fix(ical): stabiliser la clé de déduplication des devoirs

pronote_sync/sources/pronote/ical.py

@@ -370,7 +370,8 @@ def generate_homework_id(
     :rtype: str
     """
     payload = (
-        f"{due_on.isoformat()}|{subject}|{','.join(sorted(teachers))}|{normalized_text}".encode()
+        f"{due_on.isoformat()}|{subject.casefold()}|"
+        f"{','.join(sorted(teacher.casefold() for teacher in teachers))}|{normalized_text}".encode()
     )
     return hashlib.sha1(payload, usedforsecurity=False).hexdigest()[:12]
 
@@ -397,7 +398,7 @@ def collect_homeworks(lessons: list[Lesson], target_date: date) -> list[Homework
                 normalized_text = normalize_homework_text(block.text)
                 key = (
                     lesson.subject.casefold(),
-                    tuple(teacher.casefold() for teacher in lesson.teachers),
+                    tuple(sorted(teacher.casefold() for teacher in lesson.teachers)),
                     normalized_text,
                 )
                 if key not in by_context:
@@ -421,7 +422,7 @@ def collect_homeworks(lessons: list[Lesson], target_date: date) -> list[Homework
                 normalized_text = normalize_homework_text(block.text)
                 key = (
                     lesson.subject.casefold(),
-                    tuple(teacher.casefold() for teacher in lesson.teachers),
+                    tuple(sorted(teacher.casefold() for teacher in lesson.teachers)),
                     normalized_text,
                 )
                 if key not in by_context:

tests/unit/test_ical.py

@@ -398,6 +398,36 @@ def test_collect_homeworks_keeps_distinct_subjects() -> None:
     assert {homework.subject for homework in homeworks} == {"Math", "Physique"}
 
 
+def test_collect_homeworks_deduplicates_teacher_order_variants() -> None:
+    """Deux ordres d'enseignants équivalents ne créent pas de doublon.
+
+    :return: None
+    """
+    homework_block = HomeworkBlock(
+        kind="due",
+        date=date(2026, 9, 10),
+        text="Devoir commun",
+        html="<p>Devoir commun</p>",
+    )
+    lesson = Lesson(
+        id="lesson1",
+        start=datetime(2026, 9, 10, 8, 0),
+        end=datetime(2026, 9, 10, 9, 0),
+        subject="Math",
+        teachers=("M. Martin", "M. Dupont"),
+        group=None,
+        content=None,
+        homework_blocks=(homework_block,),
+    )
+    other_lesson = lesson.model_copy(
+        update={"id": "lesson2", "teachers": ("M. Dupont", "M. Martin")}
+    )
+
+    homeworks = collect_homeworks([lesson, other_lesson], target_date=date(2026, 9, 10))
+
+    assert len(homeworks) == 1
+
+
 def test_parse_body_accepts_html_variants_and_sanitizes() -> None:
     """Les attributs HTML, les espaces et le contenu actif sont traités correctement.