feat(exam): persist S4-9 region kinds + Part geometry; keep metadata out of graph

Backend follow-on to migration 73:
- schemas: ResponseAreaPayload.kind extended to response|context|question_number|
  mark_area|reference|furniture + context_type; QuestionPayload gains bounds+page.
- PUT serialization persists Part bounds/page and region context_type.
- Neo4j projection only emits Region nodes for response/context regions; the
  metadata kinds (question_number/mark_area/reference/furniture) are physical-layer
  only and stay out of cc.public.exams.
- Unit test: new kinds + Part geometry + context_type round-trip.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

modules/database/services/exam_projection.py

@@ -138,7 +138,12 @@ def project_template(template_id: str) -> Dict[str, Any]:
                 counts["assesses"] += (r["n"] if r else 0)
 
         # 6. Region nodes + HAS_REGION edges.
+        # Only response/context regions are part of the knowledge graph (RegionNode.kind). The other
+        # S4-9 kinds (question_number, mark_area, reference, furniture) are physical-layer metadata
+        # about the paper, not curriculum structure — they stay in Supabase, out of cc.public.exams.
         for rg in regions:
+            if rg.get("kind") not in ("response", "context"):
+                continue
             s.run(
                 "MERGE (r:Region {uuid_string:$uid}) "
                 "SET r.exam_code=$ec, r.page=$page, r.kind=$kind, r.response_form=$rf, r.node_storage_path=$nsp",

routers/exam/schemas.py

@@ -57,17 +57,24 @@ class QuestionPayload(BaseModel):
     mark_scheme: Dict[str, Any] = Field(default_factory=dict)
     is_container: bool = False
     spec_ref: Optional[str] = None
+    # Drawn Part box geometry (73-exam-marker-regions.sql). Null for derived main questions.
+    bounds: Optional[Dict[str, Any]] = None  # {x,y,w,h}
+    page: Optional[int] = None
 
 
 class ResponseAreaPayload(BaseModel):
-    id: Optional[str] = None  # == Neo4j Region.uuid_string
+    id: Optional[str] = None  # == Neo4j Region.uuid_string (only response/context project)
     question_id: str
     page: int
     bounds: Dict[str, Any]  # {x,y,w,h}
-    kind: Literal["response", "context"]
+    # S4-9 taxonomy (73-exam-marker-regions.sql): response/context graded-or-stimulus;
+    # question_number/mark_area = physical metadata; reference = student resource; furniture = ignore.
+    kind: Literal["response", "context", "question_number", "mark_area", "reference", "furniture"]
     response_form: Optional[
         Literal["lines", "answer-box", "working", "diagram", "tick-boxes", "table", "blanks"]
     ] = None
+    # Optional Context differentiation (v1 generic; future graph/chart/data_table/diagram/code_block/passage).
+    context_type: Optional[str] = None
     source: Literal["manual", "ai"] = "manual"
     confirmed: bool = True
     confidence: Optional[float] = None

routers/exam/templates.py

@@ -204,6 +204,8 @@ async def replace_template(
                 "mark_scheme": q.mark_scheme,
                 "is_container": q.is_container,
                 "spec_ref": q.spec_ref,
+                "bounds": q.bounds,   # drawn Part box (73); null for derived main questions
+                "page": q.page,
             }
             if q.id:
                 r["id"] = q.id
@@ -220,6 +222,7 @@ async def replace_template(
                 "bounds": ra.bounds,
                 "kind": ra.kind,
                 "response_form": ra.response_form,
+                "context_type": ra.context_type,   # 73: optional Context differentiation
                 "source": ra.source,
                 "confirmed": ra.confirmed,
                 "confidence": ra.confidence,

tests/test_exam_templates.py

@@ -234,6 +234,33 @@ def test_put_replace_persists_children_with_client_ids():
     assert body["boundaries"][0]["id"] == "b-uuid-1"
 
 
+def test_put_persists_region_kinds_and_part_geometry():
+    # S4-9 taxonomy: Part box geometry on the question; new region kinds + context_type.
+    store = {"exam_templates": [{"id": "t1", "title": "p", "status": "draft", "institute_id": INST_A, "teacher_id": TEACHER}]}
+    client, store = make_client(store=store)
+    resp = client.put("/api/exam/templates/t1", json={
+        "questions": [
+            {"id": "q1", "label": "01", "order": 0, "is_container": True},
+            {"id": "p1", "parent_id": "q1", "label": "01.1", "order": 0, "max_marks": 3,
+             "bounds": {"x": 1, "y": 2, "w": 3, "h": 4}, "page": 1},
+        ],
+        "response_areas": [
+            {"id": "r1", "question_id": "p1", "page": 1, "bounds": {"x": 1}, "kind": "response", "response_form": "lines"},
+            {"id": "c1", "question_id": "p1", "page": 1, "bounds": {"x": 1}, "kind": "context", "context_type": "data_table"},
+            {"id": "qn1", "question_id": "p1", "page": 1, "bounds": {"x": 1}, "kind": "question_number"},
+            {"id": "m1", "question_id": "p1", "page": 1, "bounds": {"x": 1}, "kind": "mark_area"},
+            {"id": "f1", "question_id": "p1", "page": 1, "bounds": {"x": 1}, "kind": "furniture"},
+        ],
+    })
+    assert resp.status_code == 200
+    part = next(q for q in store["exam_questions"] if q["id"] == "p1")
+    assert part["bounds"] == {"x": 1, "y": 2, "w": 3, "h": 4} and part["page"] == 1
+    ras = {r["id"]: r for r in store["exam_response_areas"]}
+    assert {ras["r1"]["kind"], ras["c1"]["kind"], ras["qn1"]["kind"], ras["m1"]["kind"], ras["f1"]["kind"]} == \
+        {"response", "context", "question_number", "mark_area", "furniture"}
+    assert ras["c1"]["context_type"] == "data_table"
+
+
 def test_put_replace_clears_previous_children():
     store = {
         "exam_templates": [{"id": "t1", "title": "p", "status": "draft", "institute_id": INST_A, "teacher_id": TEACHER}],