Prototype ConfigKit and PromptKit adoption and record the findings

examples/library-adoption/offline.go

@@ -0,0 +1,61 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+	"sync"
+)
+
+const validProposal = `{"corrections":[{"id":1,"original_text":"hello world","corrected_text":"Hello, world.","confidence":0.95}]}`
+const validAssessment = `{"validations":[{"correction_index":0,"approved":true,"confidence":0.95,"reason":"Punctuation and capitalization only"}]}`
+
+// roundTripFunc exercises PromptKit's built-in HTTP path without any network.
+type roundTripFunc func(*http.Request) (*http.Response, error)
+
+func (f roundTripFunc) RoundTrip(r *http.Request) (*http.Response, error) { return f(r) }
+
+func providerResponse(status int, content string, usage any) *http.Response {
+	body := map[string]any{"choices": []any{map[string]any{"message": map[string]any{"role": "assistant", "content": content}, "finish_reason": "stop"}}}
+	if status != http.StatusOK {
+		body = map[string]any{"error": map[string]any{"message": "synthetic temporary failure"}}
+	}
+	if usage != nil {
+		body["usage"] = usage
+	}
+	data, _ := json.Marshal(body)
+	return &http.Response{StatusCode: status, Header: make(http.Header), Body: io.NopCloser(strings.NewReader(string(data)))}
+}
+
+func demonstrationClient() *http.Client {
+	var mu sync.Mutex
+	calls := map[string]int{}
+	return &http.Client{Transport: roundTripFunc(func(req *http.Request) (*http.Response, error) {
+		if req.URL.Host != "offline.invalid" {
+			return nil, fmt.Errorf("unexpected offline target")
+		}
+		var body struct {
+			Model string `json:"model"`
+		}
+		if err := json.NewDecoder(req.Body).Decode(&body); err != nil {
+			return nil, err
+		}
+		mu.Lock()
+		calls[body.Model]++
+		n := calls[body.Model]
+		mu.Unlock()
+		if n == 1 {
+			return providerResponse(200, "not JSON", nil), nil
+		}
+		switch body.Model {
+		case "synthetic-grammar":
+			return providerResponse(200, validProposal, nil), nil
+		case "synthetic-review":
+			return providerResponse(200, validAssessment, nil), nil
+		default:
+			return nil, fmt.Errorf("unexpected synthetic model")
+		}
+	})}
+}