fix: render adjacent email template variables correctly (#3153)

packages/lib/utils/render-custom-email-template.test.ts

@@ -0,0 +1,32 @@
+import { describe, expect, it } from 'vitest';
+
+import { renderCustomEmailTemplate } from './render-custom-email-template';
+
+describe('renderCustomEmailTemplate', () => {
+  it('replaces a single variable', () => {
+    expect(renderCustomEmailTemplate('Hi {name}', { name: 'Sam' })).toBe('Hi Sam');
+  });
+
+  it('replaces multiple variables separated by whitespace', () => {
+    expect(
+      renderCustomEmailTemplate('Hi {name}, sign at {url}', { name: 'Sam', url: 'https://x' }),
+    ).toBe('Hi Sam, sign at https://x');
+  });
+
+  it('replaces adjacent variables and variables separated by a non-whitespace character', () => {
+    expect(
+      renderCustomEmailTemplate('{day}/{month}/{year}', { day: '01', month: '02', year: '2026' }),
+    ).toBe('01/02/2026');
+
+    expect(
+      renderCustomEmailTemplate('{firstName}-{lastName}', {
+        firstName: 'Ada',
+        lastName: 'Lovelace',
+      }),
+    ).toBe('Ada-Lovelace');
+  });
+
+  it('leaves the key in place when the variable is not provided', () => {
+    expect(renderCustomEmailTemplate('Unknown {missing} here', {})).toBe('Unknown missing here');
+  });
+});

packages/lib/utils/render-custom-email-template.ts

@@ -1,5 +1,9 @@
 export const renderCustomEmailTemplate = <T extends Record<string, string>>(template: string, variables: T): string => {
-  return template.replace(/\{(\S+)\}/g, (_, key) => {
+  // Match a run of non-brace, non-whitespace characters between braces. Using
+  // `\S+` here was greedy across braces, so placeholders separated by a
+  // non-whitespace character (e.g. "{day}/{month}/{year}") were captured as a
+  // single bogus key and left unrendered.
+  return template.replace(/\{([^\s{}]+)\}/g, (_, key) => {
     if (key in variables) {
       return variables[key];
     }