diff --git a/desktop/src/features/messages/lib/mentionHighlightExtension.ts b/desktop/src/features/messages/lib/mentionHighlightExtension.ts
index d688631101e..82b54135d63 100644
--- a/desktop/src/features/messages/lib/mentionHighlightExtension.ts
+++ b/desktop/src/features/messages/lib/mentionHighlightExtension.ts
@@ -565,10 +565,7 @@ export function buildHighlightPatterns(
       n.replace(/[.*+?^${}()|[\]\\]/g, "\\$&"),
     );
     patterns.push(
-      new RegExp(
-        `(?:^|(?<=[\\s(]))@(${escapedNames.join("|")})(?=\\W|$)`,
-        "gi",
-      ),
+      new RegExp(`(^|[\\s(])@(${escapedNames.join("|")})(?=\\W|$)`, "gi"),
     );
   }
 
@@ -580,10 +577,7 @@ export function buildHighlightPatterns(
       n.replace(/[.*+?^${}()|[\]\\]/g, "\\$&"),
     );
     patterns.push(
-      new RegExp(
-        `(?:^|(?<=\\s))#(${escapedChannels.join("|")})(?=\\W|$)`,
-        "gi",
-      ),
+      new RegExp(`(^|\\s)#(${escapedChannels.join("|")})(?=\\W|$)`, "gi"),
     );
   }
 
@@ -671,7 +665,15 @@ export function findHighlightMatches(
     pattern.lastIndex = 0;
     let m: RegExpExecArray | null = pattern.exec(text);
     while (m !== null) {
-      results.push({ from: m.index, to: m.index + m[0].length, match: m[0] });
+      // Group 1 is the boundary prefix (empty at start-of-text). It replaces
+      // the previous lookbehind, which macOS 12's WebKit cannot parse
+      // (see block/buzz#3295); skip it so offsets point at the @/# sigil.
+      const prefixLen = m[1] ? m[1].length : 0;
+      results.push({
+        from: m.index + prefixLen,
+        to: m.index + m[0].length,
+        match: m[0].slice(prefixLen),
+      });
       m = pattern.exec(text);
     }
   }
diff --git a/desktop/src/features/settings/ui/KeyboardShortcutsCard.tsx b/desktop/src/features/settings/ui/KeyboardShortcutsCard.tsx
index c9c12b94216..8b0a7de31c7 100644
--- a/desktop/src/features/settings/ui/KeyboardShortcutsCard.tsx
+++ b/desktop/src/features/settings/ui/KeyboardShortcutsCard.tsx
@@ -10,11 +10,34 @@ import {
 } from "./SettingsOptionGroup";
 import { SettingsSectionHeader } from "./SettingsSectionHeader";
 
+// Split a key-combo string on "+" separators. A "+" is a separator unless it
+// directly follows another "+" (so "⌘++" keeps "+" as a key) or only
+// whitespace remains after it (so a trailing "+" stays attached). Mirrors the
+// previous /(?<!\+)\+(?!\s*$)/ split without lookbehind/lookahead.
+function splitKeyCombo(keys: string): string[] {
+  const parts: string[] = [];
+  let current = "";
+  for (let i = 0; i < keys.length; i++) {
+    const ch = keys[i];
+    const isSeparator =
+      ch === "+" && keys[i - 1] !== "+" && keys.slice(i + 1).trim() !== "";
+    if (isSeparator) {
+      parts.push(current);
+      current = "";
+    } else {
+      current += ch;
+    }
+  }
+  parts.push(current);
+  return parts;
+}
+
 function KeyCombo({ shortcut }: { shortcut: KeyboardShortcut }) {
   const keys = getPlatformKeys(shortcut);
-  // Split on "+" but keep "+" as a standalone key (e.g. for zoom-in "⌘+")
-  const parts = keys
-    .split(/(?<!\+)\+(?!\s*$)/)
+  // Split on "+" but keep "+" as a standalone key (e.g. for zoom-in "⌘+").
+  // Implemented without RegExp lookbehind so the bundle parses on macOS 12's
+  // system WebKit (Safari 16.4 feature). See block/buzz#3295.
+  const parts = splitKeyCombo(keys)
     .map((p) => p.trim())
     .filter(Boolean);
 
diff --git a/desktop/vite.config.ts b/desktop/vite.config.ts
index ca51271dfa1..6afe2335a4d 100644
--- a/desktop/vite.config.ts
+++ b/desktop/vite.config.ts
@@ -52,6 +52,13 @@ export default defineConfig(async ({ mode }) => {
       },
     },
 
+    // Target Safari 15 so the bundle parses on macOS 12's system WebKit (613),
+    // which lacks Safari 16.4 syntax (e.g. RegExp lookbehind in literals,
+    // class static blocks). See https://github.com/block/buzz/issues/3295
+    build: {
+      target: ["es2020", "safari15"],
+    },
+
     // Vite options tailored for Tauri development and only applied in `tauri dev` or `tauri build`
     //
     // 1. prevent Vite from obscuring rust errors
diff --git a/patches/mdast-util-gfm-autolink-literal@2.0.1.patch b/patches/mdast-util-gfm-autolink-literal@2.0.1.patch
new file mode 100644
index 00000000000..3f05ef236d7
--- /dev/null
+++ b/patches/mdast-util-gfm-autolink-literal@2.0.1.patch
@@ -0,0 +1,13 @@
+diff --git a/lib/index.js b/lib/index.js
+index c5ca771c24dd914e342f791716a822431ee32b3a..7fcfaf8441a81d42cceb059c7f48925373e794d3 100644
+--- a/lib/index.js
++++ b/lib/index.js
+@@ -132,7 +132,7 @@ function transformGfmAutolinkLiterals(tree) {
+     tree,
+     [
+       [/(https?:\/\/|www(?=\.))([-.\w]+)([^ \t\r\n]*)/gi, findUrl],
+-      [/(?<=^|\s|\p{P}|\p{S})([-.\w+]+)@([-\w]+(?:\.[-\w]+)+)/gu, findEmail]
++      [/([-.\w+]+)@([-\w]+(?:\.[-\w]+)+)/gu, findEmail]
+     ],
+     {ignore: ['link', 'linkReference']}
+   )
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 8476d3dd321..59565029214 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -10,6 +10,7 @@ overrides:
 
 patchedDependencies:
   isomorphic-git: e9b414a60d4cf1d8aa18f7a779483984e821989967c235662566e94ef0238d3f
+  mdast-util-gfm-autolink-literal@2.0.1: b6c92ec682456ca4b035718f71ee2b4a77d00da4c08cbc5e235e99eaabd96c45
   virtua@0.49.3: 30a7a92b94800ec37be8d36546ea98c04a05dcd0637f9fac27a06f016ba2eff4
 
 importers:
@@ -6069,7 +6070,7 @@ snapshots:
     transitivePeerDependencies:
       - supports-color
 
-  mdast-util-gfm-autolink-literal@2.0.1:
+  mdast-util-gfm-autolink-literal@2.0.1(patch_hash=b6c92ec682456ca4b035718f71ee2b4a77d00da4c08cbc5e235e99eaabd96c45):
     dependencies:
       '@types/mdast': 4.0.4
       ccount: 2.0.1
@@ -6117,7 +6118,7 @@ snapshots:
   mdast-util-gfm@3.1.0:
     dependencies:
       mdast-util-from-markdown: 2.0.3
-      mdast-util-gfm-autolink-literal: 2.0.1
+      mdast-util-gfm-autolink-literal: 2.0.1(patch_hash=b6c92ec682456ca4b035718f71ee2b4a77d00da4c08cbc5e235e99eaabd96c45)
       mdast-util-gfm-footnote: 2.1.0
       mdast-util-gfm-strikethrough: 2.0.0
       mdast-util-gfm-table: 2.0.0
diff --git a/pnpm-workspace.yaml b/pnpm-workspace.yaml
index be122c50ced..58da346f1e0 100644
--- a/pnpm-workspace.yaml
+++ b/pnpm-workspace.yaml
@@ -20,4 +20,5 @@ overrides:
   linkify-it: "^5.0.2"
 patchedDependencies:
   isomorphic-git: patches/isomorphic-git.patch
+  mdast-util-gfm-autolink-literal@2.0.1: patches/mdast-util-gfm-autolink-literal@2.0.1.patch
   virtua@0.49.3: patches/virtua@0.49.3.patch