fleet TUI: kill confirmation modal renders as an empty red box (Static children collapse an auto-width container)

[jrob5756]

Summary

Pressing k (kill) or K (kill all) in the conductor fleet TUI shows an empty red box instead of the kill-confirmation dialog. The dialog is ConfirmKillModal (src/conductor/fleet/tui/actions.py), and it renders as nothing but its own border: thick $error — its content is laid out at zero size.

The keybindings still work (y confirms, n/esc cancels), so the kill itself functions. But the user is asked to confirm the destruction of a running workflow by a box that names nothing, shows no hint keys, and — for a foreground run — omits the checkpoint-recoverability warning that is the entire reason D1 made the TUI confirm unconditionally.

Present since the Fleet Manager PR (#431, d785a28). It has never rendered.

Reproduction

conductor fleet          # with at least one run listed
# press k

Reproduced deterministically in App.run_test() against textual 8.2.8:

dialog region: Region(x=47, y=13, width=6, height=4)
  #confirm-message size=Size(width=0, height=0)
  #confirm-hint    size=Size(width=0, height=0)

    █▀▀▀▀█
    █    █
    █    █
    █▄▄▄▄█

6×4 is exactly border (2) + padding: 1 2 (4 cols / 2 rows) around a 0×0 interior. $error is #ba3c5b in the default theme, hence "red box".

Root cause

src/conductor/fleet/tui/actions.py:229-238:

#confirm-dialog {
    width: auto;
    height: auto;
    border: thick $error;
    padding: 1 2;
}

#confirm-dialog is a Vertical whose two children are Static widgets. Static.DEFAULT_CSS sets only height: auto; its width falls back to Textual's base default of 1fr. An auto-width container whose children are all 1fr resolves to 0, so both Statics collapse to 0×0 — and the auto height then has zero-width content to measure, collapsing too.

Label does not have this problem because Label.DEFAULT_CSS sets width: auto.

Verification of the fix direction

Same harness, same CSS, only the child widget/width changed:

Variant	Result
Static, as shipped	Region(width=6, height=4), children 0×0
Label instead of Static	Region(width=34, height=6), renders correctly
Static + #confirm-message, #confirm-hint { width: auto }	Region(width=34, height=6), renders correctly

Correct render:

█▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀█
█                                █
█  Kill 1 run(s): plan?          █
█  [y] Confirm   [n/esc] Cancel  █
█                                █
█▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄█

Note the multi-line foreground-run message (build_kill_confirmation_message appends _foreground_stop_warning_lines) also needs to survive the fix — an auto-width Static sizes to its longest line, which is correct, but the fix should be checked against that case rather than only the one-line bg case.

Scope

• ConfirmKillModal only. GateOptionsModal in the same file is unaffected: it uses explicit width: 90%; max-width: 120; height: 80%. Its CSS comment already documents that auto-sizing was found broken for that modal and fixed there — the same class of defect was never revisited for the kill modal.
• The markup escape in the hint ("[bold]\\[y][/bold] ...") is fine and renders as [y] Confirm [n/esc] Cancel.

Why the tests miss it

tests/test_fleet/test_tui_actions.py drives the modal by pressing y/n and asserts on os.kill call counts/PIDs and on the message string passed to ConfirmKillModal.__init__ (test_kill_all_names_foreground_runs_in_confirmation). Nothing asserts that the modal has non-zero size or that its text reaches the screen, so a completely invisible confirmation dialog passes the entire suite.

A regression test should assert against rendered geometry/content, e.g. that #confirm-message has non-zero size and that the workflow name appears in the composited screen text — not merely that the string was constructed. The same assertion would be worth having for GateOptionsModal, since it is the one other ModalScreen in the codebase and was fixed for a related sizing failure without a test.

[jrob5756]

Starting to take a look at this.