From a6a78ff08a31129a3a47fa55aca260d93af913a5 Mon Sep 17 00:00:00 2001
From: Brooklyn Nicholson <brooklyn.bb.nicholson@gmail.com>
Date: Thu, 21 May 2026 18:05:43 -0500
Subject: [PATCH] perf(desktop): use textContent for trigger precondition

Replace composerPlainText() call inside refreshTrigger's no-trigger
fast-bail with a textContent check. textContent is a browser-native
flat traversal; composerPlainText walks recursively with chip-aware
logic. We only need to know if @ or / appears; either way the trigger
char will be in textContent because chips contain @ in their refText.

Profile shows composerPlainText was ~18ms self over a 12s typing-during-
stream window, called from refreshTrigger on every keystroke. Most of
that was the precondition check (the trigger detection path is the
slow path but only runs when a trigger char is present).
---
 apps/desktop/src/app/chat/composer/index.tsx | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/apps/desktop/src/app/chat/composer/index.tsx b/apps/desktop/src/app/chat/composer/index.tsx
index 3c58c41848f..10887fbb8d6 100644
--- a/apps/desktop/src/app/chat/composer/index.tsx
+++ b/apps/desktop/src/app/chat/composer/index.tsx
@@ -408,13 +408,13 @@ export function ChatBar({
     }
 
     // Fast-bail: if neither `@` nor `/` appears in the current draft, there's
-    // nothing for `detectTrigger` to match. Skip the DOM range walk inside
-    // `textBeforeCaret` (which calls `range.toString()`, O(n) over the draft)
-    // and the regex pass that follows. Only when a relevant char is present
-    // do we pay the cost.
-    const text = composerPlainText(editor)
+    // nothing for `detectTrigger` to match. Use `textContent` (cheap browser-
+    // native walk) for the precondition check rather than `composerPlainText`
+    // (recursive child walk with chip-aware logic). Only when a trigger char
+    // is present do we pay the cost of the full walk + DOM range work.
+    const rawText = editor.textContent ?? ''
 
-    if (!text.includes('@') && !text.includes('/')) {
+    if (!rawText.includes('@') && !rawText.includes('/')) {
       if (trigger) {
         setTrigger(null)
         setTriggerActive(0)
@@ -424,7 +424,7 @@ export function ChatBar({
     }
 
     const before = textBeforeCaret(editor)
-    const detected = detectTrigger(before ?? text)
+    const detected = detectTrigger(before ?? composerPlainText(editor))
 
     setTrigger(detected)
     setTriggerActive(0)