[Bug]: iPad portrait: no way back to the parent after opening a sub-agent thread #36165

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to reproduce or investigate the problem.

Area

apps/mobile

Steps to reproduce

1. Open the native T3 Code iOS app on an iPad in portrait orientation.
2. Open a parent thread that has a sub-agent thread.
3. Tap the sub-agent thread link from inside the parent thread.
4. Try to return to the parent using a back button or back gesture.
5. For comparison, return to the parent via the sidebar, rotate to landscape, and open the same sub-agent thread again.

Expected behavior

Opening a sub-agent thread should preserve an obvious way to return directly to its parent in either orientation, such as a back/close button or a working back gesture.

In landscape, the sub-agent opens in a full-page modal/dialog with an exit/back control that returns to the parent. Portrait should provide an equivalent return path.

Actual behavior

In portrait, the sub-agent thread opens without a back button or a working gesture to return to the parent. I have to open the sidebar and select the parent thread manually.

This does not happen in landscape: the sub-agent opens in a full-page modal/dialog with a close control, which returns me to the parent.

Related: #23765, closed through #23795, describes Android Back navigation returning to the project list instead of the delegator. This report differs: on iPad in portrait there is no back control or gesture available at all. The related PR also notes that iOS was not tested on a device.

Impact

Minor bug or occasional failure

Version or commit

2.3.0 (reported in the native iOS app). Observed on 14 November 2026.

Environment

iPad, native T3 Code iOS app. Reproduces in portrait; landscape provides a dismissible sub-agent modal/dialog. Exact iPad model and iPadOS version not recorded.

Logs or stack traces

Screenshots, recordings, or supporting files

Workaround

Open the sidebar and select the parent thread manually. Alternatively, return to the parent and open the sub-agent in landscape, where the modal/dialog has a close control.