Remove PTY inactivity timeout to keep terminal sessions alive indefinitely

Sessions now only end on process exit or explicit kill, not idle time.
The keepalive ping every 30s remains to prevent network-level disconnects.

internal/api/handlers_pty.go

@@ -23,7 +23,6 @@ import (
 )
 
 const (
-	ptyInactivityTimeout = 120 * time.Second
 	ptyKeepaliveInterval = 30 * time.Second
 	ptyDefaultCmd        = "/bin/bash"
 	ptyDefaultCols       = 80
@@ -246,10 +245,6 @@ func runPtyLoop(
 ) {
 	var wg sync.WaitGroup
 
-	// Inactivity timer — reset on input/resize, fires kill after timeout.
-	timer := time.NewTimer(ptyInactivityTimeout)
-	defer timer.Stop()
-
 	// Output pump: read from Connect stream, write to WebSocket.
 	wg.Add(1)
 	go func() {
@@ -317,7 +312,6 @@ func runPtyLoop(
 				})); err != nil {
 					slog.Debug("pty send input error", "error", err)
 				}
-				resetTimer(timer, ptyInactivityTimeout)
 
 			case "resize":
 				cols := msg.Cols
@@ -331,7 +325,6 @@ func runPtyLoop(
 					})); err != nil {
 						slog.Debug("pty resize error", "error", err)
 					}
-					resetTimer(timer, ptyInactivityTimeout)
 				}
 
 			case "kill":
@@ -364,26 +357,6 @@ func runPtyLoop(
 		}
 	}()
 
-	// Inactivity timeout goroutine.
-	wg.Add(1)
-	go func() {
-		defer wg.Done()
-		select {
-		case <-timer.C:
-			slog.Info("pty session timed out", "sandbox_id", sandboxID, "tag", tag)
-			rpcCtx, rpcCancel := context.WithTimeout(context.Background(), 5*time.Second)
-			if _, err := agent.PtyKill(rpcCtx, connect.NewRequest(&pb.PtyKillRequest{
-				SandboxId: sandboxID,
-				Tag:       tag,
-			})); err != nil {
-				slog.Debug("pty timeout kill error", "error", err)
-			}
-			rpcCancel()
-			cancel()
-		case <-ctx.Done():
-		}
-	}()
-
 	wg.Wait()
 }
 
@@ -391,15 +364,3 @@ func runPtyLoop(
 func newPtyTag() string {
 	return "pty-" + id.NewPtyTag()
 }
-
-// resetTimer safely resets a timer by stopping it and draining the channel
-// before resetting, avoiding the race documented in time.Timer.Reset.
-func resetTimer(t *time.Timer, d time.Duration) {
-	if !t.Stop() {
-		select {
-		case <-t.C:
-		default:
-		}
-	}
-	t.Reset(d)
-}