September 6, 2026 · Bug-fix release
Two fixes to the sidebar’s ambient reflection, which shipped in 1.22.0/1.22.1 and which people reported seeing nothing of. It was tied to a setting that switched it off, and even when lit it could not show what colour was where. This is also the release in which the earlier visibility work — the presence floor and the raised alpha ceiling — actually reaches users, having been arithmetically below the visible line in every build before it.
The whole-window vibrancy backdrop was gated on TerminalAppearance.isTranslucent — terminal background opacity below 0.999. That one flag controlled two unrelated things: how much the terminal’s own background let through, and whether the window had a vibrancy backdrop behind everything at all.
So a user who set terminal background opacity to 100% — a completely ordinary choice — silently lost the backdrop for the entire window. The sidebar had no glass, and with no glass there was nothing for the reflection to light. The effect was simply absent, and nothing on screen explained why.
That is not how the platform works. A sidebar is glass regardless of what sits in the content pane beside it — Finder, Mail and Xcode all keep a translucent sidebar next to a fully opaque document.
The backdrop is now a property of the window, not of the terminal. A new isBackdropEnabled is on unless Reduce Transparency is set. Opacity now controls only one thing — how much of that backdrop the terminal view lets through. At opacity 1.0 the terminal looks pixel-for-pixel identical to before, but the sidebar beside it is now glass.
The trade is deliberate: this gives up the old “fully opaque window” compositing shortcut at opacity 1.0 in exchange for the platform-standard look, where the sidebar is glass whatever the content pane is doing.
The reflection was a single averaged pastel hugging the divider. A block of red diff rows and a block of green ones averaged to one muddy blend; a fixed high display-lightness turned dark-red rows into salmon; and the falloff died about a third of the way across, so two-thirds of the sidebar never lit at all. It could report roughly how colourful the screen was, but nothing about which colour was where.
The reflection is now two layers behind the sidebar content, sharing one light source:
Both layers share one horizontal falloff — brightest at the divider, now carrying a trace all the way to the far edge — so they read as a single light spilling across the divider rather than two separate effects. Verified live on the real configuration that motivated the work (opacity 1, reflection 100%): full-red and full-green screens now produce strong, correctly-hued washes across the glass sidebar.
This is also the release in which two earlier corrections actually reach users. The presence floor — any colour on screen clears a floor of 0.70 energy, which maps to an alpha comfortably past the vibrancy threshold — and the alpha-ceiling raise from 0.40 to 0.65 were both written earlier, but every build before this one placed them arithmetically below the line at which anything is visible through the sidebar’s own vibrancy. Only now do they read.
388 tests pass across 29 suites, up from 371. The new coverage exercises the split of window backdrop from terminal opacity, the presence-floored ambient wash, and the per-band tell-tale gradient — as pure functions, so hue, lightness and alpha can be asserted without a live terminal, a window and a run loop. No user-facing behaviour regresses.