fix(ci): run CI on Node 22.x and correct undici 8 Node floor (#1563)

undici 8.5.0 requires Node >= 22.19.0 (its declared engines), so CI's
Node 20.x could not load undici's CacheStorage (missing
webidl.util.markAsUncloneable) and the proxy integration tests failed.
Bump the CI setup-node to 22.x to match the repo's Node floor.

Reconcile the declared floor with undici's real requirement: bump root
engines.node to >=22.19.0 and correct the CLI README note (undici 8.5.0
needs >=22.19.0, not >=22.7.5). Also document proxy support in the web
README and clarify that a caller-supplied eventSourceInit.fetch bypasses
the proxy wrapper by design.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S3fTN8H3R8YV4yUGvZjYnX

.github/workflows/main.yml

@@ -13,7 +13,7 @@ jobs:
       - name: Setup Node.js
         uses: actions/setup-node@v6
         with:
-          node-version: '20.x'
+          node-version: '22.x'
           cache: 'npm'
 
       - name: Install dependencies (root + all clients)

clients/cli/README.md

@@ -84,7 +84,7 @@ When a server is loaded from a `--catalog`/`--config` file, its per-server setti
 
 Connections to remote HTTP/SSE servers honor the conventional proxy environment variables: `HTTPS_PROXY` / `HTTP_PROXY` (and their lowercase forms) select the proxy, and `NO_PROXY` exempts hosts. This applies to the Node transport shared by the CLI and the web backend — no inspector-specific flag is needed. When a proxy variable is set, outbound requests are routed through undici's `EnvHttpProxyAgent`.
 
-Proxy routing is powered by the [`undici`](https://www.npmjs.com/package/undici) package (`^8.5.0`, which requires Node `>= 22.7.5` — the inspector's supported floor). It is imported lazily only when a proxy variable is set, so runs without a proxy configured pay no cost.
+Proxy routing is powered by the [`undici`](https://www.npmjs.com/package/undici) package (`^8.5.0`, which requires Node `>= 22.19.0` — the inspector's supported floor). It is imported lazily only when a proxy variable is set, so runs without a proxy configured pay no cost.
 
 ## Options
 

clients/web/README.md

@@ -71,3 +71,7 @@ export default defineConfig([
   },
 ])
 ```
+
+## HTTP proxy support
+
+The web backend connects to remote MCP servers through the shared Node transport (`core/mcp/node/transport.ts`), which honors the conventional proxy environment variables: `HTTPS_PROXY` / `HTTP_PROXY` (and their lowercase forms) select the proxy, and `NO_PROXY` exempts hosts. Routing is powered by [`undici`](https://www.npmjs.com/package/undici)'s `EnvHttpProxyAgent`, imported lazily only when a proxy variable is set, so runs without a proxy configured pay no cost. See the CLI README for more detail.

core/mcp/node/transport.ts

@@ -140,6 +140,8 @@ export function createTransportNode(
     const sseConfig = config as SseServerConfig;
     const url = new URL(sseConfig.url);
 
+    // A caller-supplied eventSourceInit.fetch wins as-is (explicit fetch is not
+    // re-wrapped for proxying); the default path uses the proxy-aware baseFetch.
     const sseFetch =
       (sseConfig.eventSourceInit?.fetch as typeof fetch) || baseFetch;
     const trackedFetch = onFetchRequest

package.json

@@ -82,6 +82,6 @@
     "ink-select-input": "^6.2.0"
   },
   "engines": {
-    "node": ">=22.7.5"
+    "node": ">=22.19.0"
   }
 }

specification/v2_cli_tui_launcher.md

@@ -65,7 +65,7 @@ Root scripts `inspector`, `web`, and `web:dev` are thin wrappers around the laun
 
 **Production web caveat:** launcher `prebuild` chains `build:runner` for web, not a full `vite build`. Running `mcp-inspector --web` (without `--dev`) requires `clients/web/dist/` from a prior `cd clients/web && npm run build`. CI builds CLI, TUI, and launcher before the launcher smoke step but does not currently validate prod web startup end-to-end.
 
-**Build targets:** client `tsup` bundles target `node22`, aligned with root `engines.node` (`>=22.7.5`).
+**Build targets:** client `tsup` bundles target `node22`, aligned with root `engines.node` (`>=22.19.0`).
 
 ---