diff --git a/host-setup/agent-safety/claude/model-tier-guard.py b/host-setup/agent-safety/claude/model-tier-guard.py
index 2e3a53571..15915d7c8 100755
--- a/host-setup/agent-safety/claude/model-tier-guard.py
+++ b/host-setup/agent-safety/claude/model-tier-guard.py
@@ -85,7 +85,7 @@ def names_model(text, model):
     """Whether a script text carries a `model: '<name>'` option naming `model`."""
     # A JavaScript key may be bare or quoted, so `{"model": "x"}` is the same option as `{model: "x"}`.
     # The value may be a full model id rather than the alias, so the alias is matched as a word inside it.
-    value = r"[^'\"`]*(?<![a-z0-9])(?i:" + re.escape(model) + r")(?![a-z0-9])[^'\"`]*"
+    value = r"[^'\"`]*(?<![A-Za-z0-9])(?i:" + re.escape(model) + r")(?![A-Za-z0-9])[^'\"`]*"
     pattern = r"(?<![\w$])['\"]?model['\"]?\s*:\s*['\"`]" + value + r"['\"`]"
     return re.search(pattern, text) is not None
 
diff --git a/host-setup/agent-safety/claude/test_model_tier_guard.py b/host-setup/agent-safety/claude/test_model_tier_guard.py
index 9cd10ea52..0995ea867 100755
--- a/host-setup/agent-safety/claude/test_model_tier_guard.py
+++ b/host-setup/agent-safety/claude/test_model_tier_guard.py
@@ -108,6 +108,7 @@ def test_a_workflow_script_naming_the_blocked_model_is_denied(self):
             'agent("x", {"model": "fable"})',
             "agent('x', {'model': 'fable'})",
             "agent('x', { model: 'claude-fable-5-1' })",
+            "agent('x', { model: 'claude-Fable-5-1' })",
         ):
             with self.subTest(script=script):
                 self.assertDenied(self.run_hook("Workflow", {"script": script}))
@@ -131,6 +132,15 @@ def test_a_script_file_is_read_even_beside_an_inline_script(self):
         tool_input = {"script": "agent('x', { model: 'opus' })", "scriptPath": str(path)}
         self.assertDenied(self.run_hook("Workflow", tool_input))
 
+    def test_a_workflow_model_merely_containing_the_blocked_alias_is_allowed(self):
+        for script in (
+            "agent('x', { model: 'fableX' })",
+            "agent('x', { model: 'Xfable' })",
+            "agent('x', { model: 'FABLEX' })",
+        ):
+            with self.subTest(script=script):
+                self.assertIsNone(self.run_hook("Workflow", {"script": script}))
+
     def test_a_workflow_at_another_model_or_saved_by_name_is_allowed(self):
         self.assertIsNone(self.run_hook("Workflow", {"script": "agent('x', { model: 'opus' })"}))
         self.assertIsNone(self.run_hook("Workflow", {"name": "saved-flow"}))