Some LLMs (e.g. qwen3 series) emit blank lines like "\n\n" before tool
calls. The backend faithfully forwards these as thought_chunk events
because streamThinkingToEventBus only filters chunk.Content == "" and
treats whitespace as content. The frontend then merges them into a
thinking event whose content is non-empty in JS truthiness terms but
visually empty, producing a "思考" card with a chevron and no text.
Filter such events out at the end of buildFullEventList so neither the
intermediate-steps tree nor the displayEvents fallback path renders
them.
wizardchen
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