Ready for first real test

tests/test_sandbox.py

@@ -0,0 +1,28 @@
+"""Sandbox security tests — the critical property is that model-generated code cannot read
+account secrets. Pure (no network)."""
+
+from __future__ import annotations
+
+import os
+
+from tools.sandbox import scrubbed_env
+
+
+def test_scrubbed_env_excludes_secrets(monkeypatch):
+    monkeypatch.setenv("ALPACA_NOVA_SECRET", "topsecret")
+    monkeypatch.setenv("FINNHUB_API_KEY", "fhkey")
+    monkeypatch.setenv("OMLX_API_KEY", "omlxkey")
+    env = scrubbed_env("/tmp/work")
+    # no secret-prefixed vars leak through
+    assert all(
+        not k.upper().startswith(("ALPACA", "FINNHUB", "OMLX", "EMAIL", "SMTP"))
+        for k in env
+    )
+    assert "ALPACA_NOVA_SECRET" not in env
+
+
+def test_scrubbed_env_minimal_and_headless():
+    env = scrubbed_env("/home/x")
+    assert env["HOME"] == "/home/x"
+    assert env["MPLBACKEND"] == "Agg"  # headless matplotlib
+    assert "PATH" in env