diff --git a/.github/workflows/ci-macos.yml b/.github/workflows/ci-macos.yml
index 39adbe03d3a0..55febe392da2 100644
--- a/.github/workflows/ci-macos.yml
+++ b/.github/workflows/ci-macos.yml
@@ -2822,6 +2822,9 @@ jobs:
         env:
           SELECTED_PACKAGES: ${{ steps.select.outputs.selected_packages }}
           SELECTED_COUNT: ${{ steps.select.outputs.selected_count }}
+          # macOS 15 disables Swift's crash backtracer by default. Preserve
+          # a bounded symbolic stack in the log when a package runner dies.
+          SWIFT_BACKTRACE: "enable=yes,interactive=no,timeout=15s,symbolicate=fast,color=no"
         run: |
           set -euo pipefail
           # The cmux-unit scheme only runs the cmuxTests app-host suite; it does
@@ -2927,6 +2930,30 @@ jobs:
             echo "::endgroup::"
           done < "$selected"
 
+      - name: Diagnose Settings UI package crash
+        if: ${{ failure() }}
+        continue-on-error: true
+        timeout-minutes: 3
+        run: |
+          set -euo pipefail
+          package="$PWD/Packages/macOS/CmuxSettingsUI"
+          bundle="$(find "$package/.build" -path '*/CmuxSettingsUIPackageTests.xctest/Contents/MacOS/CmuxSettingsUIPackageTests' -type f -print -quit)"
+          [ -n "$bundle" ] || exit 0
+          toolchain_usr="$(dirname "$(dirname "$(xcrun --find swift)")")"
+          helper="$RUNNER_TEMP/cmux-settings-testing-helper"
+          cp "$toolchain_usr/libexec/swift/pm/swiftpm-testing-helper" "$helper"
+          cat > "$RUNNER_TEMP/cmux-settings-debug.plist" <<'PLIST'
+          <?xml version="1.0" encoding="UTF-8"?>
+          <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+          <plist version="1.0"><dict><key>com.apple.security.get-task-allow</key><true/></dict></plist>
+          PLIST
+          codesign --force --sign - --entitlements "$RUNNER_TEMP/cmux-settings-debug.plist" "$helper"
+          python3 scripts/ci/run_with_timeout.py --timeout-seconds 120 -- \
+            xcrun lldb --batch \
+              -o 'settings set target.disable-aslr false' \
+              -o run -o 'thread backtrace all' \
+              -- "$helper" --test-bundle-path "$bundle" --testing-library swift-testing
+
       # A package test runner that dies on a signal prints one line from
       # SwiftPM ("Exited with unexpected signal code N") and nothing else: no
       # faulting address, no thread, no frames. That is why the only tool this
diff --git a/Packages/macOS/CmuxSettingsUI/Tests/CmuxSettingsUITests/GlobalSearchShortcutSettingsModelTests.swift b/Packages/macOS/CmuxSettingsUI/Tests/CmuxSettingsUITests/GlobalSearchShortcutSettingsModelTests.swift
index d063f00e6d60..951d7dd649ba 100644
--- a/Packages/macOS/CmuxSettingsUI/Tests/CmuxSettingsUITests/GlobalSearchShortcutSettingsModelTests.swift
+++ b/Packages/macOS/CmuxSettingsUI/Tests/CmuxSettingsUITests/GlobalSearchShortcutSettingsModelTests.swift
@@ -7,6 +7,7 @@ import Testing
 @Suite(.serialized)
 final class GlobalSearchShortcutSettingsModelTests {
     @Test func distinctChordSuffixesCanShareAPrefix() async throws {
+        FileHandle.standardError.write(Data("global-search-chord: creating fixture\n".utf8))
         let directory = try makeTemporaryDirectory()
         defer { try? FileManager.default.removeItem(at: directory) }
 
@@ -24,6 +25,7 @@ final class GlobalSearchShortcutSettingsModelTests {
             option: true,
             control: true
         )
+        FileHandle.standardError.write(Data("global-search-chord: fixture ready\n".utf8))
         let settingsChord = StoredShortcut(
             first: prefix,
             second: ShortcutStroke(key: "p")
@@ -34,12 +36,15 @@ final class GlobalSearchShortcutSettingsModelTests {
         )
 
         await model.assignChord(settingsChord, to: .openSettings)
+        FileHandle.standardError.write(Data("global-search-chord: settings chord assigned\n".utf8))
         await model.assignChord(searchChord, to: .globalSearch)
+        FileHandle.standardError.write(Data("global-search-chord: search chord assigned\n".utf8))
 
         let bindings = await store.value(for: catalog.shortcuts.bindings)
         #expect(bindings[ShortcutAction.openSettings.rawValue] == settingsChord)
         #expect(bindings[ShortcutAction.globalSearch.rawValue] == searchChord)
         #expect(model.conflictRejections[ShortcutAction.globalSearch.rawValue] == nil)
+        FileHandle.standardError.write(Data("global-search-chord: assertions complete\n".utf8))
     }
 
     @Test func persistedMediaKeyGlobalSearchBindingIsNotEffective() async throws {