Diagnostic Panel

The eleven-tab developer view of a running plugin: Overview, Host, Transport/Clock, MIDI, Audio, Parameters, Presets/State, Events, Stimulus, Performance and Package. Controlled and presentational — it takes a DiagnosticSession and its snapshot and renders them, owning no bridge and opening no feed, so it embeds equally in a drawer, a dev-runner pane or a docs page. Its one editorial rule is that every value either comes from the snapshot or renders as an explicit Unreported cell: there is no `?? 0` anywhere, because a host that never reported its latency is not a host with zero latency, and a meter frame that never arrived is not silence. The stereo verdict consults per-channel RMS before correlation for the same reason — a silent pair correlates at exactly 1.0, and would otherwise be reported as perfect mono. The Overview leads with a status strip whose health verdict overrides a host's own claim when the feeds it promised have gone silent, because a dead feed is a broken host bridge however healthy the DSP says it is; Copy report puts a ten-line plain-text summary on the clipboard ahead of the JSON, because that is what gets pasted into chat. Nothing costs a frame while the panel is closed: the four canvas viewers share one animation frame that is never scheduled unless the Audio tab is visible, each tab is memoised over the slice of the snapshot it reads, and tables past 200 rows render only the band you can see.