diff --git a/packages/cli/package.json b/packages/cli/package.json
index dd5d354d..7bdf66e5 100644
--- a/packages/cli/package.json
+++ b/packages/cli/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@openrouter/spawn",
-  "version": "0.30.9",
+  "version": "0.30.10",
   "type": "module",
   "bin": {
     "spawn": "cli.js"
diff --git a/packages/cli/src/__tests__/sandbox.test.ts b/packages/cli/src/__tests__/sandbox.test.ts
index e182ab22..603bc27b 100644
--- a/packages/cli/src/__tests__/sandbox.test.ts
+++ b/packages/cli/src/__tests__/sandbox.test.ts
@@ -5,9 +5,12 @@ mockClackPrompts();
 
 import {
   cleanupContainer,
+  dockerInteractiveSession,
   ensureDocker,
+  interactiveSession,
   isDockerAvailable,
   pullAndStartContainer,
+  runLocal,
   runLocalArgs,
   validateAgentName,
   validateLocalPath,
@@ -228,6 +231,55 @@ describe("runLocalArgs", () => {
   });
 });
 
+// ─── runLocal command validation ────────────────────────────────────────────
+
+describe("runLocal", () => {
+  it("rejects empty command", async () => {
+    await expect(runLocal("")).rejects.toThrow("Invalid command");
+  });
+
+  it("rejects null byte in command", async () => {
+    await expect(runLocal("echo\x00hello")).rejects.toThrow("Invalid command");
+  });
+
+  it("runs shell command and resolves on success", async () => {
+    const spawnSpy = mockBunSpawn(0);
+    await runLocal("echo hello");
+    expect(spawnSpy).toHaveBeenCalled();
+    spawnSpy.mockRestore();
+  });
+
+  it("throws on non-zero exit code", async () => {
+    const spawnSpy = mockBunSpawn(1);
+    await expect(runLocal("failing-cmd")).rejects.toThrow("Command failed");
+    spawnSpy.mockRestore();
+  });
+});
+
+// ─── interactiveSession command validation ──────────────────────────────────
+
+describe("local/interactiveSession", () => {
+  it("rejects empty command", async () => {
+    await expect(interactiveSession("")).rejects.toThrow("Invalid command");
+  });
+
+  it("rejects null byte in command", async () => {
+    await expect(interactiveSession("echo\x00hi")).rejects.toThrow("Invalid command");
+  });
+});
+
+// ─── dockerInteractiveSession command validation ────────────────────────────
+
+describe("dockerInteractiveSession", () => {
+  it("rejects empty command", async () => {
+    await expect(dockerInteractiveSession("")).rejects.toThrow("Invalid command");
+  });
+
+  it("rejects null byte in command", async () => {
+    await expect(dockerInteractiveSession("echo\x00hi")).rejects.toThrow("Invalid command");
+  });
+});
+
 // ─── cleanupContainer ───────────────────────────────────────────────────────
 
 describe("cleanupContainer", () => {
diff --git a/packages/cli/src/local/local.ts b/packages/cli/src/local/local.ts
index 625007ef..c39d3d10 100644
--- a/packages/cli/src/local/local.ts
+++ b/packages/cli/src/local/local.ts
@@ -49,8 +49,16 @@ export function validateLocalPath(filePath: string): string {
 
 // ─── Execution ───────────────────────────────────────────────────────────────
 
+/** Validate a command string: must be non-empty and free of null bytes. */
+function validateCommand(cmd: string): void {
+  if (!cmd || cmd.includes("\0")) {
+    throw new Error("Invalid command: must be non-empty and must not contain null bytes");
+  }
+}
+
 /** Run a shell command locally and wait for it to finish. */
 export async function runLocal(cmd: string): Promise<void> {
+  validateCommand(cmd);
   const [shell, flag] = getLocalShell();
   const proc = Bun.spawn(
     [
@@ -113,6 +121,7 @@ export function downloadFile(remotePath: string, localPath: string): void {
 
 /** Launch an interactive shell session locally. */
 export async function interactiveSession(cmd: string): Promise<number> {
+  validateCommand(cmd);
   const [shell, flag] = getLocalShell();
   return spawnInteractive([
     shell,
@@ -349,19 +358,18 @@ export async function pullAndStartContainer(agentName: string): Promise<void> {
 }
 
 /** Launch an interactive session inside the Docker container. */
-export function dockerInteractiveSession(cmd: string): Promise<number> {
-  return Promise.resolve(
-    spawnInteractive([
-      "docker",
-      "exec",
-      "-it",
-      DOCKER_CONTAINER_NAME,
-      "bash",
-      "-l",
-      "-c",
-      cmd,
-    ]),
-  );
+export async function dockerInteractiveSession(cmd: string): Promise<number> {
+  validateCommand(cmd);
+  return spawnInteractive([
+    "docker",
+    "exec",
+    "-it",
+    DOCKER_CONTAINER_NAME,
+    "bash",
+    "-l",
+    "-c",
+    cmd,
+  ]);
 }
 
 /** Remove the sandbox container (best-effort, for cleanup). */