P3+P4 app: persist audit gate (extraction_meta) + digital-text endpoint

_run_service_extract_merge now records extraction_meta {engine, slug, audit
(cover-total reconciliation), counts} on the template (migration 76) — a durable
trust signal the setup UI shows. New GET /templates/{id}/digital-text proxies the
service's /api/replica for the paper (resolved via extraction_meta.slug), returning
the digital-replica markdown. exam_extract.get_replica client added.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

routers/exam/templates.py

@@ -793,9 +793,17 @@ def _run_service_extract_merge(ctx: ExamContext, template_id: str, pdf_bytes: by
     contract = exam_extract.extract_suggestions(slug, pdf_bytes)
     rows = _map_service_contract_to_rows(template_id, contract, pdf_bytes)
     _refresh_ai_rows(ctx, template_id, rows)
-    n_pages = (contract.get("meta") or {}).get("n_pages") or (contract.get("meta") or {}).get("pages")
+    meta = contract.get("meta") or {}
+    # P3: record provenance + the audit cover-reconciliation gate so the setup UI can flag under-reads,
+    # and store the slug so the digital-text view can resolve this paper's replica.
+    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()},
+    }}
+    n_pages = meta.get("n_pages") or meta.get("pages")
     if n_pages:
-        ctx.supabase.table("exam_templates").update({"page_count": n_pages}).eq("id", template_id).execute()
+        updates["page_count"] = n_pages
+    ctx.supabase.table("exam_templates").update(updates).eq("id", template_id).execute()
     return rows
 
 
@@ -1034,6 +1042,24 @@ async def auto_map_status(
     return body
 
 
+@router.get("/templates/{template_id}/digital-text")
+async def template_digital_text(
+    template_id: str,
+    ctx: ExamContext = Depends(get_exam_context),
+) -> Dict[str, Any]:
+    """P4: the digital-replica markdown for this template's paper (stem text, parts, marks, answer-space
+    placeholders, spec refs). Resolves the paper via the slug the extraction used."""
+    template = _fetch_template_or_404(ctx, template_id)
+    _require_source_visibility_or_404(ctx, template)
+    if not exam_extract.is_enabled():
+        raise HTTPException(status_code=503, detail="Extraction service not configured")
+    slug = (template.get("extraction_meta") or {}).get("slug") or _extract_slug(ctx, template)
+    try:
+        return exam_extract.get_replica(slug)
+    except exam_extract.ExtractError as exc:
+        raise HTTPException(status_code=404, detail=f"No digital text yet — run auto-map first ({exc})")
+
+
 @router.put("/templates/{template_id}")
 async def replace_template(
     template_id: str,