test: add Cortex test suite (77 tests, no LLM calls)

Tests cover:
  - Smoke: /health, /auth/status, /distill/status (test_health.py)
  - Persona validation: path traversal, bad names, list_personas (test_persona.py)
  - Chat API: persona routing, session persistence, error handling (test_api_chat.py)
  - Files API: ALLOWED set enforcement, read/write, missing files (test_api_files.py)
  - Webhooks: NC Talk HMAC accept/reject, Google Chat JWT (test_webhooks.py)
  - Tools: scratch read/write/append/clear, tasks CRUD, cron parser + tools (test_tools.py)
  - Security: path traversal, replay attack, known gaps documented (test_security.py)

All LLM calls mocked — suite runs in ~1.4s.
Run: cd cortex && .venv/bin/pytest

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cortex/tests/test_persona.py

@@ -0,0 +1,94 @@
+"""
+Unit tests for persona.py — validation, routing, path traversal.
+No HTTP involved.
+"""
+import pytest
+from pathlib import Path
+from unittest.mock import patch
+
+
+def _make_temp_personas(tmp_path: Path) -> Path:
+    root = tmp_path / "personas"
+    for name in ("alice", "bob"):
+        p = root / name
+        p.mkdir(parents=True)
+        (p / "IDENTITY.md").write_text(f"# {name}")
+    # A directory WITHOUT IDENTITY.md — should not appear in list_personas()
+    (root / "incomplete").mkdir()
+    return root
+
+
+def test_validate_good(tmp_path):
+    root = _make_temp_personas(tmp_path)
+    import config, persona
+    with patch.object(config.settings, "personas_dir", root):
+        assert persona.validate("alice") == "alice"
+        assert persona.validate("bob") == "bob"
+
+
+def test_validate_unknown(tmp_path):
+    root = _make_temp_personas(tmp_path)
+    import config, persona
+    with patch.object(config.settings, "personas_dir", root):
+        with pytest.raises(ValueError, match="Unknown persona"):
+            persona.validate("charlie")
+
+
+def test_validate_path_traversal(tmp_path):
+    root = _make_temp_personas(tmp_path)
+    import config, persona
+    with patch.object(config.settings, "personas_dir", root):
+        with pytest.raises(ValueError, match="Invalid persona name"):
+            persona.validate("../../etc/passwd")
+        with pytest.raises(ValueError, match="Invalid persona name"):
+            persona.validate("../alice")
+        with pytest.raises(ValueError, match="Invalid persona name"):
+            persona.validate("alice/../../etc")
+
+
+def test_validate_special_chars(tmp_path):
+    root = _make_temp_personas(tmp_path)
+    import config, persona
+    with patch.object(config.settings, "personas_dir", root):
+        for bad in ("alice bob", "alice;bob", "alice\x00bob", "A" * 33, ""):
+            with pytest.raises(ValueError):
+                persona.validate(bad)
+
+
+def test_validate_allows_hyphen_underscore(tmp_path):
+    root = _make_temp_personas(tmp_path)
+    # Create a persona with hyphen and underscore in name
+    p = root / "my_ai-agent"
+    p.mkdir(parents=True)
+    (p / "IDENTITY.md").write_text("# My Agent")
+    import config, persona
+    with patch.object(config.settings, "personas_dir", root):
+        assert persona.validate("my_ai-agent") == "my_ai-agent"
+
+
+def test_list_personas(tmp_path):
+    root = _make_temp_personas(tmp_path)
+    import config, persona
+    with patch.object(config.settings, "personas_dir", root):
+        names = persona.list_personas()
+    assert "alice" in names
+    assert "bob" in names
+    assert "incomplete" not in names   # no IDENTITY.md
+
+
+def test_persona_path_uses_contextvar(tmp_path):
+    root = _make_temp_personas(tmp_path)
+    import config, persona
+    with patch.object(config.settings, "personas_dir", root):
+        persona.set_persona("alice")
+        assert persona.persona_path() == root / "alice"
+        persona.set_persona("bob")
+        assert persona.persona_path() == root / "bob"
+
+
+def test_persona_path_explicit_name(tmp_path):
+    root = _make_temp_personas(tmp_path)
+    import config, persona
+    with patch.object(config.settings, "personas_dir", root):
+        persona.set_persona("alice")
+        assert persona.persona_path("bob") == root / "bob"