[Bug]: Boring sidebar: with idle projects hidden since #26387, New thread and `chat.new` still skip the project picker, so an idle project has no direct way to start a thread#26416

Before submitting

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

Area

apps/web

Steps to reproduce

1. Turn on Settings → Labs → Boring sidebar (group by project) with several projects, some of them without active threads.
2. Open a thread in project A.
3. Click the New thread (pen) button in the sidebar header, or press the chat.new shortcut, to start a thread in project B, which has no active threads.

Expected behavior

The "New thread in…" picker opens, as it does in the default sidebar with more than one project, and project B can be picked. Shift-click and chat.newLocal keep starting in the current project.

Actual behavior

A draft opens in project A. To reach project B you have to change the project in the draft's heading, open the command palette and find "New thread in…", or pick B in the project filter first so its folder comes back.

Boring mode skips the picker on purpose: handleNewThreadClick starts in the current project whenever boringSidebarEnabled is set, and chat.new does the same ("The boring sidebar's folders already show the context"). That held when #21039 shipped, because every project had a folder with its own pen button. #26387 now hides the folder of every project without active threads unless the project filter picks it (groupSidebarThreadsByProject, keepEmptyFolders), so an idle project has no pen button left, and the header button no longer offers it either.

A possible fix is to drop the boringSidebarEnabled override in both places, so boring mode opens the picker like the default sidebar. The hidden folders keep the list short, and the picker covers the projects they hide.

Impact

Minor bug or occasional failure

Version or commit

main 2a738273e, which has #26387 (reproduced in a web dev build with four empty test projects, one of them with a thread). The latest nightly, 0.1.4-nightly.20261028.3814 (ce66aab), predates #26387: there every project still has a folder, but the header pen already skips the picker.

Environment

Web dev build (dev-runner dev) in Chrome on Linux (NixOS); the nightly desktop app on Linux (NixOS, Wayland, niri)

Logs or stack traces

No response

Screenshots, recordings, or supporting files

Boring sidebar on main: the project filter lists four projects, but only server, the one with an active thread, has a folder

Actual: the header pen opens a draft in server right away; api-server, docs-site and web-app are never offered

Expected: the same pen with the boring sidebar off opens the "New thread in…" picker with every project

Workaround

Open the command palette and pick "New thread in…", or change the project in the new draft's heading.