diff --git a/tests/test_resource_limits.py b/tests/test_resource_limits.py
index d577797c57..a55ecaccd1 100644
--- a/tests/test_resource_limits.py
+++ b/tests/test_resource_limits.py
@@ -2,6 +2,10 @@
 
 from __future__ import annotations
 
+from pathlib import Path
+import subprocess
+import sys
+import textwrap
 from types import SimpleNamespace
 
 import pytest
@@ -53,6 +57,19 @@ def test_default_is_clamped_to_hard_limit(monkeypatch):
     assert fake_resource.limits == (1024, 1024)
 
 
+def test_finite_soft_limit_raises_when_hard_limit_is_infinite(monkeypatch):
+    fake_resource = _FakeResource(soft=256, hard=_FakeResource.RLIM_INFINITY)
+    monkeypatch.setattr(resource_limits, "_resource", fake_resource)
+
+    assert resource_limits.apply_nofile_soft_limit({}) is True
+    assert fake_resource.set_calls == [
+        (
+            fake_resource.RLIMIT_NOFILE,
+            (4096, fake_resource.RLIM_INFINITY),
+        ),
+    ]
+
+
 def test_never_lowers_an_already_higher_soft_limit(monkeypatch):
     fake_resource = _FakeResource(soft=8192, hard=16384)
     monkeypatch.setattr(resource_limits, "_resource", fake_resource)
@@ -81,6 +98,36 @@ def test_unsupported_platform_is_a_safe_noop(monkeypatch):
     assert resource_limits.apply_nofile_soft_limit({}) is False
 
 
+def test_fresh_process_import_without_posix_resource_is_a_safe_noop():
+    code = textwrap.dedent(
+        """
+        import importlib.util
+        import pathlib
+        import sys
+
+        sys.modules["resource"] = None
+        module_path = pathlib.Path(sys.argv[1])
+        spec = importlib.util.spec_from_file_location(
+            "hermes_cli._resource_limits_without_posix_resource",
+            module_path,
+        )
+        module = importlib.util.module_from_spec(spec)
+        spec.loader.exec_module(module)
+
+        assert module._resource is None
+        assert module.apply_nofile_soft_limit({}) is False
+        """
+    )
+
+    subprocess.run(
+        [sys.executable, "-c", code, resource_limits.__file__],
+        check=True,
+        cwd=Path(resource_limits.__file__).resolve().parents[1],
+        capture_output=True,
+        text=True,
+    )
+
+
 @pytest.mark.parametrize("invalid", [True, -1, 4096.0, "4096", object()])
 def test_invalid_values_are_safe_noops(monkeypatch, invalid):
     fake_resource = _FakeResource(soft=256, hard=4096)
@@ -104,6 +151,18 @@ def test_setrlimit_denial_is_a_safe_noop(monkeypatch):
     assert fake_resource.limits == (256, 4096)
 
 
+def test_getrlimit_failure_is_a_safe_noop(monkeypatch):
+    class _BrokenResource(_FakeResource):
+        def getrlimit(self, resource: int) -> tuple[int, int]:
+            raise OSError("simulated getrlimit failure")
+
+    fake_resource = _BrokenResource(soft=256, hard=4096)
+    monkeypatch.setattr(resource_limits, "_resource", fake_resource)
+
+    assert resource_limits.apply_nofile_soft_limit({}) is False
+    assert fake_resource.set_calls == []
+
+
 def test_never_lowers_an_unlimited_soft_limit(monkeypatch):
     fake_resource = _FakeResource(soft=-1, hard=-1)
     fake_resource.RLIM_INFINITY = -1