fix: signature delimiter fold misses self-closing <br/> breaks (#1774)

static/js/emailLibrary/signatureFold.js

@@ -298,7 +298,7 @@ export function _foldSignature(html, hintSig) {
   m = html.match(/<div[^>]*id=["'](?:Signature|signature|divRplyFwdMsg)["'][\s\S]*$/i);
   if (m) return wrap(html.slice(0, html.length - m[0].length), '', m[0]);
 
-  m = html.match(/(<br>|\n)\s*--\s*(<br>|\n)([\s\S]*)$/i);
+  m = html.match(/(<br\s*\/?>|\n)\s*--\s*(<br\s*\/?>|\n)([\s\S]*)$/i);
   if (m) {
     const idx = html.lastIndexOf(m[0]);
     return wrap(html.slice(0, idx), m[1], m[3]);

tests/test_signature_fold_self_closing_br_js.py

@@ -0,0 +1,52 @@
+"""Pin the RFC-3676 "-- " signature delimiter fold for self-closing breaks.
+
+_foldSignature folded the standard "-- " sig delimiter only when the
+surrounding line breaks were the literal `<br>`; the regex missed `<br/>`
+and `<br />` (what Apple Mail and many clients emit), even though the very
+next matcher in the same function already uses `<br\\s*/?>`. So a plain-text
+signature delimiter with self-closing breaks was never folded.
+"""
+import json
+import shutil
+import subprocess
+from pathlib import Path
+
+import pytest
+
+_REPO = Path(__file__).resolve().parent.parent
+_MOD = _REPO / "static" / "js" / "emailLibrary" / "signatureFold.js"
+_HAS_NODE = shutil.which("node") is not None
+
+
+def _folds(html):
+    js = f"""
+    globalThis.document = {{ createElement: () => {{ let t=''; return {{ set textContent(v){{t=String(v);}}, get innerHTML(){{return t;}} }}; }} }};
+    const mod = await import('{_MOD.as_posix()}');
+    const html = {json.dumps(html)};
+    const out = mod._foldSignature(html, null);
+    console.log(JSON.stringify(out.includes('email-sig-fold')));
+    """
+    proc = subprocess.run(["node", "--input-type=module"], input=js,
+                          capture_output=True, text=True, cwd=str(_REPO), timeout=30)
+    assert proc.returncode == 0, proc.stderr
+    return json.loads(proc.stdout.strip())
+
+
+_SIG = "X" * 250  # long enough to be a "bloated" foldable signature
+
+
+@pytest.mark.skipif(not _HAS_NODE, reason="node binary not on PATH")
+def test_self_closing_br_delimiter_folds():
+    assert _folds(f"Hello, please review.<br />-- <br />John Smith<br />Acme<br />{_SIG}") is True
+    assert _folds(f"Hi.<br/>-- <br/>Jane Doe<br/>{_SIG}") is True
+
+
+@pytest.mark.skipif(not _HAS_NODE, reason="node binary not on PATH")
+def test_classic_br_delimiter_still_folds():
+    assert _folds(f"Hello.<br>-- <br>John Smith<br>{_SIG}") is True
+
+
+@pytest.mark.skipif(not _HAS_NODE, reason="node binary not on PATH")
+def test_short_signature_is_not_folded():
+    # not bloated -> wrap() returns the html unchanged (no fold)
+    assert _folds("Hello.<br />-- <br />JS") is False