Opening another session in the case you are already working in meant re-picking the case and the mode in the toolbar. An opt-in + now sits with each tab's gear and close icons (App Settings, Tabs, New Session Button on Tabs: per device, off by default everywhere). It opens a menu of the CLIs that tab's case can start, each shown with its logo and name as in the Run menus, and a pick starts one session in that tab's case, or the managed worktree it runs in, and in its named group, without changing the Run button's mode or case.
The CLIs offered follow the Run menu's own rule for the case, so a Docker case lists what its container has rather than what the host has. A tab outside any named group sends no group, so the case's default session group places the new session the way it places a toolbar Run. Wherever a tab has a row menu (the vertical rail, the sidebar) that menu gains "New session here…", the keyboard route to the same picker, since Enter on the + itself does nothing. On a phone the + joins gear and close on the active tab only, and the label reserve grows to 68px while the setting is on, so the tab's centre stays off the icons.
The shared tab layout menu no longer closes when focus leaves an item for nowhere: Safari never focuses a clicked button, so pressing an item blurred the focused one with no related target and the click was lost. This is the tile count menu's rule, and it fixes the named-group menu as well.
The phone tier stopped at innerWidth < 430 and @media (max-width: 430px), so every current large phone landed in the tablet layout: the 430pt iPhone 14 Pro Max, 15 Plus, 15 Pro Max and 16 Plus, the 440pt iPhone 16 Pro Max and 17 Pro Max, Pixel 6 Pro, 7 Pro and OnePlus 12 Pro, the 448pt Pixel 8 Pro and 9 Pro XL, and the Galaxy Z Fold 5 cover screen at 460. On those devices the header icon row replaced the session pill, the toolbar kept the desktop Run Shell button instead of Enter and the mic, the keyboard accessory bar could never become visible because its .visible rule lives inside the phone block, and the toolbar jumped to the top of the page when the keyboard opened.
The new cutoff is 600, the line test/mobile/devices.ts already draws between large phones (430-599) and small tablets (600-767). No physical device sits between 480 and 600, but a phone zoomed out one or two steps in Safari does: a 440pt iPhone at 85% or 75% page zoom reports 518px or 587px and still needs the phone controls, which a 480 cutoff would have taken away. The phone block is max-width: 599px and the tablet block starts at min-width: 600px, so a 600px device is a tablet in CSS and in getDeviceType() alike instead of straddling the boundary the way 430pt phones did.
The number changes everywhere it is encoded: JS, CSS, comments, CLAUDE.md, the CI tests that pin the phone block, and the test:mobile helpers. Measurement history that names 430px stays as written.
The active tab is the only one that grows a gear and a close button, and with a
short session name they were eating it: "w1" rendered a 13px label while gear
plus close took 50px of a 116px tab, so the tab's geometric centre landed on the
gear and a thumb aiming at the middle of the tab opened Session Options instead
of switching sessions. Reserving a minimum label width on the active tab widens
the tab by the difference instead.
The floor is set by the 10th tab onward, which renders no number badge and so
sits 10px further right; a numbered tab clears the icons at 20px but a
numberless one needs 40px. The test recomputes that inequality from the
stylesheet rather than pinning the pixel.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
JD