With this model:

• Privacy: nothing in the commitment reveals real attributes or keys.
• Upgradability: new fields can be added by bumping version and putting them in the hash.
• Auditability: the prev_commitment chain allows full history verification.
• Recovery: key rotation and recovery are encoded as new states; verifiers just follow the chain.
• Minimal trust surface: apps only depend on:
  • the latest identity_commitment
  • a proof that ties some statement to this commitment.