[Developer] #424 use GPT 5.4 mini for VPD explanations

src/main/java/com/cloudhandson/vpdbackoffice/domain/vpd/VpdPolicyExplanation.java

@@ -2,6 +2,7 @@ package com.cloudhandson.vpdbackoffice.domain.vpd;
 
 public record VpdPolicyExplanation(
     String status,
+    String modelName,
     String answer,
     String prompt,
     VpdPolicyDetail detail,

src/main/java/com/cloudhandson/vpdbackoffice/service/OpenAiCompatibleClient.java

@@ -41,6 +41,11 @@ public class OpenAiCompatibleClient {
         && hasText(ai.apiKey());
   }
 
+  public String modelName() {
+    BackofficeProperties.Ai ai = properties.ai();
+    return ai == null ? "" : ai.model();
+  }
+
   public String chat(String systemPrompt, String userPrompt) {
     if (!configured()) {
       throw new AppException("AI 호출 설정이 없습니다.");
@@ -50,7 +55,11 @@ public class OpenAiCompatibleClient {
     ObjectNode request = objectMapper.createObjectNode();
     request.put("model", ai.model());
     request.put("temperature", 0.1);
-    request.put("max_tokens", 1200);
+    if (usesCompletionTokenLimit(ai.model())) {
+      request.put("max_completion_tokens", 1200);
+    } else {
+      request.put("max_tokens", 1200);
+    }
     ArrayNode messages = request.putArray("messages");
     messages.add(message("system", systemPrompt));
     messages.add(message("user", userPrompt));
@@ -91,6 +100,10 @@ public class OpenAiCompatibleClient {
     return URI.create(withoutSlash + "/v1/chat/completions");
   }
 
+  private boolean usesCompletionTokenLimit(String model) {
+    return model != null && model.startsWith("openai.gpt-5.4");
+  }
+
   private String extractAnswer(String body) {
     try {
       JsonNode root = objectMapper.readTree(body);

src/main/java/com/cloudhandson/vpdbackoffice/service/VpdPolicyService.java

@@ -57,6 +57,7 @@ public class VpdPolicyService {
     if (!aiClient.configured()) {
       return new VpdPolicyExplanation(
           "AI_NOT_CONFIGURED",
+          aiClient.modelName(),
           "AI base URL/API Key 설정이 없어 모델 호출은 건너뛰었습니다. 아래 Prompt와 function source를 기준으로 policy/filter 내용을 확인하세요.",
           prompt,
           detail,
@@ -65,10 +66,11 @@ public class VpdPolicyService {
     }
     try {
       String answer = aiClient.chat(vpdSystemPrompt(), prompt);
-      return new VpdPolicyExplanation("SUCCESS", answer, prompt, detail, functionSource);
+      return new VpdPolicyExplanation("SUCCESS", aiClient.modelName(), answer, prompt, detail, functionSource);
     } catch (Exception e) {
       return new VpdPolicyExplanation(
           "AI_CALL_FAILED",
+          aiClient.modelName(),
           "AI 호출은 실패했지만 policy/filter 근거는 수집했습니다. 상세: " + e.getMessage(),
           prompt,
           detail,