fix:优化工作面板，支持动态字数

app/main.py

@@ -292,7 +292,7 @@ async def rewrite(req: RewriteRequest, request: Request):
     src = req.source_text or ""
     logger.info(
         "api_rewrite_in rid=%s source_chars=%d title_hint_chars=%d tone=%s audience=%s "
-        "keep_points_chars=%d avoid_words_chars=%d",
+        "keep_points_chars=%d avoid_words_chars=%d target_body_chars=%d",
         rid,
         len(src),
         len(req.title_hint or ""),
@@ -300,6 +300,7 @@ async def rewrite(req: RewriteRequest, request: Request):
         req.audience,
         len(req.keep_points or ""),
         len(req.avoid_words or ""),
+        int(req.target_body_chars or 500),
     )
     result = rewriter.rewrite(req, request_id=rid)
     tr = result.trace or {}

app/schemas.py

@@ -11,6 +11,12 @@ class RewriteRequest(BaseModel):
     audience: str = "公众号读者"
     keep_points: str = ""
     avoid_words: str = ""
+    target_body_chars: int = Field(
+        default=500,
+        ge=180,
+        le=2200,
+        description="目标改写正文字数，前端可调（中文字符数近似）",
+    )
 
 
 class RewriteResponse(BaseModel):

app/services/ai_rewriter.py

@@ -34,9 +34,9 @@ def _is_likely_timeout_error(exc: BaseException) -> bool:
     return "timed out" in s or "timeout" in s
 
 
-# 短文洗稿：正文目标约 500 字，优先完整性（软约束，不硬截断）
+# 短文洗稿：默认目标约 500 字，支持前端按需配置
 MIN_BODY_CHARS = 80
-TARGET_BODY_CHARS = 500
+DEFAULT_TARGET_BODY_CHARS = 500
 
 
 def _preview_for_log(text: str, limit: int = 400) -> str:
@@ -46,7 +46,7 @@ def _preview_for_log(text: str, limit: int = 400) -> str:
     return t[: limit - 1] + "…"
 
 
-SYSTEM_PROMPT = """
+SYSTEM_PROMPT_TEMPLATE = """
 你是资深中文科普类公众号编辑，擅长把长文、线程贴改写成**极短、好读**的推送。
 目标：在**不偏离原意**的前提下，用最少字数讲清一件事；不要写成技术方案、长文大纲或带很多小标题的文章。
 
@@ -54,14 +54,14 @@ SYSTEM_PROMPT = """
 1) **忠实原意**：只概括、转述原文已有信息，不编造事实，不偷换主题；
 2) 语气通俗、干脆，避免套话堆砌；
 3) 只输出合法 JSON：title, summary, body_markdown；
-4) **body_markdown 约束**：按内容密度使用 **4~6 个自然段**；段与段之间用一个空行分隔；**不要**使用 # / ## 标题符号；正文以 **约 500 字**为目标，优先完整表达并避免冗长重复；
+4) **body_markdown 约束**：按内容密度使用 **4~6 个自然段**；段与段之间用一个空行分隔；**不要**使用 # / ## 标题符号；正文以 **约 {target_chars} 字**为目标，优先完整表达并避免冗长重复；
 5) title、summary 也要短：标题约 8～18 字；摘要约 40～80 字；
 6) 关键观点需要加粗：请用 Markdown `**加粗**` 标出 2~4 个重点短语；
 7) JSON 字符串内引号请用「」或『』，勿用未转义的英文 "。
 """.strip()
 
 
-REWRITE_SCHEMA_HINT = """
+REWRITE_SCHEMA_HINT_TEMPLATE = """
 请输出 JSON（勿包在 ``` 里），例如：
 {
   "title": "短标题，点明主题",
@@ -72,22 +72,38 @@ REWRITE_SCHEMA_HINT = """
 body_markdown 写法：
 - 使用 **4~6 段**：每段若干完整句子，段之间 **\\n\\n**（空一行）；
 - **禁止** markdown 标题（不要用 #）；
-- 正文目标约 **500 字**（可上下浮动），以信息完整为先，避免冗长和重复；
+- 正文目标约 **{target_chars} 字**（可上下浮动），以信息完整为先，避免冗长和重复；
 - 请用 `**...**` 加粗 2~4 个关键观点词；
 - 内容顺序建议：首段交代在说什么；中间段展开关键信息；末段收束或提醒（均须紧扣原文，勿乱发挥）。
 """.strip()
 
 # 通义等模型若首次过短/结构不对，再要一次
-_JSON_BODY_TOO_SHORT_RETRY = """
+_JSON_BODY_TOO_SHORT_RETRY_TEMPLATE = """
 
 【系统复检】上一次 body_markdown 不符合要求。请重输出**完整** JSON：
-- 正文必须使用 **4~6 个自然段**（仅 \\n\\n 分段），无 # 标题；篇幅尽量收敛到约 500 字，同时保持信息完整；
+- 正文必须使用 **4~6 个自然段**（仅 \\n\\n 分段），无 # 标题；篇幅尽量收敛到约 {target_chars} 字，同时保持信息完整；
 - 忠实原稿、简短高效；
 - 引号只用「」『』；
 - 只输出 JSON。
 """.strip()
 
 
+def _target_chars(req: RewriteRequest) -> int:
+    return max(180, min(2200, int(req.target_body_chars or DEFAULT_TARGET_BODY_CHARS)))
+
+
+def _system_prompt(target_chars: int) -> str:
+    return SYSTEM_PROMPT_TEMPLATE.format(target_chars=target_chars)
+
+
+def _rewrite_schema_hint(target_chars: int) -> str:
+    return REWRITE_SCHEMA_HINT_TEMPLATE.format(target_chars=target_chars)
+
+
+def _retry_hint(target_chars: int) -> str:
+    return _JSON_BODY_TOO_SHORT_RETRY_TEMPLATE.format(target_chars=target_chars)
+
+
 class AIRewriter:
     def __init__(self) -> None:
         self._client = None
@@ -121,6 +137,7 @@ class AIRewriter:
             "provider": "dashscope" if self._prefer_chat_first else "openai_compatible",
             "source_chars_in": len(req.source_text or ""),
             "cleaned_chars": len(cleaned_source),
+            "target_body_chars": _target_chars(req),
             "openai_timeout_env_sec": settings.openai_timeout,
             "steps": [],
         }
@@ -289,8 +306,15 @@ class AIRewriter:
     def _model_rewrite(
         self, req: RewriteRequest, cleaned_source: str, timeout_sec: float, request_id: str = ""
     ) -> dict | None:
-        user_prompt = self._build_user_prompt(req, cleaned_source)
+        target_chars = _target_chars(req)
-        return self._call_model_json(user_prompt, timeout_sec=timeout_sec, request_id=request_id)
+        user_prompt = self._build_user_prompt(req, cleaned_source, target_chars)
+        return self._call_model_json(
+            user_prompt,
+            system_prompt=_system_prompt(target_chars),
+            target_chars=target_chars,
+            timeout_sec=timeout_sec,
+            request_id=request_id,
+        )
 
     def _model_polish(
         self,
@@ -301,6 +325,7 @@ class AIRewriter:
         timeout_sec: float,
         request_id: str = "",
     ) -> dict | None:
+        target_chars = _target_chars(req)
         issue_text = "\n".join([f"- {i}" for i in issues])
         user_prompt = f"""
 你上一次的改写稿未通过质检，请针对下列问题重写；体裁仍为**科普介绍类公众号**，**忠实原稿**，不要写成技术方案或内部汇报。
@@ -323,11 +348,17 @@ class AIRewriter:
 - 必须保留观点：{req.keep_points or '无'}
 - 避免词汇：{req.avoid_words or '无'}
 
-请输出一版全新稿件。{REWRITE_SCHEMA_HINT}
+请输出一版全新稿件。{_rewrite_schema_hint(target_chars)}
 """.strip()
-        return self._call_model_json(user_prompt, timeout_sec=timeout_sec, request_id=request_id)
+        return self._call_model_json(
+            user_prompt,
+            system_prompt=_system_prompt(target_chars),
+            target_chars=target_chars,
+            timeout_sec=timeout_sec,
+            request_id=request_id,
+        )
 
-    def _build_user_prompt(self, req: RewriteRequest, cleaned_source: str) -> str:
+    def _build_user_prompt(self, req: RewriteRequest, cleaned_source: str, target_chars: int) -> str:
         return f"""
 原始内容（已清洗）：
 {cleaned_source}
@@ -340,7 +371,7 @@ class AIRewriter:
 - 必须保留观点：{req.keep_points or '无'}
 - 避免词汇：{req.avoid_words or '无'}
 
-任务：在**不偏离原帖主题与事实**的前提下，改写成科普介绍风格的公众号正文（好读、讲清楚，而非技术实施方案）。{REWRITE_SCHEMA_HINT}
+任务：在**不偏离原帖主题与事实**的前提下，改写成科普介绍风格的公众号正文（好读、讲清楚，而非技术实施方案）。{_rewrite_schema_hint(target_chars)}
 """.strip()
 
     def _fallback_rewrite(
@@ -554,14 +585,21 @@ class AIRewriter:
                     escaped = False
         return "".join(out)
 
-    def _chat_completions_json(self, user_prompt: str, timeout_sec: float, request_id: str) -> dict | None:
+    def _chat_completions_json(
+        self,
+        user_prompt: str,
+        system_prompt: str,
+        target_chars: int,
+        timeout_sec: float,
+        request_id: str,
+    ) -> dict | None:
         """chat.completions：通义兼容层在 json_object 下易产出极短 JSON，故 DashScope 不传 response_format，并支持短文自动重试。"""
         max_attempts = 2 if self._prefer_chat_first else 1
         deadline = time.monotonic() + max(0.0, timeout_sec)
         pe = user_prompt
         for attempt in range(max_attempts):
             if attempt == 1:
-                pe = user_prompt + _JSON_BODY_TOO_SHORT_RETRY
+                pe = user_prompt + _retry_hint(target_chars)
             remaining = deadline - time.monotonic()
             if remaining <= 0:
                 logger.warning(
@@ -585,7 +623,7 @@ class AIRewriter:
                 create_kwargs: dict[str, Any] = {
                     "model": settings.openai_model,
                     "messages": [
-                        {"role": "system", "content": SYSTEM_PROMPT},
+                        {"role": "system", "content": system_prompt},
                         {"role": "user", "content": pe},
                     ],
                     "max_tokens": settings.openai_max_output_tokens,
@@ -684,7 +722,14 @@ class AIRewriter:
             return parsed
         return None
 
-    def _call_model_json(self, user_prompt: str, timeout_sec: float, request_id: str = "") -> dict | None:
+    def _call_model_json(
+        self,
+        user_prompt: str,
+        system_prompt: str,
+        target_chars: int,
+        timeout_sec: float,
+        request_id: str = "",
+    ) -> dict | None:
         methods = ["chat", "responses"] if self._prefer_chat_first else ["responses", "chat"]
         logger.info(
             "model_call_begin rid=%s model=%s timeout_s=%.1f prefer_chat_first=%s prompt_chars=%d "
@@ -704,7 +749,7 @@ class AIRewriter:
                     completion = self._client.responses.create(
                         model=settings.openai_model,
                         input=[
-                            {"role": "system", "content": SYSTEM_PROMPT},
+                            {"role": "system", "content": system_prompt},
                             {"role": "user", "content": user_prompt},
                         ],
                         text={"format": {"type": "json_object"}},
@@ -734,7 +779,13 @@ class AIRewriter:
             if method == "chat":
                 try:
                     t_chat = time.monotonic()
-                    out = self._chat_completions_json(user_prompt, timeout_sec, request_id)
+                    out = self._chat_completions_json(
+                        user_prompt,
+                        system_prompt=system_prompt,
+                        target_chars=target_chars,
+                        timeout_sec=timeout_sec,
+                        request_id=request_id,
+                    )
                     if out is not None:
                         return out
                     if self._prefer_chat_first:
@@ -814,11 +865,14 @@ class AIRewriter:
         elif pc > max_p:
             issues.append(f"正文段落偏多（当前 {pc} 段），建议控制在 {min_p}-{max_p} 段")
 
-        if len(body) < MIN_BODY_CHARS:
+        target_chars = _target_chars(req)
-            issues.append(f"正文过短（当前阈值 ≥{MIN_BODY_CHARS} 字）")
+        min_body_chars = max(MIN_BODY_CHARS, int(target_chars * 0.45))
-        elif len(body) > 900:
+        max_body_chars = int(target_chars * 1.7)
+        if len(body) < min_body_chars:
+            issues.append(f"正文过短（当前阈值 ≥{min_body_chars} 字）")
+        elif len(body) > max_body_chars:
             issues.append(
-                f"正文偏长（当前 {len(body)} 字），建议收敛到约 {TARGET_BODY_CHARS} 字（可上下浮动）"
+                f"正文偏长（当前 {len(body)} 字），建议收敛到约 {target_chars} 字（可上下浮动）"
             )
 
         if re.search(r"(?m)^#+\s", body):

app/static/app.js

@@ -17,6 +17,15 @@ const wechatBtn = $("wechatBtn");
 const imBtn = $("imBtn");
 const coverUploadBtn = $("coverUploadBtn");
 const logoutBtn = $("logoutBtn");
+const targetBodyCharsInput = $("targetBodyChars");
+
+function syncTargetCharChips() {
+  const val = Number((targetBodyCharsInput && targetBodyCharsInput.value) || 0);
+  document.querySelectorAll(".target-char-chip").forEach((btn) => {
+    const n = Number(btn.getAttribute("data-target-chars") || 0);
+    btn.classList.toggle("is-active", Number.isFinite(val) && val === n);
+  });
+}
 
 function countText(v) {
   return (v || "").trim().length;
@@ -183,12 +192,30 @@ if (logoutBtn) {
   });
 }
 
+document.querySelectorAll(".target-char-chip").forEach((btn) => {
+  btn.addEventListener("click", () => {
+    const n = Number(btn.getAttribute("data-target-chars") || 0);
+    if (!targetBodyCharsInput || !Number.isFinite(n) || n < 1) return;
+    targetBodyCharsInput.value = String(n);
+    syncTargetCharChips();
+  });
+});
+
+if (targetBodyCharsInput) {
+  targetBodyCharsInput.addEventListener("input", syncTargetCharChips);
+}
+
 $("rewriteBtn").addEventListener("click", async () => {
   const sourceText = $("sourceText").value.trim();
+  const targetBodyChars = Number(($("targetBodyChars") && $("targetBodyChars").value) || 500);
   if (sourceText.length < 20) {
     setStatus("原始内容太短，至少 20 个字符", true);
     return;
   }
+  if (!Number.isFinite(targetBodyChars) || targetBodyChars < 180 || targetBodyChars > 2200) {
+    setStatus("改写目标字数需在 180~2200 之间", true);
+    return;
+  }
 
   setStatus("正在改写...");
   setLoading(rewriteBtn, true, "改写并排版", "改写中...");
@@ -202,6 +229,7 @@ $("rewriteBtn").addEventListener("click", async () => {
       audience,
       keep_points: $("keepPoints").value,
       avoid_words: $("avoidWords").value,
+      target_body_chars: Math.round(targetBodyChars),
     });
     $("title").value = data.title || "";
     $("summary").value = data.summary || "";
@@ -307,3 +335,4 @@ $("imBtn").addEventListener("click", async () => {
 updateCounters();
 initMultiDropdowns();
 initWechatAccountSwitch();
+syncTargetCharChips();

app/static/style.css

@@ -327,6 +327,36 @@ label {
   margin-top: 4px;
 }
 
+.target-chars-quick {
+  display: flex;
+  gap: 8px;
+  margin-top: 8px;
+  flex-wrap: wrap;
+}
+
+.target-char-chip {
+  width: auto;
+  margin-top: 0;
+  padding: 4px 10px;
+  border-radius: 999px;
+  border: 1px solid #cbd5e1;
+  background: #fff;
+  color: #334155;
+  font-size: 12px;
+  font-weight: 700;
+  line-height: 1.5;
+}
+
+.target-char-chip:hover {
+  background: #f8fafc;
+}
+
+.target-char-chip.is-active {
+  border-color: var(--accent);
+  background: var(--accent-soft);
+  color: var(--accent-2);
+}
+
 .meta {
   color: var(--muted);
   font-size: 12px;

app/templates/index.html

@@ -94,6 +94,19 @@
         <label>必须保留观点</label>
         <input id="keepPoints" type="text" placeholder="逗号分隔" />
 
+        <div class="grid2">
+          <div>
+            <label>改写目标字数</label>
+            <input id="targetBodyChars" type="number" min="180" max="2200" step="10" value="500" placeholder="如：500" />
+            <div class="target-chars-quick" aria-label="快捷字数">
+              <button type="button" class="target-char-chip" data-target-chars="300">300</button>
+              <button type="button" class="target-char-chip is-active" data-target-chars="500">500</button>
+              <button type="button" class="target-char-chip" data-target-chars="800">800</button>
+              <button type="button" class="target-char-chip" data-target-chars="1200">1200</button>
+            </div>
+          </div>
+        </div>
+
         <button id="rewriteBtn" class="primary">改写并排版</button>
         <p id="status" class="status"></p>
       </section>
@@ -121,7 +134,7 @@
         <p id="coverHint" class="muted small">未上传时将使用后端默认封面策略。</p>
 
         <div class="field-head">
-          <label>正文（5 自然段，建议 ≤500 字）</label>
+          <label>正文（4~6 自然段，字数由左侧配置）</label>
           <span id="bodyCount" class="meta">0 字</span>
         </div>
         <div class="body-split">