feat: enhance RAG functionality with context character limits, query rewriting options, and improved timeout settings

README.md

@@ -133,15 +133,20 @@ history-api/
     GOOGLE_AI_EMBEDDING_MODEL=
 
     OPEN_ROUTER_API=
-    OPEN_ROUTER_MODEL=
-    OPEN_ROUTER_FALLBACK_MODEL=qwen/qwen3-30b-a3b-instruct-2507
+    OPEN_ROUTER_MODEL=qwen/qwen3-30b-a3b-instruct-2507
+    OPEN_ROUTER_FALLBACK_MODEL=google/gemini-2.5-flash-lite
     OPEN_ROUTER_EMBEDDING_MODEL=
 
+    RAG_LLM_TIMEOUT_SECONDS=20
     RAG_QUERY_REWRITE_ENABLED=true
+    RAG_QUERY_REWRITE_MODEL=google/gemini-2.5-flash-lite
+    RAG_QUERY_REWRITE_TIMEOUT_SECONDS=5
+    RAG_QUERY_REWRITE_MAX_TOKENS=96
     RAG_REWRITE_HISTORY_TURNS=3
     RAG_RETRIEVAL_CANDIDATES=30
-    RAG_CONTEXT_TOP_N=8
-    RAG_GENERATION_MAX_RETRIES=2
+    RAG_CONTEXT_TOP_N=5
+    RAG_CONTEXT_MAX_CHARS=8000
+    RAG_GENERATION_MAX_RETRIES=1
     RAG_GENERATION_RETRY_DELAY_MS=500
     RAG_RERANK_ENABLED=true
     RAG_RERANK_MODEL=cohere/rerank-4-pro

internal/services/chatbotService.go

@@ -176,6 +176,7 @@ func (s *chatbotService) Chat(ctx context.Context, userID string, projectID *str
 	rerankStart := time.Now()
 	results = s.rerankResults(ctx, searchQuery, results, contextLimit)
 	rerankDuration := time.Since(rerankStart)
+	results = limitRagResultsByContextChars(results, config.GetIntConfigWithDefault("RAG_CONTEXT_MAX_CHARS", 8000))
 
 	promptBuildStart := time.Now()
 	var contextBuilder strings.Builder
@@ -390,6 +391,34 @@ func limitRagResults(results []*models.RagChunk, limit int) []*models.RagChunk {
 	return results[:limit]
 }
 
+func limitRagResultsByContextChars(results []*models.RagChunk, maxChars int) []*models.RagChunk {
+	if maxChars <= 0 || len(results) == 0 {
+		return results
+	}
+
+	selected := make([]*models.RagChunk, 0, len(results))
+	used := 0
+	for _, result := range results {
+		if result == nil {
+			continue
+		}
+
+		nextLen := len(result.Content) + 64
+		if len(selected) > 0 && used+nextLen > maxChars {
+			break
+		}
+
+		selected = append(selected, result)
+		used += nextLen
+	}
+
+	if len(selected) == 0 {
+		return results[:1]
+	}
+
+	return selected
+}
+
 func normalizeAnswer(s string) string {
 	s = strings.TrimSpace(s)
 

pkg/ai/rag.go

@@ -21,20 +21,23 @@ import (
 )
 
 type RagUtils struct {
-	llm                  llms.Model
-	embedder             *embeddings.EmbedderImpl
-	httpClient           *http.Client
-	openRouterAPIKey     string
-	model                string
-	fallbackModel        string
-	generationMaxRetries int
-	generationRetryDelay time.Duration
-	rerankEnabled        bool
-	rerankModel          string
-	rerankFallbackModel  string
-	rerankMaxRetries     int
-	rerankRetryDelay     time.Duration
-	queryRewriteEnabled  bool
+	llm                   llms.Model
+	embedder              *embeddings.EmbedderImpl
+	httpClient            *http.Client
+	openRouterAPIKey      string
+	model                 string
+	fallbackModel         string
+	generationMaxRetries  int
+	generationRetryDelay  time.Duration
+	rerankEnabled         bool
+	rerankModel           string
+	rerankFallbackModel   string
+	rerankMaxRetries      int
+	rerankRetryDelay      time.Duration
+	queryRewriteEnabled   bool
+	queryRewriteModel     string
+	queryRewriteTimeout   time.Duration
+	queryRewriteMaxTokens int
 }
 
 var htmlTagRegex = regexp.MustCompile(`<[^>]*>`)
@@ -61,11 +64,17 @@ func NewRagUtils() (*RagUtils, error) {
 
 	embeddingModel := config.GetConfigWithDefault("OPEN_ROUTER_EMBEDDING_MODEL", "qwen/qwen3-embedding-8b")
 
+	llmTimeoutSeconds := config.GetIntConfigWithDefault("RAG_LLM_TIMEOUT_SECONDS", 20)
+	if llmTimeoutSeconds <= 0 {
+		llmTimeoutSeconds = 20
+	}
+
 	llm, err := openai.New(
 		openai.WithToken(openRouterAPIKey),
 		openai.WithBaseURL(openRouterBaseURL),
 		openai.WithModel(model),
 		openai.WithEmbeddingModel(embeddingModel),
+		openai.WithHTTPClient(&http.Client{Timeout: time.Duration(llmTimeoutSeconds) * time.Second}),
 	)
 	if err != nil {
 		return nil, fmt.Errorf("failed to init openrouter ai: %w", err)
@@ -107,21 +116,42 @@ func NewRagUtils() (*RagUtils, error) {
 		generationRetryDelayMs = 500
 	}
 
+	queryRewriteModel := strings.TrimSpace(config.GetConfigWithDefault("RAG_QUERY_REWRITE_MODEL", model))
+	if queryRewriteModel == "" {
+		queryRewriteModel = model
+	}
+
+	queryRewriteTimeoutSeconds := config.GetIntConfigWithDefault("RAG_QUERY_REWRITE_TIMEOUT_SECONDS", 5)
+	if queryRewriteTimeoutSeconds < 0 {
+		queryRewriteTimeoutSeconds = 0
+	}
+
+	queryRewriteMaxTokens := config.GetIntConfigWithDefault("RAG_QUERY_REWRITE_MAX_TOKENS", 96)
+	if queryRewriteMaxTokens <= 0 {
+		queryRewriteMaxTokens = 96
+	}
+	if queryRewriteMaxTokens > 512 {
+		queryRewriteMaxTokens = 512
+	}
+
 	return &RagUtils{
-		llm:                  llm,
-		embedder:             embedder,
-		httpClient:           &http.Client{Timeout: time.Duration(timeoutSeconds) * time.Second},
-		openRouterAPIKey:     openRouterAPIKey,
-		model:                model,
-		fallbackModel:        config.GetConfigWithDefault("OPEN_ROUTER_FALLBACK_MODEL", "qwen/qwen3-30b-a3b-instruct-2507"),
-		generationMaxRetries: generationMaxRetries,
-		generationRetryDelay: time.Duration(generationRetryDelayMs) * time.Millisecond,
-		rerankEnabled:        config.GetBoolConfigWithDefault("RAG_RERANK_ENABLED", true),
-		rerankModel:          config.GetConfigWithDefault("RAG_RERANK_MODEL", "cohere/rerank-4-pro"),
-		rerankFallbackModel:  config.GetConfigWithDefault("RAG_RERANK_FALLBACK_MODEL", "cohere/rerank-4-fast"),
-		rerankMaxRetries:     rerankMaxRetries,
-		rerankRetryDelay:     time.Duration(rerankRetryDelayMs) * time.Millisecond,
-		queryRewriteEnabled:  config.GetBoolConfigWithDefault("RAG_QUERY_REWRITE_ENABLED", true),
+		llm:                   llm,
+		embedder:              embedder,
+		httpClient:            &http.Client{Timeout: time.Duration(timeoutSeconds) * time.Second},
+		openRouterAPIKey:      openRouterAPIKey,
+		model:                 model,
+		fallbackModel:         config.GetConfigWithDefault("OPEN_ROUTER_FALLBACK_MODEL", "qwen/qwen3-30b-a3b-instruct-2507"),
+		generationMaxRetries:  generationMaxRetries,
+		generationRetryDelay:  time.Duration(generationRetryDelayMs) * time.Millisecond,
+		rerankEnabled:         config.GetBoolConfigWithDefault("RAG_RERANK_ENABLED", true),
+		rerankModel:           config.GetConfigWithDefault("RAG_RERANK_MODEL", "cohere/rerank-4-pro"),
+		rerankFallbackModel:   config.GetConfigWithDefault("RAG_RERANK_FALLBACK_MODEL", "cohere/rerank-4-fast"),
+		rerankMaxRetries:      rerankMaxRetries,
+		rerankRetryDelay:      time.Duration(rerankRetryDelayMs) * time.Millisecond,
+		queryRewriteEnabled:   config.GetBoolConfigWithDefault("RAG_QUERY_REWRITE_ENABLED", true),
+		queryRewriteModel:     queryRewriteModel,
+		queryRewriteTimeout:   time.Duration(queryRewriteTimeoutSeconds) * time.Second,
+		queryRewriteMaxTokens: queryRewriteMaxTokens,
 	}, nil
 }
 
@@ -202,10 +232,30 @@ Rules:
 
 <query>`, historyText, question)
 
-	raw, err := llms.GenerateFromSinglePrompt(ctx, u.llm, prompt)
+	rewriteCtx := ctx
+	cancel := func() {}
+	if u.queryRewriteTimeout > 0 {
+		rewriteCtx, cancel = context.WithTimeout(ctx, u.queryRewriteTimeout)
+	}
+	defer cancel()
+
+	options := []llms.CallOption{
+		llms.WithModel(u.queryRewriteModel),
+		llms.WithMaxTokens(u.queryRewriteMaxTokens),
+		llms.WithTemperature(0),
+	}
+
+	rewriteStart := time.Now()
+	raw, err := llms.GenerateFromSinglePrompt(rewriteCtx, u.llm, prompt, options...)
 	if err != nil {
 		return "", err
 	}
+	log.Info().
+		Str("model", u.queryRewriteModel).
+		Int("prompt_chars", len(prompt)).
+		Int("response_chars", len(raw)).
+		Dur("duration", time.Since(rewriteStart)).
+		Msg("rag query rewrite succeeded")
 
 	query := normalizeGeneratedQuery(raw)
 	if query == "" {