One-click editor actions

The selected external editor is one action away from repository rows, the Changes empty state, changed-file context menus, conflict rows, and the diff header. File actions pass the exact selected path; repository actions pass the working-tree root. Tooltips name the resolved editor when available.

Every launch uses an executable and positional argument array with no command shell. A missing app, rejected custom configuration, or launch failure leaves the repository untouched and offers Preferences recovery. Repository-specific editor overrides are resolved before the app default and never change another repository's choice.

Repeated activation of the same target while a launch is still starting is suppressed, so a stuttered double-click opens exactly one editor. See the Duplicate-open guard.

Verification includes diff-header, file/repository context-menu, conflict row, editor launch, and repository override suites. Discovery details are in Broad editor support.