Enforce session workspace boundaries

backend/api/server.py

@@ -48,6 +48,7 @@ from src.token_budget import calculate_token_budget
 
 
 STATIC_DIR = Path(__file__).resolve().parents[2] / 'frontend' / 'legacy-static'
+API_TOOL_CONTENT_MAX_CHARS = 20000
 
 VALIDATED_CHAT_MODEL_PROVIDERS = {
     # 这些 provider 已验证可以在当前 WebUI 中使用。
@@ -1293,9 +1294,12 @@ def _serialize_run_result(result: Any) -> dict[str, Any]:
 
 
 def _normalize_transcript_entry(entry: dict[str, Any]) -> dict[str, Any]:
+    content = entry.get('content', '')
+    if entry.get('role') == 'tool' and isinstance(content, str):
+        content = _truncate_api_text(content, API_TOOL_CONTENT_MAX_CHARS)
     out: dict[str, Any] = {
         'role': entry.get('role', ''),
-        'content': entry.get('content', ''),
+        'content': content,
     }
     for key in ('name', 'tool_call_id', 'tool_calls', 'metadata', 'message_id'):
         if key in entry and entry[key] not in (None, '', [], {}):
@@ -1306,6 +1310,14 @@ def _normalize_transcript_entry(entry: dict[str, Any]) -> dict[str, Any]:
     return out
 
 
+def _truncate_api_text(text: str, limit: int) -> str:
+    if len(text) <= limit:
+        return text
+    head = text[: limit // 2]
+    tail = text[-(limit // 2) :]
+    return f'{head}\n...[truncated for api response]...\n{tail}'
+
+
 def _serialize_stored_session(stored: StoredAgentSession) -> dict[str, Any]:
     return {
         'session_id': stored.session_id,