diff --git a/src/hooks/session-start.ts b/src/hooks/session-start.ts
index 3afce68..5af3c55 100644
--- a/src/hooks/session-start.ts
+++ b/src/hooks/session-start.ts
@@ -1,15 +1,17 @@
 import { readFileSync, existsSync, writeFileSync, unlinkSync, mkdirSync } from "node:fs";
 import { join, dirname } from "node:path";
 import { homedir } from "node:os";
-import { isConfigured, CONFIG, reloadApiKey } from "../config.js";
+import { isConfigured, CONFIG, PLUGIN_VERSION, reloadApiKey } from "../config.js";
 import { SupermemoryClient } from "../services/client.js";
 import { getTags } from "../services/tags.js";
 import { formatCombinedContext } from "../services/context.js";
 import { log } from "../services/logger.js";
 import { startAuthFlow, AUTH_BASE_URL } from "../services/auth.js";
 import { getSeenFacts, addSeenFacts } from "../services/factCache.js";
+import { checkNpmUpdate, formatUpdateNotice } from "../services/version-check.js";
 
 const AUTH_ATTEMPTED_FILE = join(homedir(), ".codex", "supermemory", ".auth-attempted");
+const UPDATE_COMMAND = "npx codex-supermemory@latest install";
 
 interface CodexHookPayload {
   session_id?: string;
@@ -31,6 +33,10 @@ function exitWithContext(additionalContext: string): never {
   process.exit(0);
 }
 
+function combineContextParts(parts: Array<string | null | undefined>): string {
+  return parts.map((part) => part?.trim()).filter(Boolean).join("\n\n");
+}
+
 async function main() {
   let rawInput = "";
   try {
@@ -77,6 +83,8 @@ async function main() {
   const cwd = payload.cwd || process.cwd();
   const tags = getTags(cwd);
   const client = new SupermemoryClient();
+  const updateCheck = checkNpmUpdate("codex-supermemory", PLUGIN_VERSION, UPDATE_COMMAND)
+    .then((info) => (info ? formatUpdateNotice(info) : null));
 
   log("session-start: begin", { sessionId, tags });
 
@@ -97,13 +105,17 @@ async function main() {
 
     if (newFacts.length > 0) {
       addSeenFacts(sessionId, newFacts);
-      exitWithContext(`[SUPERMEMORY CONTEXT]\n${text}\n[END SUPERMEMORY CONTEXT]`);
+      const updateNotice = await updateCheck;
+      exitWithContext(combineContextParts([
+        `[SUPERMEMORY CONTEXT]\n${text}\n[END SUPERMEMORY CONTEXT]`,
+        updateNotice,
+      ]));
     }
 
-    exitWithContext("");
+    exitWithContext(await updateCheck ?? "");
   } catch (error) {
     log("session-start: error", { error: String(error) });
-    exitWithContext("");
+    exitWithContext(await updateCheck ?? "");
   }
 }
 
diff --git a/src/services/version-check.ts b/src/services/version-check.ts
new file mode 100644
index 0000000..2688de7
--- /dev/null
+++ b/src/services/version-check.ts
@@ -0,0 +1,73 @@
+const NPM_REGISTRY_URL = "https://registry.npmjs.org";
+const CHECK_TIMEOUT_MS = 3000;
+
+export interface UpdateInfo {
+  currentVersion: string;
+  latestVersion: string;
+  updateCommand: string;
+}
+
+function parseVersion(version: string): { parts: number[]; prerelease: string | null } | null {
+  const normalized = version.trim().replace(/^v/i, "");
+  const match = normalized.match(/^(\d+)\.(\d+)\.(\d+)(?:-([0-9A-Za-z.-]+))?/);
+  if (!match) return null;
+
+  return {
+    parts: [Number(match[1]), Number(match[2]), Number(match[3])],
+    prerelease: match[4] ?? null,
+  };
+}
+
+function isVersionNewer(latestVersion: string, currentVersion: string): boolean {
+  const latest = parseVersion(latestVersion);
+  const current = parseVersion(currentVersion);
+  if (!latest || !current) return latestVersion !== currentVersion;
+
+  for (let i = 0; i < 3; i++) {
+    const latestPart = latest.parts[i] ?? 0;
+    const currentPart = current.parts[i] ?? 0;
+    if (latestPart > currentPart) return true;
+    if (latestPart < currentPart) return false;
+  }
+
+  if (!latest.prerelease && current.prerelease) return true;
+  if (latest.prerelease && !current.prerelease) return false;
+  return latest.prerelease !== current.prerelease && latest.prerelease !== null;
+}
+
+export async function checkNpmUpdate(
+  packageName: string,
+  currentVersion: string,
+  updateCommand: string,
+): Promise<UpdateInfo | null> {
+  const controller = new AbortController();
+  const timeout = setTimeout(() => controller.abort(), CHECK_TIMEOUT_MS);
+
+  try {
+    const encodedPackage = packageName.startsWith("@")
+      ? packageName.replace("/", "%2F")
+      : encodeURIComponent(packageName);
+    const response = await fetch(`${NPM_REGISTRY_URL}/${encodedPackage}/latest`, {
+      signal: controller.signal,
+    });
+    if (!response.ok) return null;
+
+    const data = (await response.json()) as { version?: unknown };
+    const latestVersion = typeof data.version === "string" ? data.version : null;
+    if (!latestVersion || !isVersionNewer(latestVersion, currentVersion)) return null;
+
+    return { currentVersion, latestVersion, updateCommand };
+  } catch {
+    return null;
+  } finally {
+    clearTimeout(timeout);
+  }
+}
+
+export function formatUpdateNotice(info: UpdateInfo): string {
+  return [
+    "[SUPERMEMORY UPDATE]",
+    `Supermemory update available: v${info.currentVersion} -> v${info.latestVersion}`,
+    `Run: ${info.updateCommand}`,
+  ].join("\n");
+}