Fix Greptile round 4: preserve backward compat, add guards, fix defaults

- Revert FocusExportEngine.dry_run_export_usage_data to use original raw
  column names (spend, total_tokens, team_id, model) preserving backward
  compatibility for existing callers
- Vantage dry-run endpoint computes its own summary from FOCUS columns
  independently, avoiding coupling to the engine method
- Set VantageExportRequest.limit default to 500 (was None) matching docstring
- Add empty-settings guard in /vantage/export returning 404 instead of
  deferring ValueError to runtime
- Fix misleading docstring in _build_tags_expr about Rust-level execution
- Clarify Tags schema comment: parquet is self-describing so existing
  exports are unaffected

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

litellm/integrations/focus/export_engine.py

@@ -55,9 +55,10 @@ class FocusExportEngine:
 
         summary = {
             "total_records": len(normalized),
-            "total_spend": self._sum_column(normalized, "BilledCost"),
-            "unique_teams": self._count_unique(normalized, "SubAccountId"),
-            "unique_models": self._count_unique(normalized, "ResourceType"),
+            "total_spend": self._sum_column(data, "spend"),
+            "total_tokens": self._sum_column(data, "total_tokens"),
+            "unique_teams": self._count_unique(data, "team_id"),
+            "unique_models": self._count_unique(data, "model"),
         }
 
         return {

litellm/integrations/focus/schema.py

@@ -45,7 +45,10 @@ FOCUS_NORMALIZED_SCHEMA = pl.Schema(
         ("SubAccountType", pl.String),
         # Changed from pl.Object to pl.String to hold JSON metadata
         # (team_id, user_id, etc.) needed by Vantage Token Allocation.
-        # Previously Tags was always None so no existing data is lost.
+        # This schema is only used for creating empty DataFrames (e.g.
+        # when transform() receives no rows).  Parquet files are
+        # self-describing and embed their own schema, so existing S3
+        # exports are unaffected.  Previously Tags was always None.
         ("Tags", pl.String),
     ]
 )

litellm/integrations/focus/transformer.py

@@ -25,8 +25,10 @@ _TAG_KEYS = (
 def _build_tags_expr(available_keys: list[str]) -> pl.Expr:
     """Build a Polars expression that produces a JSON Tags string per row.
 
-    Uses ``pl.struct`` + ``map_elements`` so the heavy iteration stays inside
-    Polars rather than materialising every row to a Python dict first.
+    Uses ``pl.struct`` + ``map_elements`` to avoid materialising the entire
+    DataFrame to a list of Python dicts.  The JSON serialisation callback
+    still runs in Python (GIL-bound), but struct-packing and loop dispatch
+    are handled by Polars' Rust engine.
     """
 
     def _struct_to_json(row: dict) -> str:

litellm/proxy/spend_tracking/vantage_endpoints.py

@@ -388,7 +388,8 @@ async def vantage_dry_run_export(
         usage_sample = data.head(min(50, len(data))).to_dicts() if not data.is_empty() else []
         normalized_sample = normalized.head(min(50, len(normalized))).to_dicts() if not normalized.is_empty() else []
 
-        # Use the same column names as FocusExportEngine.dry_run_export_usage_data
+        # Compute summary from the FOCUS-normalized DataFrame.
+        # These use post-transform column names specific to this endpoint.
         summary = {
             "total_records": len(normalized),
             "total_spend": FocusExportEngine._sum_column(normalized, "BilledCost"),
@@ -459,6 +460,13 @@ async def vantage_export(
         logger = _get_registered_vantage_logger()
         if logger is None:
             settings = await _get_vantage_settings()
+            if not settings:
+                raise HTTPException(
+                    status_code=404,
+                    detail={
+                        "error": "Vantage settings not found. Please initialize settings first using /vantage/init"
+                    },
+                )
             logger = VantageLogger(
                 api_key=settings.get("api_key"),
                 integration_token=settings.get("integration_token"),

litellm/types/proxy/vantage_endpoints.py

@@ -32,7 +32,7 @@ class VantageExportRequest(BaseModel):
     """Request model for Vantage export operations"""
 
     limit: Optional[int] = Field(
-        None, description="Optional limit on number of records to export"
+        500, description="Limit on number of records to export (default: 500)"
     )
     start_time_utc: Optional[datetime] = Field(
         None, description="Start time for data export in UTC"