[hellices]

Closes #504

Summary

main's CI failed on a7417a0 (the #500 merge, docs only) in windows-test:

• Test: test_olm_view.py::test_install_fetches_manifest_by_canonical_view_kind.
• Error: NoMatches: No nodes match 'SelectOverlay' on Select(id='install-channel').
• Traceback: runs from run_test's __aexit__ into Textual's Select._on_mount.

A screen is current as soon as it is pushed, before its widgets run their Mount handlers. The OLM wizard tests waited only for the screen, so on a slow runner they left run_test while Select._on_mount was still looking up its overlay. This is a test race, not a product bug.

• tests/ui/waits.py gains screen_ready(app, screen_type). It holds until the screen and every widget in it have finished mounting.
• The six waits that shared the race use it: five in test_olm_view.py and one in test_write_confirm_characterization.py.

Verification

• uv run pytest -p no:tach tests/ui/test_waits.py -q: 8 passed.
• The test against a real Textual app pushes a modal with a Select and asserts the Select is mounted once screen_ready holds.
  • Replacing screen_ready with return True makes that test fail locally: right after a push, the Select has not mounted yet. That is the race Windows: an OLM wizard test leaves run_test while its Select is still mounting #504 hit, reproduced deterministically.
  • Dropping the per-widget check fails the parametrized test.
• uv run pytest -n 8 -p no:tach tests/ui/ -q: 3611 passed.
• ruff check, ruff format --check and mypy on the touched files: clean.

Checklist

• This closes an accepted issue in this repository that is assigned to me.
• Tests cover the change, written to fail first where behavior changed.
• make check passes locally. (Test-only change. The UI suite and lint/type checks on the touched files were run; the full suite runs in CI.)
• User-facing docs and the README match the change, or nothing user-facing changed.
• No security invariant is weakened: writes still need a keystroke approval
  and a fail-closed audit entry, and sensitive reads are still masked.

[Copilot]

🔵 Needs a closer look

One or more reviewer sessions failed, leaving the review evidence incomplete.

No open issues 🎉

What changed in this PR

This test-only PR addresses the OLM wizard mount race reported in #504 by waiting for the screen and its widgets to finish mounting before interacting with them or ending the test.

Changes:

• Adds a shared screen_ready predicate for mount-completion checks.
• Updates all six affected wizard waits to use it.
• Adds parametrized checks and a real Textual modal test containing a Select.

File	Description
tests/​ui/​waits.py	Adds the screen-and-widget mount readiness predicate.
tests/​ui/​test_write_confirm_characterization.py	Updates one wizard wait before accepting defaults.
tests/​ui/​test_waits.py	Tests readiness states and actual Select mounting.
tests/​ui/​test_olm_view.py	Updates five wizard waits to require mount completion.

_{Review effort: Balanced}