fix(email-renderer): preserve fallbacks when AMP validation is unavailable

packages/email-renderer/src/email.ts

@@ -110,6 +110,9 @@ export async function renderEmail(
     variables?: Record<string, unknown>;
     requireVariables?: boolean;
     countdownImageUrl?: string;
+    /** Trusted host injection; never sourced from the editable document. */
+    ampValidator?: (content: string) => Promise<ValidationReport>;
+    ampValidationTimeoutMs?: number;
   } = {},
 ): Promise<Result<EmailRenderBundle>> {
   const personalized = resolveDocumentVariables(document, emailKind.variables, options.variables, {
@@ -164,10 +167,23 @@ export async function renderEmail(
     const amp = await renderTree(source, emailKind, registry, { ...base, target: "ampEmail", data: options.variables });
     if (amp.ok) {
       const content = ampHead(source, amp.value.content, base.direction);
-      const validation = await validateAmpEmail(content);
+      let timer: ReturnType<typeof setTimeout> | undefined;
+      let validation: ValidationReport;
+      const requestedTimeout = options.ampValidationTimeoutMs ?? 2000;
+      const timeout = Number.isFinite(requestedTimeout) ? Math.min(10000, Math.max(10, requestedTimeout)) : 2000;
+      try {
+        validation = await Promise.race([
+          Promise.resolve().then(() => (options.ampValidator ?? validateAmpEmail)(content)),
+          new Promise<never>((_, reject) => { timer = setTimeout(() => reject(new Error("AMP validation timed out.")), timeout); }),
+        ]);
+      } catch {
+        validation = { valid: false, diagnostics: [{code:"amp.validatorUnavailable",message:"AMP validation was unavailable or timed out. HTML and plain text remain available.",severity:"warning"}] };
+      } finally {
+        if (timer !== undefined) clearTimeout(timer);
+      }
       if (validation.valid)
         bundle.parts.amp = { contentType: "text/x-amp-html; charset=utf-8", content, validation };
-      else warnings.push(...validation.diagnostics);
+      else warnings.push(...validation.diagnostics.map(diagnostic => ({...diagnostic,severity:"warning" as const})));
     } else
       warnings.push(...amp.errors.map((error) => ({ ...error, severity: "warning" as const })));
   }