FA-84618 / Betting odds conversion / Member archive

Off-ladder prices silently snapped · case 03

A 2.01 request is treated as a valid tick.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

Signed tick distance from price a to price b on the ladder [(101, 200, 1), (200, 300, 2), (300, 400, 5), (400, 600, 10), (600, 1000, 20), (1000, 2000, 50), (2000, 3000, 100), (3000, 5000, 200), (5000, 10000, 500), (10000, 100001, 1000)] (hundredths). Prices must be within 1.01..1000 ("invalid") and exactly on a tick ("off ladder"). Tick index counts all ticks of lower bands ((hi - lo) / step each) plus (v - lo) / step within the band. Return index(b) - index(a).

Why this case matters

Trading bots express stop-loss and offset orders as tick counts across ladder bands.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
boundary off ladder	`25`	`"off ladder"`	Failed

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