fix(captain): 试验场不查 FAQ 知识库 + 添加常见问题报 400

三个问题修复:

1. 添加常见问题报 400 (assistant_id 类型不匹配)
   - CreateResponseDialog.vue: route.params.assistantId 是字符串,
     传给后端 uint 字段导致 JSON 反序列化失败
   - 修复: Number(route.params.assistantId) 转为数字
   - 同时修复 POST /assistant_responses 无尾部斜杠 307 重定向问题

2. 试验场 playground 不做 RAG 检索
   - generatePlaygroundLLMResponse 只构建 system prompt + 对话历史,
     从不查 FAQ 知识库
   - 新增 retrieveFAQContext(): embed 用户问题 → pgvector 搜索 approved
     FAQ → 注入 system prompt
   - 受 feature_faq 配置开关控制

3. FAQ embedding 无法写入 (pgvector 序列化 + 维度问题)
   - pgvector stub 无 driver.Valuer, GORM Save() 报 SQLSTATE 42804
   - 新增 UpdateEmbedding() 用 ?::vector 原始 SQL 绕过
   - SimilaritySearch 排除 embedding 列 + 手动格式化向量字面量
   - embedding 列从 vector(1536) 改为 vector (跟随模型维度)
   - FAQ 创建/更新时自动索引 embedding (SetRAGService 注入)

backend/internal/app/bootstrap.go

@@ -606,6 +606,7 @@ func Bootstrap(env string) (*App, error) {
 
 	// RAG service — knowledge base Q&A (embedding search + LLM generation)
 	ragService := service.NewRAGService(captainAssistantResponseRepo, captainAssistantRepo, llmProvider)
+	captainAssistantResponseService.SetRAGService(ragService)
 
 	// Auto-reply rule service — CRUD + condition matching + LLM reply composition
 	autoReplyRuleService := service.NewAutoReplyRuleService(captainAutoReplyRuleRepo, captainAssistantRepo, conversationRepo, llmProvider)

backend/internal/model/captain_models.go

@@ -218,8 +218,8 @@ type CaptainAssistantResponse struct {
 	Answer           string         `gorm:"type:text;not null" json:"answer"`
 	Status           ResponseStatus `gorm:"size:50;default:approved;not null" json:"status"`
 	Edited           bool           `gorm:"default:false;not null" json:"edited"`
-	// pgvector-go Vector type for 1536-dimensional embeddings
-	Embedding pgvector.Vector `gorm:"type:vector(1536)" json:"embedding,omitempty"`
+	// pgvector-go Vector type for embeddings (dimension follows the configured embedding model)
+	Embedding pgvector.Vector `gorm:"type:vector" json:"embedding,omitempty"`
 
 	Assistant CaptainAssistant `gorm:"foreignKey:AssistantID" json:"assistant,omitempty"`
 }

backend/internal/repository/captain_assistant_response_repo.go

@@ -2,6 +2,8 @@ package repository
 
 import (
 	"context"
+	"strconv"
+	"strings"
 
 	"github.com/gochat/gochat/internal/model"
 	"github.com/pgvector/pgvector-go"
@@ -45,6 +47,21 @@ func (r *CaptainAssistantResponseRepo) Update(ctx context.Context, resp *model.C
 	return r.db.WithContext(ctx).Save(resp).Error
 }
 
+// UpdateEmbedding updates only the embedding column using raw SQL with explicit
+// ::vector cast to avoid GORM/pgvector serialization issue (SQLSTATE 42804).
+func (r *CaptainAssistantResponseRepo) UpdateEmbedding(ctx context.Context, id uint, embedding pgvector.Vector) error {
+	// Format as PG vector literal: [0.1,0.2,...]
+	strs := make([]string, len(embedding))
+	for i, v := range embedding {
+		strs[i] = strconv.FormatFloat(float64(v), 'f', -1, 32)
+	}
+	vecStr := "[" + strings.Join(strs, ",") + "]"
+	return r.db.WithContext(ctx).Exec(
+		"UPDATE captain_assistant_responses SET embedding = ?::vector WHERE id = ?",
+		vecStr, id,
+	).Error
+}
+
 func (r *CaptainAssistantResponseRepo) Delete(ctx context.Context, id uint) error {
 	return r.db.WithContext(ctx).Delete(&model.CaptainAssistantResponse{}, id).Error
 }
@@ -80,10 +97,18 @@ func (r *CaptainAssistantResponseRepo) ListByDocument(ctx context.Context, docum
 // Reference: Chatwoot Captain::AssistantResponsesSearchService
 func (r *CaptainAssistantResponseRepo) SimilaritySearch(ctx context.Context, assistantID uint, embedding pgvector.Vector, limit int) ([]model.CaptainAssistantResponse, error) {
 	var responses []model.CaptainAssistantResponse
+	// Format embedding as PG vector literal for the <=> operator (stub has no driver.Valuer).
+	strs := make([]string, len(embedding))
+	for i, v := range embedding {
+		strs[i] = strconv.FormatFloat(float64(v), 'f', -1, 32)
+	}
+	vecStr := "[" + strings.Join(strs, ",") + "]"
 	// Cosine distance (<=>) orders by closest first.
+	// Omit embedding column from SELECT — the pgvector stub can't scan it back.
 	if err := r.db.WithContext(ctx).
+		Select("id, account_id, assistant_id, documentable_id, documentable_type, question, answer, status, edited, created_at, updated_at").
 		Where("assistant_id = ? AND status = ?", assistantID, model.ResponseStatusApproved).
-		Order(gorm.Expr("embedding <=> ?", embedding)).
+		Order(gorm.Expr("embedding <=> ?::vector", vecStr)).
 		Limit(limit).
 		Find(&responses).Error; err != nil {
 		return nil, err

backend/internal/router/router.go

@@ -1471,7 +1471,10 @@ func registerV1Routes(g *gin.RouterGroup, h *Handlers) {
 				assistantResponses := captain.Group("/assistant_responses")
 				{
 					// Chatwoot: resources :assistant_responses (standard CRUD)
+					// Register both "" and "/" so Gin does not 307-redirect between them.
+					assistantResponses.POST("", h.CaptainAssistantResponse.Create)
 					assistantResponses.POST("/", h.CaptainAssistantResponse.Create)
+					assistantResponses.GET("", h.CaptainAssistantResponse.List)
 					assistantResponses.GET("/", h.CaptainAssistantResponse.List)
 					assistantResponses.GET("/:response_id", h.CaptainAssistantResponse.Get)
 					assistantResponses.PUT("/:response_id", h.CaptainAssistantResponse.Update)

backend/internal/service/captain_assistant_response_service.go

@@ -22,6 +22,7 @@ type CaptainAssistantResponseService struct {
 	messageRepo      *repository.MessageRepo
 	preferenceRepo   *repository.CaptainPreferenceRepo
 	llmProvider      llm.Provider
+	ragService       *RAGService
 }
 
 func NewCaptainAssistantResponseService(
@@ -42,6 +43,11 @@ func NewCaptainAssistantResponseService(
 	}
 }
 
+// SetRAGService injects the RAG service for auto-indexing FAQ embeddings.
+func (s *CaptainAssistantResponseService) SetRAGService(rag *RAGService) {
+	s.ragService = rag
+}
+
 // --- Request/Response DTOs ---
 
 // ProcessResponseRequest is the input for generating and storing an assistant response.
@@ -269,6 +275,12 @@ func (s *CaptainAssistantResponseService) Create(ctx context.Context, accountID
 	if err := s.responseRepo.Create(ctx, resp); err != nil {
 		return nil, fmt.Errorf("create response: %w", err)
 	}
+	// Auto-index embedding for RAG search
+	if s.ragService != nil {
+		if err := s.ragService.IndexResponse(ctx, resp.ID); err != nil {
+			applogger.L().Warnf("Create assistant response: auto-index embedding failed: %v", err)
+		}
+	}
 	if created, err := s.responseRepo.GetByAccountAndID(ctx, accountID, resp.ID); err == nil {
 		return created, nil
 	}
@@ -301,6 +313,12 @@ func (s *CaptainAssistantResponseService) Update(ctx context.Context, accountID
 	if err := s.responseRepo.Update(ctx, resp); err != nil {
 		return nil, fmt.Errorf("update response: %w", err)
 	}
+	// Re-index embedding when question or answer changed
+	if (questionChanged || answerChanged) && s.ragService != nil {
+		if err := s.ragService.IndexResponse(ctx, resp.ID); err != nil {
+			applogger.L().Warnf("Update assistant response: re-index embedding failed: %v", err)
+		}
+	}
 	return resp, nil
 }
 

backend/internal/service/captain_assistant_service.go

@@ -14,6 +14,7 @@ import (
 	"github.com/gochat/gochat/internal/model"
 	"github.com/gochat/gochat/internal/repository"
 	applogger "github.com/gochat/gochat/pkg/logger"
+	"github.com/pgvector/pgvector-go"
 	"github.com/redis/go-redis/v9"
 	"gorm.io/gorm"
 )
@@ -723,7 +724,17 @@ func (s *CaptainAssistantService) generatePlaygroundLLMResponse(ctx context.Cont
 
 	cfg, _ := assistant.GetConfig()
 	ctx = withAssistantGenerationConfig(ctx, cfg)
-	messages := []llm.ChatMessage{{Role: "system", Content: s.promptBuilder.BuildAssistantPrompt(assistant, cfg)}}
+
+	// RAG: embed the latest user message and search approved FAQ responses.
+	// This mirrors Chatwoot's Captain playground which injects knowledge base context.
+	systemPrompt := s.promptBuilder.BuildAssistantPrompt(assistant, cfg)
+	ragContext := s.retrieveFAQContext(ctx, assistant.ID, cfg, history)
+	if ragContext != "" {
+		systemPrompt += "\n\n" + ragContext
+		systemPrompt += "\n\nUse the above FAQ entries as reference when answering. If the FAQ entries are relevant, incorporate their information. If not, rely on your general knowledge."
+	}
+
+	messages := []llm.ChatMessage{{Role: "system", Content: systemPrompt}}
 	for _, message := range history {
 		if message.Role == "" || message.Content == "" {
 			continue
@@ -751,6 +762,61 @@ func (s *CaptainAssistantService) generatePlaygroundLLMResponse(ctx context.Cont
 	return resp.Choices[0].Message.Content, nil
 }
 
+// retrieveFAQContext generates an embedding for the latest user message,
+// searches approved FAQ responses via pgvector, and returns formatted context.
+// Returns empty string if RAG is disabled, no embedding available, or no results.
+func (s *CaptainAssistantService) retrieveFAQContext(ctx context.Context, assistantID uint, cfg *model.AssistantConfig, history []PlaygroundMessage) string {
+	if cfg != nil && !cfg.FeatureFAQ {
+		return ""
+	}
+
+	// Extract the latest user message
+	userMsg := ""
+	for i := len(history) - 1; i >= 0; i-- {
+		if history[i].Role == "user" {
+			userMsg = history[i].Content
+			break
+		}
+	}
+	if userMsg == "" {
+		return ""
+	}
+
+	// Generate embedding for the question
+	embedResp, err := s.llmProvider.CreateEmbedding(ctx, llm.EmbeddingRequest{
+		Input: []string{userMsg},
+	})
+	if err != nil {
+		applogger.L().Warnf("retrieveFAQContext: embedding generation failed: %v", err)
+		return ""
+	}
+	if len(embedResp.Data) == 0 {
+		return ""
+	}
+
+	float32Emb := make([]float32, len(embedResp.Data[0].Embedding))
+	for i, v := range embedResp.Data[0].Embedding {
+		float32Emb[i] = float32(v)
+	}
+	pgvectorEmb := pgvector.NewVector(float32Emb)
+
+	// Search approved FAQ responses by embedding similarity
+	results, err := s.responseRepo.SearchByEmbedding(ctx, assistantID, pgvectorEmb, 5)
+	if err != nil {
+		applogger.L().Warnf("retrieveFAQContext: FAQ search failed: %v", err)
+		return ""
+	}
+	if len(results) == 0 {
+		return ""
+	}
+
+	var contextParts []string
+	for i, r := range results {
+		contextParts = append(contextParts, fmt.Sprintf("[FAQ %d]\nQ: %s\nA: %s", i+1, r.Question, r.Answer))
+	}
+	return "Knowledge Base Context:\n" + strings.Join(contextParts, "\n\n")
+}
+
 func withAssistantGenerationConfig(ctx context.Context, cfg *model.AssistantConfig) context.Context {
 	if cfg == nil || !cfg.TemperatureConfigured {
 		return ctx

backend/internal/service/rag_service.go

@@ -54,7 +54,7 @@ type AssistantRepoIface interface {
 type ResponseRepoIface interface {
 	SearchByEmbedding(ctx context.Context, assistantID uint, embedding pgvector.Vector, limit int) ([]model.CaptainAssistantResponse, error)
 	GetByID(ctx context.Context, id uint) (*model.CaptainAssistantResponse, error)
-	Update(ctx context.Context, resp *model.CaptainAssistantResponse) error
+	UpdateEmbedding(ctx context.Context, id uint, embedding pgvector.Vector) error
 }
 
 // RAGService orchestrates embedding search + LLM generation for knowledge base Q&A.
@@ -265,8 +265,7 @@ func (s *RAGService) IndexResponse(ctx context.Context, responseID uint) error {
 		for i, v := range embedResp.Data[0].Embedding {
 			float32Emb[i] = float32(v)
 		}
-		resp.Embedding = pgvector.NewVector(float32Emb)
-		if err := s.responseRepo.Update(ctx, resp); err != nil {
+		if err := s.responseRepo.UpdateEmbedding(ctx, resp.ID, pgvector.NewVector(float32Emb)); err != nil {
 			applogger.L().Errorf("RAG update response embedding: %v", err)
 			return fmt.Errorf("store embedding failed: %w", err)
 		}

backend/internal/service/rag_service_test.go

@@ -31,7 +31,7 @@ type mockResponseRepo struct {
 	searchByEmbeddingError  error
 	getByIDResult           *model.CaptainAssistantResponse
 	getByIDError            error
-	updateError             error
+	updateEmbeddingError    error
 }
 
 func (m *mockResponseRepo) SearchByEmbedding(ctx context.Context, assistantID uint, embedding pgvector.Vector, limit int) ([]model.CaptainAssistantResponse, error) {
@@ -42,8 +42,8 @@ func (m *mockResponseRepo) GetByID(ctx context.Context, id uint) (*model.Captain
 	return m.getByIDResult, m.getByIDError
 }
 
-func (m *mockResponseRepo) Update(ctx context.Context, resp *model.CaptainAssistantResponse) error {
-	return m.updateError
+func (m *mockResponseRepo) UpdateEmbedding(ctx context.Context, id uint, embedding pgvector.Vector) error {
+	return m.updateEmbeddingError
 }
 
 // ========== RAG Service Tests ==========

frontend/app/javascript/dashboard/components-next/captain/pageComponents/response/CreateResponseDialog.vue

@@ -43,12 +43,12 @@ const handleSubmit = async updatedResponse => {
     if (props.type === 'edit') {
       await updateResponse({
         ...updatedResponse,
-        assistant_id: route.params.assistantId,
+        assistant_id: Number(route.params.assistantId),
       });
     } else {
       await createResponse({
         ...updatedResponse,
-        assistant_id: route.params.assistantId,
+        assistant_id: Number(route.params.assistantId),
       });
     }
     useAlert(t(`${i18nKey.value}.SUCCESS_MESSAGE`));