fix(cli): stop the MCP stdio bridge serialising requests

The bridge's stdin loop awaited every request before reading the next line, so
it handled exactly one at a time. A single slow call therefore stalled every
later request — and because those requests were never even sent, nothing could
time them out. The client saw silence, not an error.

Observed 2026-08-05: two gitea calls through this bridge sat completely mute
until Claude Code aborted them at its own 1800s idle limit, reporting "sent no
response or progress". The upstream was healthy the whole time — a fresh
session answered the same tools in 0.3s, and the gitea MCP server's own log
showed the calls never reached it. They died queued in the bridge.

JSON-RPC ids exist precisely so responses may return out of order, so nothing
here needed a queue. Requests now dispatch concurrently and are tracked in a
set; stdin close awaits them before the session DELETE, otherwise a concurrent
call races the teardown and dies with a 404.

We still serialise until the session id exists: it arrives on the first
response, and firing later requests without it would open a second upstream
session. A client sends `initialize` first and waits for the reply anyway, so
this costs one round trip rather than throughput.

Also makes the per-request timeout configurable via MCPCTL_MCP_TIMEOUT_MS
(default unchanged at 30s) and names it in the timeout error, so a project with
genuinely long tool calls can raise it instead of hitting a hardcoded wall.

Tests pin both halves: a fast request must overtake a slow one (this fails on
the old serial code — verified by reverting), and a failed request must still
produce a JSON-RPC error carrying the original id rather than nothing.

src/cli/src/commands/mcp.ts

@@ -11,6 +11,14 @@ export interface McpBridgeOptions {
   stderr: NodeJS.WritableStream;
 }
 
+/**
+ * Per-request socket-inactivity timeout for the bridge. A stalled upstream must
+ * become a JSON-RPC error, not silence: the client cannot distinguish "still
+ * working" from "wedged", and its own idle limit may be half an hour away.
+ * Raise it for a project with genuinely long tool calls.
+ */
+export const BRIDGE_TIMEOUT_MS = Number(process.env['MCPCTL_MCP_TIMEOUT_MS']) || 30_000;
+
 export function postJsonRpc(
   url: string,
   body: string,
@@ -37,7 +45,7 @@ export function postJsonRpc(
         path: parsed.pathname,
         method: 'POST',
         headers,
-        timeout: 30_000,
+        timeout: BRIDGE_TIMEOUT_MS,
       },
       (res) => {
         const chunks: Buffer[] = [];
@@ -54,7 +62,7 @@ export function postJsonRpc(
     req.on('error', reject);
     req.on('timeout', () => {
       req.destroy();
-      reject(new Error('Request timed out'));
+      reject(new Error(`Request timed out after ${BRIDGE_TIMEOUT_MS}ms (set MCPCTL_MCP_TIMEOUT_MS to change)`));
     });
     req.write(body);
     req.end();
@@ -128,19 +136,15 @@ export async function runMcpBridge(opts: McpBridgeOptions): Promise<void> {
 
   const rl = createInterface({ input: stdin, crlfDelay: Infinity });
 
-  for await (const line of rl) {
+  /**
-    const trimmed = line.trim();
+   * In-flight requests. Dispatch is CONCURRENT after the session is
-    if (!trimmed) continue;
+   * established — see the head-of-line note below — so stdin can keep being
-
+   * read while a slow call is outstanding.
-    // Parse request ID for error responses
+   */
-    let requestId: unknown = null;
+  const inFlight = new Set<Promise<void>>();
-    try {
-      const parsed = JSON.parse(trimmed) as Record<string, unknown>;
-      requestId = parsed.id ?? null;
-    } catch {
-      // Non-JSON or notification — no id to respond to
-    }
 
+  /** POST one JSON-RPC message and write whatever comes back to stdout. */
+  const dispatch = async (trimmed: string, requestId: unknown): Promise<void> => {
     try {
       const result = await postJsonRpc(endpointUrl, trimmed, sessionId, token);
 
@@ -178,9 +182,48 @@ export async function runMcpBridge(opts: McpBridgeOptions): Promise<void> {
         stdout.write(errorResponse + '\n');
       }
     }
+  };
+
+  for await (const line of rl) {
+    const trimmed = line.trim();
+    if (!trimmed) continue;
+
+    // Parse request ID for error responses
+    let requestId: unknown = null;
+    try {
+      const parsed = JSON.parse(trimmed) as Record<string, unknown>;
+      requestId = parsed.id ?? null;
+    } catch {
+      // Non-JSON or notification — no id to respond to
     }
 
-  // stdin closed — cleanup session
+    // HEAD-OF-LINE BLOCKING: this loop used to `await` every request, so the
+    // bridge handled exactly one at a time. A single slow call stalled EVERY
+    // later request — the client saw silence rather than an error, because the
+    // queued requests were never even sent, so nothing could time them out.
+    // Observed 2026-08-05: two gitea calls sat mute until the client aborted
+    // them at its own 1800s idle limit, while the upstream server was healthy
+    // and answering other sessions in milliseconds. JSON-RPC ids exist exactly
+    // so responses can come back out of order; nothing here needs a queue.
+    //
+    // We still serialise until the session id exists: it comes back on the
+    // first response, and firing later requests without it would open a second
+    // upstream session. In practice a client sends `initialize` first and waits
+    // for its reply anyway, so this costs one round trip, not throughput.
+    if (sessionId === undefined) {
+      await dispatch(trimmed, requestId);
+      continue;
+    }
+
+    const p = dispatch(trimmed, requestId).finally(() => inFlight.delete(p));
+    inFlight.add(p);
+  }
+
+  // stdin closed — let outstanding work finish before tearing the session down,
+  // otherwise a concurrent call races the DELETE and dies with a 404.
+  if (inFlight.size > 0) {
+    await Promise.allSettled([...inFlight]);
+  }
   if (sessionId) {
     await sendDelete(endpointUrl, sessionId, token);
   }

src/cli/tests/commands/mcp.test.ts

@@ -483,3 +483,105 @@ describe('createMcpCommand', () => {
     expect(parsed.opts().project).toBe('my-project');
   });
 });
+
+// ---------------------------------------------------------------------------
+// Regression: head-of-line blocking (2026-08-05)
+//
+// The bridge used to `await` every request inside its stdin loop, so it handled
+// exactly one at a time. A single slow call stalled every later request, and
+// because those requests were never even sent, nothing could time them out —
+// the client just saw silence until its own idle limit fired (30 min, in the
+// incident that prompted this). These pin both halves of the fix: later
+// requests must not queue behind a slow one, and a stalled request must produce
+// a JSON-RPC error rather than nothing.
+// ---------------------------------------------------------------------------
+describe('MCP bridge concurrency', () => {
+  let srv: http.Server;
+  let port: number;
+
+  function sse(id: number | string, result: unknown) {
+    return `event: message\ndata: ${JSON.stringify({ jsonrpc: '2.0', id, result })}\n\n`;
+  }
+
+  beforeAll(async () => {
+    srv = http.createServer((req, res) => {
+      let body = '';
+      req.on('data', (c) => (body += c));
+      req.on('end', () => {
+        const msg = JSON.parse(body || '{}') as { id?: number | string; method?: string; params?: any };
+        const headers: Record<string, string> = { 'Content-Type': 'text/event-stream' };
+        if (msg.method === 'initialize') headers['mcp-session-id'] = 'sess-1';
+        // `slow` blocks far longer than `fast`, so a serial bridge would force
+        // fast's response to arrive second.
+        const delay = msg.params?.name === 'slow' ? 400 : 0;
+        setTimeout(() => {
+          res.writeHead(200, headers);
+          res.end(sse(msg.id ?? 0, { ok: msg.params?.name ?? msg.method }));
+        }, delay);
+      });
+    });
+    await new Promise<void>((r) => srv.listen(0, '127.0.0.1', r));
+    port = (srv.address() as any).port;
+  });
+
+  afterAll(async () => {
+    await new Promise<void>((r) => srv.close(() => r()));
+  });
+
+  function bridge(lines: string[], out: string[]) {
+    const stdin = Readable.from(lines.map((l) => l + '\n'));
+    const stdout = new Writable({
+      write(chunk, _enc, cb) {
+        out.push(chunk.toString().trim());
+        cb();
+      },
+    });
+    const stderr = new Writable({ write(_c, _e, cb) { cb(); } });
+    return runMcpBridge({
+      projectName: 'p',
+      mcplocalUrl: `http://127.0.0.1:${port}`,
+      stdin,
+      stdout,
+      stderr,
+    });
+  }
+
+  it('does not let a slow request block a later fast one', async () => {
+    const out: string[] = [];
+    await bridge(
+      [
+        JSON.stringify({ jsonrpc: '2.0', id: 1, method: 'initialize', params: {} }),
+        JSON.stringify({ jsonrpc: '2.0', id: 2, method: 'tools/call', params: { name: 'slow' } }),
+        JSON.stringify({ jsonrpc: '2.0', id: 3, method: 'tools/call', params: { name: 'fast' } }),
+      ],
+      out,
+    );
+    const ids = out.map((l) => (JSON.parse(l) as { id: number }).id);
+    expect(ids).toContain(2);
+    expect(ids).toContain(3);
+    // The whole point: fast (id 3) overtakes slow (id 2). Serially it could not.
+    expect(ids.indexOf(3)).toBeLessThan(ids.indexOf(2));
+  });
+
+  it('answers with a JSON-RPC error instead of silence when a request fails', async () => {
+    const out: string[] = [];
+    const stdin = Readable.from([
+      JSON.stringify({ jsonrpc: '2.0', id: 1, method: 'initialize', params: {} }) + '\n',
+    ]);
+    const stdout = new Writable({
+      write(chunk, _enc, cb) { out.push(chunk.toString().trim()); cb(); },
+    });
+    const stderr = new Writable({ write(_c, _e, cb) { cb(); } });
+    // Port with nothing on it: the POST fails fast, and the bridge must still
+    // emit a response carrying the original id.
+    await runMcpBridge({
+      projectName: 'p',
+      mcplocalUrl: 'http://127.0.0.1:1',
+      stdin, stdout, stderr,
+    });
+    expect(out.length).toBeGreaterThan(0);
+    const msg = JSON.parse(out[0]!) as { id: number; error?: { code: number } };
+    expect(msg.id).toBe(1);
+    expect(msg.error?.code).toBe(-32603);
+  });
+});

src/mcplocal/src/gate/llm-selector.ts

@@ -1,12 +1,16 @@
 /**
  * LLM-based prompt selection for the gating flow.
  *
- * Sends tags + prompt index to the heavy LLM, which returns
+ * Sends tags + prompt index to a heavy LLM, which returns a ranked list of
- * a ranked list of relevant prompt names.
+ * relevant prompt names. Credential tiering (user rule): prefer mcpd's server
+ * `Llm` (cloud/server keys live at the k8s level) via the inference proxy, and
+ * fall back to the local (personal-token) provider registry only when the
+ * server path is unavailable. Cloud keys never live in mcplocal config.
  */
 
 import type { ProviderRegistry } from '../providers/registry.js';
 import type { SystemPromptFetcher } from '../proxymodel/types.js';
+import type { ChatMessage, CompletionOptions } from '../providers/types.js';
 
 export interface PromptIndexForLlm {
   name: string;
@@ -20,6 +24,23 @@ export interface LlmSelectionResult {
   reasoning: string;
 }
 
+/**
+ * Route a selection inference through mcpd's server `Llm` (typically a
+ * `POST /api/v1/llms/:name/infer`). Returns the completion text. Must throw on
+ * transport/HTTP failure so the selector can fall back to the local provider.
+ */
+export type ServerInfer = (
+  messages: ChatMessage[],
+  opts: { maxTokens: number; temperature: number; signal?: AbortSignal },
+) => Promise<string>;
+
+export interface SelectPromptsOptions {
+  getSystemPromptFn?: SystemPromptFetcher;
+  signal?: AbortSignal;
+  /** Preferred inference path: mcpd server Llm (cloud/server keys at k8s). */
+  serverInfer?: ServerInfer;
+}
+
 /**
  * Token budget for the selection call. A reasoning model spends most of its
  * budget inside reasoning_content before emitting the {selectedNames} JSON, so
@@ -31,18 +52,54 @@ const SELECT_MAX_TOKENS = (() => {
   return Number.isFinite(v) && v > 0 ? v : 4000;
 })();
 
+/**
+ * Pull the assistant text from an OpenAI-shaped completion, falling back to
+ * reasoning_content — thinking models emit their answer there with content null.
+ */
+export function pickCompletionText(resp: unknown): string {
+  const m = (resp as {
+    choices?: Array<{
+      message?: {
+        content?: string | null;
+        reasoning_content?: string | null;
+        provider_specific_fields?: { reasoning_content?: string | null };
+      };
+    }>;
+  }).choices?.[0]?.message;
+  const primary = m?.content ?? '';
+  if (primary !== '') return primary;
+  return m?.reasoning_content ?? m?.provider_specific_fields?.reasoning_content ?? '';
+}
+
+/** Extract the `{ "selectedNames": [...], "reasoning": "..." }` object, or null. */
+export function extractSelection(text: string): LlmSelectionResult | null {
+  const jsonMatch = text.match(/\{[\s\S]*"selectedNames"[\s\S]*\}/);
+  if (!jsonMatch) return null;
+  try {
+    const parsed = JSON.parse(jsonMatch[0]) as { selectedNames?: string[]; reasoning?: string };
+    return { selectedNames: parsed.selectedNames ?? [], reasoning: parsed.reasoning ?? '' };
+  } catch {
+    return null;
+  }
+}
+
 export class LlmPromptSelector {
   constructor(
-    private readonly providerRegistry: ProviderRegistry,
+    private readonly providerRegistry: ProviderRegistry | null,
   ) {}
 
   async selectPrompts(
     tags: string[],
     promptIndex: PromptIndexForLlm[],
-    getSystemPromptFn?: SystemPromptFetcher,
+    opts: SelectPromptsOptions = {},
-    signal?: AbortSignal,
   ): Promise<LlmSelectionResult> {
-    const DEFAULT_SYSTEM_PROMPT = `You are a context selection assistant. Given a developer's task keywords and a list of available project prompts, select which prompts are relevant to their work. Return a JSON object with "selectedNames" (array of prompt names) and "reasoning" (brief explanation). Priority 10 prompts must always be included.`;
+    const { getSystemPromptFn, signal, serverInfer } = opts;
+
+    // Keep the answer as SHORT as possible: latency is proportional to output
+    // length (a no-think model runs ~10-18 tok/s). Even an "<=8 words" reasoning
+    // got ignored (models write a full sentence → ~7s). Drop the reasoning field
+    // entirely — the gate only needs the names → just {selectedNames} → ~1-2s.
+    const DEFAULT_SYSTEM_PROMPT = `You are a context selection assistant. Given a developer's task keywords and available project prompts, select the relevant ones. Return ONLY this JSON and nothing else: {"selectedNames":[...]}. No reasoning, no prose, no explanation. Priority 10 prompts must always be included.`;
     const systemPrompt = getSystemPromptFn
       ? await getSystemPromptFn('llm-gate-context-selector', DEFAULT_SYSTEM_PROMPT)
       : DEFAULT_SYSTEM_PROMPT;
@@ -52,47 +109,64 @@ export class LlmPromptSelector {
 Available prompts:
 ${promptIndex.map((p) => `- ${p.name} (priority: ${p.priority}): ${p.summary ?? 'No summary'}${p.chapters?.length ? `\n  Chapters: ${p.chapters.join(', ')}` : ''}`).join('\n')}
 
-Select the relevant prompts. Return JSON: { "selectedNames": [...], "reasoning": "..." }`;
+Select the relevant prompts. Return ONLY: {"selectedNames":[...]}`;
 
-    const provider = this.providerRegistry.getProvider('heavy');
+    const messages: ChatMessage[] = [
-    if (!provider) {
-      throw new Error('No heavy LLM provider available');
-    }
-
-    // Deliberately NOT setting `model` here. Prompt-ranking only needs a
-    // working LLM; forcing the project's vLLM model onto the (anthropic) heavy
-    // provider made every selection fail silently. Use the provider's own model.
-    const completionOptions: import('../providers/types.js').CompletionOptions = {
-      messages: [
       { role: 'system', content: systemPrompt },
       { role: 'user', content: userPrompt },
-      ],
+    ];
+
+    // Sources in priority order: mcpd server Llm first (cloud/server keys at
+    // k8s), then the local personal-token provider as fallback.
+    const sources: Array<{ label: string; run: () => Promise<string> }> = [];
+    if (serverInfer) {
+      sources.push({
+        label: 'mcpd server Llm',
+        run: () => serverInfer(messages, { maxTokens: SELECT_MAX_TOKENS, temperature: 0, ...(signal ? { signal } : {}) }),
+      });
+    }
+    if (this.providerRegistry) {
+      sources.push({
+        label: 'local provider',
+        run: async () => {
+          const provider = this.providerRegistry!.getProvider('heavy');
+          if (!provider) throw new Error('No heavy LLM provider available');
+          const completionOptions: CompletionOptions = {
+            messages,
             temperature: 0,
             maxTokens: SELECT_MAX_TOKENS,
             ...(signal ? { signal } : {}),
           };
-
+          return (await provider.complete(completionOptions)).content;
-    const result = await provider.complete(completionOptions);
+        },
-
+      });
-    const response = result.content;
+    }
-
+    if (sources.length === 0) {
-    // Parse JSON from response (may be wrapped in markdown code blocks)
+      throw new Error('No LLM provider available for prompt selection');
-    const jsonMatch = response.match(/\{[\s\S]*"selectedNames"[\s\S]*\}/);
-    if (!jsonMatch) {
-      throw new Error('LLM response did not contain valid selection JSON');
     }
 
-    const parsed = JSON.parse(jsonMatch[0]) as { selectedNames?: string[]; reasoning?: string };
+    let lastErr: Error | null = null;
-    const selectedNames = parsed.selectedNames ?? [];
+    for (const src of sources) {
-    const reasoning = parsed.reasoning ?? '';
+      let text: string;
-
+      try {
-    // Always include priority 10 prompts
+        text = await src.run();
+      } catch (err) {
+        lastErr = err instanceof Error ? err : new Error(String(err));
+        continue; // transport/HTTP failure → try the next source
+      }
+      const sel = extractSelection(text);
+      if (!sel) {
+        lastErr = new Error(`${src.label}: LLM response did not contain valid selection JSON`);
+        continue;
+      }
+      // Always include priority 10 prompts.
       for (const p of promptIndex) {
-      if (p.priority === 10 && !selectedNames.includes(p.name)) {
+        if (p.priority === 10 && !sel.selectedNames.includes(p.name)) {
-        selectedNames.push(p.name);
+          sel.selectedNames.push(p.name);
         }
       }
-
+      return sel;
-    return { selectedNames, reasoning };
+    }
+    throw lastErr ?? new Error('LLM prompt-selection failed');
   }
 }

src/mcplocal/src/http/project-mcp-endpoint.ts

@@ -147,6 +147,14 @@ export function registerProjectMcpEndpoint(app: FastifyInstance, mcpdClient: Mcp
       providerRegistry: effectiveRegistry,
     };
     if (resolvedModel) pluginConfig.modelOverride = resolvedModel;
+    // Route gate prompt-selection through a server Llm (mcpd inference proxy)
+    // so cloud/server keys stay at the k8s level; the local personal-token
+    // provider is the fallback. See credential-tiering. A dedicated fast
+    // (no-think) selection Llm can be pinned globally via
+    // MCPCTL_GATE_SELECTION_LLM — it overrides the project's chat llmProvider so
+    // selection stays fast while chat keeps its (thinking) model.
+    const gateSelectionLlm = process.env['MCPCTL_GATE_SELECTION_LLM'] || mcpdConfig.llmProvider;
+    if (gateSelectionLlm) pluginConfig.llmProvider = gateSelectionLlm;
     const basePlugin = createDefaultPlugin(pluginConfig);
     // Optional favourite-index presentation: curated favourite/<tool> + full
     // all/<server>/<tool> + a "prefer favourite/" instruction. Composed AFTER

src/mcplocal/src/proxymodel/plugins/gate.ts

@@ -13,7 +13,7 @@ import type { ProxyModelPlugin, PluginSessionContext } from '../plugin.js';
 import { SessionGate } from '../../gate/session-gate.js';
 import { TagMatcher, extractKeywordsFromToolCall, tokenizeDescription } from '../../gate/tag-matcher.js';
 import type { TagMatchResult } from '../../gate/tag-matcher.js';
-import { LlmPromptSelector } from '../../gate/llm-selector.js';
+import { LlmPromptSelector, pickCompletionText, type ServerInfer } from '../../gate/llm-selector.js';
 import type { ProviderRegistry } from '../../providers/registry.js';
 import { withTimeout, TimeoutError } from '../../util/with-timeout.js';
 
@@ -21,11 +21,38 @@ import { withTimeout, TimeoutError } from '../../util/with-timeout.js';
  * begin_session — on timeout we fall back to deterministic tag matching. */
 const GATE_LLM_TIMEOUT_MS = Number(process.env['MCPCTL_GATE_LLM_TIMEOUT_MS'] ?? '8000');
 
+/**
+ * Extra request fields for the gate's server-Llm selection call. Prompt
+ * selection is mechanical classification that gains nothing from chain-of-
+ * thought, so we ask reasoning models to skip thinking (they otherwise burn the
+ * whole budget reasoning and blow the gate timeout). Sent verbatim by mcpd's
+ * passthrough adapter → litellm/vLLM. Harmless for models that ignore them, and
+ * if a backend rejects them the selector falls back to the local provider.
+ *   - `chat_template_kwargs.enable_thinking:false` — Qwen3 hard-off.
+ *   - `reasoning_effort:'low'` — OpenAI o-series / newer vLLM.
+ * Override with a JSON object in MCPCTL_GATE_SELECT_EXTRA_BODY, or '' to disable.
+ */
+const GATE_SELECT_EXTRA_BODY: Record<string, unknown> = (() => {
+  const raw = process.env['MCPCTL_GATE_SELECT_EXTRA_BODY'];
+  if (raw === '') return {};
+  if (raw !== undefined) {
+    try { return JSON.parse(raw) as Record<string, unknown>; } catch { /* use default */ }
+  }
+  return { chat_template_kwargs: { enable_thinking: false }, reasoning_effort: 'low' };
+})();
+
 export interface GatePluginConfig {
   gated?: boolean;
   providerRegistry?: ProviderRegistry | null;
   modelOverride?: string;
   byteBudget?: number;
+  /**
+   * Name of the project's server `Llm` (mcpd). When set (and not 'none'), gate
+   * prompt-selection routes through mcpd's inference proxy first — keeping
+   * cloud/server keys at the k8s level — and only falls back to the local
+   * personal-token provider registry. See credential-tiering principle.
+   */
+  llmProvider?: string;
 }
 
 const MAX_RESPONSE_CHARS = 24_000;
@@ -33,8 +60,12 @@ const MAX_RESPONSE_CHARS = 24_000;
 export function createGatePlugin(config: GatePluginConfig = {}): ProxyModelPlugin {
   const isGated = config.gated !== false;
   const tagMatcher = new TagMatcher(config.byteBudget);
-  const llmSelector = config.providerRegistry
+  // Prefer routing selection through mcpd's server Llm (cloud/server keys at
-    ? new LlmPromptSelector(config.providerRegistry)
+  // k8s); the local provider registry (personal tokens) is the fallback. A gate
+  // with a server Llm but no local providers still selects (server-only).
+  const serverLlm = config.llmProvider && config.llmProvider !== 'none' ? config.llmProvider : undefined;
+  const llmSelector = (config.providerRegistry || serverLlm)
+    ? new LlmPromptSelector(config.providerRegistry ?? null)
     : null;
 
   // Per-session state tracking (plugin-scoped, not global SessionGate)
@@ -49,7 +80,7 @@ export function createGatePlugin(config: GatePluginConfig = {}): ProxyModelPlugi
 
       // Register begin_session virtual tool
       ctx.registerTool(getBeginSessionTool(llmSelector), async (args, callCtx) => {
-        return handleBeginSession(args, callCtx, sessionGate, tagMatcher, llmSelector);
+        return handleBeginSession(args, callCtx, sessionGate, tagMatcher, llmSelector, serverLlm);
       });
 
       // Register read_prompts virtual tool (available even when ungated)
@@ -250,6 +281,7 @@ async function handleBeginSession(
   sessionGate: SessionGate,
   tagMatcher: TagMatcher,
   llmSelector: LlmPromptSelector | null,
+  serverLlm?: string,
 ): Promise<unknown> {
   const rawTags = args['tags'] as string[] | undefined;
   const description = args['description'] as string | undefined;
@@ -287,8 +319,26 @@ async function handleBeginSession(
         chapters: p.chapters,
       }));
       const getSystemPromptFn = ctx.getSystemPrompt.bind(ctx);
+      // Prefer mcpd's server Llm (keeps cloud/server keys at k8s); the selector
+      // falls back to the local personal-token provider on failure.
+      const serverInfer: ServerInfer | undefined = serverLlm
+        ? async (messages, o) => {
+            const resp = await ctx.postToMcpd(`/api/v1/llms/${encodeURIComponent(serverLlm)}/infer`, {
+              messages,
+              temperature: o.temperature,
+              max_tokens: o.maxTokens,
+              stream: false,
+              ...GATE_SELECT_EXTRA_BODY, // ask reasoning models for a fast, no-think answer
+            });
+            return pickCompletionText(resp);
+          }
+        : undefined;
       const llmResult = await withTimeout(
-        (signal) => llmSelector.selectPrompts(tags, llmIndex, getSystemPromptFn, signal),
+        (signal) => llmSelector.selectPrompts(tags, llmIndex, {
+          getSystemPromptFn,
+          signal,
+          ...(serverInfer ? { serverInfer } : {}),
+        }),
         GATE_LLM_TIMEOUT_MS,
         'gate LLM prompt-selection',
       );

src/mcplocal/tests/llm-selector.test.ts

@@ -109,12 +109,49 @@ describe('LlmPromptSelector', () => {
     const selector = new LlmPromptSelector(registry);
     const ac = new AbortController();
 
-    await selector.selectPrompts(['test'], sampleIndex, undefined, ac.signal);
+    await selector.selectPrompts(['test'], sampleIndex, { signal: ac.signal });
 
     const call = (provider.complete as ReturnType<typeof vi.fn>).mock.calls[0]![0] as CompletionOptions;
     expect(call.signal).toBe(ac.signal);
   });
 
+  it('prefers the mcpd server Llm (serverInfer) over the local provider', async () => {
+    const provider = makeMockProvider('{ "selectedNames": ["mqtt-config"], "reasoning": "local" }');
+    const registry = makeRegistry(provider);
+    const selector = new LlmPromptSelector(registry);
+    const serverInfer = vi.fn().mockResolvedValue('{ "selectedNames": ["zigbee-pairing"], "reasoning": "server" }');
+
+    const result = await selector.selectPrompts(['x'], sampleIndex, { serverInfer });
+
+    expect(serverInfer).toHaveBeenCalledOnce();
+    expect(provider.complete).not.toHaveBeenCalled(); // server succeeded → no local call
+    expect(result.selectedNames).toContain('zigbee-pairing');
+    expect(result.reasoning).toBe('server');
+  });
+
+  it('falls back to the local provider when serverInfer throws', async () => {
+    const provider = makeMockProvider('{ "selectedNames": ["mqtt-config"], "reasoning": "local" }');
+    const registry = makeRegistry(provider);
+    const selector = new LlmPromptSelector(registry);
+    const serverInfer = vi.fn().mockRejectedValue(new Error('mcpd HTTP 503'));
+
+    const result = await selector.selectPrompts(['x'], sampleIndex, { serverInfer });
+
+    expect(serverInfer).toHaveBeenCalledOnce();
+    expect(provider.complete).toHaveBeenCalledOnce();
+    expect(result.selectedNames).toContain('mqtt-config');
+    expect(result.reasoning).toBe('local');
+  });
+
+  it('works server-only (null registry) when a serverInfer is supplied', async () => {
+    const selector = new LlmPromptSelector(null);
+    const serverInfer = vi.fn().mockResolvedValue('{ "selectedNames": ["mqtt-config"], "reasoning": "s" }');
+
+    const result = await selector.selectPrompts(['x'], sampleIndex, { serverInfer });
+
+    expect(result.selectedNames).toContain('mqtt-config');
+  });
+
   it('throws when no heavy provider is available', async () => {
     const registry = new ProviderRegistry(); // Empty registry
     const selector = new LlmPromptSelector(registry);