fix(email): preserve personalization tokens for template rendering

packages/email-renderer/test/template-variables.test.ts

@@ -0,0 +1,32 @@
+import { expect, test } from "bun:test";
+import { resolveDocumentVariables, type BlockDocument } from "@wrnexus/blocks";
+import { renderEmail } from "../src/index.ts";
+
+const document: BlockDocument = {
+  schemaVersion: 1, kind: "email", meta: { subject: "Hi {{recipientName|friend}}", lang: "en" },
+  theme: { tokens: {} },
+  root: { id: "root", type: "layout.email-document", version: 1, props: {}, styles: {}, slots: {
+    content: [{ id: "text", type: "content.text", version: 1, props: { text: "Hello {{recipientName|friend}}" }, styles: {}, slots: {} }],
+  } },
+};
+
+test("template rendering preserves fallback tokens rather than baking in sample or fallback values", async () => {
+  const before = structuredClone(document);
+  const rendered = await renderEmail(document, { preserveVariables: true, mjml: true, variables: { recipientName: "Preview only" } });
+  expect(rendered.ok).toBe(true);
+  if (!rendered.ok) return;
+  expect(rendered.value.subject).toBe("Hi {{recipientName|friend}}");
+  expect(rendered.value.parts.html.content).toContain("Hello {{recipientName|friend}}");
+  expect(rendered.value.parts.text.content).toContain("Hello {{recipientName|friend}}");
+  expect(rendered.value.exports?.mjml).toContain("Hello {{recipientName|friend}}");
+  expect(document).toEqual(before);
+  const resolved = await renderEmail(document, { variables: { recipientName: "Ada" }, requireVariables: true });
+  expect(resolved.ok && resolved.value.subject).toBe("Hi Ada");
+});
+
+test("preservation still validates token allowlists and cannot masquerade as resolved delivery", () => {
+  const unknown = structuredClone(document);
+  unknown.meta.subject = "{{unregistered}}";
+  expect(resolveDocumentVariables(unknown, { recipientName: "string" }, {}, { preserveTokens: true }).ok).toBe(false);
+  expect(resolveDocumentVariables(document, { recipientName: "string" }, {}, { preserveTokens: true, requireValues: true }).ok).toBe(false);
+});