feat(captain): align task payload persistence

internal/handler/api/v1/captain_task_handler.go

@@ -45,11 +45,11 @@ func (h *CaptainTaskHandler) ReplySuggestion(c *gin.Context) {
 	result, err := h.svc.ReplySuggestion(c.Request.Context(), uint(accountID), &req)
 	if err != nil {
 		applogger.L().Errorf("ReplySuggestion: %v", err)
-		response.AbortWithStatusError(c, http.StatusInternalServerError, response.ErrInternal, "failed to generate reply suggestions")
+		renderCaptainTaskError(c, err)
 		return
 	}
 
-	response.OK(c, result)
+	renderCaptainTaskPayload(c, result.Message, result.FollowUpContext)
 }
 
 // Summarize generates a concise summary of a conversation.
@@ -70,11 +70,11 @@ func (h *CaptainTaskHandler) Summarize(c *gin.Context) {
 	result, err := h.svc.Summarize(c.Request.Context(), uint(accountID), &req)
 	if err != nil {
 		applogger.L().Errorf("Summarize: %v", err)
-		response.AbortWithStatusError(c, http.StatusInternalServerError, response.ErrInternal, "failed to summarize conversation")
+		renderCaptainTaskError(c, err)
 		return
 	}
 
-	response.OK(c, result)
+	renderCaptainTaskPayload(c, result.Message, result.FollowUpContext)
 }
 
 // Rewrite rewrites a draft message to improve tone, clarity, or language.
@@ -95,11 +95,11 @@ func (h *CaptainTaskHandler) Rewrite(c *gin.Context) {
 	result, err := h.svc.Rewrite(c.Request.Context(), uint(accountID), &req)
 	if err != nil {
 		applogger.L().Errorf("Rewrite: %v", err)
-		response.AbortWithStatusError(c, http.StatusInternalServerError, response.ErrInternal, "failed to rewrite message")
+		renderCaptainTaskError(c, err)
 		return
 	}
 
-	response.OK(c, result)
+	renderCaptainTaskPayload(c, result.Message, result.FollowUpContext)
 }
 
 // --- SSE Streaming Endpoints (M12) ---
@@ -280,3 +280,20 @@ func captainEscapeJSONString(s string) string {
 	}
 	return result.String()
 }
+
+func renderCaptainTaskPayload(c *gin.Context, message string, followUpContext map[string]interface{}) {
+	payload := gin.H{"message": message}
+	if followUpContext != nil {
+		payload["follow_up_context"] = followUpContext
+	}
+	c.JSON(http.StatusOK, payload)
+}
+
+func renderCaptainTaskError(c *gin.Context, err error) {
+	status, message, ok := service.CaptainTaskErrorStatus(err)
+	if !ok {
+		status = http.StatusUnprocessableEntity
+		message = err.Error()
+	}
+	c.JSON(status, gin.H{"error": message})
+}