Pit Window

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Overview

The Pit Window widget (registry id pitwindow, built by PitWindowBar) is a horizontal bar centred on a reference driver you choose in the widget itself. It plots every car within 30 seconds of that driver’s on-track gap, so an engineer can read at a glance who a pit stop would drop the reference driver behind, or who it might jump.

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Choosing the reference driver

The reference driver comes from the Reference dropdown in the widget’s own header, and from nothing else. It opens on the race leader as of the playhead and lists every car in the timing tower’s running order, so the list reads the way the tower does. The timing tower’s own selection does not feed this widget. Selecting a driver in the tower changes the comparison chart and the other selection-driven widgets, and leaves the pit window exactly where you put it. The choice clears when you change session, so a car number cannot leak from one weekend into another, and the dropdown stays reachable in the empty state, so a reference driver with no measurable position is never a dead end.

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What It Shows

The bar spans 60 seconds, the reference driver fixed at the centre (0s). Only cars within the 30-second window either side of the reference are drawn; anything further away is simply not on the bar.

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Reading the chips

The chips are the cars. Since there are no per-driver rules, a car’s gap is read from where its chip sits against the axis, measured from the white line at 0s. Two rules keep that honest when the field is tight or a car is at the very edge of the window:

• A chip only leaves the axis to avoid a collision. Labels are assigned to lanes, and a chip climbs only as far as it must to clear the ones already placed. When it does climb, it takes a stalk down to the axis, which is what keeps it attributable to its own gap. A car with room around it always sits flat on the axis with no stalk.
• A chip at the edge slides inward rather than being clipped. A car at ±30 seconds sits at the very end of the bar, where a centred chip would hang half its width off the widget. The chip slides just far enough to stay whole. Only the label moves; the gap it reports is unchanged.

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The tyre disc

The disc is centred on the chip’s top-left corner, so three quarters of it sits outside the box. Its fill is the compound the car is currently running, using the same tyre colour tokens as every other widget, and the number printed on it is how many stops that driver has already made. The digit’s colour is a per-compound token paired to the fill, so it stays legible in both the dark and the light theme. A compound that the source has not resolved yet gets the neutral fill and still shows its number. The stop count is known and true whether or not the tyre is, so this case is never a ”?”. Both values come from the same sources the rest of the app uses, never re-derived here: the compound from the driver’s latest as-of lap through the shared compoundForLap, which means a manual compound override wins here exactly as it does in the timing tower, and the stop count from the Pit Stops table’s own buildStopsTable.

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The pit-loss reference lines

The reference lines are strategy-sourced. They come from the as-of strategy snapshot’s own resolved pit_loss block, so they are the round’s real modelled pit losses rather than a hard-coded constant. The SC and VSC pairs use the app’s usual safety-car colour tokens. The widget captions exactly what it has:

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Data Behind It

The bar itself is client-derived; its reference lines are not. screens/derive.ts’s buildPitWindowData is a pure function of the hydrated race state, the drivers map, the reference driver, the playhead cutoff, the as-of pit-loss block and the shared compound-override index:

• Each car’s gap is the timing tower’s own gap to the leader, taken from the tower’s entries as they stand, so the two widgets always show the same numbers, live or in replay. The leader (P1) is pinned to 0s. A car’s relative gap to the reference is the difference of the two gaps-to-leader. A lapped car, a car showing OUT and a car with no time are left off the bar.
• The sign convention is unchanged and independent of the drawing: positive means behind the reference, negative means ahead. Which side of the bar each sign draws on is the component’s business.
• The pit-loss lines come from the strategy snapshot as of the playhead, resolved by strategyDerive.pitLossAsOf. The widget therefore reads strategy_snapshot while, and only while, a pit loss is actually drawn on the bar.
• The constants PIT_WINDOW_HALF_SPAN_S (30) and PIT_WINDOW_PIT_UNCERTAINTY_S (0.5) live in screens/derive.ts. The uncertainty band is a fixed display affordance, not a parameter.
• The axis is generated from PIT_WINDOW_HALF_SPAN_S rather than written out, so it cannot end up describing a window the bar no longer draws.
• The underlying laps, stints and pit rows hydrate the same way as the timing tower: GET /v1/sessions/{session_key}/laps on enter/seek/reconnect, kept current by the laps and timing WS channels. Live and replay envelopes are wire-identical.

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States

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FAQ

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Next Steps