Asset Management

Overview

Ingot treats assets as "objects" that can be combined, updated, and transferred. The protocol supports fungible tokens, semi-fungible tokens, NFTs, and custom asset types through a flexible asset list system.

Asset List Specification

Assets are represented in payloads using the TLV_ASSET_LIST (type = 0x0101) TLV entry.

Structure

Each asset entry contains:

asset_type  : u8        // 0=fungible, 1=semi-fungible, 2=nft, 3=custom
asset_id    : [32]      // BLAKE3 identifier or upstream asset ID
amount      : u128le    // For NFT use 1; semi use shares; fungible use quantity
meta_tlv    : TLV[]     // Bounded extensions (e.g., display/URI, etc.)

Asset Types

• Fungible (0): Interchangeable tokens (e.g., BRC-20 compatible tokens)
• Semi-Fungible (1): Partially interchangeable assets (e.g., shares, batches)
• NFT (2): Unique, non-fungible assets (e.g., ERC-721 compatible NFTs)
• Custom (3): Application-specific asset types

Limits

• Maximum 256 asset items per list
• Single ASSET_LIST TLV total size ≤ 48 KiB
• Exceeding limits → indexer rejects parsing

Asset Merging

Ingot supports merging multiple assets into a single output:

• Merging Assets: Bundle multiple items (like tokens from different inputs) into one output
• Balance Conservation: L2 validation ensures input assets = output assets per token type
• Asset List: Explicit asset inventory in payload (TLV format)
• Unique Identification: Each asset instance is uniquely tied to its transaction position (outpoint)

Merging Example

When transferring assets, you can combine multiple asset types:

Input 1: 100 TOKEN_A
Input 2: 50 TOKEN_B
Output: 100 TOKEN_A + 50 TOKEN_B (merged in single Pay2Ingot output)

Asset Merkle Roots

For large asset collections or privacy-sensitive scenarios, use Merkle trees:

TLV_ASSET_MERKLE_ROOT (type = 0x0102)

Structure:

root : [32]     // BLAKE3-256 Merkle root

Purpose:

• When asset count is large, only place Merkle root in payload
• Specific asset entries can be selectively revealed as leaves in witness
• Provides "partial visibility" capability
• Enables privacy-preserving asset transfers

Witness: Asset Merkle Proof

WITNESS_ASSET_PROOF structure:

leaf_bytes   : TLV[]     // TLV encoding identical to ASSET_LIST unit entry
merkle_path  : [depth]   // Depth ≤ 8, each step 32B hash

Validation Flow:

1. Indexer calculates leaf hash: leaf_hash = blake3(leaf_bytes)
2. Reconstruct Merkle root along merkle_path
3. Verify reconstructed root equals ASSET_MERKLE_ROOT in payload
4. Match success → leaf considered valid reveal
5. Match failure → indexer rejects this leaf

Standard Schema Templates

Ingot provides production-ready standard schema templates:

Token Schemas

• brc20_compatible.json: BRC-20 compatible tokens (simple, community-friendly)
• trc721_advanced.json: TRC-721 advanced tokens (TLV format, governance, asset conservation)

NFT Schemas

• erc721_compatible.json: ERC-721 compatible NFTs
• music.json: Music NFTs (audio files, lyrics, copyright)

Inscription Schemas

• text.json: Text inscriptions (plain text, Markdown, code)
• image.json: Image inscriptions (SVG, PNG, JPEG, GIF, WebP)

DAO Schemas

• proposal.json: DAO proposals (parameter modifications, fund allocation, code upgrades)
• vote.json: DAO voting (weighted voting, delegation, rationale)

Application Schemas

• social_post.json: Decentralized social media posts
• identity.json: Decentralized identity (W3C DID standard)

Asset Operations

Mint

Creates the first instance of an asset:

• No parent_instance_id required
• Does not spend parent tip
• Generates first tip for the artifact

Transfer

Changes ownership of an asset:

• Requires ALLOW_MUTABLE=1 flag
• Must spend current tip
• Creates new instance with updated ownership
• Allows HASH_PAYLOAD unchanged (only ownership/lock changes)

Attach

Appends auxiliary data to an asset:

• Requires ALLOW_MUTABLE=1 flag
• Must spend current tip
• References parent tip
• Adds new data without changing core asset properties

Mutate

Modifies mutable fields of an asset:

• Requires ALLOW_MUTABLE=1 flag
• Must spend current tip
• Changes object mutable fields
• Maintains asset continuity through artifact_id

Bundle

Aggregates multiple artifact_id into a composite object:

• Requires ALLOW_MUTABLE=1 flag
• Must spend current tip
• Forms composite object from multiple artifacts
• Enables complex asset compositions

Asset Conservation Rules

L2 indexer validates asset conservation:

• Input Validation: Sum of input assets per asset_id
• Output Validation: Sum of output assets per asset_id
• Conservation: Input assets = Output assets (per token type)
• Violation: Indexer marks as invalid, doesn't become active tip

Partial Visibility

Indexers support partial asset disclosure:

• Merkle Proofs: Verify specific assets without downloading complete asset lists
• Selective Reveals: Only relevant assets are disclosed in witness
• Privacy-Preserving: Unrevealed assets remain hidden
• Verification: Indexers can verify partial asset reveals through Merkle proofs

Time Locks

Assets can be locked with time-based restrictions:

• Time Locks: Delay access to assets via ScriptHash locks
• Vesting Schedules: Assets locked until specific dates or conditions
• Use Cases: Useful for vesting schedules, timed releases, escrow services
• Implementation: Via ScriptHash lock type + VM scripts (OP_CHECKLOCKTIMEVERIFY/OP_CHECKSEQUENCEVERIFY)

Unique Identification

Each asset instance is uniquely identified:

• artifact_id: blake3("Ingot/artifact" || SCHEMA_ID || HASH_PAYLOAD)

  • Cross-version identifier for the same object
  • Used for deduplication and reference

• instance_id: blake3("Ingot/instance" || artifact_id || outpoint_bytes)

  • Identifies this UTXO instance (a specific version of the same artifact)
  • Where outpoint_bytes = txid[32] || u32le(vout)
  • Uniqueness guaranteed by UTXO model

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