feat: wire real LLM runner via third-one or OpenAI-compatible API

internal/llm/client.go

@@ -0,0 +1,119 @@
+package llm
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+	"time"
+)
+
+type Client struct {
+	endpoint   string
+	apiKey     string
+	model      string
+	httpClient *http.Client
+}
+
+func NewClient(endpoint, apiKey, model string) *Client {
+	return &Client{
+		endpoint:   strings.TrimRight(endpoint, "/"),
+		apiKey:     apiKey,
+		model:      model,
+		httpClient: &http.Client{Timeout: 60 * time.Second},
+	}
+}
+
+type ChatMessage struct {
+	Role    string `json:"role"`
+	Content string `json:"content"`
+}
+
+type chatRequest struct {
+	Model          string        `json:"model"`
+	Messages       []ChatMessage `json:"messages"`
+	ResponseFormat *responseFmt  `json:"response_format,omitempty"`
+	Temperature    float64       `json:"temperature,omitempty"`
+}
+
+type responseFmt struct {
+	Type string `json:"type"`
+}
+
+type chatResponse struct {
+	Choices []struct {
+		Message ChatMessage `json:"message"`
+	} `json:"choices"`
+	Error *struct {
+		Message string `json:"message"`
+		Type    string `json:"type"`
+	} `json:"error,omitempty"`
+}
+
+func (c *Client) Chat(ctx context.Context, systemPrompt, userPrompt string) (string, error) {
+	return c.ChatJSON(ctx, systemPrompt, userPrompt, false)
+}
+
+func (c *Client) ChatJSON(ctx context.Context, systemPrompt, userPrompt string, jsonMode bool) (string, error) {
+	messages := []ChatMessage{
+		{Role: "system", Content: systemPrompt},
+		{Role: "user", Content: userPrompt},
+	}
+
+	req := chatRequest{
+		Model:    c.model,
+		Messages: messages,
+	}
+
+	if jsonMode {
+		req.ResponseFormat = &responseFmt{Type: "json_object"}
+	}
+
+	body, err := json.Marshal(req)
+	if err != nil {
+		return "", fmt.Errorf("marshal request: %w", err)
+	}
+
+	url := c.endpoint + "/v1/chat/completions"
+	httpReq, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(body))
+	if err != nil {
+		return "", fmt.Errorf("create request: %w", err)
+	}
+	httpReq.Header.Set("Content-Type", "application/json")
+	if c.apiKey != "" {
+		httpReq.Header.Set("Authorization", "Bearer "+c.apiKey)
+	}
+
+	resp, err := c.httpClient.Do(httpReq)
+	if err != nil {
+		return "", fmt.Errorf("http do: %w", err)
+	}
+	defer resp.Body.Close()
+
+	respBody, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return "", fmt.Errorf("read response: %w", err)
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return "", fmt.Errorf("llm api error %d: %s", resp.StatusCode, string(respBody))
+	}
+
+	var chatResp chatResponse
+	if err := json.Unmarshal(respBody, &chatResp); err != nil {
+		return "", fmt.Errorf("unmarshal response: %w", err)
+	}
+
+	if chatResp.Error != nil {
+		return "", fmt.Errorf("llm error: %s", chatResp.Error.Message)
+	}
+
+	if len(chatResp.Choices) == 0 {
+		return "", fmt.Errorf("no choices in response")
+	}
+
+	return chatResp.Choices[0].Message.Content, nil
+}