[SamarpitSantoki]

Problem

On Android tablets, the split layout puts the Chats / PRs switch in its own 80dp navigation rail to the left of the sidebar. The rail holds two tabs centered in an otherwise empty column, takes width from the panes, and sits far from the other sidebar controls.

Change

• AdaptiveWorkspaceLayout no longer renders the rail, so the sidebar and detail panes get the full width.
• AndroidWorkspaceSidebar floats a compact two-icon switch at the sidebar's bottom left, opposite the New thread FAB. It uses the FAB height, a 16dp corner radius, elevation 6, and the existing androidWorkspaceNavigationColors for the selected-tab indicator.
• When the sidebar is too narrow for the switch and the extended New thread FAB side by side (tablet portrait), the switch rises to the filter row.
• Tab selection moved into useSelectAndroidWorkspaceTab, shared by the phone bottom bar and the tablet switch. Behavior is unchanged: switching tabs resets to the list and closes the open detail.
• The native T3WorkspaceNavigation view drops its now-unused rail branch. Phones keep the Material bottom navigation bar. iOS is untouched.

Scope and approval

This changes product UI, so it needs maintainer approval of the direction first. Proposal: #18683

This PR stays in draft until the direction is approved there.

Verification

• tsc-rs --noEmit in apps/mobile: clean.
• vp test run src/features/workspace/android-workspace-navigation-colors.test.ts: 11 passed. The test now covers the floating switch instead of the rail.
• Manual, Pixel Tablet emulator (Android 16, API 36), debug build of this branch:
  • Landscape: switch on the New thread row. Tapping PRs and Chats switches the sidebar list.
  • Portrait: switch rises to the filter row and does not overlap New thread. Both tabs work.
  • The rail column is gone, and the sidebar starts at the left edge.

Not checked: phones (the bottom bar code changed only by removing the rail prop), large font sizes, and a real tablet with this branch.

Screenshots

Before: Xiaomi Pad 6. After: Pixel Tablet emulator. Thread and PR titles are blurred.

Before: landscape	After: landscape (Chats)	After: landscape (PRs)

Before: portrait	After: portrait (Chats)	After: portrait (PRs)

Claude Opus 5.5 via Claude Code in T3 Code.

[maria-rcks]

Note

Written by gpt-6.1-sol on behalf of Maria

Thanks for proposing the Android tablet navigation change. The prior-approval rule applies because this replaces the native navigation rail with a floating sidebar switch, and the description says direction approval is still pending in #18683. Please obtain explicit maintainer approval of the direction and scope in that discussion before requesting reconsideration.