Add user defined system message

internal/llm/llm.go

@@ -22,8 +22,8 @@ type Config struct {
 	Key string `yaml:"key"`
 	// Model is the model identifier.
 	Model string `yaml:"model"`
-	// SystemPrompt is prepended to all conversations.
-	SystemPrompt string `yaml:"system_prompt"`
+	// SystemMessage is prepended to all conversations.
+	SystemMessage string `yaml:"system_message"`
 	// Timeout is the maximum duration for a query (e.g., "5m").
 	// Defaults to 5 minutes if empty.
 	Timeout string `yaml:"timeout"`
@@ -49,13 +49,13 @@ func (cfg Config) Validate() error {
 
 // Client wraps an OpenAI-compatible client with tool execution support.
 type Client struct {
-	client       *openai.Client
-	log          *slog.Logger
-	model        string
-	registry     *tool.Registry
-	systemPrompt string
-	timeout      time.Duration
-	tools        []openai.Tool
+	client        *openai.Client
+	log           *slog.Logger
+	model         string
+	registry      *tool.Registry
+	systemMessage string
+	timeout       time.Duration
+	tools         []openai.Tool
 }
 
 // NewClient creates a new LLM client with the provided configuration.
@@ -70,10 +70,10 @@ func NewClient(
 	}
 
 	llm := &Client{
-		log:          log,
-		model:        cfg.Model,
-		systemPrompt: cfg.SystemPrompt,
-		registry:     registry,
+		log:           log,
+		model:         cfg.Model,
+		systemMessage: cfg.SystemMessage,
+		registry:      registry,
 	}
 
 	if cfg.Timeout == "" {
@@ -122,12 +122,14 @@ func (c *Client) DefaultModel() string {
 
 // Query sends messages to the LLM using the specified model.
 // If model is empty, uses the default configured model.
+// If systemMessage is non-empty, it overrides the configured system message.
 // Returns all messages generated during the query, including tool calls
 // and tool results. The final message is the last element in the slice.
 func (c *Client) Query(
 	ctx context.Context,
 	messages []openai.ChatCompletionMessage,
 	model string,
+	systemMessage string,
 ) ([]openai.ChatCompletionMessage, error) {
 	ctx, cancel := context.WithTimeout(ctx, c.timeout)
 	defer cancel()
@@ -137,13 +139,19 @@ func (c *Client) Query(
 		model = c.model
 	}
 
-	// Prepend system prompt, if configured and not already present.
-	if c.systemPrompt != "" && (len(messages) == 0 ||
+	// Use per-request system message if provided, otherwise fall back to config.
+	effectiveMessage := c.systemMessage
+	if systemMessage != "" {
+		effectiveMessage = systemMessage
+	}
+
+	// Prepend system message, if configured and not already present.
+	if effectiveMessage != "" && (len(messages) == 0 ||
 		messages[0].Role != openai.ChatMessageRoleSystem) {
 		messages = append(
 			[]openai.ChatCompletionMessage{{
 				Role:    openai.ChatMessageRoleSystem,
-				Content: c.systemPrompt,
+				Content: effectiveMessage,
 			}},
 			messages...,
 		)
@@ -239,11 +247,13 @@ type StreamEvent struct {
 // streams results. Each complete message (assistant reply, tool call,
 // tool result) is sent to the events channel as it becomes available.
 // The channel is closed before returning.
+// If systemMessage is non-empty, it overrides the configured system message.
 // Returns all messages generated during the query.
 func (c *Client) QueryStream(
 	ctx context.Context,
 	messages []openai.ChatCompletionMessage,
 	model string,
+	systemMessage string,
 	events chan<- StreamEvent,
 ) error {
 	defer close(events)
@@ -256,13 +266,19 @@ func (c *Client) QueryStream(
 		model = c.model
 	}
 
-	// Prepend system prompt, if configured and not already present.
-	if c.systemPrompt != "" && (len(messages) == 0 ||
+	// Use per-request system message if provided, otherwise fall back to config.
+	effectiveMessage := c.systemMessage
+	if systemMessage != "" {
+		effectiveMessage = systemMessage
+	}
+
+	// Prepend system message, if configured and not already present.
+	if effectiveMessage != "" && (len(messages) == 0 ||
 		messages[0].Role != openai.ChatMessageRoleSystem) {
 		messages = append(
 			[]openai.ChatCompletionMessage{{
 				Role:    openai.ChatMessageRoleSystem,
-				Content: c.systemPrompt,
+				Content: effectiveMessage,
 			}},
 			messages...,
 		)