Merge pull request 'Propagate web-search cancellation' (#1 ) from fix/web-search-cancellation-20260725 into main

Propagate web-search cancellation
2026-07-25 21:19:08 -07:00 · 2026-07-25 21:18:08 -07:00
19 changed files with 634 additions and 91 deletions
--- a/bin/context-kit
+++ b/bin/context-kit
@@ -382,19 +382,28 @@ cleanup_owned_container() {
  docker rm -f "${container_id}" >/dev/null 2>&1 || true
 }

+cleanup_owned_stdio_container() {
+  local container_id="$1" owner="$2" attach_pid="$3"
+  cleanup_owned_container "${container_id}" "${owner}"
+  if [[ -n "${attach_pid}" ]]; then
+    kill "${attach_pid}" >/dev/null 2>&1 || true
+    wait "${attach_pid}" 2>/dev/null || true
+  fi
+}
+
 run_owned_stdio_container() {
  local role="$1"
  shift
-  local uid owner name container_id='' status=0
+  local uid owner name container_id='' attach_pid='' status=0
  uid="$(id -u)"
  owner="${PROJECT}:${role}:${uid}:$$"
  name="${PROJECT}-${role}-${uid}-$$"

-  trap 'cleanup_owned_container "${container_id}" "${owner}"' EXIT
+  trap 'cleanup_owned_stdio_container "${container_id}" "${owner}" "${attach_pid}"' EXIT
  trap 'exit 129' HUP
  trap 'exit 130' INT
  trap 'exit 143' TERM
-  container_id="$(docker create -i --rm \
+  container_id="$(docker create -i --rm --init \
    --name "${name}" \
    --label dev.context-kit=true \
    --label dev.context-kit.lifecycle=client \
@@ -411,7 +420,10 @@ run_owned_stdio_container() {
    printf '%s\n' "${container_id}" > "${CONTEXT_KIT_DOCKER_CIDFILE}"
  fi

-  docker start -ai "${container_id}" <&0 || status=$?
+  docker start -ai "${container_id}" <&0 &
+  attach_pid=$!
+  wait "${attach_pid}" || status=$?
+  attach_pid=''
  cleanup_owned_container "${container_id}" "${owner}"
  trap - EXIT HUP INT TERM
  return "${status}"
--- a/docker/web-search/.dockerignore
+++ b/docker/web-search/.dockerignore
@@ -2,6 +2,7 @@
 !Dockerfile
 !http-entrypoint.mjs
 !mcp-probe.mjs
+!patch-mcp-proxy.py
 !patch-mcp-web-search.mjs
 !overrides/
 !overrides/bing.js
--- a/docker/web-search/Dockerfile
+++ b/docker/web-search/Dockerfile
@@ -3,6 +3,7 @@ FROM node:22-bookworm-slim@sha256:813a7480f28fdadac1f7f5c824bcdad435b5bc1322a596
 ARG MCP_WEB_SEARCH_VERSION=1.3.0
 ARG MCP_WEB_SEARCH_MAX_BYTES=52428800
 ARG MCP_PROXY_VERSION=0.12.0
+ARG MCP_PYTHON_SDK_VERSION=1.28.1

 # Chromium intentionally tracks Debian security updates inside the pinned base
 # image family; Bing's browser path is more likely to break with stale Chromium
@@ -15,8 +16,13 @@ RUN apt-get update \
    python3-venv \
  && rm -rf /var/lib/apt/lists/*

+COPY patch-mcp-proxy.py /tmp/patch-mcp-proxy.py
+
 RUN python3 -m venv /opt/mcp-proxy \
-  && /opt/mcp-proxy/bin/pip install --no-cache-dir "mcp-proxy==${MCP_PROXY_VERSION}" \
+  && /opt/mcp-proxy/bin/pip install --no-cache-dir \
+    "mcp-proxy==${MCP_PROXY_VERSION}" \
+    "mcp==${MCP_PYTHON_SDK_VERSION}" \
+  && /opt/mcp-proxy/bin/python /tmp/patch-mcp-proxy.py \
  && /opt/mcp-proxy/bin/mcp-proxy --version

 COPY patch-mcp-web-search.mjs /tmp/patch-mcp-web-search.mjs
@@ -35,7 +41,7 @@ RUN npm install -g "@zhafron/mcp-web-search@${MCP_WEB_SEARCH_VERSION}" \
  && cp /tmp/context-kit-fetch/browser-fetch.js /usr/local/lib/node_modules/@zhafron/mcp-web-search/dist/src/fetch/browser.js \
  && cp /tmp/context-kit-fetch/bounds.mjs /usr/local/lib/node_modules/@zhafron/mcp-web-search/dist/src/fetch/bounds.js \
  && node /tmp/patch-mcp-web-search.mjs \
-  && rm -rf /tmp/patch-mcp-web-search.mjs /tmp/context-kit-bing-provider.js /tmp/context-kit-providers /tmp/context-kit-fetch \
+  && rm -rf /tmp/patch-mcp-proxy.py /tmp/patch-mcp-web-search.mjs /tmp/context-kit-bing-provider.js /tmp/context-kit-providers /tmp/context-kit-fetch \
  && npm cache clean --force

 RUN chmod -R a+rX /usr/local/lib/context-kit \
--- a/docker/web-search/http-entrypoint.mjs
+++ b/docker/web-search/http-entrypoint.mjs
@@ -88,13 +88,22 @@ export function createSecureMcpServer({ upstream = defaultUpstream, probe = prob
      path: request.url,
      headers: copyRequestHeaders(request.headers, target.host)
    }, upstreamResponse => {
+      upstreamResponse.on("error", () => response.destroy());
      response.writeHead(
        upstreamResponse.statusCode || 502,
        copyResponseHeaders(upstreamResponse.headers)
      );
      upstreamResponse.pipe(response);
    });
+    const abortUpstream = () => {
+      if (!upstreamRequest.destroyed) upstreamRequest.destroy(new Error("downstream disconnected"));
+    };
+    request.once("aborted", abortUpstream);
+    response.once("close", () => {
+      if (!response.writableEnded) abortUpstream();
+    });
    upstreamRequest.on("error", error => {
+      if (response.destroyed) return;
      if (!response.headersSent) response.writeHead(502, { "Content-Type": "text/plain" });
      response.end(`backend unavailable: ${error.message}`);
    });
@@ -122,6 +131,23 @@ export function superviseBackend({ probe, intervalMs = 10000, onFailure }) {
  };
 }

+export async function terminateChild(child, { graceMs = 3000 } = {}) {
+  if (child.exitCode !== null || child.signalCode !== null) return;
+  const gracefulExit = once(child, "exit").then(() => true);
+  child.kill("SIGTERM");
+  const exited = await Promise.race([
+    gracefulExit,
+    delay(graceMs).then(() => false)
+  ]);
+  if (exited || child.exitCode !== null || child.signalCode !== null) return;
+
+  const forcedExit = once(child, "exit");
+  if (!child.kill("SIGKILL") && child.exitCode === null && child.signalCode === null) {
+    throw new Error("failed to terminate mcp-proxy child");
+  }
+  await forcedExit;
+}
+
 async function waitForBackend(child, url) {
  let lastError;
  for (let attempt = 0; attempt < 60; attempt += 1) {
@@ -152,11 +178,7 @@ async function main() {
    stopSupervisor();
    server?.close();
    server?.closeAllConnections();
-    if (child.exitCode === null) {
-      child.kill("SIGTERM");
-      await Promise.race([once(child, "exit"), delay(3000)]).catch(() => {});
-      if (child.exitCode === null) child.kill("SIGKILL");
-    }
+    await terminateChild(child);
    process.exitCode = code;
  };

--- a/docker/web-search/mcp-probe.mjs
+++ b/docker/web-search/mcp-probe.mjs
@@ -3,7 +3,8 @@ import { fileURLToPath } from "node:url";
 const protocolVersion = "2024-11-05";
 const expectedTools = ["fetch_url", "search_web"];

-export async function rpc(url, id, method, params = {}, timeoutMs = 5000) {
+export async function rpc(url, id, method, params = {}, timeoutMs = 5000, signal) {
+  const timeoutSignal = AbortSignal.timeout(timeoutMs);
  const response = await fetch(url, {
    method: "POST",
    headers: {
@@ -12,7 +13,7 @@ export async function rpc(url, id, method, params = {}, timeoutMs = 5000) {
      "MCP-Protocol-Version": protocolVersion
    },
    body: JSON.stringify({ jsonrpc: "2.0", id, method, params }),
-    signal: AbortSignal.timeout(timeoutMs)
+    signal: signal ? AbortSignal.any([signal, timeoutSignal]) : timeoutSignal
  });
  const text = await response.text();
  if (!response.ok) throw new Error(`${method} returned HTTP ${response.status}: ${text.slice(0, 300)}`);
--- a/docker/web-search/overrides/browser-fetch.js
+++ b/docker/web-search/overrides/browser-fetch.js
@@ -12,10 +12,16 @@ function responseHeaders(headers) {
  return record;
 }

-export async function fetchBrowserResource(url, timeoutMs = HTTP_TIMEOUT) {
+export async function fetchBrowserResource(url, timeoutMs = HTTP_TIMEOUT, signal) {
+  signal?.throwIfAborted();
  await assertSafeUrl(url);
  return browserPool.withBrowser(async browser => {
    const page = await browser.newPage();
+    const pendingRequests = new Set();
+    const abort = () => void page.close().catch(() => undefined);
+    signal?.addEventListener("abort", abort, { once: true });
+    try {
+      signal?.throwIfAborted();
      const devtools = await page.target().createCDPSession();
      await devtools.send("Network.enable");
      await devtools.send("Network.setBlockedURLs", {
@@ -43,7 +49,7 @@ export async function fetchBrowserResource(url, timeoutMs = HTTP_TIMEOUT) {
      let blockedError;
      await page.setRequestInterception(true);
      page.on("request", request => {
-      void (async () => {
+        const pending = (async () => {
          try {
            const requestUrl = new URL(request.url());
            if (!["http:", "https:"].includes(requestUrl.protocol)) throw new Error("unsupported browser request scheme");
@@ -51,7 +57,7 @@ export async function fetchBrowserResource(url, timeoutMs = HTTP_TIMEOUT) {
            requests += 1;
            if (requests > MAX_BROWSER_REQUESTS) throw new Error("browser request limit exceeded");
            await assertSafeUrl(requestUrl);
-          const upstream = await fetchViaVettedAddress(requestUrl, timeoutMs);
+            const upstream = await fetchViaVettedAddress(requestUrl, timeoutMs, signal);
            const body = Buffer.from(await upstream.arrayBuffer());
            totalBytes += body.byteLength;
            if (totalBytes > MAX_BROWSER_TOTAL_BYTES) throw new Error("browser byte limit exceeded");
@@ -65,8 +71,10 @@ export async function fetchBrowserResource(url, timeoutMs = HTTP_TIMEOUT) {
            await request.abort("blockedbyclient").catch(() => undefined);
          }
        })();
+        pendingRequests.add(pending);
+        void pending.finally(() => pendingRequests.delete(pending));
      });
-    try {
+      signal?.throwIfAborted();
      const navigation = await page.goto(url.toString(), {
        waitUntil: "networkidle2",
        timeout: timeoutMs
@@ -88,8 +96,13 @@ export async function fetchBrowserResource(url, timeoutMs = HTTP_TIMEOUT) {
        buffer,
        byteLength: buffer.byteLength
      };
+    } catch (error) {
+      signal?.throwIfAborted();
+      throw error;
    } finally {
-      await page.close();
+      signal?.removeEventListener("abort", abort);
+      if (!page.isClosed()) await page.close();
+      await Promise.allSettled(pendingRequests);
    }
  });
 }
--- a/docker/web-search/overrides/diagnostics.mjs
+++ b/docker/web-search/overrides/diagnostics.mjs
@@ -17,24 +17,22 @@ export async function attemptProvider(provider, query, limit, lang, options = {}
  const timeoutMs = Math.max(10, Math.min(options.timeoutMs || DEFAULT_TIMEOUT_MS, 60_000));
  const now = options.now || (() => performance.now());
  const started = now();
+  options.signal?.throwIfAborted();
  if (provider.configured === false) {
    return {
      items: [],
      diagnostic: { provider: provider.name, status: "unavailable", duration_ms: 0, result_count: 0 }
    };
  }
-  let timer;
  const controller = new AbortController();
-  try {
-    const items = await Promise.race([
-      provider.search(query, limit, lang, controller.signal),
-      new Promise((_, reject) => {
-        timer = setTimeout(() => {
+  const signal = options.signal
+    ? AbortSignal.any([options.signal, controller.signal])
+    : controller.signal;
+  const timer = setTimeout(() => {
    controller.abort(new Error(`provider timed out after ${timeoutMs}ms`));
-          reject(new Error(`provider timed out after ${timeoutMs}ms`));
  }, timeoutMs);
-      })
-    ]);
+  try {
+    const items = await provider.search(query, limit, lang, signal);
    const bounded = Array.isArray(items) ? items.slice(0, limit) : [];
    return {
      items: bounded,
@@ -46,6 +44,7 @@ export async function attemptProvider(provider, query, limit, lang, options = {}
      }
    };
  } catch (error) {
+    options.signal?.throwIfAborted();
    return {
      items: [],
      diagnostic: {
@@ -57,7 +56,6 @@ export async function attemptProvider(provider, query, limit, lang, options = {}
      }
    };
  } finally {
-    controller.abort();
    clearTimeout(timer);
  }
 }
--- a/docker/web-search/overrides/registry.js
+++ b/docker/web-search/overrides/registry.js
@@ -23,15 +23,19 @@ export class ProviderRegistry {
    return this.providers.get(name);
  }

-  async searchWithFallback(q, limit, lang, preferredProvider) {
+  async searchWithFallback(q, limit, lang, preferredProvider, signal) {
    const defaultProvider = preferredProvider || DEFAULT_SEARCH_PROVIDER;
    const order = [defaultProvider, ...PROVIDERS.filter(name => name !== defaultProvider)].slice(0, MAX_PROVIDER_ATTEMPTS);
    const attempts = [];
    const started = performance.now();
    for (const providerName of order) {
+      signal?.throwIfAborted();
      const provider = this.providers.get(providerName);
      if (!provider) continue;
-      const attempt = await attemptProvider(provider, q, limit, lang, { timeoutMs: PROVIDER_TIMEOUT_MS });
+      const attempt = await attemptProvider(provider, q, limit, lang, {
+        timeoutMs: PROVIDER_TIMEOUT_MS,
+        signal
+      });
      attempts.push(attempt.diagnostic);
      if (attempt.items.length) {
        return {
--- a/docker/web-search/patch-mcp-proxy.py
+++ b/docker/web-search/patch-mcp-proxy.py
@@ -0,0 +1,168 @@
+#!/usr/bin/env python3
+from importlib.metadata import version
+from importlib.util import find_spec
+from pathlib import Path
+
+
+EXPECTED_VERSIONS = {
+    "mcp-proxy": "0.12.0",
+    "mcp": "1.28.1",
+}
+
+
+def module_path(name: str) -> Path:
+    spec = find_spec(name)
+    if spec is None or spec.origin is None:
+        raise RuntimeError(f"module not found: {name}")
+    return Path(spec.origin)
+
+
+def replace_once(path: Path, before: str, after: str) -> None:
+    source = path.read_text()
+    count = source.count(before)
+    if count != 1:
+        raise RuntimeError(f"expected one patch target in {path}, found {count}: {before}")
+    path.write_text(source.replace(before, after))
+
+
+for package, expected in EXPECTED_VERSIONS.items():
+    actual = version(package)
+    if actual != expected:
+        raise RuntimeError(f"expected {package} {expected}, found {actual}")
+
+
+proxy_path = module_path("mcp_proxy.proxy_server")
+replace_once(
+    proxy_path,
+    "import logging\nimport typing as t\n\nfrom mcp import server, types",
+    "import logging\nimport typing as t\n\nimport anyio\n\nfrom mcp import server, types",
+)
+replace_once(
+    proxy_path,
+    """                result = await remote_app.call_tool(
+                    req.params.name,
+                    (req.params.arguments or {}),
+                    meta=meta_dict,
+                    progress_callback=progress_callback,
+                )
+""",
+    """                completed = anyio.Event()
+                disconnected = False
+                downstream_request = request_ctx.get().request
+
+                async def watch_downstream_disconnect() -> None:
+                    nonlocal disconnected
+                    while not completed.is_set():
+                        if await downstream_request.is_disconnected():
+                            disconnected = True
+                            task_group.cancel_scope.cancel()
+                            return
+                        await anyio.sleep(0.05)
+
+                async with anyio.create_task_group() as task_group:
+                    if downstream_request is not None and hasattr(downstream_request, "is_disconnected"):
+                        task_group.start_soon(watch_downstream_disconnect)
+                    try:
+                        result = await remote_app.call_tool(
+                            req.params.name,
+                            (req.params.arguments or {}),
+                            meta=meta_dict,
+                            progress_callback=progress_callback,
+                        )
+                    finally:
+                        completed.set()
+                        task_group.cancel_scope.cancel()
+
+                if disconnected:
+                    raise ConnectionError("downstream client disconnected")
+""",
+)
+
+
+session_path = module_path("mcp.shared.session")
+replace_once(
+    session_path,
+    """        finally:
+            self._response_streams.pop(request_id, None)
+            self._progress_callbacks.pop(request_id, None)
+""",
+    """        except anyio.get_cancelled_exc_class():
+            # Context Kit: forward cancellation before abandoning the remote request.
+            with anyio.move_on_after(1, shield=True):
+                try:
+                    await self.send_notification(
+                        CancelledNotification(
+                            params={"requestId": request_id, "reason": "upstream request cancelled"}
+                        )
+                    )
+                except Exception:
+                    pass
+            raise
+        finally:
+            self._response_streams.pop(request_id, None)
+            self._progress_callbacks.pop(request_id, None)
+""",
+)
+
+
+streamable_http_path = module_path("mcp.client.streamable_http")
+replace_once(
+    streamable_http_path,
+    """        self.url = url
+        self.session_id = None
+        self.protocol_version = None
+""",
+    """        self.url = url
+        self.session_id = None
+        self.protocol_version = None
+        self._request_cancel_scopes: dict[RequestId, anyio.CancelScope] = {}
+""",
+)
+replace_once(
+    streamable_http_path,
+    """                    async def handle_request_async():
+                        if is_resumption:
+                            await self._handle_resumption_request(ctx)
+                        else:
+                            await self._handle_post_request(ctx)
+
+                    # If this is a request, start a new task to handle it
+                    if isinstance(message.root, JSONRPCRequest):
+                        tg.start_soon(handle_request_async)
+                    else:
+                        await handle_request_async()
+""",
+    """                    async def handle_request_async(
+                        request_context: RequestContext = ctx,
+                        resume: bool = is_resumption,
+                    ) -> None:
+                        root = request_context.session_message.message.root
+                        request_id = root.id if isinstance(root, JSONRPCRequest) else None
+                        with anyio.CancelScope() as request_scope:
+                            if request_id is not None:
+                                self._request_cancel_scopes[request_id] = request_scope
+                            try:
+                                if resume:
+                                    await self._handle_resumption_request(request_context)
+                                else:
+                                    await self._handle_post_request(request_context)
+                            finally:
+                                if self._request_cancel_scopes.get(request_id) is request_scope:
+                                    self._request_cancel_scopes.pop(request_id, None)
+
+                    # If this is a request, start a new task to handle it
+                    if isinstance(message.root, JSONRPCRequest):
+                        tg.start_soon(handle_request_async)
+                    else:
+                        if (
+                            isinstance(message.root, JSONRPCNotification)
+                            and message.root.method == "notifications/cancelled"
+                        ):
+                            request_scope = self._request_cancel_scopes.get(
+                                (message.root.params or {}).get("requestId")
+                            )
+                            if request_scope is not None:
+                                request_scope.cancel()
+                        await handle_request_async()
+""",
+)
--- a/docker/web-search/patch-mcp-web-search.mjs
+++ b/docker/web-search/patch-mcp-web-search.mjs
@@ -23,6 +23,22 @@ const replacements = [
  [
    "Search the web using multiple providers (DuckDuckGo, Bing, SearXNG). Automatically falls back to other providers if the default fails. No API keys required for DuckDuckGo and SearXNG.",
    "Search the web with bounded provider fallback and per-attempt diagnostics. SearXNG is local; Brave is available when BRAVE_SEARCH_API_KEY is configured."
+  ],
+  [
+    '}, async ({ q, limit = DEFAULT_LIMIT, lang = "en", provider }) => {',
+    '}, async ({ q, limit = DEFAULT_LIMIT, lang = "en", provider }, { signal }) => {'
+  ],
+  [
+    "providerRegistry.searchWithFallback(q, Math.min(Math.max(1, limit), 50), lang, provider)",
+    "providerRegistry.searchWithFallback(q, Math.min(Math.max(1, limit), 50), lang, provider, signal)"
+  ],
+  [
+    '}, async ({ url, format, max_length, start_index, engine, include_links, include_media, include_metadata, include_comments, comment_limit, comment_sort, max_depth, timeout_ms, fresh, download, download_dir, download_ttl_seconds, max_download_bytes }) => {',
+    '}, async ({ url, format, max_length, start_index, engine, include_links, include_media, include_metadata, include_comments, comment_limit, comment_sort, max_depth, timeout_ms, fresh, download, download_dir, download_ttl_seconds, max_download_bytes }, { signal }) => {'
+  ],
+  [
+    "        max_download_bytes\n    });",
+    "        max_download_bytes,\n        signal\n    });"
  ]
 ];

@@ -39,7 +55,13 @@ const httpPath = "/usr/local/lib/node_modules/@zhafron/mcp-web-search/dist/src/f
 let httpSource = fs.readFileSync(httpPath, "utf8");
 const privateTransport = "async function fetchViaVettedAddress(url, timeoutMs)";
 if (!httpSource.includes(privateTransport)) throw new Error(`mcp-web-search patch target not found: ${privateTransport}`);
-httpSource = httpSource.replace(privateTransport, "export async function fetchViaVettedAddress(url, timeoutMs)");
+httpSource = httpSource.replace(privateTransport, "export async function fetchViaVettedAddress(url, timeoutMs, signal)");
+const requestTimeout = "            timeout: timeoutMs\n        }, response => {";
+if (!httpSource.includes(requestTimeout)) throw new Error(`mcp-web-search patch target not found: ${requestTimeout}`);
+httpSource = httpSource.replace(requestTimeout, "            timeout: timeoutMs,\n            signal\n        }, response => {");
+const transportCall = "response = await transport(currentUrl, timeoutMs);";
+if (!httpSource.includes(transportCall)) throw new Error(`mcp-web-search patch target not found: ${transportCall}`);
+httpSource = httpSource.replace(transportCall, "response = await transport(currentUrl, timeoutMs, options?.signal);");
 fs.writeFileSync(httpPath, httpSource);

 const utilityHttpPath = "/usr/local/lib/node_modules/@zhafron/mcp-web-search/dist/src/utils/http.js";
@@ -59,17 +81,20 @@ const extractReplacements = [
  ],
  [
    "fetchCache.set(cacheKey, siteResult);\n        return siteResult;",
-    "const boundedSiteResult = boundFetchCollections(siteResult);\n        fetchCache.set(cacheKey, boundedSiteResult);\n        return boundedSiteResult;"
+    "const boundedSiteResult = boundFetchCollections(siteResult);\n        options?.signal?.throwIfAborted();\n        fetchCache.set(cacheKey, boundedSiteResult);\n        return boundedSiteResult;"
  ],
  [
    "const resource = await fetchResource(parsedUrl, options?.timeout_ms, transport, options);",
-    'const resource = options?.engine === "browser"\n        ? await fetchBrowserResource(parsedUrl, options?.timeout_ms)\n        : await fetchResource(parsedUrl, options?.timeout_ms, transport, options);'
+    'const resource = options?.engine === "browser"\n        ? await fetchBrowserResource(parsedUrl, options?.timeout_ms, options?.signal)\n        : await fetchResource(parsedUrl, options?.timeout_ms, transport, options);\n    options?.signal?.throwIfAborted();'
  ],
  [
    "fetchCache.set(cacheKey, result);\n    return result;",
-    "result = boundFetchCollections(result);\n    fetchCache.set(cacheKey, result);\n    return result;"
+    "result = boundFetchCollections(result);\n    options?.signal?.throwIfAborted();\n    fetchCache.set(cacheKey, result);\n    return result;"
  ]
 ];
+const fetchStart = "export async function fetchAndExtract(url, options, transport) {\n    const parsedUrl = new URL(url);";
+if (!extractSource.includes(fetchStart)) throw new Error(`mcp-web-search extract patch target not found: ${fetchStart}`);
+extractSource = extractSource.replace(fetchStart, "export async function fetchAndExtract(url, options, transport) {\n    options?.signal?.throwIfAborted();\n    const parsedUrl = new URL(url);");
 for (const [before, after] of extractReplacements) {
  if (!extractSource.includes(before)) throw new Error(`mcp-web-search extract patch target not found: ${before}`);
  extractSource = extractSource.replace(before, after);
--- a/scripts/fixtures/web/mock-server.mjs
+++ b/scripts/fixtures/web/mock-server.mjs
@@ -1,6 +1,7 @@
 import http from "node:http";

 let websocketUpgrades = 0;
+let slowRequests = 0;

 const server = http.createServer((request, response) => {
  const url = new URL(request.url, "http://mock-search.test");
@@ -23,6 +24,23 @@ const server = http.createServer((request, response) => {
      </body></html>`);
    return;
  }
+  if (url.pathname === "/slow") {
+    slowRequests += 1;
+    let closed = false;
+    response.once("close", () => {
+      if (closed) return;
+      closed = true;
+      slowRequests -= 1;
+    });
+    response.writeHead(200, { "Content-Type": "text/plain" });
+    response.write("pending");
+    return;
+  }
+  if (url.pathname === "/slow-count") {
+    response.writeHead(200, { "Content-Type": "text/plain" });
+    response.end(String(slowRequests));
+    return;
+  }
  if (url.pathname === "/redirect-private") {
    response.writeHead(302, { Location: "http://127.0.0.1:8765/private" });
    response.end();
--- a/scripts/mcp-smoke-client.mjs
+++ b/scripts/mcp-smoke-client.mjs
@@ -49,7 +49,7 @@ export async function runSmoke({ usage, tmpPrefix, timeoutMs, clientInfo, scenar
  }
 }

-class McpSmokeClient {
+export class McpSmokeClient {
  constructor({ command, args, tmpPrefix }) {
    this.tmpDir = mkdtempSync(join(tmpdir(), tmpPrefix));
    this.cidFile = join(this.tmpDir, "container.cid");
--- a/scripts/release-check
+++ b/scripts/release-check
@@ -170,12 +170,28 @@ if (actual !== expected) process.exit(1);
 const serverPath = "/usr/local/lib/node_modules/@zhafron/mcp-web-search/dist/src/server.js";
 const server = fs.readFileSync(serverPath, "utf8");
 if (!server.includes("max_download_bytes: z.number().int().min(1).max(MAX_BYTES).optional()")) process.exit(1);
+if (!server.includes("provider, signal)")) process.exit(1);
+if (!server.includes("max_download_bytes,\n        signal")) process.exit(1);

 const bingPath = "/usr/local/lib/node_modules/@zhafron/mcp-web-search/dist/src/providers/bing.js";
 const bing = fs.readFileSync(bingPath, "utf8");
 if (!bing.includes("Context Kit override for @zhafron/mcp-web-search 1.3.0")) process.exit(1);
 if (!bing.includes("waitForSelector")) process.exit(1);
 if (!bing.includes("decodeBingRedirect")) process.exit(1);
+' >/dev/null
+
+  docker run --rm --entrypoint /opt/mcp-proxy/bin/python \
+    "${CONTEXT_KIT_WEB_SEARCH_IMAGE}" \
+    -c '
+from pathlib import Path
+
+root = Path("/opt/mcp-proxy/lib/python3.11/site-packages")
+session = (root / "mcp/shared/session.py").read_text()
+proxy = (root / "mcp_proxy/proxy_server.py").read_text()
+transport = (root / "mcp/client/streamable_http.py").read_text()
+assert "Context Kit: forward cancellation" in session
+assert "downstream client disconnected" in proxy
+assert "_request_cancel_scopes" in transport
 ' >/dev/null

  docker run --rm --entrypoint /usr/bin/test \
@@ -249,6 +265,7 @@ assert_web_search_backend_supervision() {
 git diff --check HEAD
 git show --check --format= HEAD >/dev/null
 git ls-files --cached --error-unmatch \
+  docker/web-search/patch-mcp-proxy.py \
  docker/web-search/patch-mcp-web-search.mjs \
  docker/web-search/overrides/bing.js \
  docker/docs/constraints.txt \
@@ -258,7 +275,10 @@ git ls-files --cached --error-unmatch \
  scripts/smoke-repomix.mjs \
  scripts/test-compose-upgrade.sh \
  scripts/test-lifecycle.sh \
+  scripts/test-web-search-candidate.sh \
  scripts/test-web-search-http.mjs \
+  scripts/test-web-search-quality.mjs \
+  scripts/test-web-search-stdio-cancellation.mjs \
  docker/web-search/mcp-probe.mjs \
  docker/web-search/http-entrypoint.mjs \
  scripts/release-check >/dev/null
@@ -267,7 +287,8 @@ bash -n scripts/release-check
 bash -n scripts/test-compose-upgrade.sh
 bash -n scripts/test-lifecycle.sh
 sh -n docker/docs/entrypoint.sh
-check_node docker/web-search/patch-mcp-web-search.mjs docker/web-search/overrides/bing.js docker/web-search/overrides/brave.js docker/web-search/overrides/browser-fetch.js docker/web-search/overrides/registry.js docker/web-search/mcp-probe.mjs docker/web-search/http-entrypoint.mjs scripts/docs-rebuild.mjs scripts/mcp-smoke-client.mjs scripts/smoke-web-search.mjs scripts/smoke-docs.mjs scripts/smoke-repomix.mjs scripts/test-docs-candidate.mjs scripts/test-web-search-candidate.mjs scripts/test-web-search-http.mjs scripts/test-web-search-quality.mjs
+check_node docker/web-search/patch-mcp-web-search.mjs docker/web-search/overrides/bing.js docker/web-search/overrides/brave.js docker/web-search/overrides/browser-fetch.js docker/web-search/overrides/registry.js docker/web-search/mcp-probe.mjs docker/web-search/http-entrypoint.mjs scripts/docs-rebuild.mjs scripts/mcp-smoke-client.mjs scripts/smoke-web-search.mjs scripts/smoke-docs.mjs scripts/smoke-repomix.mjs scripts/test-docs-candidate.mjs scripts/test-web-search-candidate.mjs scripts/test-web-search-http.mjs scripts/test-web-search-quality.mjs scripts/test-web-search-stdio-cancellation.mjs scripts/fixtures/web/mock-server.mjs
+python3 -c 'import ast, pathlib; ast.parse(pathlib.Path("docker/web-search/patch-mcp-proxy.py").read_text())'

 node -e 'const fs=require("node:fs"); JSON.parse(fs.readFileSync("snippets/opencode.json", "utf8")); JSON.parse(fs.readFileSync("snippets/claude.mcp.json", "utf8"));'
 CONTEXT_KIT_WEB_SEARCH_HTTP_URL="http://127.0.0.1:8777/mcp" CONTEXT_KIT_DOCS_HTTP_URL="http://127.0.0.1:8776/mcp" bin/context-kit install opencode > "${tmp_dir}/opencode-default.json"
--- a/scripts/test-lifecycle.sh
+++ b/scripts/test-lifecycle.sh
@@ -189,6 +189,14 @@ docker() {
      if service="$(fake_service_for_container "${container_id}" 2>/dev/null)"; then
        assert_docs_sources_restored_before_state_change
        touch "${FAKE_DOCKER_STATE}/service.${service}.running"
+      elif [[ -f "${FAKE_DOCKER_STATE}/owner.${container_id}" && "${FAKE_CLIENT_START_BLOCK:-0}" -eq 1 ]]; then
+        /bin/sh -c '
+          touch "$1"
+          while [ -f "$2" ] && [ ! -f "$3" ]; do /bin/sleep 0.02; done
+        ' sh \
+          "${FAKE_DOCKER_STATE}/client-attach.started" \
+          "${FAKE_DOCKER_STATE}/owner.${container_id}" \
+          "${FAKE_DOCKER_STATE}/client-attach.release"
      fi
      ;;
    rm)
@@ -259,7 +267,8 @@ new_case() {
  unset CONTEXT_KIT_DOCKER_CIDFILE CONTEXT_KIT_RUNTIME_DIR FAKE_DOCS_UID FAKE_WEB_UID \
    FAKE_REPLACEMENT_REQUIRED FAKE_RESTART_FAIL FAKE_DROP_RUNNING FAKE_SEARXNG_FAIL \
    FAKE_WEB_SEARCH_FAIL FAKE_DOCS_FAIL FAKE_LEGACY_CONTAINER FAKE_CLIENT_OWNER_MISMATCH \
-    FAKE_EXPECT_DOCS_SOURCES FAKE_EXPECT_DOCS_SOURCES_ABSENT CONTEXT_KIT_DOCS_LOCAL_SOURCES_DIR
+    FAKE_CLIENT_START_BLOCK FAKE_EXPECT_DOCS_SOURCES FAKE_EXPECT_DOCS_SOURCES_ABSENT \
+    CONTEXT_KIT_DOCS_LOCAL_SOURCES_DIR
  mkdir -p "${FAKE_DOCKER_STATE}" "${HOME}"
  : > "${FAKE_DOCKER_LOG}"
 }
@@ -339,11 +348,40 @@ touch "${FAKE_DOCKER_STATE}/network"
 seed_service web-search-mcp
 "${CONTEXT_KIT}" web-search </dev/null
 grep -E 'docker create .*dev.context-kit.lifecycle=client .*--entrypoint mcp-proxy .*http://web-search-mcp:8000/mcp' "${FAKE_DOCKER_LOG}" >/dev/null || fail_test "stdio bridge does not reuse the shared service"
+grep -F 'docker create -i --rm --init' "${FAKE_DOCKER_LOG}" >/dev/null || fail_test "stdio bridge container does not use Docker init"
 [[ -f "${FAKE_DOCKER_STATE}/service.web-search-mcp.running" ]] || fail_test "stdio bridge stopped the shared service"
 if compgen -G "${FAKE_DOCKER_STATE}/owner.*" >/dev/null; then
  fail_test "stdio bridge did not clean up its own container"
 fi

+new_case client-signal-cleanup
+touch "${FAKE_DOCKER_STATE}/network"
+seed_service web-search-mcp
+export FAKE_CLIENT_START_BLOCK=1
+"${CONTEXT_KIT}" web-search </dev/null >"${CASE_ROOT}/client.out" 2>&1 &
+client_pid=$!
+for _ in {1..100}; do
+  [[ -f "${FAKE_DOCKER_STATE}/client-attach.started" ]] && break
+  /bin/sleep 0.01
+done
+[[ -f "${FAKE_DOCKER_STATE}/client-attach.started" ]] || fail_test "blocking stdio attach did not start"
+kill -TERM "${client_pid}"
+owner_removed=0
+for _ in {1..50}; do
+  if ! compgen -G "${FAKE_DOCKER_STATE}/owner.*" >/dev/null; then
+    owner_removed=1
+    break
+  fi
+  /bin/sleep 0.01
+done
+touch "${FAKE_DOCKER_STATE}/client-attach.release"
+set +e
+wait "${client_pid}"
+client_status=$?
+set -e
+[[ "${owner_removed}" -eq 1 ]] || fail_test "SIGTERM did not promptly remove the owned stdio container"
+[[ "${client_status}" -eq 143 ]] || fail_test "SIGTERM returned ${client_status} instead of 143"
+
 new_case client-owner-isolation
 touch "${FAKE_DOCKER_STATE}/network"
 seed_service web-search-mcp
--- a/scripts/test-web-search-candidate.mjs
+++ b/scripts/test-web-search-candidate.mjs
@@ -1,4 +1,5 @@
 import assert from "node:assert/strict";
+import { setTimeout as delay } from "node:timers/promises";

 import { probeMcp, rpc } from "../docker/web-search/mcp-probe.mjs";

@@ -56,4 +57,40 @@ const websocketCount = payload(await rpc(url, 9, "tools/call", {
 }, 30_000));
 assert.equal(websocketCount.content.trim(), "0");

-console.log("pass web-search candidate diagnostics, browser rendering, and SSRF rejection");
+let requestId = 10;
+async function slowCount() {
+  const result = payload(await rpc(url, requestId++, "tools/call", {
+    name: "fetch_url",
+    arguments: { url: "http://mock-search.test:8080/slow-count", engine: "http", format: "text", fresh: true }
+  }, 5_000));
+  return Number(result.content.trim());
+}
+
+async function waitForSlowCount(expected, timeoutMs) {
+  const deadline = Date.now() + timeoutMs;
+  let actual;
+  while (Date.now() < deadline) {
+    actual = await slowCount();
+    if (actual === expected) return;
+    await delay(50);
+  }
+  assert.equal(actual, expected, `slow request count did not reach ${expected}`);
+}
+
+const cancellation = new AbortController();
+const pendingFetch = rpc(url, requestId++, "tools/call", {
+  name: "fetch_url",
+  arguments: {
+    url: "http://mock-search.test:8080/slow",
+    engine: "browser",
+    format: "text",
+    fresh: true,
+    timeout_ms: 120_000
+  }
+}, 120_000, cancellation.signal);
+await waitForSlowCount(1, 10_000);
+cancellation.abort(new Error("candidate client disconnected"));
+await assert.rejects(pendingFetch, /candidate client disconnected/);
+await waitForSlowCount(0, 3_000);
+
+console.log("pass web-search candidate diagnostics, browser rendering, SSRF rejection, and cancellation");
--- a/scripts/test-web-search-candidate.sh
+++ b/scripts/test-web-search-candidate.sh
@@ -6,9 +6,10 @@ IMAGE="${CONTEXT_KIT_WEB_SEARCH_CANDIDATE_IMAGE:-context-kit/web-search-mcp:qual
 NETWORK="context-kit-web-quality-$RANDOM-$$"
 MOCK="${NETWORK}-mock"
 SERVER="${NETWORK}-server"
+BRIDGE="${NETWORK}-bridge"

 cleanup() {
-  docker rm -f "${SERVER}" "${MOCK}" >/dev/null 2>&1 || true
+  docker rm -f "${BRIDGE}" "${SERVER}" "${MOCK}" >/dev/null 2>&1 || true
  docker network rm "${NETWORK}" >/dev/null 2>&1 || true
 }
 trap cleanup EXIT
@@ -18,17 +19,38 @@ docker run -d --name "${MOCK}" --network "${NETWORK}" --ip 203.0.113.10 \
  --network-alias mock-search.test \
  -v "${ROOT}/scripts/fixtures/web/mock-server.mjs:/fixture/mock-server.mjs:ro" \
  node:22-bookworm-slim node /fixture/mock-server.mjs >/dev/null
-docker run -d --name "${SERVER}" --network "${NETWORK}" --ip 203.0.113.11 \
+docker run -d --init --name "${SERVER}" --network "${NETWORK}" --ip 203.0.113.11 \
+  --network-alias web-search-mcp \
  -p 127.0.0.1::8000 \
  -e SEARXNG_URL=http://mock-search.test:8080 \
  -e DEFAULT_SEARCH_PROVIDER=searxng \
  "${IMAGE}" >/dev/null

+[[ "$(docker inspect -f '{{.HostConfig.Init}}' "${SERVER}")" == true ]] || {
+  printf 'candidate web-search container does not use Docker init\n' >&2
+  exit 1
+}
+
 binding="$(docker port "${SERVER}" 8000/tcp)"
 port="${binding##*:}"
 for _ in {1..120}; do
  if curl -fsS "http://127.0.0.1:${port}/healthz" >/dev/null 2>&1; then
    node "${ROOT}/scripts/test-web-search-candidate.mjs" "http://127.0.0.1:${port}/mcp"
+    node "${ROOT}/scripts/test-web-search-stdio-cancellation.mjs" \
+      docker run --rm --init -i --name "${BRIDGE}" --network "${NETWORK}" \
+      --entrypoint mcp-proxy "${IMAGE}" --transport streamablehttp "http://web-search-mcp:8000/mcp"
+    docker exec "${SERVER}" sh -eu -c '
+      for status in /proc/[0-9]*/status; do
+        while IFS=: read -r key value; do
+          if [ "$key" = State ]; then
+            case "$value" in
+              *Z*) printf "zombie process found in %s: %s\n" "$status" "$value" >&2; exit 1 ;;
+            esac
+            break
+          fi
+        done < "$status"
+      done
+    '
    exit 0
  fi
  sleep 0.25
--- a/scripts/test-web-search-http.mjs
+++ b/scripts/test-web-search-http.mjs
@@ -1,15 +1,22 @@
 import assert from "node:assert/strict";
 import http from "node:http";
-import { once } from "node:events";
+import { EventEmitter, once } from "node:events";
+import { setTimeout as delay } from "node:timers/promises";

 import {
  createSecureMcpServer,
  mcpProxyArguments,
-  superviseBackend
+  superviseBackend,
+  terminateChild
 } from "../docker/web-search/http-entrypoint.mjs";
 import { probeMcp } from "../docker/web-search/mcp-probe.mjs";

 let backendAlive = true;
+let hangingBackendResponse;
+let resolveHangingBackendStarted;
+let resolveHangingBackendClosed;
+const hangingBackendStarted = new Promise(resolve => { resolveHangingBackendStarted = resolve; });
+const hangingBackendClosed = new Promise(resolve => { resolveHangingBackendClosed = resolve; });
 assert(mcpProxyArguments.includes("--stateless"));
 const backend = http.createServer(async (request, response) => {
  if (request.url === "/status") {
@@ -47,6 +54,14 @@ const backend = http.createServer(async (request, response) => {
    }));
    return;
  }
+  if (message.method === "tools/call" && message.params?.name === "hang") {
+    hangingBackendResponse = response;
+    response.once("close", resolveHangingBackendClosed);
+    response.writeHead(200, { "Content-Type": "application/json" });
+    response.write("pending");
+    resolveHangingBackendStarted();
+    return;
+  }
  response.writeHead(500, { "Content-Type": "text/plain" });
  response.end("backend dead");
 });
@@ -89,6 +104,35 @@ assert.equal(await rawRequest({ host: "attacker.example" }), 421);
 assert.equal(await rawRequest({ host: `127.0.0.1:${frontPort}`, origin: "https://attacker.example" }), 403);
 assert.equal(await rawRequest({ host: `127.0.0.1:${frontPort}`, origin: `http://127.0.0.1:${frontPort}` }), 403);

+let downstreamResponse;
+try {
+  const responseReceived = new Promise((resolve, reject) => {
+    const request = http.request({
+      hostname: "127.0.0.1",
+      port: frontPort,
+      path: "/mcp",
+      method: "POST",
+      headers: {
+        Accept: "application/json, text/event-stream",
+        "Content-Type": "application/json"
+      }
+    }, resolve);
+    request.once("error", reject);
+    request.end('{"jsonrpc":"2.0","id":9,"method":"tools/call","params":{"name":"hang","arguments":{}}}');
+  });
+  await hangingBackendStarted;
+  downstreamResponse = await responseReceived;
+  downstreamResponse.on("error", () => {});
+  downstreamResponse.destroy();
+  await Promise.race([
+    hangingBackendClosed,
+    delay(250).then(() => { throw new Error("upstream request remained open after downstream disconnect"); })
+  ]);
+} finally {
+  downstreamResponse?.destroy();
+  hangingBackendResponse?.destroy();
+}
+
 backendAlive = false;
 assert.equal((await fetch(`${upstream}/status`)).status, 200);
 assert.equal((await fetch(`http://127.0.0.1:${frontPort}/healthz`)).status, 503);
@@ -106,6 +150,28 @@ await new Promise((resolve, reject) => {
  });
 });

+class StubbornChild extends EventEmitter {
+  exitCode = null;
+  signalCode = null;
+  signals = [];
+
+  kill(signal) {
+    this.signals.push(signal);
+    if (signal === "SIGKILL") {
+      setTimeout(() => {
+        this.signalCode = signal;
+        this.emit("exit", null, signal);
+      }, 10);
+    }
+    return true;
+  }
+}
+
+const stubbornChild = new StubbornChild();
+await terminateChild(stubbornChild, { graceMs: 1 });
+assert.deepEqual(stubbornChild.signals, ["SIGTERM", "SIGKILL"]);
+assert.equal(stubbornChild.signalCode, "SIGKILL");
+
 front.close();
 front.closeAllConnections();
 backend.close();
--- a/scripts/test-web-search-quality.mjs
+++ b/scripts/test-web-search-quality.mjs
@@ -30,19 +30,44 @@ assert.equal(failed.diagnostic.status, "error");
 assert.equal(failed.diagnostic.error.category, "network");

 let underlyingAborted = false;
+let underlyingCleanupFinished = false;
 const timedOut = await attemptProvider({
  name: "slow",
  async search(_query, _limit, _lang, signal) {
    await new Promise((resolve, reject) => {
      signal.addEventListener("abort", () => {
        underlyingAborted = true;
+        setTimeout(() => {
+          underlyingCleanupFinished = true;
          reject(signal.reason);
+        }, 25);
      }, { once: true });
    });
  }
 }, "q", 3, "en", { timeoutMs: 20 });
 assert.equal(timedOut.diagnostic.error.category, "timeout");
 assert.equal(underlyingAborted, true);
+assert.equal(underlyingCleanupFinished, true);
+
+const cancellation = new AbortController();
+const cancellationReason = new Error("search request cancelled");
+let cancellationCleanupFinished = false;
+const cancelled = attemptProvider({
+  name: "cancelled",
+  async search(_query, _limit, _lang, signal) {
+    await new Promise((resolve, reject) => {
+      signal.addEventListener("abort", () => {
+        setTimeout(() => {
+          cancellationCleanupFinished = true;
+          reject(signal.reason);
+        }, 10);
+      }, { once: true });
+    });
+  }
+}, "q", 3, "en", { timeoutMs: 1000, signal: cancellation.signal });
+cancellation.abort(cancellationReason);
+await assert.rejects(cancelled, error => error === cancellationReason);
+assert.equal(cancellationCleanupFinished, true);

 const result = boundFetchCollections({
  links: Array.from({ length: 550 }, (_, index) => ({ url: `https://example.test/${index}` })),
--- a/scripts/test-web-search-stdio-cancellation.mjs
+++ b/scripts/test-web-search-stdio-cancellation.mjs
@@ -0,0 +1,66 @@
+import assert from "node:assert/strict";
+import { setTimeout as delay } from "node:timers/promises";
+
+import {
+  McpSmokeClient,
+  requireToolSuccess,
+  textFrom
+} from "./mcp-smoke-client.mjs";
+
+const command = process.argv[2];
+const args = process.argv.slice(3);
+if (!command) throw new Error("usage: node scripts/test-web-search-stdio-cancellation.mjs <command> [args...]");
+
+const client = new McpSmokeClient({
+  command,
+  args,
+  tmpPrefix: "context-kit-stdio-cancellation-"
+});
+
+function payload(result) {
+  const text = textFrom(requireToolSuccess("fetch_url", result));
+  return JSON.parse(text);
+}
+
+async function slowCount() {
+  const result = await client.callTool("fetch_url", {
+    url: "http://mock-search.test:8080/slow-count",
+    engine: "http",
+    format: "text",
+    fresh: true
+  });
+  return Number(payload(result).content.trim());
+}
+
+async function waitForSlowCount(expected, timeoutMs) {
+  const deadline = Date.now() + timeoutMs;
+  let actual;
+  while (Date.now() < deadline) {
+    actual = await slowCount();
+    if (actual === expected) return;
+    await delay(50);
+  }
+  assert.equal(actual, expected, `stdio slow request count did not reach ${expected}`);
+}
+
+try {
+  await client.initialize({ name: "context-kit-stdio-cancellation", version: "1" });
+  const requestId = client.nextId;
+  const pendingFetch = client.callTool("fetch_url", {
+    url: "http://mock-search.test:8080/slow",
+    engine: "browser",
+    format: "text",
+    fresh: true,
+    timeout_ms: 120_000
+  });
+  await waitForSlowCount(1, 10_000);
+  client.notify("notifications/cancelled", {
+    requestId,
+    reason: "stdio client disconnected"
+  });
+  await assert.rejects(pendingFetch, /cancel/i);
+  await waitForSlowCount(0, 3_000);
+  console.log("pass web-search stdio bridge cancellation");
+} finally {
+  await client.stop();
+}
Author	SHA1	Message	Date
ajay@krishnan.ca	634092feca	Merge pull request 'Propagate web-search cancellation' (#1 ) from fix/web-search-cancellation-20260725 into main	2026-07-25 21:19:08 -07:00
Ajay Krishnan	b4efe82ce2	Propagate web-search cancellation	2026-07-25 21:18:08 -07:00