docs: add YIP-84 (Rotate multisig signer)

YIPS/yip-84.md

@@ -0,0 +1,59 @@
+---
+yip: 84
+title: Proposal to rotate multisig signer
+author: wavey
+discussions-to: https://gov.yearn.fi/t/yip-84-proposal-to-rotate-multisig-signer/14469
+status: Proposed
+created: 2025-04-13
+---
+
+## Simple Summary
+If enacted, this proposal replaces multisig signer Monoloco with new signer Ephy and transfers 1 YFI to Ephy as compensation. Additionally, it will update active signer Lumberg's address to reflect a routine personal key rotation.
+
+## Abstract
+If enacted, this proposal replaces multisig signer Monoloco with new signer Ephy and transfers 1 YFI to Ephy as compensation. Additionally, it will update active signer Lumberg's address to reflect a routine personal key rotation.
+
+## Motivation
+### Background
+
+Yearn's main multisig, [ychad.eth](https://etherscan.io/address/0xFEB4acf3df3cDEA7399794D0869ef76A6EfAff52)[1], is a 6 of 9 multisig which has key powers within the protocol. For more information, including the current list of signers, please refer to [the docs](https://docs.yearn.fi/developers/security/multisig).[2]
+
+As established in [YIP-79](https://gov.yearn.fi/t/yip-79-multisig-compensation-and-rotation/14179)[3], signers who rotate on to the multisig shall receive 1 YFI compensation.
+
+This rotation was initiated at the request of Monoloco, who has stepped back from active involvement in DeFi. We extend our gratitude to him for his contributions and dedicated service.
+
+The proposed incoming signer is **Ephy**, Dewiz.xyz co-founder, a well-regarded contributor in the [Maker / Sky](https://forum.sky.money/u/0x3phemeralsoul/summary)[4] ecosystem and a former MakerDAO Core Unit contributor. You can find more about Ephy on [X](https://x.com/0x3phemeralsoul)[5] and [GitHub](https://github.com/0x3phemeralsoul).[6]
+
+## Specification
+### Overview
+If enacted, this proposal replaces multisig signer Monoloco with new signer Ephy and transfers 1 YFI to Ephy as compensation. Additionally, it will update active signer Lumberg's address to reflect a routine personal key rotation.
+
+### Rationale
+The rationale follows YIP‑79’s compensation and rotation policy: replace an outgoing signer at their request, add a vetted incoming signer, and update an existing signer’s key while maintaining multisig integrity.
+
+### Technical Specification
+1. Replace the following signer:
+    - outgoing: `0x1496546f89fc1605880e556c9a1d6c5e2409fb0a` (Monoloco)
+    - incoming: `0x5Db9926c93085a92F14A85daBF6FF27b07362Cae` (Ephy)
+2. Transfer 1 YFI from ychad.eth to Ephy's signer address.
+3. Rotate Lumberg's key:
+    - outgoing: `0x7321ED86B0Eb914b789D6A4CcBDd3bB10f367153` (Lumberg old)
+    - incoming: `0xeA6c0837fef621E77329f85820F503cA09f2B3a9` (Lumberg new)
+
+### Test Cases
+Not applicable.
+
+### Configurable Values
+- Compensation: 1 YFI to the incoming signer.
+- Signer rotation addresses: as specified in Technical Specification.
+- Key rotation: Lumberg old/new addresses as specified.
+
+## References
+1. https://etherscan.io/address/0xFEB4acf3df3cDEA7399794D0869ef76A6EfAff52
+2. https://docs.yearn.fi/developers/security/multisig
+3. https://gov.yearn.fi/t/yip-79-multisig-compensation-and-rotation/14179
+4. https://forum.sky.money/u/0x3phemeralsoul/summary
+5. https://x.com/0x3phemeralsoul
+6. https://github.com/0x3phemeralsoul
+## Copyright
+Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).