Bug Description

When channels.feishu.streaming: true with renderMode: "card", Feishu bot replies exhibit cumulative token duplication — each new streaming chunk re-sends all previous content, resulting in a staircase-like repetition pattern in the final message.

Environment

• OpenClaw version: 2026.3.2
• Channel: Feishu
• Model backend: Claude Opus 4.6 via CLIProxyAPI (OpenAI-compatible proxy)
• OS: Debian Linux (systemd user service)

Configuration

{
  "channels": {
    "feishu": {
      "streaming": true,
      "renderMode": "card",
      "textChunkLimit": 2000,
      "blockStreaming": false
    }
  }
}

Reproduction

1. Enable streaming: true + renderMode: "card" in Feishu channel config
2. Send a message to any agent via Feishu DM or group chat
3. Observe the reply — each token appends to the card but also re-renders all previous tokens

Actual Behavior

The card output shows cumulative duplication like this:

找到了
找到了「清明
找到了「清明归骨」
找到了「清明归骨」项目，当
找到了「清明归骨」项目，当前阶段是
找到了「清明归骨」项目，当前阶段是 Phase
找到了「清明归骨」项目，当前阶段是 Phase 5 精修。
找到了「清明归骨」项目，当前阶段是 Phase 5 精修。让我查看
...

Each streaming update appends the new token and repeats all prior content, so the final message contains massive duplication. This affects all agents with streaming enabled.

Expected Behavior

Each streaming card update should replace the card content with the latest cumulative text, not append the cumulative text to the existing card content. The final rendered message should contain no duplication.

Workaround

Setting streaming: false at the channel level resolves the issue — agents wait for the full response before sending a single complete message. Per-bot override ("streaming": false on individual bot entries) also works.

Additional Context

• This was observed across multiple agents (editor, writer, etc.) but not on an agent that had streaming: false set individually
• The issue may be related to how the Feishu card update API handles delta vs full-content updates
• Session context size does not appear to be a factor — the duplication pattern is consistent regardless of session length
• Previously reported issues: Gateway restart silently drops in-flight Feishu sessions — no user notification #38836, Feishu agent: no visible feedback between dispatch and LLM response #38837