feat: centralize utility functions, abstract SSE stream collection, and add concurrency to admin account testing.

internal/util/helpers.go

@@ -0,0 +1,37 @@
+package util
+
+import (
+	"encoding/json"
+	"net/http"
+)
+
+// WriteJSON writes a JSON response with the given status code.
+// This is a shared helper to avoid duplicate writeJSON functions
+// in openai, claude, and admin packages.
+func WriteJSON(w http.ResponseWriter, status int, payload any) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	_ = json.NewEncoder(w).Encode(payload)
+}
+
+// ToBool loosely converts an interface value to bool.
+func ToBool(v any) bool {
+	if b, ok := v.(bool); ok {
+		return b
+	}
+	return false
+}
+
+// IntFrom converts a JSON-decoded numeric value (float64, int, int64) to int.
+func IntFrom(v any) int {
+	switch n := v.(type) {
+	case float64:
+		return int(n)
+	case int:
+		return n
+	case int64:
+		return int(n)
+	default:
+		return 0
+	}
+}