feat: implement OpenAI-compatible file upload and reference handling for DeepSeek API

internal/util/standard_request.go

@@ -14,6 +14,7 @@ type StandardRequest struct {
 	Stream         bool
 	Thinking       bool
 	Search         bool
+	RefFileIDs     []string
 	PassThrough    map[string]any
 }
 
@@ -61,12 +62,19 @@ func (r StandardRequest) CompletionPayload(sessionID string) map[string]any {
 	if resolvedType, ok := config.GetModelType(modelID); ok {
 		modelType = resolvedType
 	}
+	refFileIDs := make([]any, 0, len(r.RefFileIDs))
+	for _, fileID := range r.RefFileIDs {
+		if fileID == "" {
+			continue
+		}
+		refFileIDs = append(refFileIDs, fileID)
+	}
 	payload := map[string]any{
 		"chat_session_id":   sessionID,
 		"model_type":        modelType,
 		"parent_message_id": nil,
 		"prompt":            r.FinalPrompt,
-		"ref_file_ids":      []any{},
+		"ref_file_ids":      refFileIDs,
 		"thinking_enabled":  r.Thinking,
 		"search_enabled":    r.Search,
 	}

internal/util/standard_request_test.go

@@ -22,6 +22,7 @@ func TestStandardRequestCompletionPayloadSetsModelTypeFromResolvedModel(t *testi
 				FinalPrompt:   "hello",
 				Thinking:      tc.thinking,
 				Search:        tc.search,
+				RefFileIDs:    []string{"file-a", "file-b"},
 				PassThrough: map[string]any{
 					"temperature": 0.3,
 				},
@@ -44,6 +45,13 @@ func TestStandardRequestCompletionPayloadSetsModelTypeFromResolvedModel(t *testi
 			if got := payload["temperature"]; got != 0.3 {
 				t.Fatalf("expected passthrough temperature, got %#v", got)
 			}
+			refFileIDs, ok := payload["ref_file_ids"].([]any)
+			if !ok {
+				t.Fatalf("expected ref_file_ids slice, got %#v", payload["ref_file_ids"])
+			}
+			if len(refFileIDs) != 2 || refFileIDs[0] != "file-a" || refFileIDs[1] != "file-b" {
+				t.Fatalf("unexpected ref_file_ids: %#v", refFileIDs)
+			}
 		})
 	}
 }