fix(email-renderer): validate brand settings and apply them to AMP

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

@@ -57,6 +57,25 @@ const document: BlockDocument = {
 };
 
 describe("email renderer", () => {
+  test("AMP inherits the saved brand font, colors and body width", async () => {
+    const draft = structuredClone(document);
+    Object.assign(draft.root.props, {width:"720",fontFamily:"Georgia, serif",textColor:"#112233",linkColor:"#445566",background:"#eeeeee",contentBackground:"#fafafa"});
+    const rendered = await renderEmail(draft, {amp:true});
+    expect(rendered.ok).toBe(true);
+    if (!rendered.ok) return;
+    const amp = rendered.value.parts.amp;
+    expect(amp?.validation.valid).toBe(true);
+    for (const style of ["font-family:Georgia, serif", "color:#112233", "a{color:#445566}", "background:#eeeeee", "background:#fafafa", "max-width:720px"]) expect(amp?.content).toContain(style);
+  });
+  test("brand fields reject arbitrary CSS and invalid widths before rendering", async () => {
+    for (const [key,value] of [["fontFamily","Arial;position:fixed"],["fontFamily","</style><script>alert(1)</script>"],["textColor","red;background:url(https://example.com)"],["background","#fff;display:none"],["width","600;position:absolute"],["width","9999"]]) {
+      const draft = structuredClone(document);
+      draft.root.props[key!] = value!;
+      const rendered = await renderEmail(draft, {amp:true});
+      expect(rendered.ok).toBe(false);
+      if (!rendered.ok) expect(rendered.errors.some(error => error.code === "email.brand")).toBe(true);
+    }
+  });
   test("responsive stacking begins below the desktop email width", async () => {
     const rendered = await renderEmail(document);
     expect(rendered.ok).toBe(true);