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delvtech / hyperdrive-rs

Rust SDK for the Hyperdrive AMM.
https://docs.rs/crate/hyperdrive-math/latest
Apache License 2.0
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Inconsistency when using `calculate_open_short` and `calculate_max_short` together #185

Open DannyDelott opened 1 month ago

DannyDelott commented 1 month ago

Background

The sdk's calculate_max_short method takes a budget and returns a bond amount.

The calculate_open_short takes a bond amount and returns the trader deposit (ie: budget).

We expect that the outputs of one would reflect the inputs of the other, however the steps below show that this is not the case.

Steps to reproduce

  1. Call calculate_max_short with a max uint256 budget to get the pool's max short (in bonds).
  2. Feed this bond amount into calculate_open_short to get the actual traderDeposit needed.
  3. Feed the traderDeposit back into calculate_max_short as the budget.

Expected

The bond amount returned from calculate_max_short should be the same as the bond amount we gave to calculate_open_short.

Actual

Feeding the traderDeposit back into calculate_max_short results in significantly fewer bonds shorted.

Usecase: In the Open Short form, users can input either an amount to pay (budget) or the number of bonds to short.

Depending on which one they type into, either calculate_max_short or calculate_open_short will be called to update the form.

image

DannyDelott commented 1 month ago

We're currently not passing a conservative_price argument to calcMaxShort, there is prior art on how to calculate this here that we should try:

https://github.com/delvtech/hyperdrive-rs/blob/e4fcc3994a8ec3cf657de418309c0fe9909b3b00/crates/hyperdrive-math/src/test_utils/agent.rs#L178