Handle PTY overflow parser carry safely (#198)

* Handle PTY overflow parser carry safely

* Preserve PTY write order on actor fallback

* Fix PTY write rollback and overflow escape recovery

* Fix flaky state watcher registry test

* Document parser carry reconnect invariants

Author: andyrewlee

internal/app/state_watcher_test.go

@@ -108,7 +108,7 @@ func TestStateWatcher_NotifiesOnRegistryWrite(t *testing.T) {
 
 	var notified string
 	var mu sync.Mutex
-	done := make(chan struct{})
+	done := make(chan struct{}, 1)
 
 	sw, err := newStateWatcher(registryPath, "", func(reason string, paths []string) {
 		mu.Lock()

internal/ui/center/model_input_lifecycle.go

@@ -79,6 +79,10 @@ func (m *Model) updatePtyTabReattachResult(msg ptyTabReattachResult) (*Model, te
 		createdTerminal = true
 	}
 	if tab.Terminal != nil {
+		// Do not reset parser state when reusing an existing terminal here.
+		// pendingOutput may still contain continuation bytes queued under the
+		// current parser carry, and reconnect must preserve that continuity until
+		// buffered output is explicitly reconciled.
 		tab.Terminal.AllowAltScreenScrollback = true
 		m.applyTerminalCursorPolicyLocked(tab)
 		if createdTerminal || len(tab.Terminal.Scrollback) == 0 {
@@ -91,6 +95,13 @@ func (m *Model) updatePtyTabReattachResult(msg ptyTabReattachResult) (*Model, te
 	tab.reattachInFlight = false
 	tab.Running = true
 	resetChatCursorActivityStateLocked(tab)
+	tab.parserResetPending = false
+	tab.actorWritesPending = 0
+	tab.actorWriteEpoch++
+	tab.overflowTrimCarry = vterm.ParserCarryState{}
+	tab.ptyNoiseTrailing = nil
+	tab.actorQueuedNoiseTrailing = tab.actorQueuedNoiseTrailing[:0]
+	tab.actorQueuedCarry = tab.Terminal.ParserCarryState()
 	tab.bootstrapActivity = true
 	tab.bootstrapLastOutputAt = time.Now()
 	tab.mu.Unlock()