fix: land #39337 by @goodspeed-apps for acpx MCP bootstrap

Co-authored-by: Goodspeed App Studio <goodspeed-apps@users.noreply.github.com>

extensions/acpx/openclaw.plugin.json

@@ -34,6 +34,29 @@
       "queueOwnerTtlSeconds": {
         "type": "number",
         "minimum": 0
+      },
+      "mcpServers": {
+        "type": "object",
+        "additionalProperties": {
+          "type": "object",
+          "properties": {
+            "command": {
+              "type": "string",
+              "description": "Command to run the MCP server"
+            },
+            "args": {
+              "type": "array",
+              "items": { "type": "string" },
+              "description": "Arguments to pass to the command"
+            },
+            "env": {
+              "type": "object",
+              "additionalProperties": { "type": "string" },
+              "description": "Environment variables for the MCP server"
+            }
+          },
+          "required": ["command"]
+        }
       }
     }
   },
@@ -72,6 +95,11 @@
       "label": "Queue Owner TTL Seconds",
       "help": "Idle queue-owner TTL for acpx prompt turns. Keep this short in OpenClaw to avoid delayed completion after each turn.",
       "advanced": true
+    },
+    "mcpServers": {
+      "label": "MCP Servers",
+      "help": "Named MCP server definitions to inject into ACPX-backed session bootstrap. Each entry needs a command and can include args and env.",
+      "advanced": true
     }
   }
 }

extensions/acpx/src/config.test.ts

@@ -5,6 +5,7 @@ import {
   ACPX_PINNED_VERSION,
   createAcpxPluginConfigSchema,
   resolveAcpxPluginConfig,
+  toAcpMcpServers,
 } from "./config.js";
 
 describe("acpx plugin config parsing", () => {
@@ -21,6 +22,7 @@ describe("acpx plugin config parsing", () => {
     expect(resolved.allowPluginLocalInstall).toBe(true);
     expect(resolved.cwd).toBe(path.resolve("/tmp/workspace"));
     expect(resolved.strictWindowsCmdWrapper).toBe(true);
+    expect(resolved.mcpServers).toEqual({});
   });
 
   it("accepts command override and disables plugin-local auto-install", () => {
@@ -132,4 +134,97 @@ describe("acpx plugin config parsing", () => {
       }),
     ).toThrow("strictWindowsCmdWrapper must be a boolean");
   });
+
+  it("accepts mcp server maps", () => {
+    const resolved = resolveAcpxPluginConfig({
+      rawConfig: {
+        mcpServers: {
+          canva: {
+            command: "npx",
+            args: ["-y", "mcp-remote@latest", "https://mcp.canva.com/mcp"],
+            env: {
+              CANVA_TOKEN: "secret",
+            },
+          },
+        },
+      },
+      workspaceDir: "/tmp/workspace",
+    });
+
+    expect(resolved.mcpServers).toEqual({
+      canva: {
+        command: "npx",
+        args: ["-y", "mcp-remote@latest", "https://mcp.canva.com/mcp"],
+        env: {
+          CANVA_TOKEN: "secret",
+        },
+      },
+    });
+  });
+
+  it("rejects invalid mcp server definitions", () => {
+    expect(() =>
+      resolveAcpxPluginConfig({
+        rawConfig: {
+          mcpServers: {
+            canva: {
+              command: "npx",
+              args: ["-y", 1],
+            },
+          },
+        },
+        workspaceDir: "/tmp/workspace",
+      }),
+    ).toThrow(
+      "mcpServers.canva must have a command string, optional args array, and optional env object",
+    );
+  });
+
+  it("schema accepts mcp server config", () => {
+    const schema = createAcpxPluginConfigSchema();
+    if (!schema.safeParse) {
+      throw new Error("acpx config schema missing safeParse");
+    }
+    const parsed = schema.safeParse({
+      mcpServers: {
+        canva: {
+          command: "npx",
+          args: ["-y", "mcp-remote@latest"],
+          env: {
+            CANVA_TOKEN: "secret",
+          },
+        },
+      },
+    });
+
+    expect(parsed.success).toBe(true);
+  });
+});
+
+describe("toAcpMcpServers", () => {
+  it("converts plugin config maps into ACP stdio MCP entries", () => {
+    expect(
+      toAcpMcpServers({
+        canva: {
+          command: "npx",
+          args: ["-y", "mcp-remote@latest", "https://mcp.canva.com/mcp"],
+          env: {
+            CANVA_TOKEN: "secret",
+          },
+        },
+      }),
+    ).toEqual([
+      {
+        name: "canva",
+        command: "npx",
+        args: ["-y", "mcp-remote@latest", "https://mcp.canva.com/mcp"],
+        env: [
+          {
+            name: "CANVA_TOKEN",
+            value: "secret",
+          },
+        ],
+      },
+    ]);
+  });
 });

extensions/acpx/src/config.ts

@@ -18,6 +18,19 @@ export function buildAcpxLocalInstallCommand(version: string = ACPX_PINNED_VERSI
 }
 export const ACPX_LOCAL_INSTALL_COMMAND = buildAcpxLocalInstallCommand();
 
+export type McpServerConfig = {
+  command: string;
+  args?: string[];
+  env?: Record<string, string>;
+};
+
+export type AcpxMcpServer = {
+  name: string;
+  command: string;
+  args: string[];
+  env: Array<{ name: string; value: string }>;
+};
+
 export type AcpxPluginConfig = {
   command?: string;
   expectedVersion?: string;
@@ -27,6 +40,7 @@ export type AcpxPluginConfig = {
   strictWindowsCmdWrapper?: boolean;
   timeoutSeconds?: number;
   queueOwnerTtlSeconds?: number;
+  mcpServers?: Record<string, McpServerConfig>;
 };
 
 export type ResolvedAcpxPluginConfig = {
@@ -40,6 +54,7 @@ export type ResolvedAcpxPluginConfig = {
   strictWindowsCmdWrapper: boolean;
   timeoutSeconds?: number;
   queueOwnerTtlSeconds: number;
+  mcpServers: Record<string, McpServerConfig>;
 };
 
 const DEFAULT_PERMISSION_MODE: AcpxPermissionMode = "approve-reads";
@@ -65,6 +80,36 @@ function isNonInteractivePermissionPolicy(
   return ACPX_NON_INTERACTIVE_POLICIES.includes(value as AcpxNonInteractivePermissionPolicy);
 }
 
+function isMcpServerConfig(value: unknown): value is McpServerConfig {
+  if (!isRecord(value)) {
+    return false;
+  }
+  if (typeof value.command !== "string" || value.command.trim() === "") {
+    return false;
+  }
+  if (value.args !== undefined) {
+    if (!Array.isArray(value.args)) {
+      return false;
+    }
+    for (const arg of value.args) {
+      if (typeof arg !== "string") {
+        return false;
+      }
+    }
+  }
+  if (value.env !== undefined) {
+    if (!isRecord(value.env)) {
+      return false;
+    }
+    for (const envValue of Object.values(value.env)) {
+      if (typeof envValue !== "string") {
+        return false;
+      }
+    }
+  }
+  return true;
+}
+
 function parseAcpxPluginConfig(value: unknown): ParseResult {
   if (value === undefined) {
     return { ok: true, value: undefined };
@@ -81,6 +126,7 @@ function parseAcpxPluginConfig(value: unknown): ParseResult {
     "strictWindowsCmdWrapper",
     "timeoutSeconds",
     "queueOwnerTtlSeconds",
+    "mcpServers",
   ]);
   for (const key of Object.keys(value)) {
     if (!allowedKeys.has(key)) {
@@ -152,6 +198,21 @@ function parseAcpxPluginConfig(value: unknown): ParseResult {
     return { ok: false, message: "queueOwnerTtlSeconds must be a non-negative number" };
   }
 
+  const mcpServers = value.mcpServers;
+  if (mcpServers !== undefined) {
+    if (!isRecord(mcpServers)) {
+      return { ok: false, message: "mcpServers must be an object" };
+    }
+    for (const [key, serverConfig] of Object.entries(mcpServers)) {
+      if (!isMcpServerConfig(serverConfig)) {
+        return {
+          ok: false,
+          message: `mcpServers.${key} must have a command string, optional args array, and optional env object`,
+        };
+      }
+    }
+  }
+
   return {
     ok: true,
     value: {
@@ -166,6 +227,7 @@ function parseAcpxPluginConfig(value: unknown): ParseResult {
       timeoutSeconds: typeof timeoutSeconds === "number" ? timeoutSeconds : undefined,
       queueOwnerTtlSeconds:
         typeof queueOwnerTtlSeconds === "number" ? queueOwnerTtlSeconds : undefined,
+      mcpServers: mcpServers as Record<string, McpServerConfig> | undefined,
     },
   };
 }
@@ -219,11 +281,41 @@ export function createAcpxPluginConfigSchema(): OpenClawPluginConfigSchema {
         strictWindowsCmdWrapper: { type: "boolean" },
         timeoutSeconds: { type: "number", minimum: 0.001 },
         queueOwnerTtlSeconds: { type: "number", minimum: 0 },
+        mcpServers: {
+          type: "object",
+          additionalProperties: {
+            type: "object",
+            properties: {
+              command: { type: "string" },
+              args: {
+                type: "array",
+                items: { type: "string" },
+              },
+              env: {
+                type: "object",
+                additionalProperties: { type: "string" },
+              },
+            },
+            required: ["command"],
+          },
+        },
       },
     },
   };
 }
 
+export function toAcpMcpServers(mcpServers: Record<string, McpServerConfig>): AcpxMcpServer[] {
+  return Object.entries(mcpServers).map(([name, server]) => ({
+    name,
+    command: server.command,
+    args: [...(server.args ?? [])],
+    env: Object.entries(server.env ?? {}).map(([envName, value]) => ({
+      name: envName,
+      value,
+    })),
+  }));
+}
+
 export function resolveAcpxPluginConfig(params: {
   rawConfig: unknown;
   workspaceDir?: string;
@@ -260,5 +352,6 @@ export function resolveAcpxPluginConfig(params: {
       normalized.strictWindowsCmdWrapper ?? DEFAULT_STRICT_WINDOWS_CMD_WRAPPER,
     timeoutSeconds: normalized.timeoutSeconds,
     queueOwnerTtlSeconds: normalized.queueOwnerTtlSeconds ?? DEFAULT_QUEUE_OWNER_TTL_SECONDS,
+    mcpServers: normalized.mcpServers ?? {},
   };
 }

extensions/acpx/src/runtime-internals/mcp-agent-command.ts

@@ -0,0 +1,113 @@
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+import { spawnAndCollect, type SpawnCommandOptions } from "./process.js";
+
+const ACPX_BUILTIN_AGENT_COMMANDS: Record<string, string> = {
+  codex: "npx @zed-industries/codex-acp",
+  claude: "npx -y @zed-industries/claude-agent-acp",
+  gemini: "gemini",
+  opencode: "npx -y opencode-ai acp",
+  pi: "npx pi-acp",
+};
+
+const MCP_PROXY_PATH = path.resolve(path.dirname(fileURLToPath(import.meta.url)), "mcp-proxy.mjs");
+
+type AcpxConfigDisplay = {
+  agents?: Record<string, { command?: unknown }>;
+};
+
+type AcpMcpServer = {
+  name: string;
+  command: string;
+  args: string[];
+  env: Array<{ name: string; value: string }>;
+};
+
+function normalizeAgentName(value: string): string {
+  return value.trim().toLowerCase();
+}
+
+function quoteCommandPart(value: string): string {
+  if (value === "") {
+    return '""';
+  }
+  if (/^[A-Za-z0-9_./:@%+=,-]+$/.test(value)) {
+    return value;
+  }
+  return `"${value.replace(/["\\]/g, "\\$&")}"`;
+}
+
+function toCommandLine(parts: string[]): string {
+  return parts.map(quoteCommandPart).join(" ");
+}
+
+function readConfiguredAgentOverrides(value: unknown): Record<string, string> {
+  if (!value || typeof value !== "object" || Array.isArray(value)) {
+    return {};
+  }
+  const overrides: Record<string, string> = {};
+  for (const [name, entry] of Object.entries(value)) {
+    if (!entry || typeof entry !== "object" || Array.isArray(entry)) {
+      continue;
+    }
+    const command = (entry as { command?: unknown }).command;
+    if (typeof command !== "string" || command.trim() === "") {
+      continue;
+    }
+    overrides[normalizeAgentName(name)] = command.trim();
+  }
+  return overrides;
+}
+
+async function loadAgentOverrides(params: {
+  acpxCommand: string;
+  cwd: string;
+  spawnOptions?: SpawnCommandOptions;
+}): Promise<Record<string, string>> {
+  const result = await spawnAndCollect(
+    {
+      command: params.acpxCommand,
+      args: ["--cwd", params.cwd, "config", "show"],
+      cwd: params.cwd,
+    },
+    params.spawnOptions,
+  );
+  if (result.error || (result.code ?? 0) !== 0) {
+    return {};
+  }
+  try {
+    const parsed = JSON.parse(result.stdout) as AcpxConfigDisplay;
+    return readConfiguredAgentOverrides(parsed.agents);
+  } catch {
+    return {};
+  }
+}
+
+export async function resolveAcpxAgentCommand(params: {
+  acpxCommand: string;
+  cwd: string;
+  agent: string;
+  spawnOptions?: SpawnCommandOptions;
+}): Promise<string> {
+  const normalizedAgent = normalizeAgentName(params.agent);
+  const overrides = await loadAgentOverrides({
+    acpxCommand: params.acpxCommand,
+    cwd: params.cwd,
+    spawnOptions: params.spawnOptions,
+  });
+  return overrides[normalizedAgent] ?? ACPX_BUILTIN_AGENT_COMMANDS[normalizedAgent] ?? params.agent;
+}
+
+export function buildMcpProxyAgentCommand(params: {
+  targetCommand: string;
+  mcpServers: AcpMcpServer[];
+}): string {
+  const payload = Buffer.from(
+    JSON.stringify({
+      targetCommand: params.targetCommand,
+      mcpServers: params.mcpServers,
+    }),
+    "utf8",
+  ).toString("base64url");
+  return toCommandLine([process.execPath, MCP_PROXY_PATH, "--payload", payload]);
+}

extensions/acpx/src/runtime-internals/mcp-proxy.mjs

@@ -0,0 +1,151 @@
+#!/usr/bin/env node
+
+import { spawn } from "node:child_process";
+import { createInterface } from "node:readline";
+
+function splitCommandLine(value) {
+  const parts = [];
+  let current = "";
+  let quote = null;
+  let escaping = false;
+
+  for (const ch of value) {
+    if (escaping) {
+      current += ch;
+      escaping = false;
+      continue;
+    }
+    if (ch === "\\" && quote !== "'") {
+      escaping = true;
+      continue;
+    }
+    if (quote) {
+      if (ch === quote) {
+        quote = null;
+      } else {
+        current += ch;
+      }
+      continue;
+    }
+    if (ch === "'" || ch === '"') {
+      quote = ch;
+      continue;
+    }
+    if (/\s/.test(ch)) {
+      if (current.length > 0) {
+        parts.push(current);
+        current = "";
+      }
+      continue;
+    }
+    current += ch;
+  }
+
+  if (escaping) {
+    current += "\\";
+  }
+  if (quote) {
+    throw new Error("Invalid agent command: unterminated quote");
+  }
+  if (current.length > 0) {
+    parts.push(current);
+  }
+  if (parts.length === 0) {
+    throw new Error("Invalid agent command: empty command");
+  }
+  return {
+    command: parts[0],
+    args: parts.slice(1),
+  };
+}
+
+function decodePayload(argv) {
+  const payloadIndex = argv.indexOf("--payload");
+  if (payloadIndex < 0) {
+    throw new Error("Missing --payload");
+  }
+  const encoded = argv[payloadIndex + 1];
+  if (!encoded) {
+    throw new Error("Missing MCP proxy payload value");
+  }
+  const parsed = JSON.parse(Buffer.from(encoded, "base64url").toString("utf8"));
+  if (!parsed || typeof parsed !== "object" || Array.isArray(parsed)) {
+    throw new Error("Invalid MCP proxy payload");
+  }
+  if (typeof parsed.targetCommand !== "string" || parsed.targetCommand.trim() === "") {
+    throw new Error("MCP proxy payload missing targetCommand");
+  }
+  const mcpServers = Array.isArray(parsed.mcpServers) ? parsed.mcpServers : [];
+  return {
+    targetCommand: parsed.targetCommand,
+    mcpServers,
+  };
+}
+
+function shouldInject(method) {
+  return method === "session/new" || method === "session/load" || method === "session/fork";
+}
+
+function rewriteLine(line, mcpServers) {
+  if (!line.trim()) {
+    return line;
+  }
+  try {
+    const parsed = JSON.parse(line);
+    if (
+      !parsed ||
+      typeof parsed !== "object" ||
+      Array.isArray(parsed) ||
+      !shouldInject(parsed.method) ||
+      !parsed.params ||
+      typeof parsed.params !== "object" ||
+      Array.isArray(parsed.params)
+    ) {
+      return line;
+    }
+    const next = {
+      ...parsed,
+      params: {
+        ...parsed.params,
+        mcpServers,
+      },
+    };
+    return JSON.stringify(next);
+  } catch {
+    return line;
+  }
+}
+
+const { targetCommand, mcpServers } = decodePayload(process.argv.slice(2));
+const target = splitCommandLine(targetCommand);
+const child = spawn(target.command, target.args, {
+  stdio: ["pipe", "pipe", "inherit"],
+  env: process.env,
+});
+
+if (!child.stdin || !child.stdout) {
+  throw new Error("Failed to create MCP proxy stdio pipes");
+}
+
+const input = createInterface({ input: process.stdin });
+input.on("line", (line) => {
+  child.stdin.write(`${rewriteLine(line, mcpServers)}\n`);
+});
+input.on("close", () => {
+  child.stdin.end();
+});
+
+child.stdout.pipe(process.stdout);
+
+child.on("error", (error) => {
+  process.stderr.write(`${error instanceof Error ? error.message : String(error)}\n`);
+  process.exit(1);
+});
+
+child.on("close", (code, signal) => {
+  if (signal) {
+    process.kill(process.pid, signal);
+    return;
+  }
+  process.exit(code ?? 0);
+});

extensions/acpx/src/runtime-internals/mcp-proxy.test.ts

@@ -0,0 +1,114 @@
+import { spawn } from "node:child_process";
+import { chmod, mkdtemp, rm, writeFile } from "node:fs/promises";
+import os from "node:os";
+import path from "node:path";
+import { afterEach, describe, expect, it } from "vitest";
+
+const tempDirs: string[] = [];
+const proxyPath = path.resolve("extensions/acpx/src/runtime-internals/mcp-proxy.mjs");
+
+async function makeTempScript(name: string, content: string): Promise<string> {
+  const dir = await mkdtemp(path.join(os.tmpdir(), "openclaw-acpx-mcp-proxy-"));
+  tempDirs.push(dir);
+  const scriptPath = path.join(dir, name);
+  await writeFile(scriptPath, content, "utf8");
+  await chmod(scriptPath, 0o755);
+  return scriptPath;
+}
+
+afterEach(async () => {
+  while (tempDirs.length > 0) {
+    const dir = tempDirs.pop();
+    if (!dir) {
+      continue;
+    }
+    await rm(dir, { recursive: true, force: true });
+  }
+});
+
+describe("mcp-proxy", () => {
+  it("injects configured MCP servers into ACP session bootstrap requests", async () => {
+    const echoServerPath = await makeTempScript(
+      "echo-server.cjs",
+      String.raw`#!/usr/bin/env node
+const { createInterface } = require("node:readline");
+const rl = createInterface({ input: process.stdin });
+rl.on("line", (line) => process.stdout.write(line + "\n"));
+rl.on("close", () => process.exit(0));
+`,
+    );
+
+    const payload = Buffer.from(
+      JSON.stringify({
+        targetCommand: `${process.execPath} ${echoServerPath}`,
+        mcpServers: [
+          {
+            name: "canva",
+            command: "npx",
+            args: ["-y", "mcp-remote@latest", "https://mcp.canva.com/mcp"],
+            env: [{ name: "CANVA_TOKEN", value: "secret" }],
+          },
+        ],
+      }),
+      "utf8",
+    ).toString("base64url");
+
+    const child = spawn(process.execPath, [proxyPath, "--payload", payload], {
+      stdio: ["pipe", "pipe", "inherit"],
+      cwd: process.cwd(),
+    });
+
+    let stdout = "";
+    child.stdout.on("data", (chunk) => {
+      stdout += String(chunk);
+    });
+
+    child.stdin.write(
+      `${JSON.stringify({
+        jsonrpc: "2.0",
+        id: 1,
+        method: "session/new",
+        params: { cwd: process.cwd(), mcpServers: [] },
+      })}\n`,
+    );
+    child.stdin.write(
+      `${JSON.stringify({
+        jsonrpc: "2.0",
+        id: 2,
+        method: "session/load",
+        params: { cwd: process.cwd(), sessionId: "sid-1", mcpServers: [] },
+      })}\n`,
+    );
+    child.stdin.write(
+      `${JSON.stringify({
+        jsonrpc: "2.0",
+        id: 3,
+        method: "session/prompt",
+        params: { sessionId: "sid-1", prompt: [{ type: "text", text: "hello" }] },
+      })}\n`,
+    );
+    child.stdin.end();
+
+    const exitCode = await new Promise<number | null>((resolve) => {
+      child.once("close", (code) => resolve(code));
+    });
+
+    expect(exitCode).toBe(0);
+    const lines = stdout
+      .trim()
+      .split(/\r?\n/)
+      .map((line) => JSON.parse(line) as { method: string; params: Record<string, unknown> });
+
+    expect(lines[0].params.mcpServers).toEqual([
+      {
+        name: "canva",
+        command: "npx",
+        args: ["-y", "mcp-remote@latest", "https://mcp.canva.com/mcp"],
+        env: [{ name: "CANVA_TOKEN", value: "secret" }],
+      },
+    ]);
+    expect(lines[1].params.mcpServers).toEqual(lines[0].params.mcpServers);
+    expect(lines[2].method).toBe("session/prompt");
+    expect(lines[2].params.mcpServers).toBeUndefined();
+  });
+});

extensions/acpx/src/runtime-internals/test-fixtures.ts

@@ -52,7 +52,8 @@ const commandIndex = args.findIndex(
     arg === "sessions" ||
     arg === "set-mode" ||
     arg === "set" ||
-    arg === "status",
+    arg === "status" ||
+    arg === "config",
 );
 const command = commandIndex >= 0 ? args[commandIndex] : "";
 const agent = commandIndex > 0 ? args[commandIndex - 1] : "unknown";
@@ -107,6 +108,32 @@ if (command === "sessions" && args[commandIndex + 1] === "new") {
   process.exit(0);
 }
 
+if (command === "config" && args[commandIndex + 1] === "show") {
+  const configuredAgents = process.env.MOCK_ACPX_CONFIG_SHOW_AGENTS
+    ? JSON.parse(process.env.MOCK_ACPX_CONFIG_SHOW_AGENTS)
+    : {};
+  emitJson({
+    defaultAgent: "codex",
+    defaultPermissions: "approve-reads",
+    nonInteractivePermissions: "deny",
+    authPolicy: "skip",
+    ttl: 300,
+    timeout: null,
+    format: "text",
+    agents: configuredAgents,
+    authMethods: [],
+    paths: {
+      global: "/tmp/mock-global.json",
+      project: "/tmp/mock-project.json",
+    },
+    loaded: {
+      global: false,
+      project: false,
+    },
+  });
+  process.exit(0);
+}
+
 if (command === "cancel") {
   writeLog({ kind: "cancel", agent, args, sessionName: sessionFromOption });
   emitJson({
@@ -285,6 +312,7 @@ process.exit(2);
 export async function createMockRuntimeFixture(params?: {
   permissionMode?: ResolvedAcpxPluginConfig["permissionMode"];
   queueOwnerTtlSeconds?: number;
+  mcpServers?: ResolvedAcpxPluginConfig["mcpServers"];
 }): Promise<{
   runtime: AcpxRuntime;
   logPath: string;
@@ -304,6 +332,7 @@ export async function createMockRuntimeFixture(params?: {
     nonInteractivePermissions: "fail",
     strictWindowsCmdWrapper: true,
     queueOwnerTtlSeconds: params?.queueOwnerTtlSeconds ?? 0.1,
+    mcpServers: params?.mcpServers ?? {},
   };
 
   return {

extensions/acpx/src/runtime.test.ts

@@ -322,6 +322,58 @@ describe("AcpxRuntime", () => {
     expect(logs.find((entry) => entry.kind === "status")).toBeDefined();
   });
 
+  it("routes ACPX commands through an MCP proxy agent when MCP servers are configured", async () => {
+    process.env.MOCK_ACPX_CONFIG_SHOW_AGENTS = JSON.stringify({
+      codex: {
+        command: "npx custom-codex-acp",
+      },
+    });
+    try {
+      const { runtime, logPath } = await createMockRuntimeFixture({
+        mcpServers: {
+          canva: {
+            command: "npx",
+            args: ["-y", "mcp-remote@latest", "https://mcp.canva.com/mcp"],
+            env: {
+              CANVA_TOKEN: "secret",
+            },
+          },
+        },
+      });
+
+      const handle = await runtime.ensureSession({
+        sessionKey: "agent:codex:acp:mcp",
+        agent: "codex",
+        mode: "persistent",
+      });
+      await runtime.setMode({
+        handle,
+        mode: "plan",
+      });
+
+      const logs = await readMockRuntimeLogEntries(logPath);
+      const ensureArgs = (logs.find((entry) => entry.kind === "ensure")?.args as string[]) ?? [];
+      const setModeArgs = (logs.find((entry) => entry.kind === "set-mode")?.args as string[]) ?? [];
+
+      for (const args of [ensureArgs, setModeArgs]) {
+        const agentFlagIndex = args.indexOf("--agent");
+        expect(agentFlagIndex).toBeGreaterThanOrEqual(0);
+        const rawAgentCommand = args[agentFlagIndex + 1];
+        expect(rawAgentCommand).toContain("mcp-proxy.mjs");
+        const payloadMatch = rawAgentCommand.match(/--payload\s+([A-Za-z0-9_-]+)/);
+        expect(payloadMatch?.[1]).toBeDefined();
+        const payload = JSON.parse(
+          Buffer.from(String(payloadMatch?.[1]), "base64url").toString("utf8"),
+        ) as {
+          targetCommand: string;
+        };
+        expect(payload.targetCommand).toContain("custom-codex-acp");
+      }
+    } finally {
+      delete process.env.MOCK_ACPX_CONFIG_SHOW_AGENTS;
+    }
+  });
+
   it("skips prompt execution when runTurn starts with an already-aborted signal", async () => {
     const { runtime, logPath } = await createMockRuntimeFixture();
     const handle = await runtime.ensureSession({

extensions/acpx/src/runtime.ts

@@ -12,13 +12,17 @@ import type {
   PluginLogger,
 } from "openclaw/plugin-sdk/acpx";
 import { AcpRuntimeError } from "openclaw/plugin-sdk/acpx";
-import { type ResolvedAcpxPluginConfig } from "./config.js";
+import { toAcpMcpServers, type ResolvedAcpxPluginConfig } from "./config.js";
 import { checkAcpxVersion } from "./ensure.js";
 import {
   parseJsonLines,
   parsePromptEventLine,
   toAcpxErrorEvent,
 } from "./runtime-internals/events.js";
+import {
+  buildMcpProxyAgentCommand,
+  resolveAcpxAgentCommand,
+} from "./runtime-internals/mcp-agent-command.js";
 import {
   resolveSpawnFailure,
   type SpawnCommandCache,
@@ -118,6 +122,7 @@ export class AcpxRuntime implements AcpRuntime {
   private readonly logger?: PluginLogger;
   private readonly queueOwnerTtlSeconds: number;
   private readonly spawnCommandCache: SpawnCommandCache = {};
+  private readonly mcpProxyAgentCommandCache = new Map<string, string>();
   private readonly spawnCommandOptions: SpawnCommandOptions;
   private readonly loggedSpawnResolutions = new Set<string>();
 
@@ -198,12 +203,14 @@ export class AcpxRuntime implements AcpRuntime {
     }
     const cwd = asTrimmedString(input.cwd) || this.config.cwd;
     const mode = input.mode;
+    const ensureCommand = await this.buildVerbArgs({
+      agent,
+      cwd,
+      command: ["sessions", "ensure", "--name", sessionName],
+    });
 
     let events = await this.runControlCommand({
-      args: this.buildControlArgs({
-        cwd,
-        command: [agent, "sessions", "ensure", "--name", sessionName],
-      }),
+      args: ensureCommand,
       cwd,
       fallbackCode: "ACP_SESSION_INIT_FAILED",
     });
@@ -215,11 +222,13 @@ export class AcpxRuntime implements AcpRuntime {
     );
 
     if (!ensuredEvent) {
+      const newCommand = await this.buildVerbArgs({
+        agent,
+        cwd,
+        command: ["sessions", "new", "--name", sessionName],
+      });
       events = await this.runControlCommand({
-        args: this.buildControlArgs({
-          cwd,
-          command: [agent, "sessions", "new", "--name", sessionName],
-        }),
+        args: newCommand,
         cwd,
         fallbackCode: "ACP_SESSION_INIT_FAILED",
       });
@@ -264,7 +273,7 @@ export class AcpxRuntime implements AcpRuntime {
 
   async *runTurn(input: AcpRuntimeTurnInput): AsyncIterable<AcpRuntimeEvent> {
     const state = this.resolveHandleState(input.handle);
-    const args = this.buildPromptArgs({
+    const args = await this.buildPromptArgs({
       agent: state.agent,
       sessionName: state.name,
       cwd: state.cwd,
@@ -381,11 +390,13 @@ export class AcpxRuntime implements AcpRuntime {
     signal?: AbortSignal;
   }): Promise<AcpRuntimeStatus> {
     const state = this.resolveHandleState(input.handle);
+    const args = await this.buildVerbArgs({
+      agent: state.agent,
+      cwd: state.cwd,
+      command: ["status", "--session", state.name],
+    });
     const events = await this.runControlCommand({
-      args: this.buildControlArgs({
-        cwd: state.cwd,
-        command: [state.agent, "status", "--session", state.name],
-      }),
+      args,
       cwd: state.cwd,
       fallbackCode: "ACP_TURN_FAILED",
       ignoreNoSession: true,
@@ -425,11 +436,13 @@ export class AcpxRuntime implements AcpRuntime {
     if (!mode) {
       throw new AcpRuntimeError("ACP_TURN_FAILED", "ACP runtime mode is required.");
     }
+    const args = await this.buildVerbArgs({
+      agent: state.agent,
+      cwd: state.cwd,
+      command: ["set-mode", mode, "--session", state.name],
+    });
     await this.runControlCommand({
-      args: this.buildControlArgs({
-        cwd: state.cwd,
-        command: [state.agent, "set-mode", mode, "--session", state.name],
-      }),
+      args,
       cwd: state.cwd,
       fallbackCode: "ACP_TURN_FAILED",
     });
@@ -446,11 +459,13 @@ export class AcpxRuntime implements AcpRuntime {
     if (!key || !value) {
       throw new AcpRuntimeError("ACP_TURN_FAILED", "ACP config option key/value are required.");
     }
+    const args = await this.buildVerbArgs({
+      agent: state.agent,
+      cwd: state.cwd,
+      command: ["set", key, value, "--session", state.name],
+    });
     await this.runControlCommand({
-      args: this.buildControlArgs({
-        cwd: state.cwd,
-        command: [state.agent, "set", key, value, "--session", state.name],
-      }),
+      args,
       cwd: state.cwd,
       fallbackCode: "ACP_TURN_FAILED",
     });
@@ -539,11 +554,13 @@ export class AcpxRuntime implements AcpRuntime {
 
   async cancel(input: { handle: AcpRuntimeHandle; reason?: string }): Promise<void> {
     const state = this.resolveHandleState(input.handle);
+    const args = await this.buildVerbArgs({
+      agent: state.agent,
+      cwd: state.cwd,
+      command: ["cancel", "--session", state.name],
+    });
     await this.runControlCommand({
-      args: this.buildControlArgs({
-        cwd: state.cwd,
-        command: [state.agent, "cancel", "--session", state.name],
-      }),
+      args,
       cwd: state.cwd,
       fallbackCode: "ACP_TURN_FAILED",
       ignoreNoSession: true,
@@ -552,11 +569,13 @@ export class AcpxRuntime implements AcpRuntime {
 
   async close(input: { handle: AcpRuntimeHandle; reason: string }): Promise<void> {
     const state = this.resolveHandleState(input.handle);
+    const args = await this.buildVerbArgs({
+      agent: state.agent,
+      cwd: state.cwd,
+      command: ["sessions", "close", state.name],
+    });
     await this.runControlCommand({
-      args: this.buildControlArgs({
-        cwd: state.cwd,
-        command: [state.agent, "sessions", "close", state.name],
-      }),
+      args,
       cwd: state.cwd,
       fallbackCode: "ACP_TURN_FAILED",
       ignoreNoSession: true,
@@ -585,12 +604,12 @@ export class AcpxRuntime implements AcpRuntime {
     };
   }
 
-  private buildControlArgs(params: { cwd: string; command: string[] }): string[] {
-    return ["--format", "json", "--json-strict", "--cwd", params.cwd, ...params.command];
-  }
-
-  private buildPromptArgs(params: { agent: string; sessionName: string; cwd: string }): string[] {
-    const args = [
+  private async buildPromptArgs(params: {
+    agent: string;
+    sessionName: string;
+    cwd: string;
+  }): Promise<string[]> {
+    const prefix = [
       "--format",
       "json",
       "--json-strict",
@@ -601,11 +620,58 @@ export class AcpxRuntime implements AcpRuntime {
       this.config.nonInteractivePermissions,
     ];
     if (this.config.timeoutSeconds) {
-      args.push("--timeout", String(this.config.timeoutSeconds));
+      prefix.push("--timeout", String(this.config.timeoutSeconds));
     }
-    args.push("--ttl", String(this.queueOwnerTtlSeconds));
-    args.push(params.agent, "prompt", "--session", params.sessionName, "--file", "-");
-    return args;
+    prefix.push("--ttl", String(this.queueOwnerTtlSeconds));
+    return await this.buildVerbArgs({
+      agent: params.agent,
+      cwd: params.cwd,
+      command: ["prompt", "--session", params.sessionName, "--file", "-"],
+      prefix,
+    });
+  }
+
+  private async buildVerbArgs(params: {
+    agent: string;
+    cwd: string;
+    command: string[];
+    prefix?: string[];
+  }): Promise<string[]> {
+    const prefix = params.prefix ?? ["--format", "json", "--json-strict", "--cwd", params.cwd];
+    const agentCommand = await this.resolveRawAgentCommand({
+      agent: params.agent,
+      cwd: params.cwd,
+    });
+    if (!agentCommand) {
+      return [...prefix, params.agent, ...params.command];
+    }
+    return [...prefix, "--agent", agentCommand, ...params.command];
+  }
+
+  private async resolveRawAgentCommand(params: {
+    agent: string;
+    cwd: string;
+  }): Promise<string | null> {
+    if (Object.keys(this.config.mcpServers).length === 0) {
+      return null;
+    }
+    const cacheKey = `${params.cwd}::${params.agent}`;
+    const cached = this.mcpProxyAgentCommandCache.get(cacheKey);
+    if (cached) {
+      return cached;
+    }
+    const targetCommand = await resolveAcpxAgentCommand({
+      acpxCommand: this.config.command,
+      cwd: params.cwd,
+      agent: params.agent,
+      spawnOptions: this.spawnCommandOptions,
+    });
+    const resolved = buildMcpProxyAgentCommand({
+      targetCommand,
+      mcpServers: toAcpMcpServers(this.config.mcpServers),
+    });
+    this.mcpProxyAgentCommandCache.set(cacheKey, resolved);
+    return resolved;
   }
 
   private async runControlCommand(params: {

extensions/acpx/src/service.ts

@@ -59,8 +59,9 @@ export function createAcpxRuntimeService(
       });
       const expectedVersionLabel = pluginConfig.expectedVersion ?? "any";
       const installLabel = pluginConfig.allowPluginLocalInstall ? "enabled" : "disabled";
+      const mcpServerCount = Object.keys(pluginConfig.mcpServers).length;
       ctx.logger.info(
-        `acpx runtime backend registered (command: ${pluginConfig.command}, expectedVersion: ${expectedVersionLabel}, pluginLocalInstall: ${installLabel})`,
+        `acpx runtime backend registered (command: ${pluginConfig.command}, expectedVersion: ${expectedVersionLabel}, pluginLocalInstall: ${installLabel}${mcpServerCount > 0 ? `, mcpServers: ${mcpServerCount}` : ""})`,
       );
 
       lifecycleRevision += 1;