fix Fabric authority import compatibility

Assistant: codex
Assistant-Model: gpt-5.6-sol
Assistant-Session: 01a053ff-1d6f-7fe2-ac1c-a6eb40a42a0c

api/services/fabric_graph.py

@@ -324,7 +324,10 @@ async def _record_invalid_import(
         import_run = FabricGraphImport(
             source_repo_slug=source_repo_slug,
             source_url=source_url,
-            source_commit=_source_value(payload, "commit"),
+            # Invalid payloads are retained for diagnostics, but their
+            # denormalized provenance must not make the rejection path fail.
+            # The complete input remains available in ``graph_json``.
+            source_commit=_bounded_source_value(payload, "commit", max_length=255),
             source_path=_source_value(payload, "path"),
             api_version=str(payload.get("apiVersion")) if payload.get("apiVersion") else None,
             export_kind=str(payload.get("kind")) if payload.get("kind") else None,
@@ -620,6 +623,13 @@ def _source_value(payload: dict[str, Any], field: str) -> str | None:
     return str(value) if value else None
 
 
+def _bounded_source_value(
+    payload: dict[str, Any], field: str, *, max_length: int
+) -> str | None:
+    value = _source_value(payload, field)
+    return value[:max_length] if value is not None else None
+
+
 def _parse_datetime(value: Any) -> datetime | None:
     if not isinstance(value, str) or not value:
         return None