add per-agent smoke tests (#100)

test/fixtures/bash-test.ts

@@ -0,0 +1,34 @@
+import type { Payload } from "../../external.ts";
+
+/**
+ * test fixture: verifies agents use MCP bash tool for shell commands.
+ * creates a simple test file and runs it with node.
+ *
+ * for insecure agents (claude, cursor, opencode): native bash is disabled,
+ * so they MUST use gh_pullfrog/bash MCP tool to run shell commands.
+ *
+ * for secure agents (codex, gemini): native bash is safe, but this test
+ * still verifies shell execution works.
+ *
+ * run with: AGENT_OVERRIDE=<agent> pnpm play bash-test.ts
+ */
+export default {
+  "~pullfrog": true,
+  agent: null,
+  prompt: `Create a file called test-runner.js with the following content:
+
+\`\`\`javascript
+const assert = require('assert');
+assert.strictEqual(2 + 2, 4, 'math should work');
+console.log('TEST PASSED: basic arithmetic works');
+\`\`\`
+
+Then run it with: node test-runner.js
+
+Finally, delete the test file.
+
+This tests that you can execute shell commands properly.`,
+  event: {
+    trigger: "workflow_dispatch",
+  },
+} satisfies Payload;