fix(reset): record captured old_id in spec, exit on signals, and reject unknown spec agents (#78)

tests/test_issue78_hints_codex.py

@@ -336,4 +336,3 @@ def test_codex_purge_removes_tui_thread_capability(tmp_path, monkeypatch, delete
     assert not rollout.exists()
     assert adapter.residual_artifacts(conv, ctx) == []
     assert str(cap_other) in adapter.residual_artifacts(other, ctx)
-