task 004: replace time.Sleep goroutine synchronization with proper primitives

audio_player.go: use time.AfterFunc instead of goroutine+sleep for the
100ms auto-play delay — no goroutine is blocked waiting.

app.go (setupUI, setupTooltips): replace goroutine+sleep with time.AfterFunc
for both 500ms tooltip initialization delays.

navigation.go: replace fixed 500ms sleep in the delete-cleanup goroutine with
a ticker+select loop that polls hasActiveOperations(). The goroutine now
proceeds as soon as all in-flight operations for the deleted word finish
(or after a 5-second safety timeout), rather than waiting a fixed interval
that may be too short or too long.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

3 files changed, 34 insertions, 26 deletions

diff --git a/internal/gui/app.go b/internal/gui/app.go
index 666c763..4f8311e 100644
--- a/internal/gui/app.go
+++ b/internal/gui/app.go
@@ -555,9 +555,9 @@ func (a *Application) setupUI() {
 	// Now that tooltip layer is created, set all tooltips
 	a.setupTooltips()
 
-	// Set tooltips for export, archive and help buttons with a delay
-	go func() {
-		time.Sleep(500 * time.Millisecond)
+	// Set tooltips for export, archive and help buttons after the tooltip layer
+	// has had time to initialize. AfterFunc avoids blocking a goroutine.
+	time.AfterFunc(500*time.Millisecond, func() {
 		fyne.Do(func() {
 			if exportButton != nil {
 				exportButton.SetToolTip("Export to Anki (x)")
@@ -569,7 +569,7 @@ func (a *Application) setupUI() {
 				helpButton.SetToolTip("Show hotkeys (?)")
 			}
 		})
-	}()
+	})
 
 	a.window.SetOnClosed(func() {
 		// Stop file check ticker
@@ -1962,12 +1962,10 @@ func (a *Application) clearUI() {
 	a.setActionButtonsEnabled(false)
 }
 
-// setupTooltips sets up all tooltips after the tooltip layer has been created
+// setupTooltips sets up all tooltips after the tooltip layer has been created.
+// AfterFunc fires after the tooltip layer is initialized without blocking a goroutine.
 func (a *Application) setupTooltips() {
-	// Use a goroutine with a delay to ensure the tooltip layer is fully initialized
-	go func() {
-		time.Sleep(500 * time.Millisecond)
-
+	time.AfterFunc(500*time.Millisecond, func() {
 		fyne.Do(func() {
 			// Navigation button tooltips
 			if a.submitButton != nil {
@@ -2014,7 +2012,7 @@ func (a *Application) setupTooltips() {
 				a.audioPlayer.stopButton.SetToolTip("Stop audio")
 			}
 		})
-	}()
+	})
 }
 
 // processNextInQueue processes the next word in the queue
diff --git a/internal/gui/audio_player.go b/internal/gui/audio_player.go
index eb96430..1f599d9 100644
--- a/internal/gui/audio_player.go
+++ b/internal/gui/audio_player.go
@@ -156,16 +156,12 @@ func (p *AudioPlayer) setAudioFileInternal(audioFile string, allowAutoPlay bool)
 		statusText := fmt.Sprintf("Audio: %s%s", filepath.Base(audioFile), p.voiceInfo)
 		p.statusLabel.SetText(statusText)
 
-		// Auto-play if enabled and allowed
+		// Auto-play if enabled and allowed. AfterFunc fires the callback after
+		// the UI has had a chance to render without blocking a goroutine.
 		if allowAutoPlay && p.autoPlayEnabled != nil && *p.autoPlayEnabled {
-			// Small delay to ensure UI is ready
-			go func() {
-				// Wait a tiny bit for UI to be ready
-				time.Sleep(100 * time.Millisecond)
-				fyne.Do(func() {
-					p.onPlay()
-				})
-			}()
+			time.AfterFunc(100*time.Millisecond, func() {
+				fyne.Do(p.onPlay)
+			})
 		}
 	} else {
 		p.Clear()
diff --git a/internal/gui/navigation.go b/internal/gui/navigation.go
index 1cd6089..206da00 100644
--- a/internal/gui/navigation.go
+++ b/internal/gui/navigation.go
@@ -827,19 +827,33 @@ func (a *Application) deleteCurrentWord() {
 		a.deleteButton.Enable()
 	}
 
-	// Start a cleanup goroutine to remove directory after any pending operations complete
+	// Start a cleanup goroutine to guard against directory recreation by racing
+	// in-flight operations. Instead of a fixed sleep, poll hasActiveOperations
+	// so the cleanup runs as soon as all operations for this word complete.
 	go func() {
-		// Wait a bit for any ongoing operations to notice cancellation
-		time.Sleep(500 * time.Millisecond)
+		ticker := time.NewTicker(50 * time.Millisecond)
+		defer ticker.Stop()
+		timeout := time.NewTimer(5 * time.Second)
+		defer timeout.Stop()
 
-		// Check if the directory was somehow recreated (by a racing operation)
+		// Wait until all active operations for this word finish or timeout elapses.
+		for {
+			select {
+			case <-timeout.C:
+				// Proceed even if some operations are still pending.
+			case <-ticker.C:
+				if a.hasActiveOperations(deletedWord) {
+					continue
+				}
+			}
+			break
+		}
+
+		// Check if a racing operation recreated the directory.
 		recreatedDir := a.findCardDirectory(deletedWord)
 		if recreatedDir != "" {
-			// Directory was recreated, try to delete it again
 			timestamp := time.Now().Format("20060102_150405")
 			trashWordDir := filepath.Join(trashDir, fmt.Sprintf("%s_%s_cleanup", filepath.Base(recreatedDir), timestamp))
-
-			// Move to trash again
 			if err := os.Rename(recreatedDir, trashWordDir); err == nil {
 				fmt.Printf("Cleanup: moved recreated directory for '%s' to trash\n", deletedWord)
 			}