feat: add reranker config to RAG v1 API

PiperOrigin-RevId: 735952331

Author: Google APIs

google/cloud/aiplatform/v1/tool.proto

@@ -372,9 +372,38 @@ message RagRetrievalConfig {
     string metadata_filter = 2 [(google.api.field_behavior) = OPTIONAL];
   }
 
+  // Config for ranking and reranking.
+  message Ranking {
+    // Config for Rank Service.
+    message RankService {
+      // Optional. The model name of the rank service.
+      // Format: `semantic-ranker-512@latest`
+      optional string model_name = 1 [(google.api.field_behavior) = OPTIONAL];
+    }
+
+    // Config for LlmRanker.
+    message LlmRanker {
+      // Optional. The model name used for ranking.
+      // Format: `gemini-1.5-pro`
+      optional string model_name = 1 [(google.api.field_behavior) = OPTIONAL];
+    }
+
+    // Config options for ranking. Currently only Rank Service is supported.
+    oneof ranking_config {
+      // Optional. Config for Rank Service.
+      RankService rank_service = 1 [(google.api.field_behavior) = OPTIONAL];
+
+      // Optional. Config for LlmRanker.
+      LlmRanker llm_ranker = 3 [(google.api.field_behavior) = OPTIONAL];
+    }
+  }
+
   // Optional. The number of contexts to retrieve.
   int32 top_k = 1 [(google.api.field_behavior) = OPTIONAL];
 
   // Optional. Config for filters.
   Filter filter = 3 [(google.api.field_behavior) = OPTIONAL];
+
+  // Optional. Config for ranking and reranking.
+  Ranking ranking = 4 [(google.api.field_behavior) = OPTIONAL];
 }