Stash

Stash hides macOS menu bar icons behind a single arrow, so a crowded bar collapses to one click. It targets macOS 27, the release that broke this whole category of app at once. Some of them have since come back: Bartender (Golden Gate beta), Thaw (2.0) and Brow all rebuilt on the new architecture. Ice, Hidden Bar, Barbee, Sane Bar and Glow are still broken. Ice is the one measured here — it is what I ran until it stopped working, and the log evidence below is Ice's.

Stash is the open source option next to those: the same job, nothing to buy, nothing to sign in to, and the research it is built on is in this repository.

Collapsed: only the arrow and a handful of apps are visible. Click it and the rest reappear; click again and they're gone.

Why the existing tools stopped working

Until macOS 26, the system drew every status item as its own window. That was never a public API, but it gave the whole category something to hold on to: you could enumerate those windows through CGWindowList, capture them with ScreenCaptureKit, and push them off screen.

macOS 27 draws the menu bar as one window. There is nothing left to enumerate. Two further changes make the classic workarounds fail outright:

• An NSStatusItem whose backing window reaches half the screen width is dropped from the layout instead of being clamped. The old trick — inflate a spacer item until everything to its left falls off screen — no longer pushes anything anywhere. Measured by others on a 1728pt display: 848pt hides, 849pt does not (848 + 16pt of chrome = 864 = 1728/2). That figure is not mine; the single-window rewrite and the log line below are.

• The new engine has a notion of supported status items and refuses the rest. Straight out of MenuBarAgent on the machine this was built on:

  [com.apple.menubar:statusItems] Filtering out unsupported status item: com.jordanbaird.Ice
  

  34 times in a single minute. The spacer items are actively filtered out of the bar they are trying to control.

None of this was a bug in Ice, Bartender or any of the others. It was a rewrite that removed the implementation detail their entire category depended on, with no public replacement for it. The apps that work again did not patch around it — they were rebuilt on something else, which is what this repository is about too.

macOS 27 does ship its own overflow button (•••), but it decides for itself what collapses. There is no supported way to choose per app what gets hidden.

How Stash works instead

macOS 27 still contains the facility behind assessment mode — the exam mode schools use to strip a Mac's menu bar bare during a test. It behaves as an allowlist: you hold an assertion listing which apps may draw a status item, and the system simply does not draw the rest.

That facility lives in a private framework, MenuBarClientCore, behind two undocumented classes: MBAssessmentModeConfiguration and MBAssessmentModeAssertion. Stash dlopens the framework, builds a configuration listing the apps that should stay visible, and activates an assertion with it. Collapsing and expanding is nothing more than replacing that assertion with one carrying a different allowlist. Quitting Stash invalidates it, which hands every icon straight back.

This is a private API, not a stable contract. If Apple changes or removes it, STMenuBarShim.isAvailable returns false: the arrow renders as a warning triangle, the toggle does nothing, and no apps get hidden. It does not crash, and it does not touch anything else on the system.

Read docs/superpowers/specs/2026-09-22-stash-design.md for the full reasoning, the probe output it is based on, and the pitfalls (an NSSet where the API demands an NSArray throws; an allowedSystemItems range of 0...63 silently kills Screen Mirroring). The task-by-task implementation plan lives in docs/superpowers/plans/2026-09-22-stash.md. Both documents are written in Dutch.

Architecture

Layer	Responsibility
MenuBarShim (Objective-C)	wraps the private MenuBarClientCore framework via dlopen + runtime lookup
StashCore (Swift)	pure logic: app inventory − hidden set → allowlist; persistence; assertion lifecycle
Stash (AppKit + SwiftUI)	arrow status item, settings window, accessory app

Swift 6.4, SwiftPM, no Xcode project.

Expanded: the arrow flips and everything comes back.

Limitations

These are limits of the underlying facility, not choices Stash made:

• Per app, not per icon. An app that puts up several status items goes as a whole; there is no way to hide just one of them.
• No reordering. The allowlist controls whether something is drawn, not where.
• No second bar or panel showing the hidden icons. The technique that made that kind of UI possible — enumerating and repositioning each item's own window — doesn't exist on macOS 27.
• The UI is in Dutch. ("Verbergen" = Hide, "Automatisch inklappen" = Auto-collapse, "Starten bij inloggen" = Start at login.) It isn't localized yet; the labels are short enough to follow from the screenshots.
• Private framework. Any macOS update can break Stash, and an app built on this can never ship on the Mac App Store. That is a deliberate trade-off: the supported alternative is having no control over the menu bar at all.

Install

git clone https://github.com/brentc22/stash.git
cd stash
make install
open /Applications/Stash.app

make install builds a release binary, bundles it, ad-hoc code-signs it, and copies it to /Applications.

The /Applications location is a real requirement, not a suggestion. Stash keeps its own arrow visible only when it runs as the copy of com.brentc22.Stash that LaunchServices resolves for that bundle identifier — in practice, the one in /Applications. Run the binary from anywhere else and everything else still works — the arrow reacts to clicks, other apps' icons hide and come back — but the system never draws Stash's own icon, so there is nothing left to click.

Requirements

• macOS 27.
• Xcode Command Line Tools with Swift 6.4. Xcode itself is not required and not used.
• swift test does not work here — use swift run StashTests. Running swift test prints error: no tests found; create a target in the 'Tests' directory, because there deliberately is no such target. On a Command-Line-Tools-only machine both XCTest and swift-testing fail to build or link: they need pieces that ship only inside Xcode. So the suite is a plain executable target instead, and exit code 0 means every test passed.

Building and testing

swift build             # debug build
swift run StashTests    # run the test suite (exit 0 = green)
make build              # release build
make bundle             # release build + Stash.app, ad-hoc signed
make install            # bundle + stop a running instance + copy to /Applications
make run                # make install, then open the /Applications copy
make test               # swift run StashTests
make clean              # remove .build and Stash.app
Resources/make-icon.sh  # regenerate Resources/Stash.icns

Two things about the plain swift build / swift run binary: it has no app bundle, so its own arrow never renders (see Install, above), and with no bundle identifier UserDefaults.standard writes to a different domain than the installed app reads, so settings made there don't show up in the real one. Use make install when you want to see the real thing running.

Run the test suite with Stash not running. The tests read the menu bar's own log to verify what actually changed, and a second Stash holding its own assertion makes two of those measurements ambiguous.

Settings

Right-click the arrow for "Instellingen…" (Settings): a checklist of every app Stash has seen running (apps not running right now are marked niet actief), an auto-collapse delay, and a "Starten bij inloggen" (start at login) toggle backed by SMAppService.

Uninstall

• Turn off "Starten bij inloggen" in Settings before quitting, if it was on. That unregisters the SMAppService login item cleanly; quitting first without doing this leaves the login item registered, so macOS keeps launching Stash at login even after the app itself is gone.
• Quit Stash — right-click the arrow and choose "Stash stoppen". This lifts the assessment-mode assertion and hands every hidden icon back before the app disappears.
• Remove the app: rm -rf /Applications/Stash.app.
• Remove its saved settings: rm -f ~/Library/Preferences/com.brentc22.Stash.plist. This is the hidden-apps list and the auto-collapse delay; only needed for a full clean.

License

MIT — see LICENSE.

Contributing

This has been built and tested on exactly one Mac, on one build of macOS 27.0 (26A428). If you hit different behaviour — a different LSMinimumSystemVersion cutoff, a Mac where the private framework isn't present, a build where the allowlist behaves differently — an issue with your macOS build number and what you saw is the most useful thing you can send.