feat(datasources): publish durable artifact outputs

src/govoplan_datasources/backend/payloads.py

@@ -9,6 +9,9 @@ from sqlalchemy import delete, func, insert, select
 from sqlalchemy.orm import Session
 
 from govoplan_core.core.datasources import (
+    DatasourceArtifactBackend,
+    DatasourceArtifactReference,
+    DatasourceField,
     DatasourceUnavailableError,
     DatasourceValidationError,
 )
@@ -116,6 +119,91 @@ class DatabaseRowsPayloadBackend:
         )
 
 
+class ExternalArtifactPayloadBackend:
+    """Adapts a Core artifact backend to persisted Datasources payload rows."""
+
+    def __init__(self, backend: DatasourceArtifactBackend) -> None:
+        self._backend = backend
+        self.backend = backend.backend
+
+    def read_rows(
+        self,
+        session: Session,
+        payload: DatasourcePayloadRecord,
+        *,
+        offset: int,
+        limit: int,
+    ) -> Sequence[Mapping[str, object]]:
+        return self._backend.read_rows(
+            session,
+            tenant_id=payload.tenant_id,
+            artifact=_artifact_from_payload(payload),
+            offset=offset,
+            limit=limit,
+        )
+
+    def verify(
+        self,
+        session: Session,
+        payload: DatasourcePayloadRecord,
+    ) -> None:
+        self._backend.verify(
+            session,
+            tenant_id=payload.tenant_id,
+            artifact=_artifact_from_payload(payload),
+        )
+
+    def delete(
+        self,
+        session: Session,
+        payload: DatasourcePayloadRecord,
+    ) -> None:
+        self._backend.delete(
+            session,
+            tenant_id=payload.tenant_id,
+            artifact=_artifact_from_payload(payload),
+        )
+
+
+def _artifact_from_payload(
+    payload: DatasourcePayloadRecord,
+) -> DatasourceArtifactReference:
+    metadata = dict(payload.metadata_)
+    raw_schema = metadata.get("artifact_schema")
+    schema = tuple(
+        DatasourceField(
+            name=str(item.get("name") or ""),
+            data_type=str(item.get("data_type") or "unknown"),
+            nullable=bool(item.get("nullable", True)),
+        )
+        for item in raw_schema
+        if isinstance(item, Mapping)
+    ) if isinstance(raw_schema, Sequence) and not isinstance(
+        raw_schema, (str, bytes)
+    ) else ()
+    return DatasourceArtifactReference(
+        backend=payload.backend,
+        locator=str(payload.locator or ""),
+        checksum=payload.checksum,
+        row_count=payload.row_count,
+        byte_count=payload.byte_count,
+        schema=schema,
+        fingerprint=str(metadata.get("publication_fingerprint") or ""),
+        media_type=payload.media_type,
+        checkpoint=dict(payload.checkpoint_),
+        metadata={
+            str(key): value
+            for key, value in metadata.items()
+            if key not in {"artifact_schema", "artifact_validation"}
+        },
+        validation=(
+            dict(metadata.get("artifact_validation"))
+            if isinstance(metadata.get("artifact_validation"), Mapping)
+            else {}
+        ),
+    )
+
+
 class PayloadBackendRegistry:
     def __init__(
         self,
@@ -363,6 +451,7 @@ __all__ = [
     "DATABASE_ROWS_BACKEND",
     "DatabaseRowsPayloadBackend",
     "DatasourcePayloadBackend",
+    "ExternalArtifactPayloadBackend",
     "PayloadBackendRegistry",
     "create_database_rows_payload",
     "create_external_payload_reference",