## Evidence from logs


Mar 12 12:01:27 Started streaming: cardId=7616214340648340671, messageId=om_x100b5417e74b60a4c3a474e9be9dc4f
Mar 12 12:02:10 Closed streaming: cardId=7616214340648340671
Mar 12 12:02:10 Started streaming: cardId=7616214523998375126, messageId=om_x100b5417e2e3907cc2906e393e5ae37
Mar 12 12:02:11 Closed streaming: cardId=7616214523998375126
Mar 12 12:02:11 dispatch complete (queuedFinal=true, replies=2)


Two different cardIds were created, but the first card contained content from both replies.

## Root cause analysis

Looking at the `mergeStreamingText` function in `extensions/feishu/src/streaming-card.ts`:


export function mergeStreamingText(
  previousText: string | undefined,
  nextText: string | undefined,
): string {
  // ... various merge attempts ...
  
  // Fallback for fragmented partial chunks: append as-is to avoid losing tokens.
  return `${previous}${next}`;  // ← This causes unrelated content to be merged
}

When two replies have completely different content (no overlap), the fallback behavior is to concatenate them. This is intended for partial streaming chunks, but incorrectly merges unrelated final replies.

## Suggested fix

1. Track whether streaming session has received a final delivery
2. If a new final reply arrives after a previous final was already delivered, start a new streaming card instead of merging
3. Or: Modify `mergeStreamingText` to have a "strict" mode that refuses to merge completely unrelated content