Template flow cleaned up

lib/create/loadTemplateReviewBySlug.ts

@@ -0,0 +1,44 @@
+import messages from "../../messages/en/index";
+import {
+  fetchTemplateBySlug,
+  type RuleTemplateDto,
+} from "./fetchTemplates";
+
+export type LoadTemplateReviewResult =
+  | { ok: true; template: RuleTemplateDto }
+  | { ok: false; message: string };
+
+/**
+ * Shared prelude for the two template-review actions (Customize and
+ * "Use without changes") in `CreateFlowLayoutClient`. Wraps the slug →
+ * `RuleTemplateDto` fetch and normalizes its three possible failures
+ * (network / server / not-found) into a single localized error message
+ * suitable for the template-review banner.
+ *
+ * Keeping the localized copy here (rather than in the fetch layer) means
+ * callers only forward `result.message` to `setTemplateReviewApplyError`,
+ * and both handlers resolve identical error text from a single source.
+ *
+ * Malformed template bodies (`body` not an object, missing `sections`,
+ * etc.) remain the caller's responsibility because the expected shape
+ * differs between Customize (prefill lookup) and Use-without-changes
+ * (full section extraction). Those checks stay in the handlers that need
+ * them so errors surface at the step where the shape matters.
+ */
+export async function loadTemplateReviewBySlug(
+  slug: string,
+): Promise<LoadTemplateReviewResult> {
+  const errors = messages.create.templateReview.errors;
+  const result = await fetchTemplateBySlug(slug);
+  if (result === null) {
+    return { ok: false, message: errors.notFound };
+  }
+  if ("error" in result) {
+    const trimmed = typeof result.error === "string" ? result.error.trim() : "";
+    return {
+      ok: false,
+      message: trimmed.length > 0 ? trimmed : errors.applyFailed,
+    };
+  }
+  return { ok: true, template: result };
+}