feat: Add headless template type

packages/shared/src/index.ts

@@ -2,3 +2,4 @@ export * from './schemas/index.js';
 export * from './operators.js';
 export * from './template.js';
 export * from './i18n/index.js';
+export * from './unsubscribe.js';

packages/shared/src/unsubscribe.ts

@@ -0,0 +1,26 @@
+/**
+ * Detects whether an email body contains an unsubscribe signal.
+ *
+ * Used to warn authors of HEADLESS emails that no unsubscribe mechanism
+ * was found — Plunk cannot verify the link works, but can check for common patterns.
+ *
+ * Returns true if any of the following are present:
+ * - Plunk template variables: {{unsubscribeUrl}} or {{manageUrl}}
+ * - An <a> tag whose href contains unsubscribe-related keywords
+ * - An <a> tag whose visible text contains unsubscribe-related keywords
+ */
+export function detectUnsubscribeSignal(body: string): boolean {
+  if (!body) return false;
+
+  // Plunk's own managed unsubscribe variables
+  if (/\{\{(?:unsubscribeUrl|manageUrl)\}\}/.test(body)) return true;
+
+  // href containing unsubscribe keywords
+  if (/href=["'][^"']*(?:unsubscribe|opt[_-]?out|remove)[^"']*["']/i.test(body)) return true;
+
+  // Anchor text containing unsubscribe keywords
+  if (/<a\b[^>]*>(?:[^<]*(?:unsubscribe|opt[_-]?\s*out|manage\s+preferences|email\s+preferences|remove\s+me)[^<]*)<\/a>/i.test(body))
+    return true;
+
+  return false;
+}