int_corner_drift_from_early_stint

Item 02h.

Part of the Residual family.

Item 02h. int_corner_skill_residuals residualized a SECOND time: for each (stint_id, corner_name), the mean of the three phase residuals over the stint’s own first 6 valid laps (valid_lap_in_stint 1-6) is taken as a BASELINE, and every later lap’s residual minus that baseline is DRIFT. Grain: (lap_id, corner_name), same as int_corner_skill_residuals. WHY. 02c’s residuals do not persist lap-to-lap (measured lag-1 within-stint autocorrelation 0.032-0.176) because (field trailing-5 median - own) is a relative-PACE construct, and the columns that survive ablation elsewhere in the contract all sit at .27-.42 (proximity .421, thermal’s push_residual .343, dirty_air .266). A driver who is steadily 0.05s worse than the field all race has zero drift and is captured by pace already three times over; a driver who opens that gap from 0.05s to 0.35s across the stint has +0.30s of drift, which is the tyre-degradation signal a pace residual cannot distinguish from a driver who is simply slow-but-stable. LEAKAGE. The baseline window is FIXED at valid_lap_in_stint 1-6, not trailing relative to the query lap. Every row with a non-NULL drift value has valid_lap_in_stint >= 7, strictly after the baseline window, so the baseline never draws on the lap it is subtracted from or any lap after it. Rows with valid_lap_in_stint <= 6 — the baseline-defining window — get drift = NULL by construction (verified: zero exceptions). Stints with fewer than 7 valid laps get NULL throughout (no lap to report a drift value for). A (stint, corner, phase) baseline additionally requires >= 3 non-NULL observations inside the 6-lap window.

Lineage

Overview

Property	Value
Layer	intermediate
Family	Residual
Contract enforced	No
Tags	feature_engineering
Upstream	int_corner_skill_residuals, int_stint_geometry

7 tests guard this model - 7 generic, 0 singular.

Columns

Column	Type	Nullable	Tests	Description
corner_id		Yes	not_null, unique	PK = lap_id || ‘C’ || corner_name
lap_id		Yes	not_null	FK to stg_laps
stint_id		Yes	not_null	FK to int_stint_geometry
corner_name		Yes	not_null	Named corner from dim_corners
valid_lap_in_stint		Yes	not_null	Ordinal among valid laps only within this stint (from int_stint_geometry). Drift is NULL for values 1-6, the baseline-defining window.
drift_in_baseline_window		Yes	not_null	TRUE when this row sits inside the baseline window (valid_lap_in_stint <= 6) or the stint never reached 7 valid laps — i.e. TRUE whenever all three drift columns are necessarily NULL for a reason other than a missing corner residual. Diagnostic, not a feature.
braking_drift_s		Yes		braking_loss_s minus the stint’s own early-stint (valid_lap_in_stint 1-6) mean braking_loss_s for this corner. NULL inside the baseline window, on stints shorter than 7 valid laps, on a baseline with fewer than 3 usable observations, or where this lap’s own braking_loss_s is NULL.
mid_drift_s		Yes		mid_corner_residual_s minus the stint’s own early-stint mean mid_corner_residual_s for this corner. Same NULL policy as braking_drift_s.
exit_drift_s		Yes		exit_residual_s minus the stint’s own early-stint mean exit_residual_s for this corner. Same NULL policy as braking_drift_s.