feat: add QTI assessment-item type and renderable preset-bit ordering

Expose format_presets.RENDERABLE_PRESETS_ORDER as a stable,
append-only preset id ordering so Studio and Kolibri derive
File.included_presets bitmask positions from shared bit locations.

Fixes #224

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Author: rtibblesbot

le_utils/constants/exercises.py

@@ -39,11 +39,13 @@
 SINGLE_SELECTION = "single_selection"
 FREE_RESPONSE = "free_response"
 PERSEUS_QUESTION = "perseus_question"
+QTI = "QTI"
 
 question_choices = (
     (INPUT_QUESTION, "Input Question"),
     (MULTIPLE_SELECTION, "Multiple Selection"),
     (SINGLE_SELECTION, "Single Selection"),
     (FREE_RESPONSE, "Free Response"),
     (PERSEUS_QUESTION, "Perseus Question"),
+    (QTI, "QTI"),
 )

le_utils/constants/format_presets.py

@@ -159,3 +159,10 @@ def _initialize_preset_list():
 
 
 PRESETLIST = list(_initialize_preset_list())
+
+# Bit order for the File.included_presets renderable bitmask.
+# Consumers compute the bit value as 2 ** RENDERABLE_PRESETS_ORDER.index(preset_id).
+# APPEND-ONLY: never reorder or remove an existing entry — that would
+# silently change the bit value of every preset after it and corrupt
+# already-persisted bitmasks. Only append new preset ids at the end.
+RENDERABLE_PRESETS_ORDER = [preset.id for preset in PRESETLIST if not preset.supplementary]

tests/test_exercises.py

@@ -0,0 +1,9 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from le_utils.constants import exercises
+
+
+def test_QTI_is_in_question_choices():
+    assert exercises.QTI == "QTI"
+    assert (exercises.QTI, "QTI") in exercises.question_choices

tests/test_presets.py

@@ -16,3 +16,23 @@ def test_format_presets_are_synced():
 
 def test_PRESETLIST_exists():
     assert format_presets.PRESETLIST, "PRESETLIST did not genereate properly"
+
+
+def test_RENDERABLE_PRESETS_ORDER_matches_PRESETLIST_ids():
+    preset_ids = {preset.id for preset in format_presets.PRESETLIST if not preset.supplementary}
+    assert set(format_presets.RENDERABLE_PRESETS_ORDER) == preset_ids
+
+
+def test_RENDERABLE_PRESETS_ORDER_excludes_supplementary_presets():
+    assert "video_thumbnail" not in format_presets.RENDERABLE_PRESETS_ORDER
+    assert "qti_thumbnail" not in format_presets.RENDERABLE_PRESETS_ORDER
+
+
+def test_RENDERABLE_PRESETS_ORDER_index_is_stable():
+    # Pin known bit positions: reordering silently breaks Studio/Kolibri's
+    # already-persisted File.included_presets bitmask values.
+    assert format_presets.RENDERABLE_PRESETS_ORDER.index("high_res_video") == 0
+    assert format_presets.RENDERABLE_PRESETS_ORDER.index("low_res_video") == 1
+    assert format_presets.RENDERABLE_PRESETS_ORDER.index("video_dependency") == 2
+    assert format_presets.RENDERABLE_PRESETS_ORDER.index("qti") == 13
+    assert format_presets.RENDERABLE_PRESETS_ORDER.index("kpub") == 17