From ef72a20beebe7a99c1dc0cc905b5dd42c9f93be2 Mon Sep 17 00:00:00 2001
From: Cursor Agent <cursoragent@cursor.com>
Date: Mon, 18 May 2026 11:06:47 +0000
Subject: [PATCH] fix(macOS): avoid main-thread memory spike on Replace All

Replace All previously collected every match NSRange before mutating the
text storage. Notes with huge match counts could allocate unbounded memory
and freeze the UI. Use NSMutableString.replaceOccurrences for the same
non-overlapping case-insensitive semantics without materializing all ranges.

Co-authored-by: Danny Peck <dannypeck@gmail.com>
---
 macOS/SynapseNotes/EditorView.swift | 33 ++++++++++++++++-------------
 1 file changed, 18 insertions(+), 15 deletions(-)

diff --git a/macOS/SynapseNotes/EditorView.swift b/macOS/SynapseNotes/EditorView.swift
index 7617eec..c379f3a 100644
--- a/macOS/SynapseNotes/EditorView.swift
+++ b/macOS/SynapseNotes/EditorView.swift
@@ -2740,29 +2740,32 @@ class LinkAwareTextView: NSTextView {
     private func replaceAllMatches(query: String, replacement: String) {
         guard !query.isEmpty, let storage = textStorage else { return }
         let content = storage.string
-        var matches: [NSRange] = []
-        var searchStart = content.startIndex
-        while searchStart < content.endIndex,
-              let r = content.range(of: query, options: .caseInsensitive, range: searchStart..<content.endIndex) {
-            matches.append(NSRange(r, in: content))
-            searchStart = r.upperBound
-        }
-        guard !matches.isEmpty else { return }
-
-        // Build the post-replace string in one shot, then ask the delegate to permit a
-        // single full-document change. This keeps undo as one coalesced operation.
+        // Use Foundation's single-pass replace instead of collecting every match range.
+        // A note can contain millions of occurrences of a short query; materializing
+        // `[NSRange]` for each would spike memory and freeze the main thread.
         let mutable = NSMutableString(string: content)
-        for range in matches.reversed() {
-            mutable.replaceCharacters(in: range, with: replacement)
+        let initialSearchRange = NSRange(location: 0, length: (mutable as NSString).length)
+        let replacedCount = mutable.replaceOccurrences(
+            of: query,
+            with: replacement,
+            options: .caseInsensitive,
+            range: initialSearchRange
+        )
+        let resultString = mutable as String
+
+        guard replacedCount > 0 else {
+            applySearchHighlights(query: query, focusIndex: 0)
+            return
         }
+
         let fullRange = NSRange(location: 0, length: storage.length)
-        guard shouldChangeText(in: fullRange, replacementString: mutable as String) else { return }
+        guard shouldChangeText(in: fullRange, replacementString: resultString) else { return }
         // Highlight ranges are about to be invalidated by the full-document replace.
         // Drop them now so the debounced restyle (which re-applies highlights via
         // reapplySearchHighlights) can't read out-of-bounds NSRanges and crash.
         lastSearchHighlightRanges = []
         lastSearchFocusIndex = -1
-        storage.replaceCharacters(in: fullRange, with: mutable as String)
+        storage.replaceCharacters(in: fullRange, with: resultString)
         didChangeText()
 
         applySearchHighlights(query: query, focusIndex: 0)