#19 feat: LLM 응답 불가 시 사장님 웹 실시간 알림 SSE 구현

src/main/java/com/nailagent/backend/global/sse/SseController.java

@@ -0,0 +1,33 @@
+package com.nailagent.backend.global.sse;
+
+import com.nailagent.backend.global.common.ApiResponse;
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.tags.Tag;
+import jakarta.validation.Valid;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.MediaType;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.*;
+import org.springframework.web.servlet.mvc.method.annotation.SseEmitter;
+
+@Tag(name = "SSE", description = "실시간 알림 관련 API")
+@RestController
+@RequestMapping("/api/v1/sse")
+@RequiredArgsConstructor
+public class SseController {
+
+    private final SseService sseService;
+
+    @Operation(summary = "SSE 연결", description = "사장님 웹에서 실시간 알림을 수신하기 위한 SSE 연결을 맺습니다.")
+    @GetMapping(value = "/connect", produces = MediaType.TEXT_EVENT_STREAM_VALUE)
+    public SseEmitter connect() {
+        return sseService.connect();
+    }
+
+    @Operation(summary = "알림 전송", description = "AI 서버가 LLM 응답 불가 시 사장님 웹으로 알림을 전송합니다.")
+    @PostMapping("/notify")
+    public ResponseEntity<ApiResponse<Void>> notify(@Valid @RequestBody SseNotifyRequest request) {
+        sseService.send(request.getCustomerName(), request.getWaiting());
+        return ResponseEntity.ok(ApiResponse.ok(null));
+    }
+}

src/main/java/com/nailagent/backend/global/sse/SseNotifyRequest.java

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+package com.nailagent.backend.global.sse;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+import io.swagger.v3.oas.annotations.media.Schema;
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotNull;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+@Getter
+@NoArgsConstructor
+public class SseNotifyRequest {
+
+    @NotBlank(message = "고객명은 필수입니다")
+    @JsonProperty("customer_name")
+    @Schema(description = "고객명", example = "눈송이")
+    private String customerName;
+
+    @NotNull(message = "대기 여부는 필수입니다")
+    @Schema(description = "고객 응답 대기 여부", example = "true")
+    private Boolean waiting;
+}

src/main/java/com/nailagent/backend/global/sse/SseService.java

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+package com.nailagent.backend.global.sse;
+
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.stereotype.Service;
+import org.springframework.web.servlet.mvc.method.annotation.SseEmitter;
+
+import java.io.IOException;
+import java.util.Map;
+
+@Slf4j
+@Service
+public class SseService {
+
+    private SseEmitter emitter;
+
+    public SseEmitter connect() {
+        if (emitter != null) {
+            emitter.complete();
+        }
+        SseEmitter newEmitter = new SseEmitter(Long.MAX_VALUE);
+        emitter = newEmitter;
+        newEmitter.onCompletion(() -> { if (emitter == newEmitter) emitter = null; });
+        newEmitter.onTimeout(() -> { if (emitter == newEmitter) emitter = null; });
+        return newEmitter;
+    }
+
+    public void send(String customerName, Boolean waiting) {
+        SseEmitter current = emitter;
+        if (current == null) {
+            log.warn("SSE 연결된 클라이언트 없음 - 알림 전송 불가");
+            return;
+        }
+        try {
+            current.send(SseEmitter.event()
+                    .name("inquiry")
+                    .data(Map.of(
+                            "customerName", customerName,
+                            "waiting", waiting
+                    )));
+        } catch (IOException e) {
+            log.error("SSE 전송 실패", e);
+            if (emitter == current) emitter = null;
+        }
+    }
+}