fix(notifications): use <wbr> instead of soft-hyphens in HTML emails

src/sentry/templates/sentry/emails/_group.html

@@ -15,7 +15,7 @@ <h3>
           {% endif %}
           <br />
           {% if metadata.value %}
-            <small>{{ metadata.value|truncatechars:100|soft_break:40 }}</small>
+            <small>{{ metadata.value|truncatechars:100|soft_break_html:40 }}</small>
           {% endif %}
           {% else %}
           {%if rule %}
@@ -57,7 +57,7 @@ <h3>
         {% endif %}
         <br />
         {% if metadata.value %}
-          <small>{{ metadata.value|truncatechars:100|soft_break:40 }}</small>
+          <small>{{ metadata.value|truncatechars:100|soft_break_html:40 }}</small>
         {% endif %}
      </h3>
     </div>

src/sentry/templates/sentry/emails/issue_alert_base.html

@@ -110,7 +110,7 @@ <h3>
                         {% endif %}
                         <br />
                         {% if metadata.value %}
-                          <small>{{ metadata.value|truncatechars:100|soft_break:40 }}</small>
+                          <small>{{ metadata.value|truncatechars:100|soft_break_html:40 }}</small>
                         {% endif %}
                       {% else %}
                         <a href="{% absolute_uri link %}">{{ metadata.value|truncatechars:40 }}</a><br />
@@ -151,7 +151,7 @@ <h3>
                       {% endif %}
                       <br />
                       {% if subtitle and not is_new_design %}
-                        <small>{{ subtitle|truncatechars:40|soft_break:40 }}</small>
+                        <small>{{ subtitle|truncatechars:40|soft_break_html:40 }}</small>
                       {% endif %}
                     </h3>
                   </div>

src/sentry/templatetags/sentry_helpers.py

@@ -179,7 +179,11 @@ def small_count(v, precision=1):
 
 @register.filter
 def as_tag_alias(v):
-    return {"sentry:release": "release", "sentry:dist": "dist", "sentry:user": "user"}.get(v, v)
+    return {
+        "sentry:release": "release",
+        "sentry:dist": "dist",
+        "sentry:user": "user",
+    }.get(v, v)
 
 
 @register.simple_tag(takes_context=True)
@@ -295,6 +299,28 @@ def soft_break(value, length):
     )
 
 
+@register.filter(is_safe=True)
+def soft_break_html(value, length):
+    """HTML-safe variant of ``soft_break``.
+
+    Uses ``<wbr>`` tags instead of Unicode soft-hyphens (``\\u00ad``) and
+    zero-width spaces (``\\u200b``).  This provides identical line-break
+    hints for email clients while ensuring that copied text contains no
+    invisible characters that break searches in editors and tools.
+    """
+    from django.utils.html import escape
+
+    escaped = escape(value)
+    return mark_safe(
+        _soft_break(
+            escaped,
+            length,
+            functools.partial(soft_hyphenate, length=max(length // 10, 10), hyphen="<wbr>"),
+            delimiter_break="<wbr>",
+        )
+    )
+
+
 @register.simple_tag
 def random_int(a, b=None):
     if b is None:

src/sentry/utils/strings.py

@@ -88,11 +88,25 @@ def soft_hyphenate(value: str, length: int, hyphen: str = "\u00ad") -> str:
     return hyphen.join([value[i : (i + length)] for i in range(0, len(value), length)])
 
 
-def soft_break(value: str, length: int, process: Callable[[str], str] = lambda chunk: chunk) -> str:
+def soft_break(
+    value: str,
+    length: int,
+    process: Callable[[str], str] = lambda chunk: chunk,
+    delimiter_break: str = "\u200b",
+) -> str:
     """
     Encourages soft breaking of text values above a maximum length by adding
     zero-width spaces after common delimiters, as well as soft-hyphenating long
     identifiers.
+
+    Args:
+        value: The text to process.
+        length: Minimum token length before soft-breaking kicks in.
+        process: Callable applied to non-delimiter chunks (e.g. ``soft_hyphenate``).
+        delimiter_break: Character inserted after each delimiter to hint a line
+            break.  Defaults to ``\\u200b`` (zero-width space).  Pass ``<wbr>``
+            for HTML contexts so that copied text contains no invisible
+            characters.
     """
     delimiters = re.compile(r"([{}]+)".format("".join(map(re.escape, ",.$:/+@!?()<>[]{}"))))
 
@@ -103,11 +117,11 @@ def soft_break_delimiter(match: re.Match[str]) -> str:
         chunks = delimiters.split(value)
         for i, chunk in enumerate(chunks):
             if i % 2 == 1:  # check if this is this a delimiter
-                results.extend([chunk, "\u200b"])
+                results.extend([chunk, delimiter_break])
             else:
                 results.append(process(chunk))
 
-        return "".join(results).rstrip("\u200b")
+        return "".join(results).rstrip(delimiter_break)
 
     return re.sub(rf"\S{{{length},}}", soft_break_delimiter, value)