The guard, and why HBAR/USDC never fills on testnet

A fill needs both Chainlink feeds to be fresh (maxOracleAge) and the pool's TWAP over twapWindow to sit within maxDeviationBps of the Chainlink price. The trigger is read from Chainlink, and the minimum output is Chainlink's price less your slippage. Someone who pushes the pool around can't trigger your order or fill it at a bad price; the order waits.

The only HBAR/USDC pool on testnet (0.0.9283328) prices HBAR at about 2.02 USDC while Chainlink says 0.104, so its guard stays closed and HBAR orders are held, which is the guard doing its job. Aligning that pool would take selling about 51,500 HBAR into it (the exact figure moves with Chainlink; yarn foundry:pool-gap prints today's), and creating a new pool costs SaucerSwap's poolCreateFee of 1e16 tinycents ($1,000,000, about 12,975,835 testnet HBAR). No testnet HBAR pool sits within 2% of Chainlink. The DAI/USDC pool does (23 bps), so DAI orders fill: a working stablecoin stop-loss. Both markets run the same code, and on an arbitraged network HBAR/USDC fills too.

Proof on a mainnet fork. Mainnet's HBAR/USDC pool is arbitraged, so there the same guard opens. A fork test reads the real mainnet 0.15% pool and Chainlink and asserts GuardState.Open — on testnet the guard correctly holds, on a mainnet fork it opens:

yarn foundry:fork-guard    # forks Hedera mainnet, asserts the HBAR/USDC guard opens

It needs a mainnet RPC (the hedera_mainnet endpoint, public hashio by default) and skips with a message if one isn't reachable. It reads Chainlink and the pool TWAP only — no swap, no HTS — so it is a pure, real read of live mainnet state. At last run the pool sat ~7 bps from Chainlink and the guard opened.

To see how far a pool is from Chainlink and what it would take to bring it back:

yarn foundry:pool-gap             # HBAR/USDC
MARKET=2 yarn foundry:pool-gap    # DAI/USDC

It reads the pool's tick, liquidity and initialized ticks plus both feeds on a fork (the first run can take a minute), and prints the token and amount to sell into the pool, or that the pool is already inside the guard's limit. Swapping that amount through the SaucerSwap router re-aligns it. It moves the price for everyone and anyone can push it back, which is why the guard exists.