fix(layout-v2): settle the panel on open, and ship the rail compact by default

[tsahimatsliah]

Two v2 rail fixes. They share SidebarDesktopV2.tsx, so they ride together as separate commits rather than as two PRs that would conflict with each other.

1. Panel content reflows while the panel opens

The context panel animates its own width from 0 to 240px, and its children stretch to that animating width, so everything inside is laid out again on every frame of the transition.

List panels survive it: their rows are left-aligned, so they simply get clipped and it reads as a reveal. The streak panel does not, because it is built from a grid-cols-10 calendar and justify-between hero rows. The dot columns redistribute and the rows slide apart for the length of the animation, which is the "moves in a weird way" the report describes.

The content is now pinned to the panel's open width, so the layout stays settled and overflow-hidden reveals it. Settings keeps stretching, since that panel legitimately fills the whole sidebar.

2. The rail ships compact by default

An unset sidebarCompact now reads as compact, so accounts land on the label-free rail.

The flag stays three-valued rather than being inverted: unset means the user never chose and gets the new default, while an explicit false still means they picked Comfortable and keeps their labels. Nobody's existing choice flips.

All three readers go through one useSidebarCompact() hook, because they have to agree without looking related: the rail sizes itself from the flag, MainLayout pads the page content to match that width, and the appearance settings page renders the selected density. Two of them disagreeing puts the content over the rail or leaves a gap beside it.

Follow-ups this creates

• The sidebar tour (feat(sidebar): v2 sidebar tour and ambient coaches behind sidebar_tour #6429, unmerged) has a Compact mode switch reading the raw flag. It needs the hook or it will render off while the rail is compact.
• fix(layout-v2): persist the compact sidebar and shortcuts dock #6415 (unmerged) adds a fourth reader in its ProfileMenu density section, same treatment.

Verification

• shared: 330 suites / 2195 tests, exit 0
• webapp: 526 tests, exit 0
• typecheck-strict-changed and eslint clean

Not verified in a browser: the v2 rail needs an authenticated session, so the preview on this PR is the real check. Worth watching the panel open on the streak tab specifically, and confirming an account that previously chose Comfortable still gets labels.

🤖 Generated with Claude Code

Preview domain

https://claude-v2-panel-expand-reflow.preview.app.daily.dev

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Project	Deployment	Actions	Updated (UTC)
daily-webapp	Ready	Preview	Aug 19, 2026 6:50am

1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
storybook	Ignored		Aug 19, 2026 6:50am

[tsahimatsliah]

Superseded by #6415, which now contains every commit from this branch — c57c49f51 is an ancestor of that branch's head after the merge in 1eab3690c.

The panel expand-reflow fix, useSidebarCompact, and the useSettingsBooleanFlag default all moved across unchanged. The one thing that did not carry over verbatim is this PR's appearance.tsx hunk: #6415 had already replaced the "Compact sidebar (hide labels)" switch with its SidebarDensitySection picker, so that hunk was dropped as superseded rather than reinstated. Same flag, same behaviour.

#6415's SidebarDensitySection was also pointed at useSidebarCompact(), so the picker and the rail can no longer report different densities for an account that never touched the setting.

Closing in favour of #6415.