#29663 cmux NEXT: remove New Worktree from the composer location bar

Leo, 2026-10-31: "WHO THE F*** PUT FING WORKTREE ON THERE" / "OURS IS FING STUFF" / "STUPID".

The bar above the cmux NEXT composer read project ⌄ | ⑂ New Worktree | machine ⌄. This removes the New Worktree control from that bar and its code path (the worktree handler in ComposerContext.tsx). Project and machine are unchanged.

Added by #22131 ("environment picker and New Worktree in the composer location row (preview)", 2026-10-19), found with git log -S'value={t("worktree.new")} chevron={false}'.

What stays: New Worktree is still an action in the folder menu. Before #22131 the menu had it, and #22131 hid it from the menu only while the bar showed the control. Now the menu always offers it again. Nothing else is removed.

• startFolder.gallery.ts: the New Worktree plays now open the folder menu and pick the option, instead of clicking the removed button.
• NewTabScreen.test.tsx: new test. The location bar has no New Worktree button, and the folder menu still lists New Worktree.

Design spec: composer location strip (design/composer.md). This removes one control and adds nothing.

Agent session: agent session

🤖 Generated with Claude Code

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Summary by cubic

Removes the New Worktree control from the composer location bar in cmux NEXT so the bar holds only the folder and machine pickers. New Worktree stays available as an action in the folder menu, restoring the behavior from before #22131 added the standalone control.

• Removes the worktree handler and its button from ComposerContext.tsx, and the environment picker tests now start worktrees from the folder menu.
• Updates the start-folder gallery play to open the folder menu and pick New Worktree instead of clicking the removed button.
• Adds a test asserting the location bar shows no New Worktree button while the folder menu still lists the action.