bytedance/deer-flow · warning · HTTPException

Input text exceeds {max_chars} characters

Error message

Input text exceeds {max_chars} characters

What it means

Raised by POST /input-polish with status 400 when the trimmed text length exceeds config.input_polish.max_chars. The limit is enforced server-side on the same normalized string sent to the model, keeping the user-facing boundary and the LLM input consistent. The response detail includes the configured max so clients can display it.

Source

Thrown at backend/app/gateway/routers/input_polish.py:84

    body: InputPolishRequest,
    request: Request,
    config: AppConfig = Depends(get_config),
) -> InputPolishResponse:
    del request  # Required by the auth decorator.

    if not config.input_polish.enabled:
        raise HTTPException(status_code=404, detail="Input polishing is disabled")

    # Validate the same normalized view of the input that we send to the model,
    # so the user-facing length boundary and the model input cannot disagree
    # (e.g. a padded draft passing the check but arriving with stray whitespace).
    text = body.text.strip()
    if not text:
        raise HTTPException(status_code=400, detail="Input text is required")

    max_chars = config.input_polish.max_chars
    if len(text) > max_chars:
        raise HTTPException(status_code=400, detail=f"Input text exceeds {max_chars} characters")

    model_name = config.input_polish.model_name
    try:
        raw = await run_oneshot_llm(
            system_instruction=_build_system_instruction(),
            user_content=_build_user_content(text, body.locale),
            run_name="input_polish",
            app_config=config,
            model_name=model_name,
            thread_id=body.thread_id,
        )
        rewritten = _clean_rewritten_text(raw)
    except Exception as exc:
        logger.exception("Failed to polish input: thread_id=%s err=%s", body.thread_id, exc)
        raise HTTPException(status_code=503, detail="Failed to polish input") from exc

    if not rewritten:
        raise HTTPException(status_code=503, detail="Failed to polish input")

View on GitHub (pinned to 1dd6ba1acb)

Solutions

1. Enforce the same limit client-side (maxLength on the textarea / pre-check trim().length) and show a character counter.
2. Split very long drafts or summarize before polishing instead of sending as-is.
3. If longer input is genuinely needed, raise input_polish.max_chars in config.yaml.

Example fix

// before
await polish({ text: draft }); // 12k chars -> 400

// after
const MAX = await getInputPolishLimits(); // exposes max_chars
if (draft.trim().length > MAX) {
  showWarning(`Draft exceeds ${MAX} characters — trim before polishing`);
} else {
  await polish({ text: draft.trim() });
}

const text = draft.trim();
if (text.length > MAX_CHARS) { warn(`Limit ${MAX_CHARS} chars (you have ${text.length})`); return; }
await polish({ text });

const withinPolishLimit = (s: string, max: number) => s.trim().length <= max;

When it happens

Trigger: Polishing a very long draft (e.g. pasted document) beyond the configured cap; client maxlength differing from server max_chars; lowering max_chars in config while the UI still allows longer input.

Common situations: Users pasting whole files into the composer; environments where operators tune max_chars down for cost; frontend using a stale default limit after a config change.

Related errors

• Input text is required
• {e}
• Invalid provider ID
• Missing code or state parameter
• URL is required

AI-assisted analysis of bytedance/deer-flow@1dd6ba1acb (2026-08-14). Data as JSON: /api/errors/2433e7b44be841b8. Report an issue: GitHub.