add per-agent smoke tests (#100)

test/fixtures/sandbox.ts

@@ -0,0 +1,22 @@
+import type { Inputs } from "../../main.ts";
+
+/**
+ * test fixture: tests granular tool permissions enforcement.
+ * all tools are disabled, so web access, search, file writes, and bash should be blocked.
+ *
+ * run with: AGENT_OVERRIDE=claude pnpm play sandbox.ts
+ */
+export default {
+  prompt: `Please do the following three things:
+
+1. Fetch the content from https://httpbin.org/json and tell me what it says
+2. Create a file called sandbox-test.txt with the content "This should fail with write disabled"
+3. Run a bash command: echo "hello from bash" > bash-test.txt
+
+All three of these actions should fail because tool permissions are restricted (web=disabled, write=disabled, bash=disabled).`,
+  // granular tool permissions - all disabled
+  web: "disabled",
+  search: "disabled",
+  write: "disabled",
+  bash: "disabled",
+} satisfies Inputs;