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Overview

The Race Strategy Tool is a family of six Watchparty widgets that show what an external strategy-solving engine predicts for the rest of a race: Strategy Status, Strategy Table, Predicted Race History, Predicted Pylon, Predicted Pit Window and SC, and Stop Sensitivity. All six are race-only, all six read the same per-lap engine solve, and all six are built on one shared derivation module so their honest-state rules never drift apart.
The engine behind this tool is an interim build (0.5.0-interim). Probabilities are a uniform 1-in-n split, not a calibrated likelihood, and safety-car-now guidance is not yet implemented. Every widget says so in place rather than hiding the caveat.

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How It Works

The engine. services/strategy feeds live race state into an external RST (race strategy) engine, a compiled binary treated as a black box behind a versioned file-based contract (services/strategy/engine/CONTRACT.md). For each lap that settles, the engine runs a deterministic stage and a game-theory stage and returns four outputs: race_history (predicted cumulative time per driver per remaining lap), strategy_rankings (ranked stop-lap strategies per driver), sensitivity (predicted total time against stop lap), and sc_now (a safety-car-now recommendation, currently unimplemented). Publishing. A solved lap produces a strategy_snapshot payload (the full engine output for that lap); every evaluated lap, solved or not, produces a strategy_status payload (gate result, skip reasons, degradations, residuals, timings). Both are published as metric_outputs rows and streamed as insight envelopes: insight:strategy_snapshot and insight:strategy_status, over the channel vpw:v1:{session_key}:insight:{metric_id}. model_id is strategy_snapshot / strategy_status; model_version is the composite engine_version+WRAPPER_VERSION, currently 0.5.0-interim+b1.9.0. Hydration. The webapp reads both metrics the same way every other insight does: a REST snapshot on session enter and on rehydrate (GET /v1/sessions/{session_key}/metrics?metric_id=strategy_snapshot, likewise for strategy_status), then live updates over the WebSocket channels above. No gateway or contract change was needed to add these two metrics; channel and endpoint derive from metric_id alone. The shared derivation layer. apps/pitwall-web/src/screens/strategyDerive.ts is the one place all seven widgets’ data passes through. It owns:
  • As-of-lap selection. The six data widgets (Table, Predicted Race History, Predicted Pylon, Predicted Podium, Predicted Pit Window and SC, Stop Sensitivity) read the latest strategy_snapshot at or before the playhead lap, and stamp “as of lap N” when that snapshot is behind the playhead. The Status panel is the exception: it reads the exact playhead lap’s strategy_status row, so a degraded or skipped lap is reported honestly rather than silently inheriting a neighbouring lap’s data.
  • The 1e300 / DBL_MAX sentinel rule. The engine writes the C++ DBL_MAX sentinel (1.7976931348623157e308) into any predicted_time or delta value for a strategy that cannot physically complete from the current race state. strategy_rankings rows arrive already normalised by the publisher (null plus an unreachable: true flag), but race_history.cumulative_time and sensitivity.predicted_time are lifted from the engine verbatim and can still carry the raw sentinel on the wire. strategyDerive.ts’s isUnreachableTime (magnitude at or above 1e300) is the single client-side decoding point for that: it truncates a predicted race-history line at the last reachable lap, and drops (and counts) unreachable sensitivity points. No widget ever renders a raw sentinel value.
  • Shared empty-state text. When no snapshot exists at or before the playhead, all four data widgets show the same message, built from the exact-lap status row’s gate and reasons where one exists (No prediction at lap N: <gate>: <reasons>), or a generic No strategy data at lap N. when there is no status row either.
  • The gate strip. One cell per evaluated lap, coloured by that lap’s gate (solved, degraded, skipped, suspended), clickable to scrub the transport when the lap’s on-track position is known. This lives in the Status panel but is derived once, in the shared module, for the whole race.

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Where You See It in the App

All seven widgets are entries in Watchparty’s feature registry (apps/pitwall-web/src/screens/features.tsx): strategystatus, strategytable, strategyracehistory, strategypylon, strategypodium, strategypitwindow, strategysensitivity. Open them from the widget palette during a race session; every one of them renders “Session is not a race” outside a race, since the app never computes a strategy bundle at all for a non-race session. The suite also has two modes that sit outside the ordinary lap-by-lap solve: a pre-race prediction from the round’s own race data bundle, and no-write what-if studies. Both are covered on Pre-Race and What-If Studies. A mixed model_version across stored rows (for example, a partial re-precompute) blanks both strategy_snapshot and strategy_status together, so all seven widgets fall back to the generic no-data state at once rather than one metric silently going stale while the other updates.

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FAQ

That strategy cannot physically complete from the current race state (the engine’s DBL_MAX sentinel, decoded client-side). A rank-1 strategy carrying that sentinel is a contract violation, not a display choice, and renders as an explicit error rather than a smoothed-over number.
Not on the current engine. It is a uniform 1-in-n split over a driver’s valid strategies. Every widget that shows it says so.

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Next Steps

Strategy Status

The gate, reasons, and whole-race health strip that explains the other four widgets.

Strategy Table

Ranked stop-lap strategies per driver.

Predicted Race History

Predicted remainder overlaid on the real race-history chart.

Predicted Pylon

The predicted finishing order as a timing tower.

Predicted Podium

The predicted top three, the head of that same order.

Predicted Pit Window and SC

Each driver’s next predicted stop, plus safety-car guidance.

Stop Sensitivity

Predicted total race time against stop lap.

Pre-Race and What-If Studies

The lap-0 prediction, and running the engine against different inputs.
Last modified on September 21, 2026