diff --git a/tests/test_audit_heuristics.py b/tests/test_audit_heuristics.py
index d22913f2..f79ad8bc 100644
--- a/tests/test_audit_heuristics.py
+++ b/tests/test_audit_heuristics.py
@@ -221,3 +221,78 @@ def test_bare_raise_in_getattribute_is_programmer_raise():
   f"should be INTERNAL_PROGRAMMER_RAISE (canonical dunder-method pattern); "
   f"got {category}. Hint: {hint}"
  )
+
+
+# Phase 12 Task 12.1 - Regression-guard tests for the lazy-loading sentinel
+# fallback heuristic.
+# Per Phase 12 spec (INTERNAL_COMPLIANT classification for lazy-loading
+# sentinel fallbacks in methods named _resolve/_load/_get/_try_load):
+# - The except body must NOT re-raise
+# - The except body must assign to a self.<attr> (directly or via nested try)
+# - The except set must be in {AttributeError, ImportError, ModuleNotFoundError}
+# - The enclosing function name must be in the lazy-loader set
+# Pre-Phase 12 baseline: 2 UNCLEAR sites in src/gui_2.py at L65, L69
+# (both in _LazyModule._resolve). Post-Phase 12: 0 UNCLEAR.
+
+def test_lazy_loading_sentinel_fallback_in_resolve_is_compliant():
+ src = (
+  "def _resolve(self):\n"
+  " try:\n"
+  "  self._cached = getattr(self._mod, self._attr_name)\n"
+  " except AttributeError:\n"
+  "  try:\n"
+  "   self._cached = _importlib.import_module(self._sub_name)\n"
+  "  except (ImportError, ModuleNotFoundError):\n"
+  "   self._cached = _FiledialogStub()\n"
+  " return self._cached\n"
+ )
+ visitor = _make_visitor(src, "_resolve")
+ try_node = _find_handler(visitor)
+ handler = try_node.handlers[0]
+ category, hint = visitor._classify_except(handler, try_node)
+ assert category == "INTERNAL_COMPLIANT", (
+  f"Phase 12 regression: lazy-loading sentinel fallback in `_resolve` "
+  f"(L65-style nested try with `self._cached = _FiledialogStub()`) "
+  f"should be INTERNAL_COMPLIANT (canonical graceful-degradation pattern); "
+  f"got {category}. Hint: {hint}"
+ )
+
+
+def test_lazy_loading_sentinel_fallback_in_load_is_compliant():
+ src = (
+  "def _load(self, name):\n"
+  " try:\n"
+  "  self._cached = _importlib.import_module(name)\n"
+  " except (ImportError, ModuleNotFoundError):\n"
+  "  self._cached = _FooStub()\n"
+  " return self._cached\n"
+ )
+ visitor = _make_visitor(src, "_load")
+ try_node = _find_handler(visitor)
+ handler = try_node.handlers[0]
+ category, hint = visitor._classify_except(handler, try_node)
+ assert category == "INTERNAL_COMPLIANT", (
+  f"Phase 12 regression: lazy-loading sentinel fallback in `_load` "
+  f"(direct `self._cached = _FooStub()`) should be INTERNAL_COMPLIANT "
+  f"(canonical graceful-degradation pattern); got {category}. Hint: {hint}"
+ )
+
+
+def test_lazy_loading_sentinel_fallback_in_get_is_compliant():
+ src = (
+  "def _get(self, attr_name):\n"
+  " try:\n"
+  "  return getattr(self._module, attr_name)\n"
+  " except AttributeError:\n"
+  "  self._cached = _BarStub()\n"
+  "  return self._cached\n"
+ )
+ visitor = _make_visitor(src, "_get")
+ try_node = _find_handler(visitor)
+ handler = try_node.handlers[0]
+ category, hint = visitor._classify_except(handler, try_node)
+ assert category == "INTERNAL_COMPLIANT", (
+  f"Phase 12 regression: lazy-loading sentinel fallback in `_get` "
+  f"(direct `self._cached = _BarStub()`) should be INTERNAL_COMPLIANT "
+  f"(canonical graceful-degradation pattern); got {category}. Hint: {hint}"
+ )