MIP-0003: Address-Native Identity and Removal of MID

[christopherwxyz]

This discussion is for review and feedback on MIP-0003: Address-Native Identity and Removal of MID.

Original discussion: https://github.com/officialunofficial/makechain/discussions/352

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Summary

MIP-0003 replaces MID (Make ID) with owner_address as the sole canonical account identifier:

• Remove mid (uint64) from MessageData, state keys, and all API surfaces
• Add owner_address (bytes(20)) as the canonical identity field
• Remove relay-injected system messages (KEY_ADD, OWNERSHIP_TRANSFER, STORAGE_RENT, RELAY_SIGNER_ADD, RELAY_SIGNER_REMOVE)
• Replace STORAGE_RENT with settlement-backed STORAGE_CLAIM
• Custody-authorized SIGNER_ADD/SIGNER_REMOVE authorized directly against owner_address
• Any valid 20-byte address is a valid Makechain principal — no onchain registration required

This is the foundational identity change that MIP-0004 and MIP-0005 build upon.

Author: @marthendalnunes

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Please review and share feedback on the proposal.