Independent IMAP folder and subfolder selection in email sync settings

[HollaTheWoodFairy]

Scope & Context

We are working on the email account settings, specifically the IMAP folder import configuration under Settings → Accounts → Emails → Some folders. The ticket is about enabling independent selection of root folders and their subfolders when defining which folders to synchronize.

Current behavior

On the Settings → Accounts → Emails page, selecting a root folder automatically selects all of its subfolders. It is not possible to:

• select a root folder without also selecting all of its children
• deselect a single subfolder while keeping the parent selected

The checkboxes on subfolders appear to be controlled entirely by the parent state, giving the user no granular control.

Expected behavior

Root folders and subfolders should be independently selectable. A user should be able to:

• Select a root folder (e.g. Ausgang) without automatically selecting its subfolders (Ablage-ordner, 2023, 2024, 2025)
• Select individual subfolders without selecting the parent root folder
• Have the root folder checkbox show an indeterminate state (–) when only some children are selected

This matches standard tree-select UX patterns used in file explorers and permission trees.

Technical inputs

• Locate the folder tree checkbox toggle handler in the email settings component
• Replace the current "select parent = select all children" logic with independent per-node state
• Add indeterminate checkbox state on parent nodes when a subset of children is checked (indeterminate HTML attribute on <input type="checkbox">)
• Ensure the sync logic reads per-folder selection state individually rather than inferring child state from the parent

I created this with AI hoping to capture the problem more precisely and in greater detail to simplify development.