exam: capture sections + choice_groups + marks_confidence in extraction_meta (WS-2 R3)

Persist the paper's question-layout signals (A-level Section A/B, EITHER/OR choice
groups, marks confidence) onto exam_templates.extraction_meta so the setup UI can
show them. Data was carried by the contract but dropped at persistence.

Co-Authored-By: Claude Opus 4.8 <[email protected]>
Claude-Session: https://claude.ai/code/session_01GruxHXxfdp4kZCgAMVFgvV

routers/exam/schemas.py

@@ -80,6 +80,9 @@ class ResponseAreaPayload(BaseModel):
     ] = None
     # Optional Context differentiation (v1 generic; future graph/chart/data_table/diagram/code_block/passage).
     context_type: Optional[str] = None
+    # Rich recognition payload (75-exam-marker-region-meta.sql): figure name/description, OMR geometry, unit…
+    # Carried on canvas save so a named context figure survives a round-trip.
+    meta: Optional[Dict[str, Any]] = None
     source: Literal["manual", "ai"] = "manual"
     confirmed: bool = True
     confidence: Optional[float] = Field(default=None, ge=0, le=1)

routers/exam/templates.py

@@ -745,6 +745,9 @@ def _map_service_contract_to_rows(template_id: str, contract: Dict[str, Any],
             "bounds": _frac_box_to_canvas(q.get("bounds"), q.get("page") or 1, pages),
             "page": q.get("page"), "source": "ai", "confirmed": False,
             "confidence": _safe_confidence(q.get("confidence")), "derivation": "extract-service",
+            # analyse contract v2 (migration 78): command verb + stem prose per part
+            "command_word": (q.get("command_word") or None) if not q.get("is_container") else None,
+            "preamble": q.get("preamble") or None,
         })
     for q in questions:                                 # FK safety: de-parent a dangling parent_id
         if q["parent_id"] and q["parent_id"] not in q_ids:
@@ -799,6 +802,10 @@ def _run_service_extract_merge(ctx: ExamContext, template_id: str, pdf_bytes: by
     updates: Dict[str, Any] = {"extraction_meta": {
         "engine": "extract-service", "slug": slug, "audit": meta.get("audit") or {},
         "counts": {k: len(v) for k, v in rows.items()},
+        # question-layout signals for the setup UI: paper sections (e.g. A-level Section A/B) + EITHER/OR choices
+        "sections": meta.get("sections") or [],
+        "choice_groups": meta.get("choice_groups") or [],
+        "marks_confidence": meta.get("marks_confidence"),
     }}
     n_pages = meta.get("n_pages") or meta.get("pages")
     if n_pages:
@@ -1140,6 +1147,7 @@ async def replace_template(
                 "kind": ra.kind,
                 "response_form": ra.response_form,
                 "context_type": ra.context_type,   # 73: optional Context differentiation
+                "meta": ra.meta,                   # 75: rich recognition payload (name/description/OMR/…)
                 "source": ra.source,
                 "confirmed": ra.confirmed,
                 "confidence": ra.confidence,