Anchoring - Lucid

Anchoring is how Lucid makes AI interactions permanently verifiable. Cryptographic receipts are batched into epochs, compressed into a Merkle Mountain Range (MMR) root, and committed on-chain. Anyone can later verify that a specific interaction occurred without trusting Lucid.

The Receipt-to-Chain Pipeline

AI interaction
  -> Receipt created (SHA-256 of RFC 8785 canonical JSON)
  -> Ed25519 signed by orchestrator
  -> Appended to MMR
  -> Epoch finalized (>100 receipts OR >1 hour)
  -> MMR root committed on-chain (Solana + EVM)
  -> Epoch bundle archived to DePIN storage

Key Algorithms

Receipt Hashing

Every receipt is hashed using SHA-256 over RFC 8785 canonical JSON (JCS). This ensures identical receipts produce identical hashes regardless of JSON key ordering or formatting.

Merkle Mountain Range (MMR)

Receipts are appended to an MMR — an append-only authenticated data structure. The root is computed via SHA-256 with right-to-left peak bagging. Properties:

Append-only (no rewriting history)
Efficient inclusion proofs (O(log N))
Supports batched verification

Epoch Finalization

An epoch closes when either condition is met:

100+ receipts accumulated
1+ hour since epoch opened

On-Chain Commitment

The thought_epoch Solana program stores MMR roots on-chain with three instruction variants:

Instruction	Description
`commit_epoch`	Single epoch root (32-byte MMR root)
`commit_epochs`	Batch up to 16 roots in one transaction
`commit_epoch_v2`	Extended metadata: epoch ID, leaf count, timestamp, MMR size

Each commitment is stored in a PDA derived from the authority’s public key.

Multi-Chain Anchoring

Lucid anchors to both Solana and EVM chains simultaneously. Configure via the ANCHORING_CHAINS environment variable:

ANCHORING_CHAINS=solana-devnet,base

EVM anchoring uses the EpochRegistry contract, which stores the same root hash, epoch ID, and metadata.

Gas Costs

Operation	Cost
iGas (per inference call)	1 LUCID
mGas (per epoch root commitment)	5 LUCID
Batch commit (16 roots)	7 LUCID total

DePIN Archival

After on-chain commitment, the full epoch bundle (all receipts, MMR state, metadata) is archived to decentralized storage:

Provider	Tier	Use Case
Arweave	Permanent	Immutable epoch bundles, passport metadata
Lighthouse	Evolving	MMR checkpoints, memory snapshots

All DePIN uploads go through the AnchorDispatcher, which handles storage selection, CID tracking, and deduplication.

Verifying a Receipt

To verify that a specific receipt was included in an anchored epoch:

# Get an inclusion proof
curl https://api.lucid.foundation/v1/receipts/:id/proof \
  -H "Authorization: Bearer lk_..."

# Verify against on-chain root
curl -X POST https://api.lucid.foundation/v1/receipts/:id/verify \
  -H "Authorization: Bearer lk_..."

The proof contains the receipt hash, the MMR path, and the on-chain epoch root — sufficient for independent verification.

​The Receipt-to-Chain Pipeline

​Key Algorithms

​Receipt Hashing

​Merkle Mountain Range (MMR)

​Epoch Finalization

​On-Chain Commitment

​Multi-Chain Anchoring

​Gas Costs

​DePIN Archival

​Verifying a Receipt