feat: resize QTI images at publish to their authored size

- Sized <img> (integer width and height) ship a resized copy per size in the QTI package; width/height stay in the XML.
- Rewrites go per element, so one image at two sizes ships two files.
- Derived Perseus markdown carries ` =WxH`, so publish resizes and fills the images map.
- Legacy items keep the size on their QTI <img>.

Refs #6189

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Author: rtibblesbot

contentcuration/contentcuration/tests/utils/qti/test_html_to_markdown.py

@@ -41,6 +41,19 @@ def test_image_gets_content_storage_prefix():
     assert expected in result
 
 
+def test_image_without_a_pixel_size_pair_carries_no_suffix():
+    expected = "![d]({})".format(exercises.CONTENT_STORAGE_FORMAT.format("abc123.png"))
+    for size in (
+        "",
+        'width="200"',
+        'height="150"',
+        'width="50%" height="150"',
+        'width="0" height="150"',
+    ):
+        result = _markdown_from_html(f'<p><img alt="d" src="abc123.png" {size}/></p>')
+        assert result == expected, size
+
+
 def test_interaction_is_dropped_from_prompt():
     fragment = "<p>Fill <qti-text-entry-interaction/> in</p>"
     assert html_to_markdown(_elements(fragment)) == "Fill  in"
@@ -172,6 +185,9 @@ def test_table():
             "inline."
         ),
         "![alt text]({})".format(exercises.CONTENT_STORAGE_FORMAT.format("abc123.png")),
+        "![sized]({} =200x150)".format(
+            exercises.CONTENT_STORAGE_FORMAT.format("abc123.png")
+        ),
         "> A blockquote paragraph.",
         "- First bullet\n- Second bullet\n  - Nested bullet\n- Third bullet",
         "1. First numbered\n2. Second numbered",

contentcuration/contentcuration/tests/utils/qti/test_media.py

@@ -1,6 +1,7 @@
 from contentcuration.tests.utils.qti.test_validation import VALID_CHOICE_ITEM
 from contentcuration.utils.assessment.qti.media import get_qti_media_references
 from contentcuration.utils.assessment.qti.media import rewrite_qti_media_paths
+from contentcuration.utils.assessment.qti.media import rewrite_qti_sized_image_paths
 from contentcuration.utils.assessment.qti.media import set_qti_item_language
 from contentcuration.utils.assessment.qti.validation import validate_qti_item
 
@@ -85,6 +86,38 @@ def test_rewrite_ignores_values_not_in_mapping():
     )
 
 
+def _path_for_size(filename, width, height):
+    return f"images/{width}x{height}-{filename}"
+
+
+def test_sized_rewrite_points_each_sized_img_at_its_size():
+    xml = (
+        f'<item>\n  <img alt="a > b" src="{CHECKSUM_A}.png" width="200" height="150"/>'
+        f"<img height='75' src='{CHECKSUM_A}.png' width='100' />"
+        f'<img src="{CHECKSUM_B}.png" width="200" height="150"></img></item>'
+    )
+    assert rewrite_qti_sized_image_paths(xml, _path_for_size) == (
+        f'<item>\n  <img alt="a > b" src="images/200x150-{CHECKSUM_A}.png" width="200" height="150"/>'
+        f"<img height='75' src='images/100x75-{CHECKSUM_A}.png' width='100' />"
+        f'<img src="images/200x150-{CHECKSUM_B}.png" width="200" height="150"></img></item>'
+    )
+
+
+def test_sized_rewrite_leaves_imgs_without_a_pixel_size_or_checksum_src():
+    xml = (
+        f'<item><img src="{CHECKSUM_A}.png"/>'
+        f'<img src="{CHECKSUM_A}.png" width="200"/>'
+        f'<img src="{CHECKSUM_A}.png" width="50%" height="150"/>'
+        f'<img srcset="{CHECKSUM_A}.png 1x" width="200" height="150"/>'
+        f'<img permanentSrc="{CHECKSUM_A}.png" width="200" height="150"/>'
+        f'<img data-src="{CHECKSUM_A}.png" width="200" height="150"/>'
+        f'<img alt=\'src="{CHECKSUM_A}.png"\' width="200" height="150"/>'
+        '<img src="https://example.com/x.png" width="200" height="150"/>'
+        f'<object data="{CHECKSUM_A}.png" width="200" height="150"></object></item>'
+    )
+    assert rewrite_qti_sized_image_paths(xml, _path_for_size) == xml
+
+
 ITEM_WITHOUT_LANGUAGE = (
     '<qti-assessment-item xmlns="http://www.imsglobal.org/xsd/imsqtiasi_v3p0" '
     'identifier="i" title="t" adaptive="false" time-dependent="false">'