fix(tui): keep streaming progress stable during interaction

ui-tui/src/app/interactionMode.ts

@@ -0,0 +1,52 @@
+import { SCROLLING_IDLE_MS, TYPING_IDLE_MS } from '../config/timing.js'
+
+export type InteractionMode = 'idle' | 'scrolling' | 'typing'
+
+type Timer = null | ReturnType<typeof setTimeout>
+
+let mode: InteractionMode = 'idle'
+let scrollingTimer: Timer = null
+let typingTimer: Timer = null
+
+const clear = (t: Timer): null => {
+  if (t) {
+    clearTimeout(t)
+  }
+
+  return null
+}
+
+export function getInteractionMode(): InteractionMode {
+  return mode
+}
+
+export function markTyping(): void {
+  mode = 'typing'
+  typingTimer = clear(typingTimer)
+  scrollingTimer = clear(scrollingTimer)
+  typingTimer = setTimeout(() => {
+    typingTimer = null
+    mode = 'idle'
+  }, TYPING_IDLE_MS)
+}
+
+export function markScrolling(): void {
+  if (mode === 'typing') {
+    return
+  }
+
+  mode = 'scrolling'
+  scrollingTimer = clear(scrollingTimer)
+  scrollingTimer = setTimeout(() => {
+    scrollingTimer = null
+    if (mode === 'scrolling') {
+      mode = 'idle'
+    }
+  }, SCROLLING_IDLE_MS)
+}
+
+export function resetInteractionMode(): void {
+  scrollingTimer = clear(scrollingTimer)
+  typingTimer = clear(typingTimer)
+  mode = 'idle'
+}