diff --git a/.codex-plugin/plugin.json b/.codex-plugin/plugin.json
index 1e90d221e..71cf5d45c 100644
--- a/.codex-plugin/plugin.json
+++ b/.codex-plugin/plugin.json
@@ -16,17 +16,7 @@
     "mcp-server"
   ],
   "skills": "./skills",
-  "mcpServers": {
-    "rea": {
-      "command": "node",
-      "args": [
-        "./scripts/plugin-mcp-launcher.mjs",
-        "rea-agents@6.4.0"
-      ],
-      "startup_timeout_sec": 30,
-      "cwd": "."
-    }
-  },
+  "mcpServers": "./.mcp.json",
   "interface": {
     "displayName": "REA",
     "shortDescription": "Reverse engineer anything with agents",
diff --git a/.mcp.json b/.mcp.json
new file mode 100644
index 000000000..8463e6859
--- /dev/null
+++ b/.mcp.json
@@ -0,0 +1,12 @@
+{
+  "mcpServers": {
+    "rea": {
+      "command": "node",
+      "args": [
+        "./scripts/plugin-mcp-launcher.mjs",
+        "rea-agents@6.4.0"
+      ],
+      "cwd": "."
+    }
+  }
+}
diff --git a/docs/releasing.md b/docs/releasing.md
index 4e651dd2e..192378cd5 100644
--- a/docs/releasing.md
+++ b/docs/releasing.md
@@ -242,7 +242,9 @@ tag remains in main's ancestry. Keep the released tag unchanged.
 The synchronization must include `.release-please-manifest.json`,
 `package.json`, both root versions in `package-lock.json`, `CHANGELOG.md`,
 `server.json`, both plugin manifests (`.claude-plugin/plugin.json` and
-`.codex-plugin/plugin.json`), and the versioned documentation examples. Run
+`.codex-plugin/plugin.json`), the Codex server declaration (`.mcp.json`), both
+marketplaces (`.claude-plugin/marketplace.json` and
+`.agents/plugins/marketplace.json`), and the versioned documentation examples. Run
 `npm run docs:generate`, `npm run docs:check`, and the release configuration
 tests against the combined tree. After the merge, verify that the released
 tag is an ancestor of main:
diff --git a/package.json b/package.json
index bcfa09f3e..d7795a3e2 100644
--- a/package.json
+++ b/package.json
@@ -72,6 +72,7 @@
     "scripts/prepare.mjs",
     ".claude-plugin/plugin.json",
     ".codex-plugin/plugin.json",
+    ".mcp.json",
     "skills",
     "README.md",
     "DISCLAIMER.md",
diff --git a/release-please-config.json b/release-please-config.json
index 5543ecc6d..133b81777 100644
--- a/release-please-config.json
+++ b/release-please-config.json
@@ -49,7 +49,7 @@
         },
         {
           "type": "json",
-          "path": ".codex-plugin/plugin.json",
+          "path": ".mcp.json",
           "jsonpath": "$.mcpServers.rea.args[1]"
         },
         {
diff --git a/scripts/plugin-mcp-launcher.mjs b/scripts/plugin-mcp-launcher.mjs
index 71198caf9..f75935faa 100644
--- a/scripts/plugin-mcp-launcher.mjs
+++ b/scripts/plugin-mcp-launcher.mjs
@@ -1,9 +1,10 @@
 #!/usr/bin/env node
 
 import { spawn } from "node:child_process";
-import { mkdtemp, rm } from "node:fs/promises";
+import { access, mkdtemp, rm } from "node:fs/promises";
 import { constants, tmpdir } from "node:os";
 import { join } from "node:path";
+import { fileURLToPath } from "node:url";
 
 import { packageRunnerCommand } from "./lib/packageRunnerCommand.mjs";
 
@@ -26,6 +27,32 @@ if (
 }
 
 async function launch(packageSpecifier) {
+  // npm installs already carry the release-pinned runtime. Run it in this
+  // process so the plugin keeps the caller's working directory and the
+  // runtime retains ownership of provider and worker cleanup.
+  const { default: bundledPackage } = await import("../package.json", {
+    with: { type: "json" },
+  });
+  let bundledRuntimeMatchesPin =
+    packageSpecifier === `${bundledPackage.name}@${bundledPackage.version}`;
+  if (bundledRuntimeMatchesPin) {
+    try {
+      await access(new URL("../dist/mcp/main.js", import.meta.url));
+    } catch (cause) {
+      if (!isMissing(cause)) throw cause;
+      bundledRuntimeMatchesPin = false;
+    }
+  }
+  if (bundledRuntimeMatchesPin) {
+    process.argv = [
+      process.execPath,
+      fileURLToPath(new URL("./rea.mjs", import.meta.url)),
+      "mcp",
+    ];
+    await import("./rea.mjs");
+    return;
+  }
+
   const [command, ...args] = packageRunnerCommand(
     "npx",
     packageSpecifier,
@@ -93,3 +120,12 @@ async function launch(packageSpecifier) {
     }
   });
 }
+
+function isMissing(cause) {
+  return (
+    typeof cause === "object" &&
+    cause !== null &&
+    "code" in cause &&
+    cause.code === "ENOENT"
+  );
+}
diff --git a/scripts/verify-package-pack.mjs b/scripts/verify-package-pack.mjs
index 668a22430..6dda321a9 100644
--- a/scripts/verify-package-pack.mjs
+++ b/scripts/verify-package-pack.mjs
@@ -71,21 +71,38 @@ export async function verifyPackagePack({ root, workspace }) {
     const manifest = JSON.parse(
       (await exec("tar", ["-xOf", tarball, `package/${path}`])).stdout,
     );
+    const serverConfig = path.startsWith(".codex")
+      ? JSON.parse(
+          (
+            await exec("tar", [
+              "-xOf",
+              tarball,
+              "package/.mcp.json",
+            ])
+          ).stdout,
+        )
+      : manifest;
+    const expectedArgs = [
+      `${path.startsWith(".claude") ? "${CLAUDE_PLUGIN_ROOT}/" : "./"}scripts/plugin-mcp-launcher.mjs`,
+      `${packedManifest.name}@${packedManifest.version}`,
+    ];
     if (
       manifest.version !== packedManifest.version ||
       manifest.skills !== "./skills" ||
-      manifest.mcpServers?.rea?.command !== "node" ||
-      (path.startsWith(".codex") && manifest.mcpServers?.rea?.cwd !== ".") ||
-      JSON.stringify(manifest.mcpServers?.rea?.args) !==
-        JSON.stringify([
-          `${path.startsWith(".claude") ? "${CLAUDE_PLUGIN_ROOT}/" : "./"}scripts/plugin-mcp-launcher.mjs`,
-          `${packedManifest.name}@${packedManifest.version}`,
-        ])
+      (path.startsWith(".codex")
+        ? manifest.mcpServers !== "./.mcp.json" ||
+          serverConfig.mcpServers?.rea?.cwd !== "."
+        : false) ||
+      serverConfig.mcpServers?.rea?.command !== "node" ||
+      JSON.stringify(serverConfig.mcpServers?.rea?.args) !==
+        JSON.stringify(expectedArgs)
     )
       throw new Error(
         `Packaged plugin ${path} does not match the exact runtime and canonical skill release`,
       );
   }
+  if (!packedFiles.includes("package/.mcp.json"))
+    throw new Error("Packaged Codex MCP server declaration is missing");
   for (const path of [
     "scripts/plugin-mcp-launcher.mjs",
     "scripts/lib/packageRunnerCommand.mjs",
diff --git a/tests/boundary/process/pluginMcpLauncher.test.ts b/tests/boundary/process/pluginMcpLauncher.test.ts
index 9f47a1a7a..093425e7d 100644
--- a/tests/boundary/process/pluginMcpLauncher.test.ts
+++ b/tests/boundary/process/pluginMcpLauncher.test.ts
@@ -10,7 +10,7 @@ const launcher = fileURLToPath(
   new URL("../../../scripts/plugin-mcp-launcher.mjs", import.meta.url),
 );
 
-const start = (path: string, packageSpecifier = "rea-agents@6.4.0") => {
+const start = (path: string, packageSpecifier = "rea-agents@6.4.0-rc.1") => {
   const child = spawn(process.execPath, [launcher, packageSpecifier], {
     env: {
       ...process.env,
diff --git a/tests/conformance/releaseConfiguration.test.ts b/tests/conformance/releaseConfiguration.test.ts
index 65f785929..8bb6687d1 100644
--- a/tests/conformance/releaseConfiguration.test.ts
+++ b/tests/conformance/releaseConfiguration.test.ts
@@ -20,6 +20,7 @@ const pluginManifests = [
   ".claude-plugin/plugin.json",
   ".codex-plugin/plugin.json",
 ] as const;
+const pluginServerConfig = ".mcp.json";
 
 describe("release configuration", () => {
   it("keeps doctor and setup runtime support aligned with package engines", async () => {
@@ -54,13 +55,16 @@ describe("release configuration", () => {
               path: "server.json",
               jsonpath: "$.packages[0].version",
             },
-            ...pluginManifests.flatMap((path) =>
-              ["$.version", "$.mcpServers.rea.args[1]"].map((jsonpath) => ({
-                type: "json",
-                path,
-                jsonpath,
-              })),
-            ),
+            ...pluginManifests.map((path) => ({
+              type: "json",
+              path,
+              jsonpath: "$.version",
+            })),
+            {
+              type: "json",
+              path: pluginServerConfig,
+              jsonpath: "$.mcpServers.rea.args[1]",
+            },
             ...[
               ".claude-plugin/marketplace.json",
               ".agents/plugins/marketplace.json",
@@ -164,7 +168,11 @@ describe("plugin manifests", () => {
       files: string[];
     };
     expect(pkg.files).toEqual(
-      expect.arrayContaining([...pluginManifests, "skills"]),
+      expect.arrayContaining([
+        ...pluginManifests,
+        pluginServerConfig,
+        "skills",
+      ]),
     );
     for (const path of pluginManifests)
       expect(await readJson(path)).toMatchObject({ skills: "./skills" });
@@ -186,7 +194,7 @@ describe("plugin manifests", () => {
   });
 
   it.each(pluginManifests)(
-    "pins the plugin manifest %s and its server launch to the package version",
+    "pins the plugin manifest %s and Codex's server config path",
     async (path) => {
       const packageJson = (await readJson("package.json")) as {
         name: string;
@@ -195,20 +203,33 @@ describe("plugin manifests", () => {
 
       expect(await readJson(path)).toMatchObject({
         version: packageJson.version,
-        mcpServers: {
-          rea: {
-            command: "node",
-            args: [
-              `${path.startsWith(".claude") ? "${CLAUDE_PLUGIN_ROOT}/" : "./"}scripts/plugin-mcp-launcher.mjs`,
-              `${packageJson.name}@${packageJson.version}`,
-            ],
-            ...(path.startsWith(".codex") ? { cwd: "." } : {}),
-          },
-        },
+        ...(path.startsWith(".codex")
+          ? { mcpServers: `./${pluginServerConfig}` }
+          : {}),
       });
     },
   );
 
+  it("pins the plugin server launch from the shared MCP declaration", async () => {
+    const packageJson = (await readJson("package.json")) as {
+      name: string;
+      version: string;
+    };
+
+    expect(await readJson(pluginServerConfig)).toMatchObject({
+      mcpServers: {
+        rea: {
+          command: "node",
+          args: [
+            "./scripts/plugin-mcp-launcher.mjs",
+            `${packageJson.name}@${packageJson.version}`,
+          ],
+          cwd: ".",
+        },
+      },
+    });
+  });
+
   it.each(pluginManifests)(
     "stores %s in the form Release Please rewrites it to",
     async (path) => {