diff --git a/src/cli/update-command.test.ts b/src/cli/update-command.test.ts
index 4aa1b5b..63ae24d 100644
--- a/src/cli/update-command.test.ts
+++ b/src/cli/update-command.test.ts
@@ -75,6 +75,7 @@ describe("atomic-agent update", () => {
     expect(await updateCommand(["--help"], deps)).toBe(0);
     expect(stdout()).toMatch(/atomic-agent update/);
     expect(stdout()).toMatch(/--check/);
+    expect(stdout()).toMatch(/--yes/);
     expect(check).not.toHaveBeenCalled();
   });
 
@@ -134,8 +135,20 @@ describe("atomic-agent update", () => {
     expect(runInstaller).not.toHaveBeenCalled();
   });
 
-  it("updates in place when a newer version exists (non-interactive)", async () => {
-    expect(await updateCommand([], deps)).toBe(0);
+  it("refuses non-TTY update without --yes, exiting 1", async () => {
+    expect(await updateCommand([], deps)).toBe(1);
+    expect(stderr()).toMatch(/non-interactive.*--yes/);
+    expect(runInstaller).not.toHaveBeenCalled();
+  });
+
+  it("refuses non-TTY --version without --yes, exiting 1", async () => {
+    expect(await updateCommand(["--version", "v0.3.2"], deps)).toBe(1);
+    expect(stderr()).toMatch(/non-interactive.*--yes/);
+    expect(runInstaller).not.toHaveBeenCalled();
+  });
+
+  it("updates in place with --yes in non-TTY", async () => {
+    expect(await updateCommand(["--yes"], deps)).toBe(0);
     expect(stdout()).toMatch(/current: 0\.3\.1 → latest: 0\.3\.2/);
     expect(runInstaller).toHaveBeenCalledTimes(1);
     expect(runInstaller).toHaveBeenCalledWith(
@@ -147,6 +160,20 @@ describe("atomic-agent update", () => {
     expect(stdout()).toMatch(/updated to 0\.3\.2/);
   });
 
+  it("short flag -y works the same as --yes", async () => {
+    expect(await updateCommand(["-y"], deps)).toBe(0);
+    expect(runInstaller).toHaveBeenCalledTimes(1);
+  });
+
+  it("--yes skips the interactive prompt in TTY", async () => {
+    const confirm = vi.fn().mockResolvedValue(true);
+    expect(await updateCommand(["--yes"], { ...deps, isTTY: () => true, confirm })).toBe(
+      0,
+    );
+    expect(confirm).not.toHaveBeenCalled();
+    expect(runInstaller).toHaveBeenCalledTimes(1);
+  });
+
   it("streams installer lines prefixed with [update]", async () => {
     runInstaller.mockImplementation(
       async (opts?: { onLine?: (line: string) => void }) => {
@@ -155,7 +182,7 @@ describe("atomic-agent update", () => {
         return { ok: true, installDir: "/tmp/install" };
       },
     );
-    expect(await updateCommand([], deps)).toBe(0);
+    expect(await updateCommand(["--yes"], deps)).toBe(0);
     expect(stdout()).toMatch(/\[update\] downloading atomic-agent/);
     expect(stdout()).toMatch(/\[update\] installed atomic-agent/);
   });
@@ -184,19 +211,34 @@ describe("atomic-agent update", () => {
     runInstaller.mockRejectedValue(
       new AppUpdateError("install script exited with code 7"),
     );
-    expect(await updateCommand([], deps)).toBe(1);
+    expect(await updateCommand(["--yes"], deps)).toBe(1);
     expect(stderr()).toMatch(/install script exited with code 7/);
     expect(stdout()).not.toMatch(/updated to/);
   });
 
-  it("--version pins a specific tag even when the running version is newer", async () => {
+  it("--version pins a specific tag with --yes", async () => {
     check.mockResolvedValue(
       makeResult({ updateAvailable: false, latestTag: "v0.3.1", latestVersion: "0.3.1" }),
     );
-    expect(await updateCommand(["--version", "v0.3.2"], deps)).toBe(0);
+    expect(await updateCommand(["--version", "v0.3.2", "--yes"], deps)).toBe(0);
     expect(stdout()).toMatch(/installing v0\.3\.2/);
     expect(runInstaller).toHaveBeenCalledWith(
       expect.objectContaining({ version: "v0.3.2" }),
     );
   });
+
+  it("--version refuses non-TTY without --yes", async () => {
+    expect(await updateCommand(["--version", "v0.3.2"], deps)).toBe(1);
+    expect(stderr()).toMatch(/non-interactive.*--yes/);
+    expect(runInstaller).not.toHaveBeenCalled();
+  });
+
+  it("--version proceeds in TTY without --yes", async () => {
+    const confirm = vi.fn().mockResolvedValue(true);
+    expect(
+      await updateCommand(["--version", "v0.3.2"], { ...deps, isTTY: () => true, confirm }),
+    ).toBe(0);
+    expect(confirm).toHaveBeenCalledTimes(1);
+    expect(runInstaller).toHaveBeenCalledTimes(1);
+  });
 });
diff --git a/src/cli/update-command.ts b/src/cli/update-command.ts
index e3b7c85..348bb07 100644
--- a/src/cli/update-command.ts
+++ b/src/cli/update-command.ts
@@ -41,6 +41,7 @@ const HELP = [
   "",
   "Flags:",
   "  --check              Check only: report current vs latest, install nothing",
+  "  --yes, -y            Skip confirmation prompt (required in non-TTY environments)",
   "  --version <tag>      Install a specific release tag (e.g. v0.3.2) instead of latest",
   "  -h, --help           Show this help",
   "",
@@ -58,18 +59,23 @@ const HELP = [
 /** Parse flags into a discriminated plan; returns a usage error string on bad input. */
 function parseArgs(
   args: string[],
-): { ok: true; checkOnly: boolean; version?: string } | { ok: false; error: string } {
+): { ok: true; checkOnly: boolean; version?: string; yes: boolean } | { ok: false; error: string } {
   let checkOnly = false;
   let version: string | undefined;
+  let yes = false;
   for (let i = 0; i < args.length; i += 1) {
     const arg = args[i];
     if (arg === "-h" || arg === "--help") {
-      return { ok: true, checkOnly: false };
+      return { ok: true, checkOnly: false, yes: false };
     }
     if (arg === "--check") {
       checkOnly = true;
       continue;
     }
+    if (arg === "--yes" || arg === "-y") {
+      yes = true;
+      continue;
+    }
     if (arg === "--version") {
       const value = args[i + 1];
       if (!value || value.startsWith("-")) {
@@ -87,7 +93,7 @@ function parseArgs(
       error: "--check and --version are mutually exclusive",
     };
   }
-  return { ok: true, checkOnly, version };
+  return { ok: true, checkOnly, version, yes };
 }
 
 async function defaultConfirm(prompt: string): Promise<boolean> {
@@ -145,7 +151,13 @@ export async function updateCommand(
         return 1;
       }
       process.stdout.write(`installing ${parsed.version}…\n`);
-      if (isTTY()) {
+      if (!parsed.yes) {
+        if (!isTTY()) {
+          process.stderr.write(
+            "non-interactive update requires --yes (or -y) to confirm\n",
+          );
+          return 1;
+        }
         const ok = await confirm(`update to ${parsed.version}? [y/N] `);
         if (!ok) {
           process.stdout.write("update cancelled\n");
@@ -184,7 +196,13 @@ export async function updateCommand(
     process.stdout.write(
       `current: ${result.currentVersion} → latest: ${result.latestVersion}\n`,
     );
-    if (isTTY()) {
+    if (!parsed.yes) {
+      if (!isTTY()) {
+        process.stderr.write(
+          "non-interactive update requires --yes (or -y) to confirm\n",
+        );
+        return 1;
+      }
       const ok = await confirm(`update to ${result.latestVersion}? [y/N] `);
       if (!ok) {
         process.stdout.write("update cancelled\n");