feat: add DuckDuckGo free fallback for web_search (no API key needed)

Dockerfile

@@ -20,7 +20,7 @@ RUN git clone --depth 1 --branch v2026.4.30 https://github.com/NousResearch/herm
 RUN python3 -m venv /app/venv
 ENV PATH="/app/venv/bin:$PATH"
 RUN pip install --quiet --upgrade pip && \
-    pip install --quiet psutil networkx && \
+    pip install --quiet psutil networkx duckduckgo-search && \
     pip install --quiet -e "/app/hermes-agent[feishu,mcp,cron,pty]" && \
     pip install --quiet aiohttp cryptography 2>&1 | tail -10
 
@@ -46,6 +46,10 @@ RUN python3 /tmp/patch_resolve_media_paths.py; rm -f /tmp/patch_resolve_media_pa
 COPY scripts/patch_weixin_cross_loop.py /tmp/patch_weixin_cross_loop.py
 RUN python3 /tmp/patch_weixin_cross_loop.py; rm -f /tmp/patch_weixin_cross_loop.py
 
+# Patch: DuckDuckGo free fallback for web_search (no API key needed)
+COPY scripts/patch_web_search_fallback.py /tmp/patch_web_search_fallback.py
+RUN python3 /tmp/patch_web_search_fallback.py; rm -f /tmp/patch_web_search_fallback.py
+
 # Install Node.js 23
 RUN ARCH=$(dpkg --print-architecture) \
     && if [ "$ARCH" = "amd64" ]; then NODE_ARCH="x64"; else NODE_ARCH="$ARCH"; fi \

scripts/patch_web_search_fallback.py

@@ -0,0 +1,102 @@
+#!/usr/bin/env python3
+"""
+patch_web_search_fallback.py — DuckDuckGo 免费 fallback
+
+当所有付费搜索后端（Firecrawl / Tavily / Exa / Parallel）都不可用时，
+自动 fallback 到 DuckDuckGo 搜索，无需任何 API key。
+
+Monkey-patch 目标（tools/web_tools.py）：
+  - _get_backend()        : 无可用后端时返回 "duckduckgo"
+  - web_search_tool()     : 分发 duckduckgo 后端
+  - _is_backend_available(): duckduckgo 始终返回 True
+"""
+
+import json
+import logging
+
+logger = logging.getLogger(__name__)
+
+
+def _ddg_search(query: str, limit: int = 5) -> dict:
+    """通过 DuckDuckGo 搜索，返回标准格式结果。"""
+    try:
+        from duckduckgo_search import DDGS
+
+        results = []
+        with DDGS() as ddgs:
+            for i, r in enumerate(ddgs.text(query, max_results=limit)):
+                results.append({
+                    "title": r.get("title", ""),
+                    "url": r.get("href", ""),
+                    "description": r.get("body", ""),
+                    "position": i + 1,
+                })
+
+        return {"success": True, "data": {"web": results}}
+    except Exception as e:
+        logger.error("DuckDuckGo search failed: %s", e)
+        return {"success": False, "error": f"DuckDuckGo search failed: {e}"}
+
+
+def patch():
+    """Apply the DuckDuckGo fallback patch to web_tools."""
+    import tools.web_tools as wt
+
+    # ── 1. 让 _get_backend() 在无可用后端时返回 "duckduckgo" ──
+    _original_get_backend = wt._get_backend
+
+    def _get_backend_patched():
+        configured = (wt._load_web_config().get("backend") or "").lower().strip()
+        # 用户显式指定了某个后端 → 尊重配置（即使 key 可能无效）
+        if configured in ("parallel", "firecrawl", "tavily", "exa"):
+            return configured
+
+        # 按优先级检查哪个后端可用
+        for backend in ("firecrawl", "parallel", "tavily", "exa"):
+            if wt._is_backend_available(backend):
+                return backend
+
+        # 全都不可用 → DuckDuckGo 兜底
+        return "duckduckgo"
+
+    wt._get_backend = _get_backend_patched
+
+    # ── 2. 在 web_search_tool() 中添加 duckduckgo 分发 ──
+    _original_web_search = wt.web_search_tool
+
+    def web_search_patched(query: str, limit: int = 5) -> str:
+        backend = wt._get_backend()
+
+        if backend == "duckduckgo":
+            logger.info("DuckDuckGo search (free fallback): '%s' (limit: %d)", query, limit)
+            response_data = _ddg_search(query, limit)
+            return json.dumps(response_data, indent=2, ensure_ascii=False)
+
+        # 其他后端走原逻辑
+        return _original_web_search(query, limit)
+
+    wt.web_search_tool = web_search_patched
+
+    # ── 3. 让 _is_backend_available("duckduckgo") 始终返回 True ──
+    _original_is_backend_available = wt._is_backend_available
+
+    def _is_backend_available_patched(backend: str) -> bool:
+        if backend == "duckduckgo":
+            return True
+        return _original_is_backend_available(backend)
+
+    wt._is_backend_available = _is_backend_available_patched
+
+    # ── 4. 让 web_extract 也能在 duckduckgo 后端下工作 ──
+    # web_extract 不依赖搜索后端（它直接抓 URL），但如果 _get_backend
+    # 返回 "duckduckgo" 且 web_extract 内部也调用 _get_backend，需要兼容。
+    # 目前 web_extract 不调用 _get_backend，所以不需要 patch。
+
+    logger.info(
+        "Web search: DuckDuckGo free fallback enabled "
+        "(no API key required, auto-activates when paid backends unavailable)"
+    )
+
+
+if __name__ == "__main__":
+    patch()

start.sh

@@ -545,6 +545,12 @@ update_hermes_agent_background() {
     if [ -f "/app/scripts/patch_resolve_media_paths.py" ]; then
         python3 /app/scripts/patch_resolve_media_paths.py 2>/dev/null
     fi
+    if [ -f "/app/scripts/patch_weixin_cross_loop.py" ]; then
+        python3 /app/scripts/patch_weixin_cross_loop.py 2>/dev/null
+    fi
+    if [ -f "/app/scripts/patch_web_search_fallback.py" ]; then
+        python3 /app/scripts/patch_web_search_fallback.py 2>/dev/null
+    fi
     # Copy patch files if they exist
     for patch_file in prompt_builder.py send_message_tool.py; do
         if [ -f "/app/patches/hermes-agent/agent/$patch_file" ] && [ -f "$AGENT_DIR/agent/$patch_file" ]; then