Thank you @chainlink for awarding YieldCoin the grand prize in the Chromion hackathon! We all know the entire world is going to run on Chainlink, so this is a great honor, and (was) a personal life goal. Thank you @CyfrinUpdraft for the resources to learn invariant testing, formal verification, and the security first approach! Thank you @concero_io for inspiring the idea, Parent-Child architecture, and custom CCIP tx types! Thank you everyone for the support! YieldCoin development continues alongside researching a proposal for the vLEI hackathon, Contract Level Identity (name pending review): A Decentralized Fuzzy Extractor, to address the critical need for absolute sybil-resistance by consensus - an inherent requirement for onchain identity and compliance. Read the YieldCoin dev notes taken during the hackathon here: medium.com/@contractlevel/de…

5 stages of contractlevel/skills/property-workflow

Yieldcoin doesnt implement erc4626 due to the crosschain nature of the strategy rebalancing itself, However Yieldcoin's 3rd party intents/claims were specifically designed to allow integration of something like CCIP adapters for crosschain intents/claims, ai treasury agents, etc

less centralized dependencies is good

Comparing the DefiLlama response for base APY to the new Yieldcoin relay, which uses the official Aave API and calculates Compound using onchain state. these are the 12 supported strategies. aave v4 on eth is the current optimal

one of @chainlink's best dev resources just got an upgrade

annoying set back but can (probably) be worked around by replacing defillama api call in yieldcoin relay with calls to aave's official api and calculating compound apy directly from onchain state dont even need to redeploy to cre yieldcoin live on 6 mainnets by end of month

defillama announced on 22nd sep that yield endpoints will be gated by $3000/year from nov 13th

the best frontend in defi is app.uniswap.org/ user interfaces for financial infrastructure should be simple, boring, and easy to understand

Deploying to testnets revealed an issue with Yieldcoin's cloudflare relay API that sits between Yieldcoin's @chainlink CRE workflow and @DefiLlama API. The relay couldn't reliably handle requests across multiple nodes. Each one called and parsed full defillama payload, exhausting the cloudflare worker limits. fix was to schedule the relay api to call defillama api every few mins in the 10 or so mins leading up to a scheduled rebalance cron, and caching the yield data for the supported pools

A personal highlight from @ZealynxSecurity Yieldcoin v2 audit findings: a certain recovery path could misrepresent the TVL of the system by including funds saved in a recovery mode, that were already designated for an epoch net-withdraw cohort the fix was to exclude the recovery amount from tvl reporting when intended for epoch withdraws, but still include it when intended for rebalances there's something really beautiful about a niche execution path finding

No matter how much testing, verification, or AI scans are done, an independent expert human will always be an essential part of the smart contract process. You just never know what you missed

Perhaps the most architecturally significant finding flagged in @ZealynxSecurity Yieldcoin v2 audit was that a malicious user could grief-drain the Yieldcoin vaults' $LINK reserves. Each crosschain vault holds LINK to pay for the protocol's use of @chainlink #CCIP. Crosschain txes are protocol-level operations rather than per-user operations, and Yieldcoin subsidizing its own protocol-level operation costs is a deliberate design decision. Epochs are periods when users submit deposit/withdraw intents, with the net difference bridged. A minimum 1 $USDC (1e6) is applied to per-user deposits. Due to crosschain share accounting, a similar per-user minimum enforcement was not feasible on the withdraw side (except >0) This meant a single USDC deposit could be split up into 1 million withdraw intents, and potentially drain Yieldcoin's LINK reserves. A handful of mitigations were implemented before deciding on the final architecture. Candidates included forfeiting epoch net-withdraw amounts less than 1e6, and charging epoch net-withdraw cohorts 1e6. These would've had a much worse UX for honest users. The final, implemented mitigation is simply to revert closing an epoch if the epoch closes with a net-withdraw amount below 1e6 USDC. The Yieldcoin CRE workflow implements this same check before closing. The contracts still have a minimum epoch period of 1 hour, but the Yieldcoin CRE workflow will be configured for daily, or even weekly epoch settlement.

Highly recommend reading @ZealynxSecurity audit report for Yieldcoin v2's core evm logic - lots of very valuable insights for crosschain security and recovery: github.com/ZealynxSecurity/a…

Great news. CCIP 2.0's default settings includes waiting for source chain finality before destination execution.

Final audit prep this weekend: - run test suite with foundry, medusa, recon-fuzzer - 100% coverage confirmed - use up last of certora minutes on state machine and solvency invariants - ai scanning tools - reconciliation of docs with codebase Excited and relieved.