diff --git a/.github/workflows/build-and-upload.yml b/.github/workflows/build-and-upload.yml
index 8ddc9daa..17e8d705 100644
--- a/.github/workflows/build-and-upload.yml
+++ b/.github/workflows/build-and-upload.yml
@@ -72,6 +72,78 @@ jobs:
       - name: Build macOS binaries (Electron)
         run: npm run build:mac --workspace @neuralnomads/codenomad-electron-app
 
+      - name: Repackage Electron macOS zips (ditto)
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          # Prefer the workflow-provided version; fall back to package.json.
+          VERSION_TO_USE="${VERSION:-}"
+          if [ -z "$VERSION_TO_USE" ]; then
+            VERSION_TO_USE=$(node -p "require('./packages/electron-app/package.json').version")
+          fi
+
+          release_root="packages/electron-app/release"
+          shopt -s nullglob globstar
+
+          apps=("$release_root"/**/CodeNomad.app)
+          if [ "${#apps[@]}" -eq 0 ]; then
+            echo "No CodeNomad.app found under $release_root" >&2
+            exit 1
+          fi
+
+          for app in "${apps[@]}"; do
+            bundle_dir=$(basename "$(dirname "$app")")
+            arch="x64"
+            if [[ "$bundle_dir" == *"arm64"* ]]; then
+              arch="arm64"
+            fi
+
+            out_zip="$release_root/CodeNomad-${VERSION_TO_USE}-mac-${arch}.zip"
+            rm -f "$out_zip"
+            echo "ditto -ck: $app -> $out_zip"
+            ditto -ck --sequesterRsrc --keepParent "$app" "$out_zip"
+          done
+
+      - name: Validate Electron macOS codesign (unzipped)
+        shell: bash
+        run: |
+          set -euo pipefail
+          shopt -s nullglob
+
+          tmp_dir=$(mktemp -d)
+          trap 'rm -rf "$tmp_dir"' EXIT
+
+          zips=(packages/electron-app/release/CodeNomad-*-mac-*.zip)
+          if [ "${#zips[@]}" -eq 0 ]; then
+            echo "No Electron macOS zip artifacts found to validate" >&2
+            exit 1
+          fi
+
+          for zip in "${zips[@]}"; do
+            echo "Validating codesign for: $zip"
+            extract_dir="$tmp_dir/$(basename "$zip" .zip)"
+            mkdir -p "$extract_dir"
+
+            # Use ditto for extraction as well to preserve bundle metadata.
+            ditto -x -k "$zip" "$extract_dir"
+
+            app_path=""
+            for candidate in "$extract_dir"/*.app "$extract_dir"/*/*.app; do
+              if [ -d "$candidate" ]; then
+                app_path="$candidate"
+                break
+              fi
+            done
+
+            if [ -z "$app_path" ]; then
+              echo "No .app found after extracting $zip" >&2
+              exit 1
+            fi
+
+            codesign --verify --deep --strict --verbose=2 "$app_path"
+          done
+
       - name: Upload release assets
         if: ${{ inputs.upload && inputs.tag != '' }}
         run: |
diff --git a/packages/ui/src/components/file-viewer/monaco-diff-viewer.tsx b/packages/ui/src/components/file-viewer/monaco-diff-viewer.tsx
index c6694f80..ace89d5f 100644
--- a/packages/ui/src/components/file-viewer/monaco-diff-viewer.tsx
+++ b/packages/ui/src/components/file-viewer/monaco-diff-viewer.tsx
@@ -61,6 +61,11 @@ export function MonacoDiffViewer(props: MonacoDiffViewerProps) {
         // Keep enough gutter space so unified diffs don't overlap `+`/`-` markers.
         lineNumbersMinChars: 4,
         lineDecorationsWidth: 12,
+        // Use legacy diff algorithm for better performance with large files
+        // See: https://github.com/microsoft/vscode/issues/184037
+        diffAlgorithm: "legacy",
+        // Limit computation time to avoid freezing on large files
+        maxComputationTime: 10000,
       })
 
       setReady(true)
diff --git a/packages/ui/src/components/message-timeline.tsx b/packages/ui/src/components/message-timeline.tsx
index c0e1d9d7..fc4ef7f3 100644
--- a/packages/ui/src/components/message-timeline.tsx
+++ b/packages/ui/src/components/message-timeline.tsx
@@ -1,4 +1,4 @@
-import { For, Show, createEffect, createMemo, createSignal, onCleanup, type Component } from "solid-js"
+import { For, Show, createEffect, createMemo, createSignal, onCleanup, on, untrack, type Component } from "solid-js"
 import MessagePreview from "./message-preview"
 import { messageStoreBus } from "../stores/message-v2/bus"
 import type { ClientPart } from "../types/message"
@@ -350,11 +350,9 @@ const MessageTimeline: Component<MessageTimelineProps> = (props) => {
     clearCloseTimer()
   })
 
-  createEffect(() => {
-    const activeId = props.activeMessageId
-
+  createEffect(on(() => props.activeMessageId, (activeId) => {
     if (!activeId) return
-    const targetSegment = props.segments.find((segment) => segment.messageId === activeId)
+    const targetSegment = untrack(() => props.segments).find((segment) => segment.messageId === activeId)
     if (!targetSegment) return
     const element = buttonRefs.get(targetSegment.id)
     if (!element) return
@@ -366,7 +364,7 @@ const MessageTimeline: Component<MessageTimelineProps> = (props) => {
         window.clearTimeout(timer)
       }
     })
-  })
+  }))
 
   createEffect(() => {
     const element = tooltipElement()