diff --git a/src/cli.ts b/src/cli.ts
index e5142cd57..fa70b501b 100644
--- a/src/cli.ts
+++ b/src/cli.ts
@@ -12,7 +12,7 @@ import {
 import { existsSync, readdirSync, renameSync, readFileSync } from 'node:fs'
 import { join } from 'node:path'
 import { agentDir, sessionsDir, authFilePath } from './app-paths.js'
-import { initResources, buildResourceLoader } from './resource-loader.js'
+import { initResources, buildResourceLoader, getNewerManagedResourceVersion } from './resource-loader.js'
 import { ensureManagedTools } from './tool-bootstrap.js'
 import { loadStoredEnvKeys } from './wizard.js'
 import { getPiDefaultModelAndProvider, migratePiCredentials } from './pi-migration.js'
@@ -35,6 +35,26 @@ interface CliFlags {
   messages: string[]
 }
 
+function exitIfManagedResourcesAreNewer(currentAgentDir: string): void {
+  const currentVersion = process.env.GSD_VERSION || '0.0.0'
+  const managedVersion = getNewerManagedResourceVersion(currentAgentDir, currentVersion)
+  if (!managedVersion) {
+    return
+  }
+
+  const yellow = '\x1b[33m'
+  const dim = '\x1b[2m'
+  const reset = '\x1b[0m'
+  const bold = '\x1b[1m'
+
+  process.stderr.write(
+    `[gsd] ${yellow}Version mismatch detected${reset}\n` +
+    `[gsd] Synced resources are from ${bold}v${managedVersion}${reset}, but this \`gsd\` binary is ${dim}v${currentVersion}${reset}.\n` +
+    `[gsd] Run ${bold}npm install -g gsd-pi@latest${reset} or ${bold}gsd update${reset}, then try again.\n`,
+  )
+  process.exit(1)
+}
+
 function parseCliArgs(argv: string[]): CliFlags {
   const flags: CliFlags = { extensions: [], messages: [] }
   const args = argv.slice(2) // skip node + script
@@ -232,6 +252,7 @@ if (isPrintMode) {
     }
   }
 
+  exitIfManagedResourcesAreNewer(agentDir)
   initResources(agentDir)
   const resourceLoader = new DefaultResourceLoader({
     agentDir,
@@ -316,6 +337,7 @@ const sessionManager = cliFlags.continue
   ? SessionManager.continueRecent(cwd, projectSessionsDir)
   : SessionManager.create(cwd, projectSessionsDir)
 
+exitIfManagedResourcesAreNewer(agentDir)
 initResources(agentDir)
 const resourceLoader = buildResourceLoader(agentDir)
 await resourceLoader.reload()
diff --git a/src/resource-loader.ts b/src/resource-loader.ts
index c7c00331c..676e52979 100644
--- a/src/resource-loader.ts
+++ b/src/resource-loader.ts
@@ -3,6 +3,7 @@ import { homedir } from 'node:os'
 import { cpSync, existsSync, mkdirSync, readFileSync, readdirSync, writeFileSync } from 'node:fs'
 import { dirname, join, relative, resolve } from 'node:path'
 import { fileURLToPath } from 'node:url'
+import { compareSemver } from './update-check.js'
 
 // Resolve resources directory — prefer dist/resources/ (stable, set at build time)
 // over src/resources/ (live working tree, changes with git branch).
@@ -17,6 +18,11 @@ const distResources = join(packageRoot, 'dist', 'resources')
 const srcResources = join(packageRoot, 'src', 'resources')
 const resourcesDir = existsSync(distResources) ? distResources : srcResources
 const bundledExtensionsDir = join(resourcesDir, 'extensions')
+const resourceVersionManifestName = 'managed-resources.json'
+
+interface ManagedResourceManifest {
+  gsdVersion: string
+}
 
 function isExtensionFile(name: string): boolean {
   return name.endsWith('.ts') || name.endsWith('.js')
@@ -82,6 +88,41 @@ function getExtensionKey(entryPath: string, extensionsDir: string): string {
   return relPath.split(/[\\/]/)[0]
 }
 
+function getManagedResourceManifestPath(agentDir: string): string {
+  return join(agentDir, resourceVersionManifestName)
+}
+
+function getBundledGsdVersion(): string {
+  try {
+    const pkg = JSON.parse(readFileSync(join(packageRoot, 'package.json'), 'utf-8'))
+    return typeof pkg?.version === 'string' ? pkg.version : '0.0.0'
+  } catch {
+    return process.env.GSD_VERSION || '0.0.0'
+  }
+}
+
+function writeManagedResourceManifest(agentDir: string): void {
+  const manifest: ManagedResourceManifest = { gsdVersion: getBundledGsdVersion() }
+  writeFileSync(getManagedResourceManifestPath(agentDir), JSON.stringify(manifest))
+}
+
+export function readManagedResourceVersion(agentDir: string): string | null {
+  try {
+    const manifest = JSON.parse(readFileSync(getManagedResourceManifestPath(agentDir), 'utf-8')) as ManagedResourceManifest
+    return typeof manifest?.gsdVersion === 'string' ? manifest.gsdVersion : null
+  } catch {
+    return null
+  }
+}
+
+export function getNewerManagedResourceVersion(agentDir: string, currentVersion: string): string | null {
+  const managedVersion = readManagedResourceVersion(agentDir)
+  if (!managedVersion) {
+    return null
+  }
+  return compareSemver(managedVersion, currentVersion) > 0 ? managedVersion : null
+}
+
 /**
  * Syncs all bundled resources to agentDir (~/.gsd/agent/) on every launch.
  *
@@ -116,6 +157,8 @@ export function initResources(agentDir: string): void {
   if (existsSync(srcSkills)) {
     cpSync(srcSkills, destSkills, { recursive: true, force: true })
   }
+
+  writeManagedResourceManifest(agentDir)
 }
 
 /**
diff --git a/src/tests/app-smoke.test.ts b/src/tests/app-smoke.test.ts
index 1c94190c0..69893d360 100644
--- a/src/tests/app-smoke.test.ts
+++ b/src/tests/app-smoke.test.ts
@@ -126,7 +126,7 @@ test("loader sets all 4 GSD_ env vars and PI_PACKAGE_DIR", async () => {
 // ═══════════════════════════════════════════════════════════════════════════
 
 test("initResources syncs extensions, agents, and skills to target dir", async () => {
-  const { initResources } = await import("../resource-loader.ts");
+  const { initResources, readManagedResourceVersion } = await import("../resource-loader.ts");
   const tmp = mkdtempSync(join(tmpdir(), "gsd-resources-test-"));
   const fakeAgentDir = join(tmp, "agent");
 
@@ -146,6 +146,10 @@ test("initResources syncs extensions, agents, and skills to target dir", async (
     // Skills synced
     assert.ok(existsSync(join(fakeAgentDir, "skills")), "skills directory synced");
 
+    // Version manifest synced
+    const managedVersion = readManagedResourceVersion(fakeAgentDir);
+    assert.ok(managedVersion, "managed resource version written");
+
     // Idempotent: run again, no crash
     initResources(fakeAgentDir);
     assert.ok(existsSync(join(fakeAgentDir, "extensions", "gsd", "index.ts")), "idempotent re-sync works");
diff --git a/src/tests/integration/pack-install.test.ts b/src/tests/integration/pack-install.test.ts
index 7afcfa586..4abd4cbfb 100644
--- a/src/tests/integration/pack-install.test.ts
+++ b/src/tests/integration/pack-install.test.ts
@@ -12,7 +12,7 @@
 import test from "node:test";
 import assert from "node:assert/strict";
 import { execFileSync, spawn } from "node:child_process";
-import { createReadStream, existsSync, mkdirSync, mkdtempSync, readFileSync, rmSync } from "node:fs";
+import { createReadStream, existsSync, mkdirSync, mkdtempSync, readFileSync, rmSync, writeFileSync } from "node:fs";
 import { join } from "node:path";
 import { tmpdir } from "node:os";
 import { createGunzip } from "node:zlib";
@@ -229,3 +229,48 @@ test("gsd launches and loads extensions without errors", async () => {
     "no ERR_MODULE_NOT_FOUND",
   );
 });
+
+test("gsd exits early with a clear message when synced resources are newer than the binary", async () => {
+  const fakeHome = mkdtempSync(join(tmpdir(), "gsd-version-skew-"));
+  const fakeAgentDir = join(fakeHome, ".gsd", "agent");
+  mkdirSync(fakeAgentDir, { recursive: true });
+  writeFileSync(
+    join(fakeAgentDir, "managed-resources.json"),
+    JSON.stringify({ gsdVersion: "999.0.0" }),
+  );
+
+  try {
+    const result = await new Promise<{ code: number | null; stderr: string }>((resolve) => {
+      let stderr = "";
+      const child = spawn("node", ["dist/loader.js"], {
+        cwd: projectRoot,
+        env: {
+          ...process.env,
+          HOME: fakeHome,
+          BRAVE_API_KEY: "test",
+          BRAVE_ANSWERS_KEY: "test",
+          CONTEXT7_API_KEY: "test",
+          JINA_API_KEY: "test",
+          TAVILY_API_KEY: "test",
+        },
+        stdio: ["pipe", "pipe", "pipe"],
+      });
+
+      child.stderr.on("data", (data: Buffer) => {
+        stderr += data.toString();
+      });
+
+      child.stdin.end();
+      child.on("close", (code) => {
+        resolve({ code, stderr });
+      });
+    });
+
+    assert.equal(result.code, 1, "startup exits with code 1 on version skew");
+    assert.match(result.stderr, /Version mismatch detected/, "prints a friendly skew header");
+    assert.match(result.stderr, /npm install -g gsd-pi@latest|gsd update/, "prints upgrade guidance");
+    assert.doesNotMatch(result.stderr, /\[gsd\] Extension load error/, "fails before extension loading");
+  } finally {
+    rmSync(fakeHome, { recursive: true, force: true });
+  }
+});