feat: implement AI gateway phase one runtime

apps/api/internal/clients/openai.go

@@ -0,0 +1,87 @@
+package clients
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"net/http"
+	"strings"
+)
+
+type OpenAIClient struct {
+	HTTPClient *http.Client
+}
+
+func (c OpenAIClient) Run(ctx context.Context, request Request) (Response, error) {
+	apiKey := credential(request.Candidate.Credentials, "apiKey", "api_key", "key", "token")
+	if apiKey == "" {
+		return Response{}, &ClientError{Code: "missing_credentials", Message: "openai api key is required", Retryable: false}
+	}
+	endpoint := openAIEndpoint(request.Kind)
+	if endpoint == "" {
+		return Response{}, &ClientError{Code: "unsupported_kind", Message: "unsupported openai request kind", Retryable: false}
+	}
+	body := cloneBody(request.Body)
+	body["model"] = request.Candidate.ModelName
+	raw, _ := json.Marshal(body)
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, joinURL(request.Candidate.BaseURL, endpoint), bytes.NewReader(raw))
+	if err != nil {
+		return Response{}, err
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Authorization", "Bearer "+apiKey)
+	resp, err := httpClient(c.HTTPClient).Do(req)
+	if err != nil {
+		return Response{}, &ClientError{Code: "network", Message: err.Error(), Retryable: true}
+	}
+	result, err := decodeHTTPResponse(resp)
+	if err != nil {
+		return Response{}, err
+	}
+	return Response{Result: result, Usage: usageFromOpenAI(result), Progress: providerProgress(request)}, nil
+}
+
+func openAIEndpoint(kind string) string {
+	switch kind {
+	case "chat.completions":
+		return "/chat/completions"
+	case "responses":
+		return "/responses"
+	case "images.generations":
+		return "/images/generations"
+	case "images.edits":
+		return "/images/edits"
+	default:
+		return ""
+	}
+}
+
+func cloneBody(body map[string]any) map[string]any {
+	out := map[string]any{}
+	for key, value := range body {
+		out[key] = value
+	}
+	return out
+}
+
+func joinURL(base string, path string) string {
+	base = strings.TrimRight(strings.TrimSpace(base), "/")
+	if base == "" {
+		base = "https://api.openai.com/v1"
+	}
+	return base + path
+}
+
+func httpClient(client *http.Client) *http.Client {
+	if client != nil {
+		return client
+	}
+	return http.DefaultClient
+}
+
+func providerProgress(request Request) []Progress {
+	return []Progress{
+		{Phase: "submitting", Progress: 0.35, Message: "provider request submitted", Payload: map[string]any{"clientId": request.Candidate.ClientID}},
+		{Phase: "fetching_result", Progress: 0.8, Message: "provider response received", Payload: map[string]any{"provider": request.Candidate.Provider}},
+	}
+}