Thanks for this, @ten9876 — clean, well-scoped a11y work that closely mirrors the existing PhaseKnob precedent. I checked the key correctness points and they hold up:

• Factory key is correct. VfoWidget has Q_OBJECT and lives in namespace AetherSDR, so metaObject()->className() is "AetherSDR::VfoWidget" — the vfoAccessibleFactory key match will fire. (Matches how phaseKnobFactory keys on "AetherSDR::PhaseKnob".)
• Units are right. SliceModel::frequency() returns MHz (SliceModel.h:38), so the ", %1 MHz" summary is accurate — no Hz→MHz mismatch.
• Null safety on m_slice in accessibleSummary() is handled.
• LevelBar matched by objectName is the right call given it has no Q_OBJECT; setObjectName(...) runs in buildTabContent(), well before any AT query, so the lazy lookup resolves fine.
• Single-install static guard mirrors PhaseKnob exactly.

Two minor, optional notes (neither blocking):

1. Dead branch in accessibleSummary(). SliceModel::letter() never returns empty — it falls back to 'A' + m_id (SliceModel.h:34-36). So the letter.isEmpty() ? "VFO" : "VFO slice %1" ternary's first arm is unreachable. Harmless, but you could drop it for clarity (the !m_slice guard above already covers the no-slice case with "VFO flag").

2. Translatable text. The summary uses QStringLiteral rather than tr(). Since this is spoken AT text, tr() would be marginally more correct for future localization — though the codebase is inconsistent here (the VfoWidget itself mixes tr("Signal meter") with plain-literal accessible names), so this matches local convention either way.

LGTM. Nice fill of the collapsed-flag gap.

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Reviewed the diff against the codebase. This is a clean, well-scoped accessibility addition — thanks @ten9876.

What I verified

• Follows the established precedent. LevelBarAccessible / the factory registration mirror PhaseKnob.cpp (static-flag-guarded installFactory, NoRole to drop a decorative render-only widget from AT navigation) almost line-for-line. Good consistency.
• Frequency unit is correct. SliceModel::frequency() returns MHz (SliceModel.h:38), so arg(..., 0, 'f', 6) yields 14.225000 as the description shows — not a Hz value. ✅
• No null-deref / leak risk. accessibleSummary() guards m_slice; the VfoWidget factory branch only runs on a key match (so the qobject_cast<QWidget*> is always non-null); Qt owns the returned interface. Summary is computed at query time, so it's always fresh.
• No Qt-floor concern. Only long-standing APIs (QAccessibleWidget, installFactory, NoRole, the Grouping ctor) — nothing Qt 6.5+, consistent with the Linux CI floor.
• LevelBar objectName tagging is safe. LevelBar is fully custom-painted (no QSS selectors keyed on objectName), so setObjectName() has no styling side effects.

Minor, non-blocking

• Matching LevelBar by objectName is the right call given it has no Q_OBJECT of its own, but it's a slightly looser contract than the class-name key path — if anything else ever reuses "AetherSDR.LevelBar" the factory would wrap it. The namespaced constant makes a collision unlikely, so this is fine as-is; just worth a mental note.
• The out-of-scope deferral of live NameChanged re-announcement on TX-toggle/collapse is the right scoping, and you flagged it honestly. A collapsed flag's summary being correct on query/navigation already closes the reported gap.

Looks good to merge from my side. Nice, focused fix.

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