Unifyl — a dual-pane file manager for macOS

Engineering notes

Write-ups from building Unifyl. Debugging stories and macOS internals — no release-note filler.

All 15 of our translations were missing the same 620 strings — and every check was green

August 2026

The parity audit compared catalogues to each other. A key missing from every file at once is in perfect parity. When everything is wrong the same way, nothing looks wrong.

AppKit asks every menu to update on every keypress. My app said yes.

August 2026

Holding an arrow key stuttered, so I profiled the table view — and found the menu bar redecorating all nine menus per keystroke. Main thread 61% → 2%.

Why does macOS think my file manager wants Photos access? Finding the guilty path with lldb

August 2026

TCC names the service, never the path. But while the permission dialog is up, the guilty thread is frozen inside open() — and the path pointer is still sitting in x0.