Configure PromptKit transient retries

internal/core/config/validation_contract_test.go

@@ -89,6 +89,22 @@ func TestValidatePromptKitSourcesAreMutuallyExclusive(t *testing.T) {
 	assertValidationContains(t, cfg, "promptkit profile_dir and profile_file are mutually exclusive")
 }
 
+func TestValidatePromptKitTransientRetries(t *testing.T) {
+	if got := Default().PromptKit.TransientRetries; got != defaultTransientRetries {
+		t.Fatalf("default transient retries = %d, want %d", got, defaultTransientRetries)
+	}
+	for _, retries := range []int{0, 4} {
+		cfg := Default()
+		cfg.PromptKit.TransientRetries = retries
+		if err := cfg.Validate(); err != nil {
+			t.Fatalf("Validate() with transient retries %d error = %v", retries, err)
+		}
+	}
+	negative := Default()
+	negative.PromptKit.TransientRetries = -1
+	assertValidationContains(t, negative, "promptkit.transient_retries must not be negative")
+}
+
 func TestValidatePromptKitLocalBackendEndpoints(t *testing.T) {
 	tests := []struct {
 		name          string