--- name: debridge-signing description: > Sign and broadcast deBridge transactions. Routes to the correct signing method based on the detected signer: OWS local self-custody wallet, private key with ethers/viem, Foundry cast, browser wallet (MetaMask), or Privy embedded wallet. Use this skill whenever a deBridge transaction needs to be signed and sent on-chain — including bridge transactions, swap transactions, and token approvals. Also use when the user asks "how do I sign this transaction", "send the transaction", "approve the token", "broadcast to chain", "sign with OWS", "ows wallet", or needs help with EIP-712 typed data signing. This skill is called automatically by the bridge and swap workflows, but can also be used standalone for signing guidance. license: MIT metadata: author: deBridge version: "0.1.0" --- # Transaction Signing PREREQUISITE: Read ../common/SKILL.md for environment detection, auth, and chain configuration. ## Quick Reference | Want to... | Go to | |-----------------------------------|------------------------------------| | Sign with OWS (recommended) | [ows-signing.md](https://github.com/debridge-finance/debridge-skills/blob/b3bc79abefd7e7fa7092c810c5f4f02136567d4e/skills/signing/ows-signing.md) | | Sign with ethers.js or viem | [sdk-signer.md](https://github.com/debridge-finance/debridge-skills/blob/b3bc79abefd7e7fa7092c810c5f4f02136567d4e/skills/signing/sdk-signer.md) | | Sign with Foundry cast | [foundry-cast.md](https://github.com/debridge-finance/debridge-skills/blob/b3bc79abefd7e7fa7092c810c5f4f02136567d4e/skills/signing/foundry-cast.md)| | Sign with MetaMask / browser | [metamask.md](https://github.com/debridge-finance/debridge-skills/blob/b3bc79abefd7e7fa7092c810c5f4f02136567d4e/skills/signing/metamask.md) | | Sign via Privy MCP | [privy-mcp.md](https://github.com/debridge-finance/debridge-skills/blob/b3bc79abefd7e7fa7092c810c5f4f02136567d4e/skills/signing/privy-mcp.md) | | Set up a wallet from scratch | ../wallets/SKILL.md | ## What Needs Signing deBridge transactions from `mcp__debridge__create_tx` (cross-chain) or `mcp__debridge__transaction_same_chain_swap` (same-chain) return up to two transaction objects to sign: 1. **Token approval tx** (if allowance insufficient) — a standard EVM transaction calling `approve()` on the token contract. 2. **Bridge/swap tx** — an EVM transaction that may include EIP-712 typed data for DLN order creation. Both are standard `{to, data, value, chainId}` objects. Sign and broadcast to the source chain RPC. ## Signer Routing Use the `Signer` value from WALLET_DISCOVERY to select the right reference: | Signer value | Environment | Read this file | |-----------------|----------------|--------------------------------------| | ows | CLI | [ows-signing.md](https://github.com/debridge-finance/debridge-skills/blob/b3bc79abefd7e7fa7092c810c5f4f02136567d4e/skills/signing/ows-signing.md) | | env-privkey | CLI + Node.js | [sdk-signer.md](https://github.com/debridge-finance/debridge-skills/blob/b3bc79abefd7e7fa7092c810c5f4f02136567d4e/skills/signing/sdk-signer.md) | | env-privkey | CLI + cast | [foundry-cast.md](https://github.com/debridge-finance/debridge-skills/blob/b3bc79abefd7e7fa7092c810c5f4f02136567d4e/skills/signing/foundry-cast.md) | | foundry-cast | CLI | [foundry-cast.md](https://github.com/debridge-finance/debridge-skills/blob/b3bc79abefd7e7fa7092c810c5f4f02136567d4e/skills/signing/foundry-cast.md) | | browser-wallet | Browser | [metamask.md](https://github.com/debridge-finance/debridge-skills/blob/b3bc79abefd7e7fa7092c810c5f4f02136567d4e/skills/signing/metamask.md) | | ethers-viem | CLI / Headless | [sdk-signer.md](https://github.com/debridge-finance/debridge-skills/blob/b3bc79abefd7e7fa7092c810c5f4f02136567d4e/skills/signing/sdk-signer.md) | | mcp-wallet | Any | [privy-mcp.md](https://github.com/debridge-finance/debridge-skills/blob/b3bc79abefd7e7fa7092c810c5f4f02136567d4e/skills/signing/privy-mcp.md) | | none | Any | ../wallets/SKILL.md — set up first | ### Resolving env-privkey When Signer = `env-privkey`, a private key exists but a signing library is still needed. Pick based on what is available: 1. Node.js + ethers or viem installed → [sdk-signer.md](https://github.com/debridge-finance/debridge-skills/blob/b3bc79abefd7e7fa7092c810c5f4f02136567d4e/skills/signing/sdk-signer.md) 2. `cast` available → [foundry-cast.md](https://github.com/debridge-finance/debridge-skills/blob/b3bc79abefd7e7fa7092c810c5f4f02136567d4e/skills/signing/foundry-cast.md) 3. None of the above → install one: `npm install ethers` is the fastest path. ## Transaction Flow After `mcp__debridge__create_tx` or `mcp__debridge__transaction_same_chain_swap` returns tx data: ### Step 0: Preflight Checks Before signing, the agent MUST verify: 1. **Native balance for gas + fixFee** — Parse `fixFee` (wei) and `estimatedTransactionFee.total` from the response. Check that the wallet's native balance on the source chain covers both. If insufficient, stop and tell the user how much more they need. 2. **ERC-20 allowance** (EVM only, non-native tokens) — If the response does NOT include `approveTx`, the agent MUST still check the token's allowance for the bridge contract (`tx.to`). Use `scripts/erc20-approve.mjs` to check and approve if needed. Do NOT assume the MCP always returns `approveTx` — it may not. 3. **SOL rent/fees** (Solana source) — Solana bridge txs require ~0.024 SOL for rent deposits + tx fees, on top of the bridge amount. Check SOL balance before signing. ### Step 1: Check for Approval If the response includes an approval transaction (`approveTx`): 1. Sign and send the approval tx first. 2. Wait for confirmation (1 block). 3. Proceed to Step 2. If no `approveTx` but source token is ERC-20, run `scripts/erc20-approve.mjs` to check/approve (see Step 0). ### Step 2: Sign and Send Bridge Transaction 1. Take the main tx object (`tx` field from `create_tx` response). 2. Sign with the detected signer. 3. Broadcast to the source chain RPC. 4. Record the transaction hash. ### Step 3: Hand Off to Monitoring (cross-chain only) For cross-chain bridges, pass the tx hash and order ID to ../swap/monitoring.md for order tracking. Same-chain swaps settle in a single transaction — no monitoring needed. ## RPC Endpoints Most signers need an RPC connection to the source chain: - OWS: for EVM, `ows sign tx` handles signing locally — broadcast via RPC separately; for Solana, set `SOLANA_RPC_URL` or use the default public RPC - ethers/viem: pass RPC URL to provider constructor - cast: use `--rpc-url` flag - browser wallet: uses the wallet's connected RPC - Privy MCP: handles RPC internally — no RPC URL needed from the agent Use public RPCs or the user's configured RPC. Prefer user-provided RPCs or environment variables (`$ETH_RPC_URL`, `$RPC_URL`) over hardcoded defaults. The balance query skills include public RPCs as fallback defaults — override them when the user has configured RPCs. For programmatic RPC discovery from Chainlist, read ../common/rpc-discovery.md. ## Common Errors | Error | Cause | Fix | |-----------------------------|--------------------------------|-------------------------------------------------| | Insufficient funds for gas | Wallet has no native token | Fund wallet with ETH/native token on source chain | | Nonce too low | Pending tx or state mismatch | Wait for pending tx or reset nonce | | Transaction reverted | Approval not confirmed yet | Wait for approval confirmation before bridge tx | | Invalid signature | Wrong chain ID in signer | Ensure signer chain ID matches source chain | ## References - [ows-signing.md](https://github.com/debridge-finance/debridge-skills/blob/b3bc79abefd7e7fa7092c810c5f4f02136567d4e/skills/signing/ows-signing.md) — OWS local self-custody signing (EVM, Solana, Tron) - [sdk-signer.md](https://github.com/debridge-finance/debridge-skills/blob/b3bc79abefd7e7fa7092c810c5f4f02136567d4e/skills/signing/sdk-signer.md) — ethers.js and viem signing - [foundry-cast.md](https://github.com/debridge-finance/debridge-skills/blob/b3bc79abefd7e7fa7092c810c5f4f02136567d4e/skills/signing/foundry-cast.md) — Foundry cast CLI signing - [metamask.md](https://github.com/debridge-finance/debridge-skills/blob/b3bc79abefd7e7fa7092c810c5f4f02136567d4e/skills/signing/metamask.md) — Browser wallet signing - [privy-mcp.md](https://github.com/debridge-finance/debridge-skills/blob/b3bc79abefd7e7fa7092c810c5f4f02136567d4e/skills/signing/privy-mcp.md) — Privy embedded wallet signing via MCP