websearch: 默认 auto 付费冻结，SearXNG 优先 + 显式解冻开关

- 默认 auto 只走免费链 searxng -> duckduckgo；即使环境里有
  付费 key 也不调用 Perplexity/Exa/Tavily/Brave，SearXNG
  失败也不回落付费，默认使用零付费花费。
- 付费后端代码/测试/文档全部保留；显式 pin（tavily/exa/
  perplexity/brave）仍照常调用，是有意覆盖不是默认。
- 解冻开关 WEBSEARCH_ENABLE_PAID，仅精确值 "1" 才恢复旧链
  （perplexity/exa/tavily/brave/searxng/duckduckgo），默认关；
  开关经 worker search_env 透传进 MCP config env。
- HttpClient 超时/DNS 失败改报显式错误（timeout after Ns /
  URL error），绝不把超时写成“无结果”。
- SearXNG 默认参数核实：代码无 SEARXNG_URL 硬编码默认值；
  SEARXNG_ENGINES 默认 bing,360search 已在基线；WEBSEARCH_TIMEOUT
  默认 20 秒。主机 env 实测仅 SEARXNG_URL=http://searx.diante.me
  一行，故默认 pin 生效；文档 https 漂移改回 http（主机 nginx
  仅听 80、无 443 vhost，https 在 TLS 层即失败）。
- 旧测试更新原因：test_websearch_mcp 原断言默认 auto 为
  perplexity 优先，与新冻结语义直接冲突，故改为断言冻结后
  的 searxng -> duckduckgo 回退 + 不泄漏 key；旧 perplexity ->
  exa 回退断言移至解冻开关测试（WEBSEARCH_ENABLE_PAID=1 下）。
  未删断言、未加 skip、未放宽门禁。
- 文档另删 WEBSEARCH_PROVIDERS 说法：代码从未实现该变量。
- 未推、未建 PR、未合并、未部署、未改主机 env/nginx/filter/
  证书、未做付费后端 live 验证、未创建生产任务。

cloud/tests/test_websearch_mcp.py

@@ -67,18 +67,38 @@ def _exa_body():
 
 
 class ChainTestCase(unittest.TestCase):
-    def test_fallback_perplexity_to_exa_and_key_not_leaked(self):
+    def test_default_auto_frozen_falls_back_searxng_to_duckduckgo_and_key_not_leaked(self):
+        # Paid-freeze update of the old perplexity -> exa fallback
+        # test: default auto no longer contains any paid backend,
+        # even when all four paid keys are set, so the fallback
+        # that still exists by default is searxng -> duckduckgo
+        # and no paid URL is ever touched. The old perplexity ->
+        # exa fallback is preserved, but only under
+        # WEBSEARCH_ENABLE_PAID=1; see test_websearch_paid_freeze.py.
+        html = (
+            '<a class="result__a" href="//duckduckgo.com/l/?uddg='
+            'https%3A%2F%2Fexample.com%2Fddg">DDG Title</a>'
+            '<a class="result__snippet">ddg snippet</a>')
         http = FakeHttp([
-            ("perplexity", {}, 500),
-            ("api.exa.ai", _exa_body(), 200),
+            ("searx", {}, 500),
+            ("duckduckgo", html, 200),
         ])
+        env = dict(_FAKE_KEYS)
+        env["SEARXNG_URL"] = "http://searx.test"
         out = search("test query", provider="auto",
-                     env=dict(_FAKE_KEYS), http=http)
-        self.assertEqual(out["provider"], "exa")
+                     env=env, http=http)
+        self.assertEqual(out["provider"], "duckduckgo")
         self.assertEqual(out["results"][0]["url"],
-                         "https://example.com/exa")
-        self.assertEqual(out["attempted"][0]["provider"], "perplexity")
+                         "https://example.com/ddg")
+        self.assertEqual(out["attempted"][0]["provider"], "searxng")
         self.assertFalse(out["attempted"][0]["ok"])
+        self.assertEqual(
+            [a["provider"] for a in out["attempted"]],
+            ["searxng", "duckduckgo"])
+        for _method, url, _payload in http.seen:
+            for paid in ("perplexity", "exa.ai", "tavily",
+                         "search.brave.com"):
+                self.assertNotIn(paid, url)
         blob = json.dumps(out)
         for secret in _FAKE_KEYS.values():
             self.assertNotIn(secret, blob)

cloud/tests/test_websearch_paid_freeze.py

@@ -0,0 +1,280 @@
+"""Paid-freeze tests: default auto is free-only, pin still works,
+unfreeze is explicit (WEBSEARCH_ENABLE_PAID=1, exact value "1").
+
+No network, no real keys: every HTTP call goes through a FakeHttp,
+and the fake key values are deliberately distinctive so a leak into
+an error string or a tool result would be caught by assertion.
+"""
+
+import json
+import os
+import socket
+import sys
+import unittest
+import urllib.error
+from pathlib import Path
+from unittest import mock
+
+try:
+    from cloud.websearch import (
+        DEFAULT_CHAIN, DEFAULT_FREE_CHAIN, HttpClient, WebSearchError,
+        available_providers, paid_search_enabled,
+        resolve_provider_chain, search)
+    from cloud.websearch_mcp import handle_request
+except ImportError:
+    sys.path.insert(0, str(Path(__file__).resolve().parents[2]))
+    from cloud.websearch import (
+        DEFAULT_CHAIN, DEFAULT_FREE_CHAIN, HttpClient, WebSearchError,
+        available_providers, paid_search_enabled,
+        resolve_provider_chain, search)
+    from cloud.websearch_mcp import handle_request
+
+_FAKE_KEYS = {
+    "PERPLEXITY_API_KEY": "pplx-SECRET-111",
+    "EXA_API_KEY": "exa-SECRET-222",
+    "TAVILY_API_KEY": "tvly-SECRET-333",
+    "BRAVE_API_KEY": "brave-SECRET-444",
+}
+
+_DDG_HTML = (
+    '<a class="result__a" href="//duckduckgo.com/l/?uddg='
+    'https%3A%2F%2Fexample.com%2Fddg">DDG Title</a>'
+    '<a class="result__snippet">ddg snippet</a>')
+
+
+class FakeHttp:
+    """post_json/get keyed by URL substring; failures raise like HTTP."""
+
+    def __init__(self, routes):
+        self.routes = routes
+        self.seen = []
+
+    def post_json(self, url, headers, payload):
+        self.seen.append(("POST", url, payload))
+        return self._route(url)
+
+    def get(self, url, headers=None):
+        self.seen.append(("GET", url, headers))
+        return self._route(url)
+
+    def _route(self, url):
+        for needle, body, status in self.routes:
+            if needle in url:
+                if status != 200:
+                    raise WebSearchError("HTTP %s" % status)
+                if isinstance(body, dict):
+                    return 200, json.dumps(body).encode(), "application/json"
+                return 200, body.encode(), "text/html"
+        raise WebSearchError("HTTP 404")
+
+
+def _searxng_body():
+    return {"results": [
+        {"title": "SearXNG Hit", "url": "https://example.com/sx",
+         "content": "searxng snippet"}]}
+
+
+def _paid_env(**extra):
+    env = dict(_FAKE_KEYS)
+    env["SEARXNG_URL"] = "http://searx.test"
+    env.update(extra)
+    return env
+
+
+def _paid_hosts_seen(http):
+    hosts = []
+    for _method, url, _payload in http.seen:
+        for paid in ("perplexity", "exa.ai", "tavily",
+                     "search.brave.com"):
+            if paid in url:
+                hosts.append(paid)
+    return hosts
+
+
+class FrozenDefaultTestCase(unittest.TestCase):
+    def test_default_auto_excludes_paid_even_with_all_keys(self):
+        env = _paid_env()
+        self.assertEqual(available_providers(env),
+                         ["searxng", "duckduckgo"])
+        self.assertEqual(resolve_provider_chain("auto", env),
+                         ["searxng", "duckduckgo"])
+        http = FakeHttp([("searx", _searxng_body(), 200)])
+        out = search("q", provider="auto", env=env, http=http)
+        self.assertEqual(out["provider"], "searxng")
+        self.assertEqual(_paid_hosts_seen(http), [])
+
+    def test_default_auto_without_searxng_url_is_duckduckgo_only(self):
+        env = dict(_FAKE_KEYS)
+        self.assertEqual(resolve_provider_chain("auto", env),
+                         ["duckduckgo"])
+        http = FakeHttp([("duckduckgo", _DDG_HTML, 200)])
+        out = search("q", provider="auto", env=env, http=http)
+        self.assertEqual(out["provider"], "duckduckgo")
+        self.assertEqual(_paid_hosts_seen(http), [])
+
+    def test_searxng_failure_never_falls_back_to_paid(self):
+        http = FakeHttp([("searx", {}, 500),
+                         ("duckduckgo", "<html>challenge</html>", 200)])
+        with self.assertRaises(WebSearchError) as ctx:
+            search("q", provider="auto", env=_paid_env(), http=http)
+        self.assertEqual(
+            [a["provider"] for a in ctx.exception.attempted],
+            ["searxng", "duckduckgo"])
+        self.assertEqual(_paid_hosts_seen(http), [])
+        # No fabricated result: the error names both free stages.
+        self.assertIn("searxng", str(ctx.exception))
+        self.assertIn("duckduckgo", str(ctx.exception))
+
+    def test_duckduckgo_fallback_failure_reports_clearly(self):
+        # DuckDuckGo under the VM/host egress returns a 202-style
+        # robot-challenge page: the parser yields no results, which
+        # must surface as an honest "no results" failure for that
+        # stage, never as a fabricated hit.
+        http = FakeHttp([("searx", {}, 500),
+                         ("duckduckgo", "<html>anomaly</html>", 200)])
+        with self.assertRaises(WebSearchError) as ctx:
+            search("q", provider="auto", env=_paid_env(), http=http)
+        attempted = {a["provider"]: a for a in ctx.exception.attempted}
+        self.assertEqual(attempted["duckduckgo"]["error"], "no results")
+        self.assertFalse(attempted["duckduckgo"]["ok"])
+        for secret in _FAKE_KEYS.values():
+            self.assertNotIn(secret, str(ctx.exception))
+
+
+class ExplicitPinTestCase(unittest.TestCase):
+    def test_explicit_pin_paid_still_works_while_frozen(self):
+        http = FakeHttp([
+            ("api.tavily.com",
+             {"results": [{"title": "T", "url": "https://example.com/t",
+                           "content": "tavily content"}]}, 200),
+        ])
+        out = search("q", provider="tavily", env=_paid_env(), http=http)
+        self.assertEqual(out["provider"], "tavily")
+        self.assertEqual(out["results"][0]["snippet"], "tavily content")
+
+    def test_explicit_pin_paid_failure_does_not_fall_back(self):
+        http = FakeHttp([("perplexity", {}, 500),
+                         ("api.exa.ai", {"results": [
+                             {"title": "E", "url": "https://example.com/e",
+                              "text": "x"}]}, 200)])
+        with self.assertRaises(WebSearchError):
+            search("q", provider="perplexity", env=_paid_env(), http=http)
+        self.assertEqual(_paid_hosts_seen(http), ["perplexity"])
+
+    def test_frozen_default_applies_to_scope_code_too(self):
+        body = {"results": [
+            {"title": "GH", "url": "https://github.com/a/b",
+             "content": "code hit"},
+            {"title": "Other", "url": "https://example.com/other",
+             "content": "off-scope"}]}
+        http = FakeHttp([("searx", body, 200)])
+        out = search("q", provider="auto", env=_paid_env(),
+                     http=http, scope="code")
+        self.assertEqual(out["provider"], "searxng")
+        self.assertEqual(
+            [r["url"] for r in out["results"]], ["https://github.com/a/b"])
+        self.assertEqual(_paid_hosts_seen(http), [])
+
+
+class UnfreezeSwitchTestCase(unittest.TestCase):
+    def test_switch_off_by_default_and_non_1_values_do_not_unfreeze(self):
+        self.assertFalse(paid_search_enabled({}))
+        for value in ("0", "true", "yes", "", "on"):
+            env = _paid_env(WEBSEARCH_ENABLE_PAID=value)
+            self.assertFalse(paid_search_enabled(env), value)
+            self.assertEqual(resolve_provider_chain("auto", env),
+                             ["searxng", "duckduckgo"])
+
+    def test_switch_on_restores_legacy_chain_and_fallback(self):
+        env = _paid_env(WEBSEARCH_ENABLE_PAID="1")
+        self.assertTrue(paid_search_enabled(env))
+        self.assertEqual(resolve_provider_chain("auto", env),
+                         list(DEFAULT_CHAIN))
+        # The pre-freeze perplexity -> exa fallback, preserved
+        # verbatim under the explicit switch (plus the no-leak
+        # assertion from the old default-chain test).
+        http = FakeHttp([
+            ("perplexity", {}, 500),
+            ("api.exa.ai", {"results": [
+                {"title": "Exa Hit", "url": "https://example.com/exa",
+                 "text": "exa snippet", "score": 0.9}]}, 200),
+        ])
+        out = search("test query", provider="auto", env=env, http=http)
+        self.assertEqual(out["provider"], "exa")
+        self.assertEqual(out["results"][0]["url"],
+                         "https://example.com/exa")
+        self.assertEqual(out["attempted"][0]["provider"], "perplexity")
+        self.assertFalse(out["attempted"][0]["ok"])
+        blob = json.dumps(out)
+        for secret in _FAKE_KEYS.values():
+            self.assertNotIn(secret, blob)
+
+    def test_constants_state_the_contract(self):
+        self.assertEqual(DEFAULT_FREE_CHAIN, ("searxng", "duckduckgo"))
+        self.assertEqual(
+            DEFAULT_CHAIN,
+            ("perplexity", "exa", "tavily", "brave", "searxng",
+             "duckduckgo"))
+
+
+class TimeoutClarityTestCase(unittest.TestCase):
+    def test_http_client_maps_timeout_to_explicit_error(self):
+        client = HttpClient(timeout=20)
+        with mock.patch("urllib.request.urlopen",
+                        side_effect=socket.timeout("timed out")):
+            with self.assertRaises(WebSearchError) as ctx:
+                client.get("http://searx.test/search?q=x")
+        self.assertIn("timeout after 20s", str(ctx.exception))
+
+        with mock.patch(
+                "urllib.request.urlopen",
+                side_effect=urllib.error.URLError(
+                    socket.timeout("timed out"))):
+            with self.assertRaises(WebSearchError) as ctx:
+                client.get("http://searx.test/search?q=x")
+        self.assertIn("timeout after 20s", str(ctx.exception))
+
+    def test_http_client_does_not_relabel_dns_failure_as_timeout(self):
+        client = HttpClient(timeout=20)
+        with mock.patch(
+                "urllib.request.urlopen",
+                side_effect=urllib.error.URLError(
+                    "Temporary failure in name resolution")):
+            with self.assertRaises(WebSearchError) as ctx:
+                client.get("http://searx.test/search?q=x")
+        self.assertNotIn("timeout", str(ctx.exception))
+        self.assertIn("name resolution", str(ctx.exception))
+
+    def test_search_reports_timeout_as_error_not_no_results(self):
+        class TimeoutHttp(FakeHttp):
+            def get(self, url, headers=None):
+                self.seen.append(("GET", url, headers))
+                if "searx" in url:
+                    raise WebSearchError(
+                        "timeout after 20s waiting for HTTP response")
+                return self._route(url)
+
+        http = TimeoutHttp([("duckduckgo", _DDG_HTML, 200)])
+        out = search("q", provider="auto", env=_paid_env(), http=http)
+        self.assertEqual(out["provider"], "duckduckgo")
+        attempted = {a["provider"]: a for a in out["attempted"]}
+        self.assertIn("timeout after 20s",
+                      attempted["searxng"]["error"])
+        self.assertNotEqual(attempted["searxng"]["error"], "no results")
+
+
+class McpDescriptionTestCase(unittest.TestCase):
+    def test_tools_list_describes_frozen_default_and_unfreeze(self):
+        resp = handle_request(
+            {"jsonrpc": "2.0", "id": 1, "method": "tools/list"})
+        tool = [t for t in resp["result"]["tools"]
+                if t["name"] == "web_search"][0]
+        desc = tool["description"]
+        self.assertIn("SearXNG", desc)
+        self.assertIn("DuckDuckGo", desc)
+        self.assertIn("WEBSEARCH_ENABLE_PAID=1", desc)
+        self.assertIn("paid", desc.lower())
+
+
+if __name__ == "__main__":
+    unittest.main()

cloud/tests/test_websearch_worker.py

@@ -124,10 +124,24 @@ class DockerEnvTestCase(unittest.TestCase):
         self.assertIsNone(err)
         self.assertEqual(env.get("SEARXNG_URL"), "http://searx.diante.me")
 
+    def test_paid_unfreeze_switch_passes_into_container_env(self):
+        # The freeze switch must reach the MCP process (which reads
+        # only config.toml env, never worker env); without this
+        # passthrough, WEBSEARCH_ENABLE_PAID=1 on the host would
+        # silently leave default auto frozen inside containers.
+        from unittest import mock
+        with mock.patch.dict(os.environ,
+                             {"WEBSEARCH_ENABLE_PAID": "1"}):
+            ok, _, _, env, err = self._docker_context()
+        self.assertTrue(ok)
+        self.assertIsNone(err)
+        self.assertEqual(env.get("WEBSEARCH_ENABLE_PAID"), "1")
+
     def test_no_search_env_means_no_extra_env(self):
         from unittest import mock
         with mock.patch.dict(os.environ, {}, clear=False):
-            for k in ("SEARXNG_URL", "PERPLEXITY_API_KEY", "EXA_API_KEY",
+            for k in ("SEARXNG_URL", "WEBSEARCH_ENABLE_PAID",
+                      "PERPLEXITY_API_KEY", "EXA_API_KEY",
                       "TAVILY_API_KEY", "BRAVE_API_KEY"):
                 os.environ.pop(k, None)
             ok, _, _, env, err = self._docker_context()

cloud/websearch.py

@@ -21,6 +21,16 @@ Design notes (what is copied from oh-my-pi, and what is not):
   here is a small stdlib HTML parser: script/style stripped, text
   collapsed, long pages truncated head+tail like Hermes' deterministic
   budget (default 15000 chars, 75% head / 25% tail, ``[TRUNCATED]``).
+- FROZEN default chain (paid freeze): the default ``auto`` chain
+  contains only the free backends, SearXNG then DuckDuckGo, even
+  when paid keys happen to be set -- a SearXNG failure never falls
+  back to a paid backend, so default use can never incur paid cost.
+  The four paid backends (Perplexity, Exa, Tavily, Brave) keep their
+  code, tests and docs, and still run when explicitly pinned
+  (provider="tavily" etc.), which is a deliberate override, not a
+  default. Only WEBSEARCH_ENABLE_PAID=1 (exact value "1", default
+  off) restores the old default chain; unfreezing is an explicit act
+  and may incur paid cost, never a silent default.
 
 Security notes:
 - API keys come only from the process environment, never from
@@ -57,6 +67,9 @@ from html.parser import HTMLParser
 
 __all__ = [
     "DEFAULT_CHAIN",
+    "DEFAULT_FREE_CHAIN",
+    "PAID_PROVIDERS",
+    "paid_search_enabled",
     "CODE_SEARCH_DOMAINS",
     "WebSearchError",
     "SearchResult",
@@ -72,6 +85,12 @@ __all__ = [
 
 DEFAULT_CHAIN = ("perplexity", "exa", "tavily", "brave", "searxng",
                  "duckduckgo")
+# Paid backends, frozen out of the default auto chain (see the module
+# docstring). DEFAULT_CHAIN keeps the legacy full order so the
+# unfrozen chain is exactly the old one; DEFAULT_FREE_CHAIN is what
+# default auto actually walks while frozen.
+PAID_PROVIDERS = ("perplexity", "exa", "tavily", "brave")
+DEFAULT_FREE_CHAIN = ("searxng", "duckduckgo")
 DEFAULT_FETCH_CHAR_LIMIT = 15000
 
 # Programming-only search scope (``search(..., scope="code")``).
@@ -246,6 +265,27 @@ class HttpClient:
             raise WebSearchError(
                 "HTTP %s" % exc.code) from _ProviderHttpError(
                     exc.code, body)
+        except (socket.timeout, TimeoutError) as exc:
+            # A timeout is a timeout, never "no results": the caller
+            # (search's attempted entry, named by provider) must be
+            # able to tell which stage timed out, and a timed-out
+            # SearXNG must not be rewritten as an empty answer.
+            # HTTPError is a URLError subclass, so this branch must
+            # stay after the HTTPError branch above.
+            raise WebSearchError(
+                "timeout after %ss waiting for HTTP response"
+                % self.timeout) from exc
+        except urllib.error.URLError as exc:
+            reason = getattr(exc, "reason", None)
+            if isinstance(reason, (socket.timeout, TimeoutError)):
+                raise WebSearchError(
+                    "timeout after %ss waiting for HTTP response"
+                    % self.timeout) from exc
+            # DNS / connection failures keep their own message;
+            # they are not timeouts and must not be relabelled.
+            raise WebSearchError(
+                "URL error: %s" % reason if reason else "URL error"
+                ) from exc
 
     def get_text(self, url, headers=None):
         status, body, _ctype = self.get(url, headers)
@@ -534,11 +574,32 @@ _PROVIDERS = {
 }
 
 
-def available_providers(env=None):
-    """Providers usable right now: keyed ones with a key, plus free ones."""
+def paid_search_enabled(env=None):
+    """True only when the paid-unfreeze switch is explicitly on.
+
+    The switch is WEBSEARCH_ENABLE_PAID, and only the exact value
+    "1" counts (same strict convention as WEBSEARCH_ALLOW_PRIVATE_URLS
+    elsewhere in this module): any other value, including "true" or
+    "yes", leaves the paid backends frozen out of default auto.
+    Explicit pinning is unaffected by this switch either way.
+    """
     env = env if env is not None else os.environ
+    return env.get("WEBSEARCH_ENABLE_PAID") == "1"
+
+
+def available_providers(env=None):
+    """Providers usable right now, under the paid-freeze rule.
+
+    Frozen (default): only the free chain -- SearXNG when its URL
+    is set, plus DuckDuckGo -- even when paid keys are present.
+    Unfrozen (WEBSEARCH_ENABLE_PAID=1): the legacy full chain,
+    keyed backends only when their key is set, as before.
+    """
+    env = env if env is not None else os.environ
+    chain = (DEFAULT_CHAIN if paid_search_enabled(env)
+             else DEFAULT_FREE_CHAIN)
     out = []
-    for name in DEFAULT_CHAIN:
+    for name in chain:
         if name in _FREE_PROVIDERS:
             if name == "searxng" and not env.get("SEARXNG_URL"):
                 continue
@@ -552,8 +613,11 @@ def resolve_provider_chain(provider="auto", env=None):
     """Resolve the chain oh-my-pi style: auto walks, pinned does not.
 
     ``provider`` may be "auto" (default chain, filtered to what is
-    configured), a single name (that provider only, even if it fails),
-    or a comma-separated list (that order only). Unknown names raise
+    configured -- frozen by default to the free chain, SearXNG then
+    DuckDuckGo, unless WEBSEARCH_ENABLE_PAID=1 restores the legacy
+    full chain), a single name (that provider only, even if it fails
+    -- pinning a paid backend bypasses the freeze, deliberately), or
+    a comma-separated list (that order only). Unknown names raise
     ValueError before any HTTP happens.
     """
     env = env if env is not None else os.environ

cloud/websearch_mcp.py

@@ -35,9 +35,19 @@ _TOOLS = [
             "Search the web and return ranked results with title, URL "
             "and snippet, plus a synthesised answer when the provider "
             "supplies one. Use web_fetch to read specific pages. "
-            "provider may be 'auto' (walk Perplexity, Exa, Tavily, "
-            "Brave, then keyless SearXNG / DuckDuckGo, falling back "
-            "on failure) or a single provider name to pin it. "
+            "provider may be 'auto' (frozen default: keyless SearXNG "
+            "first, then DuckDuckGo as the free fallback, falling "
+            "back on failure; the paid backends Perplexity, Exa, "
+            "Tavily and Brave are NOT in the default chain even "
+            "when their keys are set, and a SearXNG failure never "
+            "falls back to a paid backend, so default use never "
+            "incurs paid cost) or a single provider name to pin it "
+            "(pinning a paid backend still calls it: that is an "
+            "explicit override, not a default). Set "
+            "WEBSEARCH_ENABLE_PAID=1 to restore the old default "
+            "chain (Perplexity, Exa, Tavily, Brave, SearXNG, "
+            "DuckDuckGo); unfreezing is explicit and may incur "
+            "paid cost. "
             "scope 'code' restricts results to programming sources "
             "only (official language docs, GitHub, package "
             "registries, Stack Overflow, CVE/NVD); anything else "

cloud/worker.py

@@ -3188,9 +3188,15 @@ class Worker:
         # auto 链会跳过 SearXNG、只剩 DuckDuckGo（实弹 e2e 已证实）。
         # 只透传已设置的项，值绝不进日志；付费 key 与网关 key 一样
         # 走 extra_env（容器内进程本就需要它调 API）。
+        # WEBSEARCH_ENABLE_PAID rides along so the paid-freeze
+        # switch set on the host actually reaches the MCP process
+        # (which reads only config.toml env, never worker env).
+        # Default is frozen; the switch is honoured only when set
+        # to exactly "1" (see websearch.paid_search_enabled).
         search_env = {
             k: os.environ[k]
             for k in ("SEARXNG_URL", "SEARXNG_ENGINES",
+                      "WEBSEARCH_ENABLE_PAID",
                       "PERPLEXITY_API_KEY", "EXA_API_KEY",
                       "TAVILY_API_KEY", "BRAVE_API_KEY")
             if os.environ.get(k)