func (l *Logic) Run() {
 		case <-l.done:
 			return
 		case update := <-l.configChan:
+			log.Printf("Logic: ConfigEvent")
 			update.apply(l.state)
 			l.frameChan <- l.state.layout(l.browserManager)
 		case y := <-l.lastLineYChan:
@@ -151,11 +154,13 @@ func (l *Logic) Run() {
 				l.frameChan <- l.state.layout(l.browserManager)
 			}
 		case events := <-l.inputChan:
+			log.Printf("Logic: InputEvents")
 			for _, evt := range events {
 				evt.Handler(evt.Data)
 			}
 			l.frameChan <- l.state.layout(l.browserManager)
 		case query := <-l.searchQueryChan:
+			log.Printf("Logic: SearchQuery")
 			if query != l.state.Browser.Query {
 				l.state.Browser.Query = query
 				if l.state.page == BrowserPage {
@@ -164,9 +169,11 @@ func (l *Logic) Run() {
 			}
 			l.frameChan <- l.state.layout(l.browserManager)
 		case path := <-l.openFileChan:
+			log.Printf("Logic: OpenFileChan %s", path)
 			// Dispatch ReadFileTask to worker pool
 			l.workerPool.Dispatch(pool.NewReadFileTask(path, l.mockFS))
 		case res := <-l.workerPool.ResultChan():
+			log.Printf("Logic: WorkerResult %s", res.TaskType)
 			l.handleWorkerResult(res)
 		case <-l.resultChan:
 			l.frameChan <- l.state.layout(l.browserManager)
@@ -179,6 +186,7 @@ func (l *Logic) handleWorkerResult(res pool.Result) {
 	if res.IsBrowserResult() {
 		l.browserManager.HandleResult(res)
 	} else if res.TaskType == pool.TypeReadFile {
+		log.Printf("Logic: TypeReadFile result success=%v", res.Success)
 		if res.Success {
 			if content, ok := res.Data.([]byte); ok {
 				l.state.ActiveFileContent = string(content)