[Bug]: Returning from fullscreen Terminal leaves the Android thread sidebar hidden

[PixPMusic]

Area

apps/mobile

Steps to reproduce

1. Launch the mobile app in showcase mode on an unfolded Android foldable, with the thread sidebar visible.
2. Open a thread, then open its Terminal from the thread toolbar.
3. Tap Maximize terminal (the fullscreen button).
4. Tap the top-left toolbar Back button to return to the thread.
5. Observe that the thread sidebar is still hidden and the thread toolbar has no control to restore it.

Expected behavior

Returning from the fullscreen terminal should leave the thread list accessible: either restore the sidebar or provide a visible control to reveal it from the thread screen.

Actual behavior

The conversation occupies the full width after returning. The sidebar, thread search, and sidebar settings/new-task controls are gone. The thread toolbar only offers files, terminal, git, and inspector actions; it has no “Show threads” action.

Impact

Minor bug or occasional failure. This sequence consistently removes access to the thread list from the conversation screen until the user discovers the terminal workaround.

Version or commit

Unmodified main at ccf220be205f0e509021dbc8cbda90daa638e20d.

Environment

• Pixel 9 Pro Fold emulator, unfolded inner display, Android 15 / API 35.
• 2076 × 2152, 390 dpi (approximately 852 × 883 dp).
• Locally built T3 Code Dev with EXPO_PUBLIC_SHOWCASE=1, dark theme, disposable showcase environments.
• Reproduced with the in-app toolbar Back button. Android 17 and iOS were not tested.

Screenshots and recording

Watch the complete reproduction (30-second MP4)

Before opening Terminal	After fullscreen → toolbar Back

Terminal and fullscreen intermediate screenshots. The recording uses only showcase fixtures.

Workaround

Verified: reopen Terminal, tap Show threads, then use the toolbar Back button. The sidebar remains visible on the thread again.

Related work

#5338 covers the broader Android tablet control gaps. This report isolates the terminal fullscreen/back sequence that hides an already-visible sidebar. Open PRs #6521 and #11339 overlap with the missing recovery controls; those branches were not used for this reproduction.

[juliusmarminge]

Triage

Confirmed in source on current main (b900fc94e). The reporter’s SHA (ccf220be…) is not on this clone; the Android thread header and terminal close path still match the recording. This is a real Android split-view one-way door, not a wash of #5338 / #6521 / #11339. Those cover the missing tablet toggle in general. This report is the sequence that actually hides an already-visible sidebar and then lands on chrome that cannot bring it back.

Split view turns on at ≥720dp wide and ≥600dp tall (apps/mobile/src/lib/layout.ts). The Pixel 9 Pro Fold inner display (852 × 883 dp) qualifies. Sidebar visibility is workspace-level useState(true) in AdaptiveWorkspaceLayout (primarySidebarPreferredVisible). togglePrimarySidebar flips that flag and it survives route changes. It is not persisted to disk.

Terminal is the only Android in-flow header on main that can hide the sidebar (ThreadTerminalRouteScreen: Maximize terminal / Show threads → togglePrimarySidebar).

Toolbar Back is handleCloseTerminal: navigation.goBack() (or replace("Thread") if there is no history). It does not call togglePrimarySidebar / revealPrimarySidebar. The hidden preference is still false when the thread remounts.

The thread screen cannot recover it on Android:

• iOS split left items include Maximize / Show thread sidebar plus New task (splitLeftHeaderItems).
• Android androidHeaderActions is only files, terminal, git, inspector. No sidebar action.
• Split-view Android thread header sets onBack={undefined}, so there is also no header path back to Home.
• WorkspaceSidebarToolbar returns null on Android.
• revealPrimarySidebar exists in the layout but is not on the context; only the hidden sidebar’s onRequestVisibility (search focus) uses it.

Home in split view is an empty detail pane (headerShown: false on Android). WorkspaceEmptyDetail still says “Choose a thread from the sidebar” and only offers New Task. Hardware back from the maximized thread therefore lands on a blank pane with no reveal either. The reporter’s workaround is the only in-app restore on main: reopen Terminal (which still has Show threads) and go back.

That is the AGENTS.md reverse-state hole: Terminal added a way to hide the sidebar on Android without a way to see or restore it on the destination screen.

Related, not duplicates

Work	What it did	Why this still happens
Open #5338	Broader Android tablet gap: no New task, no collapse, phone/iPad chrome drift	Describes a sidebar that never collapses. Terminal later grew Maximize, which created this hide-then-stuck sequence. Keep #5338 for the rest of the tablet chrome.
Open #6521	Android toggle on thread + files headers; Show sidebar on Home empty pane; shouldOfferSidebarReveal tests	Not merged. Would close this repro.
Open #11339	Same recovery control on thread / files / Home; terminal icon cleanup	Not merged. Also would close this repro. Do not land both.
ThreadFilesRouteScreen Android tree header	Refresh only	Same missing toggle if someone hides the sidebar elsewhere; not this path.

Not iOS: splitLeftHeaderItems already has the reverse control. Android 17 was not tested; any window that hits the split threshold has the same header fork.

Suggested fix

Keep this a small Android split-view affordance bugfix. Do not auto-show the sidebar on terminal close — Maximize is intentional. The bug is the missing reverse control after Back.

1. Add the toggle to the Android thread header when layout.usesSplitView, same action as Terminal: Maximize content / Show threads, togglePrimarySidebar. That is the minimum close for this recording. fix(mobile): let Android tablets collapse the thread sidebar #11339 pushes it into androidHeaderActions; feat(mobile): let Android collapse the thread sidebar #6521 uses trailing. Either is fine.
2. Close the Home one-way door at the same time: Android split Home draws no header, so WorkspaceEmptyDetail must offer Show threads while the sidebar is hidden (shouldOfferSidebarReveal in feat(mobile): let Android collapse the thread sidebar #6521). Otherwise hardware back from this state is a second trap.
3. Files tree header on Android should get the same control so the three surfaces beside the sidebar stay reversible. Do not expand into New task / filter parity ([Bug]: Android tablet view differs from phone and lacks new-task sidebar controls #5338).
4. Land one existing PR, do not open a third. Rebase feat(mobile): let Android collapse the thread sidebar #6521 (has the reveal helper + tests) or fix(mobile): let Android tablets collapse the thread sidebar #11339 (newer against current ThreadRouteScreen) and close the other as superseded. This issue is the concrete repro they close.
5. Tests: hide from Terminal, goBack, assert the thread header (or Home empty pane after back) offers Show threads. iOS / compact must stay unchanged.
6. Visual close: unfolded foldable, sidebar visible → Terminal → Maximize → toolbar Back → Show threads on the thread (or Home) → sidebar returns. Repeat after the reporter’s Terminal workaround so both directions still work.

Do not treat keep-alive of the sidebar, or restoring visibility inside handleCloseTerminal, as the fix. That fights the Maximize control the terminal already owns.

Workaround

Verified by the reporter: reopen Terminal, tap Show threads, then toolbar Back. The sidebar stays visible on the thread. No other in-app restore on main.

Classification: bug · accepted · minor (Android split / foldable; one-way door, no data loss, Terminal workaround)
Labels: add bug, accepted, via-triage
Discord tags: mobile-android, ui