Problem

When the user sends a message in the desktop app, there is a noticeable delay (0.3–3 s depending on model TTFT) before anything appears in the conversation area. During this gap:

1. The Composer clears its input (the text vanishes)
2. The Transcript stays completely blank — no user message, no assistant indicator
3. Only when the backend emits the first text or reasoning token does the user message finally appear

This creates a "dead zone" where the user's message has seemingly vanished into the void.

Root Cause

In useController.ts, the reducer holds the user's text in pendingUser and only flushes it to items (the rendered list) on the first non-turn_started/non-turn_done event:

// Line 147 (before fix)
if (s.pendingUser !== undefined && e.kind !== "turn_started" && e.kind !== "turn_done") {
  s = flushPendingUser(s);
}

The turn_started handler never touched pendingUser:

// Line 155 (before fix)
case "turn_started":
  return { ...s, running: true, turnActive: true, currentAssistant: undefined, ... };

So the user message only becomes visible when the first text/reasoning event arrives from the backend — which could be hundreds of milliseconds to several seconds later.

Fix

Two changes in applyEvent:

1. Flush pendingUser on turn_started — the user message appears the instant the backend acknowledges the turn, not when the first token arrives.

2. Pre-create an empty assistant bubble with a blinking cursor — gives immediate visual feedback that the model is processing (similar to ChatGPT/Claude's typing indicator). The Composer's status bar already shows "thinking… 0s", and now the Transcript also shows the cursor.

case "turn_started": {
  let cur: State = s;
  if (cur.pendingUser !== undefined) cur = flushPendingUser(cur);
  const { items, id, seq } = ensureAssistant(cur);
  return { ...cur, items, currentAssistant: id, seq, live: { id, text: "", reasoning: "" }, running: true, turnActive: true, turnStartAt: Date.now(), turnTokens: 0 };
}

The guard condition is simplified from e.kind !== "turn_started" && e.kind !== "turn_done" to just e.kind !== "turn_done" — the turn_done exclusion is kept for the cancel-before-reply edge case.

Before / After

Verification

• pnpm typecheck ✅ clean
• pnpm build ✅ built in 10.58s
• No new dependencies
• No i18n changes
• No CSS changes (.cursor animation already exists at styles.css:1172)
• Diff: 1 file, +11 / −3