Implement display artifacts, pricing integrity, draft base and publish preview bundle

backend/app/services/publish_preview_cache.py

@@ -0,0 +1,59 @@
+from __future__ import annotations
+
+import json
+from pathlib import Path
+from uuid import uuid4
+
+from app.core.config import settings
+from app.repositories.scheme_artifacts import create_scheme_artifact, list_scheme_artifacts
+
+
+def _preview_storage_dir() -> Path:
+    path = Path(settings.storage_preview_dir)
+    path.mkdir(parents=True, exist_ok=True)
+    return path
+
+
+async def save_publish_preview_artifact(
+    *,
+    scheme_id: str,
+    scheme_version_id: str,
+    payload: dict,
+    baseline_scheme_version_id: str | None,
+) -> dict:
+    artifact_dir = _preview_storage_dir() / uuid4().hex
+    artifact_dir.mkdir(parents=True, exist_ok=True)
+    storage_path = artifact_dir / "publish-preview.json"
+    storage_path.write_text(json.dumps(payload, ensure_ascii=False, indent=2), encoding="utf-8")
+
+    artifact = await create_scheme_artifact(
+        scheme_id=scheme_id,
+        scheme_version_id=scheme_version_id,
+        artifact_type="publish_preview",
+        artifact_variant=baseline_scheme_version_id or "default",
+        storage_path=str(storage_path),
+        meta_json={
+            "baseline_scheme_version_id": baseline_scheme_version_id,
+            "summary": payload.get("summary"),
+        },
+    )
+    return artifact
+
+
+async def get_latest_publish_preview_artifact(
+    *,
+    scheme_version_id: str,
+    baseline_scheme_version_id: str | None,
+):
+    rows = await list_scheme_artifacts(scheme_version_id=scheme_version_id)
+    variant = baseline_scheme_version_id or "default"
+
+    matching = [
+        row for row in rows
+        if row.artifact_type == "publish_preview" and row.artifact_variant == variant
+    ]
+    if not matching:
+        return None
+
+    matching.sort(key=lambda row: (row.created_at, row.id), reverse=True)
+    return matching[0]