Performance work for the upcoming Android port needs a numeric
baseline we can quote across desktop and mobile, instead of "feels
slow". DiagnosticsHudPlugin wraps Bevy's FrameTimeDiagnosticsPlugin
and renders a tiny corner readout the developer can toggle with F3.
- Hidden by default — production builds ship the plugin but the
overlay starts invisible.
- F3 reads ButtonInput<KeyCode> directly (not gated by pause /
modal state); diagnostics should always be reachable.
- Reads `smoothed()` FPS + frame_time so the cell isn't a jittery
per-frame scoreboard. Format: "FPS NN \u{2022} M.MM ms".
- Anchored top-right at z = Z_SPLASH + 100 so the readout sits
above every modal / toast / splash layer.
- Update system bails when hidden so we don't pay the
diagnostic-store lookup or text mutation when nobody's looking.
Next up on the perf track: get the Android build target wired so we
can put real numbers in this readout from a phone or emulator.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
funman300