Thanks for this, @haider855 — this is a well-executed contribution. The telemetry stays in Celsius and only converts at display time, the preference is persisted as one nested-JSON object under the AmpApplet key (Principle V), styling goes through ThemeManager::applyStyleSheet, and the conversion-rounding test cases (94.5/83.1 F, 32.0 F) are a nice touch. All six checks pass, including the Qt Accessibility static analysis.

A few notes, none blocking:

Verified, not a concern: The "True"/"False" string storage for the bool looked unusual at first, but it matches the established house convention — DisplaySettings.h does the exact same thing (o["leanMode"] = ... QStringLiteral("True") : QStringLiteral("False")). Consistent with the codebase, so leave it as is.

Nice catch: Adding m_hasTempA so the display shows the — placeholder until the first setTemp() (instead of a misleading 0.0 C) is a real improvement over the prior behavior.

Minor — i18n consistency: The tooltip, accessible name, and nextUnit strings are wrapped in tr(), but setAccessibleDescription("Toggles amplifier temperature between Celsius and Fahrenheit") is a raw literal. For consistency with the other user-facing strings on this widget, consider wrapping it in tr() too.

Optional — theme tokens (Principle IX): The button stylesheet hardcodes #00b4d8 for the focus border (the highlight colour) and #203040/#ffffff for hover. A recent commit (0d2622c) migrated hardcoded highlight/disabled colours to ThemeManager tokens. The adjacent telemetry labels in this same file still use raw hex, so you're consistent with the surrounding code and I wouldn't hold the PR for it — just flagging in case you'd like to pull the focus/hover colours from theme tokens while you're here.

Overall this looks good to me. Thanks for the clean tests and the accessibility handling (the QAccessible::NameChanged event on toggle is the right call).

_{🤖 aethersdr-agent · cost: $2.7796 · model: claude-opus-4-8}

Thanks for this, @haider855 — really nicely done. The scope is tight (just the applet, its header, the test, and the CMake target), telemetry stays in Celsius with conversion only at display time, the m_hasTempA placeholder handling is a good touch, and the accessibility wiring (setAccessibleName + QAccessibleEvent on NameChanged) is more thorough than most UI PRs. All six CI checks are green, including the a11y static analysis. The widget regression test covering default/single/dual/reload is exactly what this kind of change needs.

One substantive convention note, plus a minor one:

1. Store the preference as a native JSON bool, not a "True"/"False" string.

The nested-JSON-under-one-key approach is the right call (Principle V). But the value is being serialized as a string:

obj[kTempFahrenheitField] = enabled ? QStringLiteral("True") : QStringLiteral("False");
...
.value(kTempFahrenheitField).toString(QStringLiteral("False")) == QStringLiteral("True");

The codebase convention for booleans inside a JSON settings object is a native JSON bool. The directly analogous applet, EqApplet, does:

cfg["showTx"] = m_showTx;                         // write (bool)
m_showTx = cfg.value("showTx").toBool(true);      // read

and MqttSettings does the same for its nested object (.toBool(false)). The "True"/"False" string form is what AppSettings uses for top-level flat XML keys (SmartSDR/.NET style), not for values nested in a JSON blob. Your code round-trips correctly as written, so this isn't a bug — but matching EqApplet would make it obj[kTempFahrenheitField] = enabled; and .toBool(false), which is simpler and consistent.

2. (Minor, optional) Theme tokens for the new hover/focus colors.

kBtnStyle in this file uses {{color.background.2}} / {{color.text.primary}} tokens, and recent work (commit 0d2622c, Principle IX) migrated hardcoded state colors to ThemeManager tokens. The new button's :hover/:focus borders (#203040, #00b4d8) are hardcoded. The base text color matches the existing kTelStyle it replaces, so the area is already mixed — just flagging in case there are tokens that fit, no need to block on it.

Neither is blocking from my side. Nice contribution.

_{🤖 aethersdr-agent · cost: $2.7019 · model: claude-opus-4-8}

Approving — clean, well-tested, CI green across all six, applies cleanly to main.

Verified: display-only C→F conversion (degC*9/5+32; telemetry stays Celsius), Principle-V persistence (nested AmpApplet JSON, read-modify-write), accessible toggle, and a new registered regression test. The unsigned commit is moot on squash-merge (GitHub signs the squash).

Note: this and #3651 both touch AmpApplet.cpp — merging this first means #3651 will need a rebase (handled separately). Nice work @haider855.