---
name: eth-anchor
description: >
  Anchor a Merkle root (root_hex) to Ethereum using a minimal calldata transaction,
  emit PROOF.json + tx metadata, with plan/apply/rollback and verification.
  Consumes merkle-forest ROOT.txt (or explicit ROOT_HEX). Triggers: 'eth anchor',
  'anchor root on ethereum', 'calldata tx', 'proof on chain'.
version: 1.0.0
---

# ETH Anchor (Calldata TX)

This skill anchors a **root_hex** to Ethereum by sending a small transaction
with the root embedded in **data** (calldata). It outputs a proof receipt
linking **ROOT.txt → tx hash → chain**.

## Requirements
- `cast` (Foundry) **or** `ethers`-compatible RPC with `curl` is possible; v1 uses `cast`.
- RPC URL for the target network.
- A funded private key (hot key) OR hardware wallet workflow (not implemented in v1).

## Quick Start

```bash
cd ~/.claude/skills/eth-anchor

# inputs
export ROOT_FILE="$HOME/.claude/skills/merkle-forest/outputs/runs/<run>/ROOT.txt"
# or: export ROOT_HEX="..."

# chain
export ETH_RPC_URL="https://..."
export CHAIN_ID=1                     # 1 mainnet, 11155111 sepolia, etc
export TO_ADDRESS="0x0000000000000000000000000000000000000000"  # burn/null is fine for data-only tx

# signer
export ETH_PRIVATE_KEY="0x..."        # ensure funded

# safety
export DRY_RUN=1
export REQUIRE_CONFIRM=1
export CONFIRM_PHRASE="I UNDERSTAND THIS WILL SEND AN ETH TRANSACTION"

./scripts/00_preflight.sh
./scripts/10_plan.sh

export DRY_RUN=0
./scripts/11_apply.sh

./scripts/90_verify.sh
./scripts/99_report.sh
```

## Inputs

| Parameter | Required | Default | Description |
|---|---:|---|---|
| ROOT_FILE | No | (empty) | Path to ROOT.txt from merkle-forest |
| ROOT_HEX | No | (empty) | Explicit root hex (overrides ROOT_FILE) |
| ETH_RPC_URL | Yes | (none) | RPC endpoint |
| CHAIN_ID | No | 1 | Chain id |
| TO_ADDRESS | No | 0x000…000 | Recipient (data-only tx) |
| GAS_LIMIT | No | 60000 | Gas limit |
| VALUE_WEI | No | 0 | Value to send (normally 0) |
| ETH_PRIVATE_KEY | Yes | (none) | Hot key for signing (v1) |
| DRY_RUN | No | 1 | Apply refuses unless DRY_RUN=0 |
| REQUIRE_CONFIRM | No | 1 | Require confirmation phrase |
| CONFIRM_PHRASE | No | I UNDERSTAND THIS WILL SEND AN ETH TRANSACTION | Safety phrase |

## Outputs (per run)

`outputs/runs/<label>_<timestamp>/`
- `root_hex.txt`
- `tx_hash.txt`
- `tx_receipt.json`
- `PROOF.json`
- `status_matrix.json`
- `audit_report.md`

## Notes
- Data payload: `0x` + `root_hex` (32 bytes / 64 hex). If root_hex is not 32 bytes, v1 right-pads to 32 bytes.
- This is a simple anchor. If you later want "contract-based attestations", we can add an EAS backend.

## EU Compliance
EU (Ireland - Dublin), Irish jurisdiction. Anchors are public chain data.