> ## Documentation Index
> Fetch the complete documentation index at: https://offthepace.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# int_corner_skill_residuals

> One row per lap per named corner.

<Note>Part of the [Residual](/transform/families/residual) family.</Note>

One row per lap per named corner. Decomposes corner skill into braking, mid-corner, and exit phases relative to field median (backward-only trailing-5 window, rebuilt 02g). Grain: (lap\_id, corner\_name). Null when field sample \< 5 drivers. Enables high-res corner-by-corner skill profiling.
WINDOW CHANGE (rebuilt 02g): field medians now use RANGE BETWEEN 5 PRECEDING AND 1 PRECEDING (trailing-5, all drivers at each lap level, excluding the focal lap). Previous construction used FLOOR(lap/5)\*5 block buckets which reached forward 1.877 laps on average (38.45% of the median drawn from future, up to 76% at block position 0), placing future label signals in the baseline. Rebuild eliminated reach; contamination signal was weak (corr +0.0344 vs +0.0083 control, marginal; sd 0.116 vs 0.043 block, noise-shaped).
COVERAGE: Lap-2 coverage loss (21.4pp on laps ≤ 6) is deterministic and non-leaking—lap 2 has no predecessor, so trailing window returns NULL. This loss sits on lap\_number (already in contract via age\_in\_stint) and is declarable, not a hazard. No expanding window rescue attempted: lap 1 never reaches any lap to base a median on. An expanding window would pool early and late race track states (2026-09-08, measured trailing-5 vs expanding, identical formula, identical coverage loss on lap 2 in both cases). Trailing-5 kept for consistency with its width replacing the old block.
SIGN CONVENTION (00d, 2026-09-20): all three phases are POSITIVE = SECONDS LOST vs the field median, negative = seconds gained, and corner\_residual\_total\_s is their straight sum and therefore a real "seconds lost at this corner". The direction of the underlying measure decides the subtraction: braking\_point\_m and v\_min\_kph are higher-is-faster so their residuals are (field - own); throttle\_point\_m is higher-is-slower (on power later) so its residual is (own - field). Before 00d, braking\_loss\_s alone was built as (own - field), so positive meant braking LATER = faster, while mart\_corner\_skill\_driver summed all three z-scores into corner\_skill\_index and ordered ASC with no negation in between -- one of three terms entered a shipped public leaderboard inverted, and corner\_residual\_total\_s summed a gain with two losses. Fixed at the source rather than negated in the mart (the ruling and the full consumer trace are in \_improvements/work/00-corrections.md, 00d). The direction is now pinned against the raw geometry by transform/tests/assert\_corner\_skill\_sign\_convention.sql, which no sign-agnostic closure or count test could catch -- that is how the defect survived both the 02g and 02c rebuilds of this model.

## Lineage

```mermaid theme={null}
flowchart LR
  int_corner_metrics --> int_corner_skill_residuals
  int_stint_geometry --> int_corner_skill_residuals
  stg_laps --> int_corner_skill_residuals
  stg_sector_times --> int_corner_skill_residuals
  int_corner_skill_residuals --> int_lap_corner_inputs
  int_corner_skill_residuals --> mart_corner_skill_driver
  style int_corner_skill_residuals fill:#e40404,stroke:#e40404,color:#fff
```

## Overview

| Property          | Value                                                                                                                                                                    |
| ----------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| Layer             | `intermediate`                                                                                                                                                           |
| Family            | [Residual](/transform/families/residual)                                                                                                                                 |
| Contract enforced | No                                                                                                                                                                       |
| Tags              | `feature_engineering`                                                                                                                                                    |
| Upstream          | [`int_corner_metrics`](./int_corner_metrics), [`int_stint_geometry`](./int_stint_geometry), [`stg_laps`](../stg/stg_laps), [`stg_sector_times`](../stg/stg_sector_times) |

**10 tests** [guard](/transform/ci/overview) this model  -  6 generic, 4 singular.

## Columns

| Column                    | Type | Nullable | Tests                                                                        | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
| ------------------------- | ---- | -------- | ---------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `corner_id`               |      | Yes      | [`not_null`](/transform/ci/structural), [`unique`](/transform/ci/structural) | PK = lap\_id \|\| '*C*' \|\| corner\_name                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
| `lap_id`                  |      | Yes      | [`not_null`](/transform/ci/structural)                                       | FK to stg\_laps                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| `corner_name`             |      | Yes      | [`not_null`](/transform/ci/structural)                                       | Named corner from dim\_corners                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| `braking_loss_s`          |      | Yes      |                                                                              | Seconds lost on corner entry vs the backward-only trailing-5 field median, as (field median - own braking\_point\_m) \* dt\_per\_dm at the sector-2 trap speed. POSITIVE = braked EARLIER than the field = time LOST. Negative = braked later = time gained. NULL when field\_corner\_sample\_n \< 5 or the corner is taken flat (no braking\_point\_m), both real answers rather than missing data. The (field - own) orientation is the fix 00d made and matches the house convention already in the feature contract (int\_lap\_telemetry\_aggregates' braking\_point\_drift\_m is base - lap).                                                              |
| `mid_corner_residual_s`   |      | Yes      |                                                                              | Seconds lost at the apex vs the trailing-5 field median, as (field v\_min - own v\_min) converted at the field apex speed. POSITIVE = carried LESS speed than the field = time LOST. Highest-coverage of the three phases: every corner has an apex.                                                                                                                                                                                                                                                                                                                                                                                                            |
| `exit_residual_s`         |      | Yes      |                                                                              | Seconds lost on exit vs the trailing-5 field median, as (own throttle\_point\_m - field median) \* dt\_per\_dm. POSITIVE = regained full throttle LATER than the field = time LOST. Note the subtraction runs the other way round from the other two phases because throttle\_point\_m is higher-is-slower while braking\_point\_m and v\_min\_kph are higher-is-faster; all three still read positive = loss.                                                                                                                                                                                                                                                  |
| `corner_residual_total_s` |      | Yes      |                                                                              | braking\_loss\_s + mid\_corner\_residual\_s + exit\_residual\_s: total seconds lost at this corner vs the field median. Non-NULL only where all three phases are measurable (the intersection, 38.59% of corner rows), which is why int\_lap\_corner\_inputs aggregates each phase over its own measurable corners instead of using this column. Only a meaningful total since 00d gave the three phases one sign convention -- before that it summed a gain with two losses, which is why 06b moved its headline off it. Closure pinned by transform/tests/assert\_corner\_closure.sql.                                                                        |
| `field_corner_sample_n`   |      | Yes      | [`not_null`](/transform/ci/structural)                                       | Number of field observations behind this corner/lap's median. Trailing-5 window (laps t-5 to t-1, RANGE frame): counts valid, non-NULL braking\_point\_m rows across ALL drivers in that lap interval. Reported UNFLOORED and never NULL, which is the trailing\_observation\_count contract: the count is what the >= 5 floor is applied to, so flooring it here would make "no prior lap at all" and "four prior laps" indistinguishable and leave the residual NULLs unexplainable. 0 on lap 2, which has no predecessor. The residuals themselves NULL out through trailing\_median's own min\_observations=5, and corner\_unmapped\_flag carries the gate. |
| `corner_unmapped_flag`    |      | Yes      | [`not_null`](/transform/ci/structural)                                       | TRUE when field\_corner\_sample\_n \< 5 (residuals are NULL)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |