RAGFlow go API server (#13240)

# RAGFlow Go Implementation Plan 🚀

This repository tracks the progress of porting RAGFlow to Go. We'll
implement core features and provide performance comparisons between
Python and Go versions.

## Implementation Checklist

- [x] User Management APIs
- [x] Dataset Management Operations
- [x] Retrieval Test
- [x] Chat Management Operations
- [x] Infinity Go SDK

---------

Signed-off-by: Jin Hai <haijin.chn@gmail.com>
Co-authored-by: Yingfeng Zhang <yingfeng.zhang@gmail.com>

internal/engine/types/types.go

@@ -0,0 +1,54 @@
+//
+//  Copyright 2026 The InfiniFlow Authors. All Rights Reserved.
+//
+//  Licensed under the Apache License, Version 2.0 (the "License");
+//  you may not use this file except in compliance with the License.
+//  You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+//  Unless required by applicable law or agreed to in writing, software
+//  distributed under the License is distributed on an "AS IS" BASIS,
+//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//  See the License for the specific language governing permissions and
+//  limitations under the License.
+//
+
+package types
+
+// SearchRequest unified search request for all engines
+type SearchRequest struct {
+	// Common fields
+	IndexNames []string  // For ES: index names; For Infinity: treated as table names
+	Question   string    // Search query text
+	Vector     []float64 // Embedding vector (optional, for hybrid search)
+
+	// Query analysis results (from QueryBuilder.Question)
+	MatchText string   // Processed match text for ES query_string
+	Keywords  []string // Extracted keywords from question
+
+	// Filters
+	KbIDs  []string // Knowledge base IDs filter
+	DocIDs []string // Document IDs filter
+
+	// Pagination
+	Page int // Page number (1-based)
+	Size int // Page size
+	TopK int // Number of candidates for retrieval
+
+	// Search mode
+	KeywordOnly bool // If true, only do keyword search (no vector search)
+
+	// Scoring parameters
+	SimilarityThreshold    float64 // Minimum similarity score (default: 0.1)
+	VectorSimilarityWeight float64 // Weight for vector vs keyword (default: 0.3)
+
+	// Engine-specific options (optional, for advanced use)
+	Options map[string]interface{}
+}
+
+// SearchResponse unified search response for all engines
+type SearchResponse struct {
+	Chunks []map[string]interface{} // Search results
+	Total  int64                    // Total number of matches
+}