feat(overlay): ghost text

integration/overlay.go

@@ -15,10 +15,11 @@ const (
 )
 
 type Overlay struct {
-	mu      sync.Mutex
-	Visible bool
-	Items   []core.Suggestion
-	Cursor  int
+	mu           sync.Mutex
+	Visible      bool
+	Items        []core.Suggestion
+	Cursor       int
+	LastGhostLen int
 }
 
 var (
@@ -65,6 +66,48 @@ func fixedWidth(s string, width int) string {
 	return s
 }
 
+func (o *Overlay) RenderGhostText(buffer string) string {
+	o.mu.Lock()
+	defer o.mu.Unlock()
+
+	if !o.Visible || len(o.Items) == 0 {
+		return ""
+	}
+
+	var s strings.Builder
+
+	ghostText := ""
+	if buffer != "" {
+		topCmd := o.Items[0].Cmd
+		if strings.HasPrefix(strings.ToLower(topCmd), strings.ToLower(buffer)) {
+			ghostText = topCmd[len(buffer):]
+		}
+	}
+
+	padLen := o.LastGhostLen - len(ghostText)
+	if padLen < 0 {
+		padLen = 0
+	}
+	
+	// add extra padding to erase any stray characters left by fast backspaces 
+	// before the debounce timer fired. 10 spaces is safe and won't hit right prompts
+	padLen += 10
+
+	if ghostText != "" || padLen > 0 {
+		s.WriteString("\0337") // SAVE CURSOR at prompt
+		if ghostText != "" {
+			s.WriteString("\033[90m" + ghostText + "\033[0m")
+		}
+		if padLen > 0 {
+			s.WriteString(strings.Repeat(" ", padLen))
+		}
+		s.WriteString("\0338") // RESTORE CURSOR back to prompt
+		o.LastGhostLen = len(ghostText)
+	}
+
+	return s.String()
+}
+
 func (o *Overlay) Render() string {
 	o.mu.Lock()
 	defer o.mu.Unlock()
@@ -75,7 +118,7 @@ func (o *Overlay) Render() string {
 
 	var s strings.Builder
 	s.WriteString("\033[?7l")
-	s.WriteString("\0337") // DEC save cursor
+	s.WriteString("\0337") // DEC save cursor for menu drawing
 
 	windowSize := maxItems
 	if len(o.Items) < windowSize {
@@ -189,6 +232,14 @@ func (o *Overlay) ClearAndDisable() string {
 
 	var s strings.Builder
 	s.WriteString("\033[?7l")
+
+	if o.LastGhostLen > 0 {
+		s.WriteString("\0337") // save
+		s.WriteString(strings.Repeat(" ", o.LastGhostLen+10))
+		s.WriteString("\0338") // restore
+		o.LastGhostLen = 0
+	}
+
 	s.WriteString("\0337")
 
 	for i := 0; i < maxItems+2; i++ {

root/wrapper.go

@@ -11,7 +11,9 @@ import (
 	"os/signal"
 	"path/filepath"
 	"strings"
+	"sync"
 	"syscall"
+	"time"
 
 	"github.com/creack/pty"
 	"github.com/versenilvis/iris/commands/core"
@@ -185,7 +187,10 @@ func runWrapper() {
 			}
 			os.Stdout.Write([]byte(overlay.Clear()))
 			overlay.UpdateItems(results)
-			os.Stdout.Write([]byte(overlay.Render()))
+			var rBuf strings.Builder
+			rBuf.WriteString(overlay.RenderGhostText(query))
+			rBuf.WriteString(overlay.Render())
+			os.Stdout.Write([]byte(rBuf.String()))
 		}
 	}()
 
@@ -193,32 +198,51 @@ func runWrapper() {
 	suggestionsEnabled := true
 	mode := loadMode()
 
+	var renderTimer *time.Timer
+	var renderMu sync.Mutex
+
 	// renderOverlay decides whether to draw the suggestion menu based on current state
 	renderOverlay := func() {
+		renderMu.Lock()
+		defer renderMu.Unlock()
+
+		if renderTimer != nil {
+			renderTimer.Stop()
+		}
+
 		if !suggestionsEnabled {
 			return
 		}
 
-		if naiveBuffer == "" {
+		bufCopy := naiveBuffer
+		modeCopy := mode
+
+		if bufCopy == "" {
 			os.Stdout.Write([]byte(overlay.ClearAndDisable()))
 			return
 		}
 
-		debugLog("[Render] query: '%s', mode: %s", naiveBuffer, mode)
-		results := mergeResults(naiveBuffer, mode)
-		debugLog("[Render] results found: %d", len(results))
+		// Debounce for 15ms to allow PTY to process the keystroke and update the terminal cursor.
+		// This completely prevents the asynchronous ghost text race condition where the PTY echo
+		// overwrites the first letter of our ghost text!
+		renderTimer = time.AfterFunc(15*time.Millisecond, func() {
+			debugLog("[Render] query: '%s', mode: %s", bufCopy, modeCopy)
+			results := mergeResults(bufCopy, modeCopy)
+			debugLog("[Render] results found: %d", len(results))
 
-		if len(results) == 0 {
-			os.Stdout.Write([]byte(overlay.ClearAndDisable()))
-		} else {
-			var buf strings.Builder
-			if overlay.Visible {
-				buf.WriteString(overlay.Clear())
+			var b strings.Builder
+			if len(results) == 0 {
+				b.WriteString(overlay.ClearAndDisable())
+			} else {
+				if overlay.Visible {
+					b.WriteString(overlay.Clear())
+				}
+				overlay.UpdateItems(results)
+				b.WriteString(overlay.RenderGhostText(bufCopy))
+				b.WriteString(overlay.Render())
 			}
-			overlay.UpdateItems(results)
-			buf.WriteString(overlay.Render())
-			os.Stdout.Write([]byte(buf.String()))
-		}
+			os.Stdout.Write([]byte(b.String()))
+		})
 	}
 
 	renderOverlay()
@@ -269,9 +293,25 @@ func runWrapper() {
 									overlay.Cursor = len(overlay.Items) - 1
 								}
 							}
-							os.Stdout.Write([]byte(overlay.Render()))
+							var rBuf strings.Builder
+							rBuf.WriteString(overlay.RenderGhostText(naiveBuffer))
+							rBuf.WriteString(overlay.Render())
+							os.Stdout.Write([]byte(rBuf.String()))
 							i += 2
 							continue
+						} else if overlay.Visible && inputSlice[i+2] == 'C' { // right arrow
+							topCmd := overlay.Items[0].Cmd
+							if strings.HasPrefix(strings.ToLower(topCmd), strings.ToLower(naiveBuffer)) {
+								ghostText := topCmd[len(naiveBuffer):]
+								if len(ghostText) > 0 {
+									intercepted = true
+									naiveBuffer += ghostText
+									ptmx.Write([]byte(ghostText))
+									shouldOverlayDraw = true
+									i += 2
+									continue
+								}
+							}
 						}
 					}