Fix: update docs generator (#14070)

### What problem does this PR solve?

Refactor: update docs generator

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

1. Support multiple document generator components and correctly display
messages in the message component. The document generator will not
overwrite other messages.

<img width="700" alt="Screenshot from 2026-04-13 13-56-17"
src="https://github.com/user-attachments/assets/3f3e06e8-33ce-4df1-8b05-510c86af70a4"
/>

2. Support Chinese content and ensure correct Markdown rendering in PDF
and DOCX
<img width="700" alt="image"
src="https://github.com/user-attachments/assets/69bf1f7b-261d-48e5-a9f3-8e94462b90ed"
/>

3. Simplify configuration page and support more output format
 
<img height="700" alt="image"
src="https://github.com/user-attachments/assets/8647374c-c055-4daa-ad71-cd9052eb138e"
/>

4. Hide download from other components except for message 
<img width="700" alt="image"
src="https://github.com/user-attachments/assets/a723dfcb-b60d-4eb5-b2f6-d41ca5955eb4"
/>

<img width="700" alt="image"
src="https://github.com/user-attachments/assets/a8762ac4-807b-4f0b-9287-65f82f7c9c98"
/>

5. Sanitize filename
 
<img width="700" alt="image"
src="https://github.com/user-attachments/assets/df49509f-37c0-40f9-b03d-bd6ce7fdefa8"
/>


6. And more changes on usability

agent/component/message.py

@@ -54,6 +54,9 @@ class MessageParam(ComponentParamBase):
         self.outputs = {
             "content": {
                 "type": "str"
+            },
+            "downloads": {
+                "type": "list"
             }
         }
 
@@ -66,10 +69,66 @@ class MessageParam(ComponentParamBase):
 class Message(ComponentBase):
     component_name = "Message"
 
+    @staticmethod
+    def _is_download_info(value: Any) -> bool:
+        return isinstance(value, dict) and all(
+            key in value for key in ("doc_id", "filename", "mime_type")
+        )
+
+    def _extract_downloads(self, value: Any) -> list[dict[str, Any]]:
+        if isinstance(value, str):
+            try:
+                value = json.loads(value)
+            except Exception:
+                return []
+
+        if self._is_download_info(value):
+            return [value]
+
+        if isinstance(value, list) and all(self._is_download_info(item) for item in value):
+            return value
+
+        return []
+
+    def _stringify_message_value(
+        self,
+        value: Any,
+        delimiter: str = None,
+        downloads: list[dict[str, Any]] | None = None,
+        fallback_to_str: bool = False,
+    ) -> str:
+        extracted_downloads = self._extract_downloads(value)
+        if extracted_downloads:
+            if downloads is not None:
+                downloads.extend(extracted_downloads)
+            return ""
+
+        if value is None:
+            return ""
+
+        if isinstance(value, list) and delimiter:
+            return delimiter.join([str(vv) for vv in value])
+
+        if isinstance(value, str):
+            return value
+
+        try:
+            return json.dumps(value, ensure_ascii=False)
+        except Exception:
+            if fallback_to_str:
+                return str(value)
+            return ""
+
     def get_input_elements(self) -> dict[str, Any]:
         return self.get_input_elements_from_text("".join(self._param.content))
 
-    def get_kwargs(self, script:str, kwargs:dict = {}, delimiter:str=None) -> tuple[str, dict[str, str | list | Any]]:
+    def get_kwargs(
+        self,
+        script: str,
+        kwargs: dict = {},
+        delimiter: str = None,
+        downloads: list[dict[str, Any]] | None = None,
+    ) -> tuple[str, dict[str, str | list | Any]]:
         for k,v in self.get_input_elements_from_text(script).items():
             if k in kwargs:
                 continue
@@ -84,15 +143,8 @@ class Message(ComponentBase):
                 else:
                     for t in iter_obj:
                         ans += t
-            elif isinstance(v, list) and delimiter:
-                ans = delimiter.join([str(vv) for vv in v])
-            elif not isinstance(v, str):
-                try:
-                    ans = json.dumps(v, ensure_ascii=False)
-                except Exception:
-                    pass
             else:
-                ans = v
+                ans = self._stringify_message_value(v, delimiter, downloads)
             if not ans:
                 ans = ""
             kwargs[k] = ans
@@ -115,6 +167,7 @@ class Message(ComponentBase):
         s = 0
         all_content = ""
         cache = {}
+        downloads = []
         for r in re.finditer(self.variable_ref_patt, rand_cnt, flags=re.DOTALL):
             if self.check_if_canceled("Message streaming"):
                 return
@@ -154,11 +207,9 @@ class Message(ComponentBase):
                 continue
             elif inspect.isawaitable(v):
                 v = await v
-            elif not isinstance(v, str):
-                try:
-                    v = json.dumps(v, ensure_ascii=False)
-                except Exception:
-                    v = str(v)
+            v = self._stringify_message_value(
+                v, downloads=downloads, fallback_to_str=True
+            )
             yield v
             self.set_input_value(exp, v)
             all_content += v
@@ -171,6 +222,7 @@ class Message(ComponentBase):
             all_content += rand_cnt[s: ]
             yield rand_cnt[s: ]
 
+        self.set_output("downloads", downloads)
         self.set_output("content", all_content)
         self._convert_content(all_content)
         await self._save_to_memory(all_content)
@@ -191,12 +243,14 @@ class Message(ComponentBase):
             self.set_output("content", partial(self._stream, rand_cnt))
             return
 
-        rand_cnt, kwargs = self.get_kwargs(rand_cnt, kwargs)
+        downloads = []
+        rand_cnt, kwargs = self.get_kwargs(rand_cnt, kwargs, downloads=downloads)
         template = _jinja2_sandbox.from_string(rand_cnt)
         try:
             content = template.render(kwargs)
-        except Exception:
-            pass
+        except Exception as e:
+            logging.warning(f"Jinja2 template rendering failed: {e}")
+            content = rand_cnt  # fallback to unrendered content
 
         if self.check_if_canceled("Message processing"):
             return
@@ -204,6 +258,7 @@ class Message(ComponentBase):
         for n, v in kwargs.items():
             content = re.sub(n, v, content)
 
+        self.set_output("downloads", downloads)
         self.set_output("content", content)
         self._convert_content(content)
         self._save_to_memory(content)

agent/dsl_migration.py

@@ -22,6 +22,7 @@ import re
 COMPONENT_RENAMES = {
     "Splitter": "TokenChunker",
     "HierarchicalMerger": "TitleChunker",
+    "PDFGenerator": "DocGenerator",
 }
 
 NODE_TYPE_RENAMES = {