diff --git a/tests/test_cron_cloud_context.py b/tests/test_cron_cloud_context.py
new file mode 100644
index 000000000..79933996a
--- /dev/null
+++ b/tests/test_cron_cloud_context.py
@@ -0,0 +1,91 @@
+"""Tests for cloud-context warning injection (#378, #456)."""
+
+import pytest
+import sys
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).parent.parent))
+
+from cron.scheduler import (
+    _LOCAL_SERVICE_PATTERNS,
+    _detect_local_service_refs,
+    _inject_cloud_context,
+)
+
+
+class TestDetectLocalServiceRefs:
+    """Pattern detection for local service references in prompts."""
+
+    def test_localhost_with_port(self):
+        refs = _detect_local_service_refs("Check localhost:11434 is up")
+        assert len(refs) >= 1
+        assert any("11434" in r for r in refs)
+
+    def test_127_with_port(self):
+        refs = _detect_local_service_refs("curl http://127.0.0.1:8080/health")
+        assert len(refs) >= 1
+
+    def test_check_ollama(self):
+        refs = _detect_local_service_refs("Check Ollama is responding")
+        assert len(refs) >= 1
+
+    def test_ollama_responding(self):
+        refs = _detect_local_service_refs("Verify Ollama responding on this machine")
+        assert len(refs) >= 1
+
+    def test_curl_localhost(self):
+        refs = _detect_local_service_refs("curl localhost and report status")
+        assert len(refs) >= 1
+
+    def test_ping_localhost(self):
+        refs = _detect_local_service_refs("ping localhost to check connectivity")
+        assert len(refs) >= 1
+
+    def test_no_false_positive_cloud(self):
+        refs = _detect_local_service_refs("Check the weather in Paris today")
+        assert len(refs) == 0
+
+    def test_no_false_positive_api(self):
+        refs = _detect_local_service_refs("Call the OpenRouter API endpoint")
+        assert len(refs) == 0
+
+    def test_multiple_refs(self):
+        refs = _detect_local_service_refs("curl localhost:11434 then ping localhost")
+        assert len(refs) >= 2
+
+
+class TestInjectCloudContext:
+    """Cloud-context warning injection."""
+
+    def test_prepends_warning(self):
+        prompt = "Check Ollama is responding"
+        result = _inject_cloud_context(prompt, ["Check Ollama"], "nous")
+        assert result.startswith("[SYSTEM NOTE")
+        assert "nous" in result
+        assert prompt in result
+
+    def test_preserves_original_prompt(self):
+        prompt = "Check Ollama at localhost:11434"
+        result = _inject_cloud_context(prompt, ["localhost:11434"], "openrouter")
+        assert prompt in result
+
+    def test_mentions_cannot_reach(self):
+        prompt = "curl localhost"
+        result = _inject_cloud_context(prompt, ["curl localhost"], "nous")
+        assert "CANNOT reach" in result or "cannot reach" in result
+
+    def test_suggests_local_provider(self):
+        prompt = "Check Ollama"
+        result = _inject_cloud_context(prompt, ["Check Ollama"], "nous")
+        assert "local" in result.lower()
+
+
+class TestCloudBypassLocal:
+    """Local endpoints should not trigger injection."""
+
+    def test_local_endpoint_skips(self):
+        # The caller checks _is_cloud before calling _detect_local_service_refs
+        # so this is tested at integration level. Here we verify detection
+        # still finds refs (the bypass is the caller\'s responsibility).
+        refs = _detect_local_service_refs("Check Ollama at localhost:11434")
+        assert len(refs) > 0  # Detection works, caller decides whether to inject