WebSocket 전역 연결 전환 및 Mock AI 클라이언트 구현

src/main/java/com/sofa/linkiving/domain/chat/ai/AnswerClient.java

@@ -0,0 +1,8 @@
+package com.sofa.linkiving.domain.chat.ai;
+
+import com.sofa.linkiving.domain.chat.dto.request.RagAnswerReq;
+import com.sofa.linkiving.domain.chat.dto.response.RagAnswerRes;
+
+public interface AnswerClient {
+	RagAnswerRes generateAnswer(RagAnswerReq request);
+}

src/main/java/com/sofa/linkiving/domain/chat/ai/MockAnswerClient.java

@@ -0,0 +1,36 @@
+package com.sofa.linkiving.domain.chat.ai;
+
+import java.util.List;
+
+import org.springframework.context.annotation.Primary;
+import org.springframework.stereotype.Component;
+
+import com.sofa.linkiving.domain.chat.dto.request.RagAnswerReq;
+import com.sofa.linkiving.domain.chat.dto.response.RagAnswerRes;
+
+import lombok.extern.slf4j.Slf4j;
+
+@Slf4j
+@Component
+@Primary
+public class MockAnswerClient implements AnswerClient {
+
+	@Override
+	public RagAnswerRes generateAnswer(RagAnswerReq request) {
+		log.info("[Mock AI Request] User: {}, Question: {}, Mode: {}, HistoryCnt: {}",
+			request.userId(), request.question(), request.mode(), request.history().size());
+
+		return new RagAnswerRes(
+			"임시 답변",
+			List.of("3", "4"),
+			List.of(
+				new RagAnswerRes.ReasoningStep(
+					"임시 답변 스탭",
+					List.of("3", "4")
+				)
+			),
+			List.of("3", "4"),
+			false
+		);
+	}
+}

src/main/java/com/sofa/linkiving/domain/chat/controller/ChatApi.java

@@ -2,6 +2,8 @@
 
 import org.springframework.validation.annotation.Validated;
 
+import com.sofa.linkiving.domain.chat.dto.request.AnswerCancelReq;
+import com.sofa.linkiving.domain.chat.dto.request.AnswerReq;
 import com.sofa.linkiving.domain.chat.dto.request.CreateChatReq;
 import com.sofa.linkiving.domain.chat.dto.response.ChatsRes;
 import com.sofa.linkiving.domain.chat.dto.response.CreateChatRes;
@@ -20,18 +22,45 @@
 @Tag(name = "Chat", description = """
 	AI 채팅 통합 명세 (HTTP + WebSocket)
 
-	### 📡 1. WebSocket 연결 정보 (필수)
-		답변을 실시간으로 수신하기 위해 **반드시 소켓 연결 및 구독**이 선행되어야 합니다.
-
+	### 📡 1. WebSocket 연결 정보
 		* **Socket Endpoint:** `ws://{domain}/ws/chat`
-		* **Subscribe Path:** `/topic/chat/{chatId}`
-		* **Auth Header:** `Authorization: Bearer {accessToken}` (CONNECT 프레임 헤더)
+		* **Subscribe Path:** `/user/queue/chat` (전역 구독)
+
 	### 🚀 2. 동작 흐름
-		1. **소켓 연결:** 프론트엔드에서 WebSocket 연결 및 `/topic/chat/{chatId}` 구독
-		2. **질문 전송:** `/app/send/{chatId}` (STOMP)로 질문 전송
-		3. **답변 수신:** 소켓 구독 채널로 토큰 단위 답변 스트리밍 (`String` 데이터)
-		4. **완료:** `END_OF_STREAM` 메시지 수신 시 스트리밍 종료
+		1. **소켓 연결:** 로그인 직후 `/user/queue/chat` 구독
+		2. **질문 전송:** `/send` 로 요청 전송
+			- Body: `{ "chatId": 1, "message": "질문" }`
+		3. **답변 수신:** 구독한 경로로 답변 도착 (chatId 포함됨)
+			**CASE A: 답변 생성 성공 (success: true)**
+				- AI의 답변과 참고 링크가 포함됩니다.
+				```json
+					{
+					"success": true,
+					"chatId": 1,
+					"messageId": 105,
+					"content": "질문하신 내용에 대한 AI 답변입니다...",
+					"step": ["질문 분석", "데이터 검색", "답변 생성"],
+					"links": [
+						{ "linkId": 10, "title": "관련 문서 제목", "url": "https://...", "imageUrl": "http://...", "summary": "요약 내용" }
+					]
+				}
+				```
 
+			**CASE B: 답변 생성 실패 (success: false)**
+				- 에러 상황입니다. `content` 필드에 **사용자가 보냈던 원래 질문**이 담겨옵니다.
+				- 프론트엔드 처리: 이 값을 다시 입력창(Input)에 채워주세요.
+					```json
+					{
+						"success": false,
+						"chatId": 1,
+						"messageId": null,
+						"content": "내 질문 내용",
+						"step": null,
+						"links": null
+					}
+					```
+		4. **답변 취소**: `/cancel` 로 요청 전송
+			- Body: `{ "chatId": 1 }`
 	""")
 public interface ChatApi {
 	@Operation(summary = "채팅 기록 조회", description = "채팅 기록을 최신순으로 조회합니다. 무한 스크롤 방식으로 제공됩니다.")
@@ -58,8 +87,7 @@ BaseResponse<CreateChatRes> createChat(
 	@Operation(summary = "링크 삭제", description = "해당 링크방과 채팅 기록을 전부 Hard Delete 진행합니다.")
 	BaseResponse<String> deleteChat(Member member, Long chatId);
 
-	void sendMessage(@Parameter(description = "채팅방 Id", required = true) Long chatId,
-		@Parameter(description = "사용자 질문 내용", required = true) String message, Member member);
+	void sendMessage(AnswerReq req, Member member);
 
-	void cancelMessage(@Parameter(description = "채팅방 Id", required = true) Long chatId, Member member);
+	void cancelMessage(AnswerCancelReq req, Member member);
 }

src/main/java/com/sofa/linkiving/domain/chat/controller/ChatController.java

@@ -1,6 +1,5 @@
 package com.sofa.linkiving.domain.chat.controller;
 
-import org.springframework.messaging.handler.annotation.DestinationVariable;
 import org.springframework.messaging.handler.annotation.MessageMapping;
 import org.springframework.messaging.handler.annotation.Payload;
 import org.springframework.web.bind.annotation.DeleteMapping;
@@ -12,6 +11,8 @@
 import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.RestController;
 
+import com.sofa.linkiving.domain.chat.dto.request.AnswerCancelReq;
+import com.sofa.linkiving.domain.chat.dto.request.AnswerReq;
 import com.sofa.linkiving.domain.chat.dto.request.CreateChatReq;
 import com.sofa.linkiving.domain.chat.dto.response.ChatsRes;
 import com.sofa.linkiving.domain.chat.dto.response.CreateChatRes;
@@ -51,15 +52,15 @@ public BaseResponse<String> deleteChat(@AuthMember Member member, @PathVariable
 	}
 
 	@Override
-	@MessageMapping("/send/{chatId}")
-	public void sendMessage(@DestinationVariable Long chatId, @Payload String message, @AuthMember Member member) {
-		chatFacade.generateAnswer(chatId, member, message);
+	@MessageMapping("/send")
+	public void sendMessage(@Payload AnswerReq req, @AuthMember Member member) {
+		chatFacade.generateAnswer(req.chatId(), member, req.message());
 	}
 
 	@Override
-	@MessageMapping("/cancel/{chatId}")
-	public void cancelMessage(@DestinationVariable Long chatId, @AuthMember Member member) {
-		chatFacade.cancelAnswer(chatId, member);
+	@MessageMapping("/cancel")
+	public void cancelMessage(@Payload AnswerCancelReq req, @AuthMember Member member) {
+		chatFacade.cancelAnswer(req.chatId(), member);
 	}
 
 	@Override

src/main/java/com/sofa/linkiving/domain/chat/dto/request/AnswerCancelReq.java

@@ -0,0 +1,9 @@
+package com.sofa.linkiving.domain.chat.dto.request;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+public record AnswerCancelReq(
+	@Schema(description = "채팅방 ID")
+	Long chatId
+) {
+}

src/main/java/com/sofa/linkiving/domain/chat/dto/request/AnswerReq.java

@@ -0,0 +1,11 @@
+package com.sofa.linkiving.domain.chat.dto.request;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+public record AnswerReq(
+	@Schema(description = "채팅방 ID")
+	Long chatId,
+	@Schema(description = "유저 질문 내용")
+	String message
+) {
+}

src/main/java/com/sofa/linkiving/domain/chat/dto/request/RagAnswerReq.java

@@ -0,0 +1,13 @@
+package com.sofa.linkiving.domain.chat.dto.request;
+
+import java.util.List;
+
+import com.sofa.linkiving.domain.chat.enums.Mode;
+
+public record RagAnswerReq(
+	Long userId,
+	String question,
+	List<String> history,
+	Mode mode
+) {
+}

src/main/java/com/sofa/linkiving/domain/chat/dto/response/AnswerRes.java

@@ -0,0 +1,46 @@
+package com.sofa.linkiving.domain.chat.dto.response;
+
+import java.util.List;
+
+import com.sofa.linkiving.domain.chat.entity.Message;
+import com.sofa.linkiving.domain.link.dto.internal.LinkDto;
+import com.sofa.linkiving.domain.link.dto.response.LinkCardRes;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+public record AnswerRes(
+	@Schema(description = "성공 여부")
+	Boolean success,
+	@Schema(description = "채팅방 ID")
+	Long chatId,
+	@Schema(description = "메세지 ID")
+	Long messageId,
+	@Schema(description = "답변 내용")
+	String content,
+	@Schema(description = "스텝 목록")
+	List<String> step,
+	@Schema(description = "첨부된 링크 목록")
+	List<LinkCardRes> links
+) {
+	public static AnswerRes of(Long chatId, Message message, List<String> step, List<LinkDto> linkDtos) {
+		return new AnswerRes(
+			true,
+			chatId,
+			message.getId(),
+			message.getContent(),
+			step,
+			linkDtos.stream().map(LinkCardRes::from).toList()
+		);
+	}
+
+	public static AnswerRes error(Long chatId, String content) {
+		return new AnswerRes(
+			false,
+			chatId,
+			null,
+			content,
+			null,
+			null
+		);
+	}
+}

src/main/java/com/sofa/linkiving/domain/chat/dto/response/RagAnswerRes.java

@@ -0,0 +1,17 @@
+package com.sofa.linkiving.domain.chat.dto.response;
+
+import java.util.List;
+
+public record RagAnswerRes(
+	String answer,
+	List<String> linkIds,
+	List<ReasoningStep> reasoningSteps,
+	List<String> relatedLinks,
+	boolean isFallback
+) {
+	public record ReasoningStep(
+		String step,
+		List<String> linkIds
+	) {
+	}
+}

src/main/java/com/sofa/linkiving/domain/chat/enums/Mode.java

@@ -0,0 +1,31 @@
+package com.sofa.linkiving.domain.chat.enums;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonValue;
+
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+
+@Getter
+@RequiredArgsConstructor
+public enum Mode {
+	DETAILED("detailed"),
+	CONCISE("concise");
+
+	private final String value;
+
+	@JsonCreator
+	public static Mode from(String value) {
+		for (Mode mode : Mode.values()) {
+			if (mode.getValue().equalsIgnoreCase(value)) {
+				return mode;
+			}
+		}
+		return DETAILED;
+	}
+
+	@JsonValue
+	public String getValue() {
+		return value;
+	}
+}