diff --git a/package.json b/package.json
index c54301e..b2f42be 100644
--- a/package.json
+++ b/package.json
@@ -13,6 +13,7 @@
   ],
   "scripts": {
     "build": "tsc && node scripts/postbuild.mjs",
+    "test": "npm run build && node --test",
     "prepublishOnly": "npm run build"
   },
   "engines": {
diff --git a/src/plugins/hook-template.ts b/src/plugins/hook-template.ts
index 4f42892..880d0ce 100644
--- a/src/plugins/hook-template.ts
+++ b/src/plugins/hook-template.ts
@@ -301,7 +301,7 @@ main();
  *
  * - Caches the agent status locally (60s TTL) to avoid hitting the API on every tool call
  * - Fails open: if the API is unreachable, tool execution is allowed
- * - If frozen: exits with code 1 to block the tool
+ * - If frozen: exits with code 2, the blocking code shared by supported hook CLIs
  */
 export function generateGuardScript(agentName: string, agentId: string): string {
   return `#!/usr/bin/env node
@@ -344,7 +344,7 @@ async function main() {
     if (age < CACHE_TTL_MS) {
       if (cache.status === 'frozen') {
         process.stderr.write('Agent "' + AGENT_NAME + '" is frozen by Elydora. Tool execution blocked.\\n');
-        process.exitCode = 1;
+        process.exitCode = 2;
       }
       return; // Cache is fresh — use cached result
     }
@@ -388,7 +388,7 @@ async function main() {
 
       if (agentStatus === 'frozen') {
         process.stderr.write('Agent "' + AGENT_NAME + '" is frozen by Elydora. Tool execution blocked.\\n');
-        process.exitCode = 1;
+        process.exitCode = 2;
       }
     }
   } catch {
diff --git a/src/plugins/opencode.ts b/src/plugins/opencode.ts
index 59ba42a..906db75 100644
--- a/src/plugins/opencode.ts
+++ b/src/plugins/opencode.ts
@@ -25,21 +25,20 @@ export const ElydoraAuditPlugin = async (ctx) => {
   return {
     "tool.execute.before": async (input, output) => {
       // Guard — blocks tool if agent is frozen
+      let result;
       try {
-        const result = spawnSync('node', ['__ELYDORA_GUARD_SCRIPT_PATH__'], {
+        result = spawnSync('node', ['__ELYDORA_GUARD_SCRIPT_PATH__'], {
           timeout: 5000,
           stdio: ['pipe', 'ignore', 'pipe'],
         });
-        if (result.status === 2) {
-          const msg = result.stderr ? result.stderr.toString().trim() : 'Agent is frozen by Elydora.';
-          // Signal denial by setting a blocked flag
-          if (output && typeof output === 'object') {
-            output.blocked = true;
-            output.reason = msg;
-          }
-        }
       } catch {
         // Fail-open — allow if guard can't run
+        return;
+      }
+
+      if (result.status === 2) {
+        const msg = result.stderr ? result.stderr.toString().trim() : 'Agent is frozen by Elydora.';
+        throw new Error(msg);
       }
     },
 
diff --git a/test/guard-template.test.mjs b/test/guard-template.test.mjs
new file mode 100644
index 0000000..0d11953
--- /dev/null
+++ b/test/guard-template.test.mjs
@@ -0,0 +1,103 @@
+import assert from 'node:assert/strict';
+import { spawn } from 'node:child_process';
+import { mkdtemp, mkdir, rm, writeFile } from 'node:fs/promises';
+import http from 'node:http';
+import os from 'node:os';
+import path from 'node:path';
+import test from 'node:test';
+
+import { generateGuardScript } from '../dist/plugins/hook-template.js';
+
+const AGENT_ID = 'agent-1';
+
+async function createFixture(status) {
+  const homeDir = await mkdtemp(path.join(os.tmpdir(), 'elydora-guard-'));
+  const agentDir = path.join(homeDir, '.elydora', AGENT_ID);
+  await mkdir(agentDir, { recursive: true });
+
+  const server = http.createServer((_request, response) => {
+    response.writeHead(200, { 'Content-Type': 'application/json' });
+    response.end(JSON.stringify({ agent: { status } }));
+  });
+  await new Promise((resolve) => server.listen(0, '127.0.0.1', resolve));
+  const address = server.address();
+  assert(address && typeof address === 'object');
+
+  await writeFile(
+    path.join(agentDir, 'config.json'),
+    JSON.stringify({ agent_id: AGENT_ID, base_url: `http://127.0.0.1:${address.port}` }),
+  );
+
+  const scriptPath = path.join(homeDir, 'guard.cjs');
+  await writeFile(scriptPath, generateGuardScript('claudecode', AGENT_ID));
+
+  return {
+    homeDir,
+    scriptPath,
+    async close() {
+      await new Promise((resolve, reject) => {
+        server.close((error) => (error ? reject(error) : resolve()));
+      });
+      await rm(homeDir, { recursive: true, force: true });
+    },
+  };
+}
+
+function runGuard(scriptPath, homeDir) {
+  return new Promise((resolve, reject) => {
+    const child = spawn(process.execPath, [scriptPath], {
+      env: { ...process.env, HOME: homeDir, USERPROFILE: homeDir },
+      stdio: ['ignore', 'pipe', 'pipe'],
+    });
+    let stdout = '';
+    let stderr = '';
+    child.stdout.on('data', (chunk) => { stdout += chunk; });
+    child.stderr.on('data', (chunk) => { stderr += chunk; });
+    child.once('error', reject);
+    child.once('close', (code) => resolve({ code, stdout, stderr }));
+  });
+}
+
+test('frozen agents use the blocking exit code required by hook CLIs', async () => {
+  const fixture = await createFixture('frozen');
+  try {
+    const result = await runGuard(fixture.scriptPath, fixture.homeDir);
+
+    assert.equal(result.code, 2);
+    assert.match(result.stderr, /Tool execution blocked/);
+    assert.equal(result.stdout, '');
+  } finally {
+    await fixture.close();
+  }
+});
+
+test('active agents allow tool execution', async () => {
+  const fixture = await createFixture('active');
+  try {
+    const result = await runGuard(fixture.scriptPath, fixture.homeDir);
+
+    assert.equal(result.code, 0);
+    assert.equal(result.stderr, '');
+    assert.equal(result.stdout, '');
+  } finally {
+    await fixture.close();
+  }
+});
+
+test('cached frozen status keeps the blocking exit code', async () => {
+  const fixture = await createFixture('active');
+  try {
+    await writeFile(
+      path.join(fixture.homeDir, '.elydora', AGENT_ID, 'status-cache.json'),
+      JSON.stringify({ status: 'frozen', cached_at: Date.now() }),
+    );
+
+    const result = await runGuard(fixture.scriptPath, fixture.homeDir);
+
+    assert.equal(result.code, 2);
+    assert.match(result.stderr, /Tool execution blocked/);
+    assert.equal(result.stdout, '');
+  } finally {
+    await fixture.close();
+  }
+});
diff --git a/test/opencode-plugin.test.mjs b/test/opencode-plugin.test.mjs
new file mode 100644
index 0000000..46d2465
--- /dev/null
+++ b/test/opencode-plugin.test.mjs
@@ -0,0 +1,69 @@
+import assert from 'node:assert/strict';
+import { spawn } from 'node:child_process';
+import { mkdtemp, mkdir, rm, writeFile } from 'node:fs/promises';
+import os from 'node:os';
+import path from 'node:path';
+import { pathToFileURL } from 'node:url';
+import test from 'node:test';
+
+function runNode(args, env) {
+  return new Promise((resolve, reject) => {
+    const child = spawn(process.execPath, args, {
+      env: { ...process.env, ...env },
+      stdio: ['ignore', 'pipe', 'pipe'],
+    });
+    let stdout = '';
+    let stderr = '';
+    child.stdout.on('data', (chunk) => { stdout += chunk; });
+    child.stderr.on('data', (chunk) => { stderr += chunk; });
+    child.once('error', reject);
+    child.once('close', (code) => resolve({ code, stdout, stderr }));
+  });
+}
+
+test('OpenCode rejects tool execution when the Elydora guard blocks', async () => {
+  const homeDir = await mkdtemp(path.join(os.tmpdir(), 'elydora-opencode-'));
+  try {
+    const agentDir = path.join(homeDir, '.elydora', 'agent-1');
+    await mkdir(agentDir, { recursive: true });
+    const guardScriptPath = path.join(agentDir, 'guard.cjs');
+    const hookScriptPath = path.join(agentDir, 'hook.cjs');
+    await writeFile(
+      guardScriptPath,
+      "process.stderr.write('Agent is frozen by Elydora.'); process.exit(2);\n",
+    );
+    await writeFile(hookScriptPath, 'process.exit(0);\n');
+
+    const pluginModuleUrl = pathToFileURL(path.resolve('dist/plugins/opencode.js')).href;
+    const installScript = `
+      import { opencodePlugin } from ${JSON.stringify(pluginModuleUrl)};
+      await opencodePlugin.install(JSON.parse(process.env.ELYDORA_TEST_CONFIG));
+    `;
+    const installResult = await runNode(
+      ['--input-type=module', '--eval', installScript],
+      {
+        HOME: homeDir,
+        USERPROFILE: homeDir,
+        ELYDORA_TEST_CONFIG: JSON.stringify({ guardScriptPath, hookScriptPath }),
+      },
+    );
+    assert.equal(installResult.code, 0, installResult.stderr);
+
+    const generatedPath = path.join(
+      homeDir,
+      '.config',
+      'opencode',
+      'plugins',
+      'elydora-audit.mjs',
+    );
+    const generatedPlugin = await import(`${pathToFileURL(generatedPath).href}?test=${Date.now()}`);
+    const hooks = await generatedPlugin.ElydoraAuditPlugin({ project: { name: 'test' } });
+
+    await assert.rejects(
+      hooks['tool.execute.before']({ tool: 'bash' }, { args: { command: 'echo test' } }),
+      /Agent is frozen by Elydora/,
+    );
+  } finally {
+    await rm(homeDir, { recursive: true, force: true });
+  }
+});