Fix dynamic memoir image limits

api/tests/test_memoir_image_settings.py

@@ -13,6 +13,8 @@ class MemoirImageSettingsTest(unittest.TestCase):
         os.environ,
         {
             "MEMOIR_IMAGE_MAX_PER_CHAPTER": "not-an-int",
+            "MEMOIR_IMAGE_CHARS_PER_EXTRA": "bad-extra",
+            "MEMOIR_IMAGE_MAX_CAP": "bad-cap",
             "MEMOIR_IMAGE_POLL_INTERVAL": "bad",
             "MEMOIR_IMAGE_MAX_ATTEMPTS": "oops",
         },
@@ -22,6 +24,8 @@ class MemoirImageSettingsTest(unittest.TestCase):
         settings = MemoirImageSettings.from_env()
 
         self.assertEqual(settings.max_per_chapter, 2)
+        self.assertEqual(settings.chars_per_extra_image, 1500)
+        self.assertEqual(settings.max_images_cap, 8)
         self.assertEqual(settings.poll_interval_seconds, 3)
         self.assertEqual(settings.max_attempts, 60)
 
@@ -31,3 +35,8 @@ class MemoirImageSettingsTest(unittest.TestCase):
             settings = MemoirImageSettings.from_env()
 
         self.assertEqual(settings.liblib_template_uuid, DEFAULT_LIBLIB_TEMPLATE_UUID)
+
+    def test_effective_max_images_never_drops_below_base_max_per_chapter(self):
+        settings = MemoirImageSettings(enabled=True, max_per_chapter=2, max_images_cap=1)
+
+        self.assertEqual(settings.effective_max_images(0), 2)