capacitr

Files (6)

• SKILL.md
• api-reference.md · references/
• error-handling.md · references/
• x402-flow.md · references/
• analyze.sh · scripts/
• discovery.sh · scripts/

SKILL.md (first lines)

# capacitr

Market discovery as a single x402-paid HTTP call. Paste a URL or
sentence; get back ranked Polymarket / Hyperliquid / Deribit markets
with Quotient intelligence (fair odds, spread, BLUF) overlaid. One
endpoint, one payment, one response.

## Proven on-chain settlement

Verified end-to-end against both Coinbase and MetaMask facilitators on
Base mainnet. Each row is a real on-chain transfer to the Capacitr
payee `0x6503fB61705EB6B3C57EE1ab88a1a75A6eE01869`:

| Asset      | Method   | Facilitator      | Tx |
|------------|----------|------------------|----|
| USDC       | eip3009  | Coinbase CDP     | [`0x484cc8…398a`](https://basescan.org/tx/0x484cc87aa896bbabb73238fdcc97df84110cec4eb95c984d3802143f2242398a) |
| $CAPACITR  | permit2  | Coinbase CDP     | [`0xa6a8eb…5864`](https://basescan.org/tx/0xa6a8ebc4cde81f35a8a967c71f038f02de694c814ad0986997ff2f25c4815864) |
| $CAPACITR  | erc7710  | MetaMask CDP     | [`0xa286dd…066e`](https://basescan.org/tx/0xa286dd9127f9eb284d0a45b9effa96952ec46c6ff62106da2061f5aa99d3066e) |

Your agent platform signs the right primitive for the
`assetTransferMethod` declared in the 402 envelope; Capacitr routes
verify + settle to the matching facilitator. No further integration
required.

## Base URL

```bash
: "${CAPACITR_BASE_URL:=https://app.capacitr.xyz}"
```

## Always-on preflight

```bash
curl -sS "$CAPACITR_BASE_URL/api/skill/discovery" | jq .
```

Returns current prices, accepted assets, EIP-712 domain hints, and the
canonical `accepts[]` shape. Treat `prices_version` as the cache key —
if a later `402` carries a different `prices_version`, re-fetch
discovery before re-signing.

## The paid endpoint — `POST /api/analyze-link`

**Default: pay in $CAPACITR.** USDC supported as a fallback when the
agent's wallet doesn't hold $CAPACITR. All prices come from discovery
— never hard-code.

### Flow

1. POST without `X-Payment`. Expect `402` with `x402.accepts[]`.
2. **Prefer the `accepts[]` entry where `extra.symbol === "capacitr"`.**
   Fall back to USDC only if your wallet doesn't hold $CAPACITR on Base.

   ```bash
   # Pick CAPACITR if present, otherwise USDC
   accept=$(jq -r '.x402.accepts | (map(select(.extra.symbol == "capacitr"))[0] // map(select(.extra.symbol == "usdc"))[0])')
   ```
3. Read `accepts[].extra.assetTransferMethod` to know which signing
   primitive to use (see below). Sign with your wallet.
4. Retry with `X-Payment: <base64 JSON>` header → 200 + payload.

### Why $CAPACITR?

- Aligns agent payment with the token holders driving Capacitr's
  research surface — directly compounds protocol value rather than
  flowing out to a generic stablecoin.
- Lower per-call cost than USDC equivalent.
- Same on-chain settlement guarantees via Coinbase CDP (the
  `permit2 + eip2612GasSponsoring` flow chains `token.permit()` →
  `x402ExactPermit2Proxy.settleWithPermit()` and the facilitator pays
  gas — agent wallet only needs $CAPACITR balance, no ETH).

### Asset transfer methods

The 402 envelope declares **one** method per `accepts[]` entry. Pick
the entry whose method your wallet can sign:

```
accepts[i].extra.assetTransferMethod ∈ { "eip3009", "permit2", "erc7710" }
```

| Method      | Used for             | Signing                                                   |
|-------------|----------------------|-----------------------------------------------------------|
| **permit2** | **$CAPACITR (default)** | Two EIP-712 sigs: token `Permit` + Permit2 `PermitWitnessTransferFrom` |
| **erc7710** | $CAPACITR (operator may pick instead of permit2) | One delegation signed by a MetaMask Smart Account (or EIP-7702-upgraded EOA) |
| **eip3009** | USDC (fallback)      | One EIP-712 sig: `TransferWithAuthorization`              |

The operator picks at most one method per asset for $CAPACITR. If they
flip the operator switch, agents see the new method in the next 402
envelope.

### `permit2` — `$CAPACITR` via Coinbase (default)

Two signatures from any EOA. The facilitator chains
`token.permit(...)` → `x402ExactPermit2Proxy.settleWithPermit(...)` and
pays gas.

```
PERMIT2_CANONICAL     = 0x000000000022D473030F116dDEE9F6B43aC78BA3
X402_EXACT_PROXY      = 0x402085c248EeA27D92E8b30b2C58ed07f9E20001

# 1. EIP-2612 permit signature against the token
domain  = { name: <accepts.extra.name>, version: <accepts.extra.version>,
            chainId: 8453, verifyingContract: <accepts.asset> }
types   = { Permit: [
              {name: "owner",    type: "address"},
              {name: "spender",  type: "address"},
              {name: "value",    type: "uint256"},
              {name: "nonce",    type: "uint256"},
              {name: "deadline", type: "uint256"},
            ] }
message = { owner: <agent EOA>, spender: PERMIT2_CANONICAL,
            value: MAX_UINT256, nonce: <token.nonces(owner)>, deadline }

# 2. Permit2 PermitWitnessTransferFrom signature
domain  = { name: "Permit2", chainId: 8453,
            verifyingContract: PERMIT2_CANONICAL }
types   = { PermitWitnessTransferFrom: [
              {name: "permitted", type: "TokenPermissions"},

From Eskyee/agentbot-opensource, MIT.

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