Agent Skill Registry

An onchain registry for canonicalizing agent skills, designed to complement ERC-8004 Trustless Agents and ERC-8183 Agentic Commerce.

ERC-8004 introduces Identity, Reputation, and Validation registries for agents. ERC-8183 adds an escrow protocol for agent-based jobs. Neither defines a canonical way to identify the skills an agent offers, or to record which skills an agent used to complete a job. This project fills that gap.

Contracts

Contract	Purpose
SkillRegistry	ERC-721 registry: one token per skill, minted to the skill's owner. tokenURI points at the offchain skill manifest, with an onchain manifestHash commitment for integrity.
SkillAttestation	Events-only contract covering both usage attestations (self / evaluator / hook attestation paths) and installation declarations (single + batch install / uninstall). One address; two semantic modes.
SkillAttestationHook	Optional IACPHook for ERC-8183 jobs: on complete(), decodes a skill declaration from optParams and emits hook-attested usage.

Deployments

All contracts use CREATE2 through the canonical Foundry deterministic deployer (0x4e59b44847b379578588920cA78FbF26c0B4956C). Mined salts produce vanity addresses whose 5th–6th hex characters (aa / bb / cc) distinguish the three contracts at a glance.

SkillRegistry lands at the same address on every chain (no constructor args). SkillAttestation and SkillAttestationHook have constructor args that include the ERC-8004 IdentityRegistry, which differs between testnet and mainnet — so those two contracts have one canonical testnet address and (eventually) a different canonical mainnet address.

Sepolia

Contract	Address
SkillRegistry	0x8239AAbaa1A44338bEeFAAf4C3a373d2a18D5DC4
SkillAttestation	0x8239bb93AD4C3EB1581B7359Afbe3Bc7BE15A9cf
SkillAttestationHook	0x8239CC872158ae66f95C85a3721cbE9644Bdf079

Project Layout

src/
  SkillRegistry.sol
  SkillAttestation.sol
  hooks/
    SkillAttestationHook.sol  # reference IACPHook for ERC-8183 jobs
  interfaces/
    ISkillRegistry.sol
    ISkillAttestation.sol
    IERC8183.sol          # minimal local read-side interface
    IACPHook.sol          # ERC-8183 hook interface
test/
  SkillRegistry.t.sol
  SkillUsage.t.sol           # usage-mode behaviors of SkillAttestation
  SkillInstallation.t.sol    # installation-mode behaviors of SkillAttestation
  SkillAttestationHook.t.sol
  mocks/
    MockERC721.sol        # stands in for an ERC-8004 Identity Registry
    MockERC8183.sol       # minimal configurable job source
script/
  DeploySkillRegistry.s.sol
  DeploySkillAttestation.s.sol
  DeploySkillAttestationHook.s.sol
REPUTATION.md
README.md

Setup

Prerequisites:

• Foundry (forge, cast, anvil)

Clone and install submodule dependencies:

git clone <this-repo>
cd agent-skill-registry
forge install

Dependencies (in lib/):

• forge-std
• openzeppelin-contracts

Remappings are defined in remappings.txt.

Compile

forge build

Test

Run the full suite:

forge test

Run a single suite with verbose logs:

forge test --match-contract SkillAttestationTest -vv

Gas report:

forge test --gas-report

Deploy

All three scripts deploy via CREATE2 through the canonical Foundry deterministic deployer and assert the resulting address matches the hardcoded vanity-mined target before broadcasting. Provide a funded deployer key via --private-key, --account, or --interactive.

To also verify source on Etherscan in the same run, export an ETHERSCAN_API_KEY (Etherscan V2 — one key works across mainnet, Sepolia, Base, Base Sepolia, etc., per the [etherscan] config in foundry.toml) and append --verify to any deploy command.

SkillRegistry

Has no constructor arguments.

forge script script/DeploySkillRegistry.s.sol:DeploySkillRegistry \
  --rpc-url "$RPC_URL" \
  --account my-keystore \
  --broadcast --verify

SkillAttestation

Requires the ERC-8004 Identity Registry address and a deployed SkillRegistry.

IDENTITY_REGISTRY=0x... SKILL_REGISTRY=0x... \
  forge script script/DeploySkillAttestation.s.sol:DeploySkillAttestation \
    --rpc-url "$RPC_URL" \
    --account my-keystore \
    --broadcast --verify

SkillAttestationHook

Requires a deployed SkillAttestation address.

SKILL_ATTESTATION=0x... \
  forge script script/DeploySkillAttestationHook.s.sol:DeploySkillAttestationHook \
    --rpc-url "$RPC_URL" \
    --account my-keystore \
    --broadcast --verify

Manual verification fallback

Because the deploy scripts call the CREATE2 deployer factory directly rather than using Solidity's new Contract{salt: ...} syntax, forge's auto-verify can occasionally miss the deployed contract. If --verify silently skips a contract, run forge verify-contract against the known address:

forge verify-contract \
  0x8239AAbaa1A44338bEeFAAf4C3a373d2a18D5DC4 \
  src/SkillRegistry.sol:SkillRegistry \
  --chain sepolia \
  --watch

For contracts with constructor args, append --constructor-args $(cast abi-encode "constructor(address,address)" $IDENTITY_REGISTRY $SKILL_REGISTRY) (or the appropriate signature for that contract).

Integration Notes

Filing feedback on skill usage

When an evaluator files feedback in the ERC-8004 Reputation Registry about an agent's performance on a skill, the feedback SHOULD carry:

tag1 = "asr:skill"
tag2 = "<chainId>:<skillRegistryAddress>:<skillId>"

Indexers filter on these tags to produce per-agent-per-skill and per-skill aggregate reputation. See docs/REPUTATION.md for full semantics and indexer guidance.

Using SkillAttestationHook with ERC-8183

1. Deploy SkillAttestationHook pointing at the desired SkillAttestation.
2. When creating a job, pass the hook address as the hook parameter to createJob.
3. When the evaluator calls complete(jobId, reason, optParams), encode optParams as:

   abi.encode(
     uint256 agentId,
     uint256[] skillIds,
     bytes32[] evidenceHashes,
     string[] evidenceURIs
   )

   All three arrays MUST be the same length. Pass empty bytes to opt out for a specific completion.
4. The hook will emit one SkillUsed event per skill, with attester set to the hook's address. Indexers distinguish hook-attested from evaluator-attested events by comparing attester against job.hook / job.evaluator.

License

UNLICENSED (see SPDX headers in source files).