Response drift: kalshi — `events[].collateral_return_type` not accessed by normalizer

[realfishsam]

Exchange

kalshi

Severity

MEDIUM

What Our Normalizer Expects

The kalshi normalizer does not access collateral_return_type from raw event objects. The field is not declared in the KalshiRawEvent TypeScript interface and is not mapped to any unified field.

What The Live API Returns

The live events endpoint (GET /trade-api/v2/events) returns:

events[].collateral_return_type: string

This field determines how collateral is returned to participants upon market settlement (e.g., proportional, winner-take-all, refund on void).

Impact

• Normalized kalshi events carry no information about collateral return behavior
• Consumers cannot correctly model expected returns or risk exposure without knowing how collateral is returned on settlement
• Particularly important for voided or ambiguous market resolution scenarios

Suggested Fix

1. Add collateral_return_type?: string to the KalshiRawEvent interface
2. Surface it on normalized events (e.g., in sourceMetadata or as a dedicated field)

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Found by automated response shape drift audit