feat: add TypeSafe Jev as HITL audit backend

Let audit_agent approve or reject with one System One call instead of chat JSON, while keeping the OpenAI-compatible backend as an option.

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/typesafe/client.go

@@ -0,0 +1,196 @@
+package typesafe
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+	"time"
+)
+
+const (
+	DefaultBaseURL = "https://api.typesafe.ai"
+	DefaultModel   = "jev-latest"
+)
+
+// Client calls TypeSafe System One (Jev).
+type Client struct {
+	httpClient *http.Client
+	baseURL    string
+	apiKey     string
+	model      string
+}
+
+// APIError is a non-2xx TypeSafe HTTP response.
+type APIError struct {
+	StatusCode int
+	Body       string
+}
+
+func (e *APIError) Error() string {
+	return fmt.Sprintf("typesafe api error: status=%d body=%s", e.StatusCode, e.Body)
+}
+
+// NewClient builds a System One client. Empty baseURL/model use TypeSafe defaults.
+func NewClient(baseURL, apiKey, model string, httpClient *http.Client) *Client {
+	if httpClient == nil {
+		httpClient = &http.Client{Timeout: 90 * time.Second}
+	}
+	baseURL = strings.TrimSuffix(strings.TrimSpace(baseURL), "/")
+	if baseURL == "" {
+		baseURL = DefaultBaseURL
+	}
+	model = strings.TrimSpace(model)
+	if model == "" {
+		model = DefaultModel
+	}
+	return &Client{
+		httpClient: httpClient,
+		baseURL:    baseURL,
+		apiKey:     strings.TrimSpace(apiKey),
+		model:      model,
+	}
+}
+
+// Question is a typed System One question (noul / choice / score).
+type Question map[string]any
+
+// Noul builds a yes/no question.
+func Noul(instructions string, trueMean, falseMean string) Question {
+	q := Question{
+		"type":         "noul",
+		"instructions": instructions,
+	}
+	if strings.TrimSpace(trueMean) != "" || strings.TrimSpace(falseMean) != "" {
+		q["criteria"] = map[string]string{
+			"true":  trueMean,
+			"false": falseMean,
+		}
+	}
+	return q
+}
+
+// Choice builds a closed-set question.
+func Choice(instructions string, criteria map[string]string) Question {
+	return Question{
+		"type":         "choice",
+		"instructions": instructions,
+		"criteria":     criteria,
+	}
+}
+
+// Result is a System One evaluation response.
+type Result struct {
+	Model   string                    `json:"model"`
+	Answers map[string]map[string]any `json:"answers"`
+	Usage   Usage                     `json:"usage"`
+}
+
+// Usage reports token counts.
+type Usage struct {
+	InputTokens  int `json:"input_tokens"`
+	OutputTokens int `json:"output_tokens"`
+}
+
+// Noul returns the probability that question id is yes.
+func (r *Result) Noul(id string) float64 {
+	if r == nil {
+		return 0
+	}
+	ans, ok := r.Answers[id]
+	if !ok || ans == nil {
+		return 0
+	}
+	switch v := ans["noul"].(type) {
+	case float64:
+		return v
+	case json.Number:
+		f, _ := v.Float64()
+		return f
+	default:
+		return 0
+	}
+}
+
+// Choice returns the selected option and confidence.
+func (r *Result) Choice(id string) (choice string, confidence float64) {
+	if r == nil {
+		return "", 0
+	}
+	ans, ok := r.Answers[id]
+	if !ok || ans == nil {
+		return "", 0
+	}
+	choice, _ = ans["choice"].(string)
+	switch v := ans["confidence"].(type) {
+	case float64:
+		confidence = v
+	case json.Number:
+		confidence, _ = v.Float64()
+	}
+	return strings.TrimSpace(choice), confidence
+}
+
+type systemOneRequest struct {
+	State     any                 `json:"state"`
+	Model     string              `json:"model"`
+	Questions map[string]Question `json:"questions"`
+}
+
+// SystemOne evaluates state against questions.
+func (c *Client) SystemOne(ctx context.Context, state any, questions map[string]Question) (*Result, error) {
+	if c == nil {
+		return nil, fmt.Errorf("typesafe client is not initialized")
+	}
+	if strings.TrimSpace(c.apiKey) == "" {
+		return nil, fmt.Errorf("typesafe api key is empty")
+	}
+	if len(questions) == 0 {
+		return nil, fmt.Errorf("typesafe questions are empty")
+	}
+	if ctx == nil {
+		ctx = context.Background()
+	}
+
+	body, err := json.Marshal(systemOneRequest{
+		State:     state,
+		Model:     c.model,
+		Questions: questions,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("marshal typesafe payload: %w", err)
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, c.baseURL+"/v1/systemone", bytes.NewReader(body))
+	if err != nil {
+		return nil, fmt.Errorf("build typesafe request: %w", err)
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Authorization", "Bearer "+c.apiKey)
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("call typesafe api: %w", err)
+	}
+	defer resp.Body.Close()
+
+	respBody, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("read typesafe response: %w", err)
+	}
+	if resp.StatusCode != http.StatusOK {
+		return nil, &APIError{StatusCode: resp.StatusCode, Body: string(respBody)}
+	}
+
+	var out Result
+	if err := json.Unmarshal(respBody, &out); err != nil {
+		return nil, fmt.Errorf("decode typesafe response: %w", err)
+	}
+	if out.Answers == nil {
+		out.Answers = map[string]map[string]any{}
+	}
+	return &out, nil
+}