feat: add Polkadot SDK JSON-RPC methods documentation

advanced/multichain/rpc-reference/polkadot-rpc.mdx

@@ -0,0 +1,154 @@
+---
+title: 'Polkadot'
+description: Polkadot SDK JSON-RPC Methods
+---
+
+<Note type="warning">
+  **Please note:** The Polkadot RPC standard is still under review and specifications may change.
+  Implementation details and method signatures are subject to updates.
+</Note>
+
+## polkadot_signTransaction
+
+This method returns a signature for the provided transaction payload. It will be signed by a keypair corresponding to the requested signer address.
+
+### Parameters
+
+1. `Object` - Request parameters:
+   - `address`: `string` - SS58 encoded address of the signer
+   - `transactionPayload`: `Object` - As per Polkadot type `SignerPayloadJSON` containing:
+     - `address`: `string` - The SS58 encoded address (must match outer address)
+     - `assetId`: `HexString | null` - (optional) The id of the asset used to pay fees
+     - `blockHash`: `HexString` - The checkpoint hash of the block, 32 bytes
+     - `blockNumber`: `HexString` - The checkpoint block number (hex encoded)
+     - `era`: `HexString` - The mortality period of this transaction
+     - `genesisHash`: `HexString` - The genesis hash of the chain, 32 bytes
+     - `metadataHash`: `HexString | null` - (optional) The hash of the metadata for verification
+     - `method`: `string` - The SCALE encoded method data (hex encoded)
+     - `mode`: `number` - (optional) The mode for metadata verification (0=none, 1=exact, 2=partial)
+     - `nonce`: `HexString` - The nonce for this transaction (hex encoded)
+     - `specVersion`: `HexString` - The current specification version (hex encoded)
+     - `tip`: `HexString` - The tip for this transaction (hex encoded amount)
+     - `transactionVersion`: `HexString` - The current transaction version (hex encoded)
+     - `signedExtensions`: `string[]` - The array of signed extension identifiers
+     - `version`: `number` - The extrinsic version number
+     - `withSignedTransaction`: `boolean` - (optional) Request signed transaction bytes
+
+### Returns
+
+1. `Object` - Signature result:
+   - `signature`: `string` - Hex-encoded signature
+
+### Example
+
+```javascript
+// Request
+{
+    "id": 1,
+    "jsonrpc": "2.0",
+    "method": "polkadot_signTransaction",
+    "params": {
+        "address": "15UyNqZ7NB1QQVpY9xv7VGwkxtvXePKihFHx8kH4VgEcS1gU",
+        "transactionPayload": {
+            "address": "15UyNqZ7NB1QQVpY9xv7VGwkxtvXePKihFHx8kH4VgEcS1gU",
+            "assetId": null,
+            "blockHash": "0x1b1c32a33c3622044a3be1b7753ff9b24695c327fc9254f97c...",
+            "blockNumber": "0x00000393",
+            "era": "0x0500",
+            "genesisHash": "0x91b171bb158e2d3848fa23a9f1c25182fb8e20313b2c1eb49219da7a70ce90c3",
+            "metadataHash": null,
+            "method": "0x0400....",
+            "mode": 0,
+            "nonce": "0x00000000",
+            "specVersion": "0x00000000",
+            "tip": "0x00000000000000000000000000000000",
+            "transactionVersion": "0x00000004",
+            "signedExtensions": [
+                "CheckNonZeroSender",
+                "CheckSpecVersion",
+                "CheckTxVersion",
+                "CheckGenesis",
+                "CheckMortality",
+                "CheckNonce",
+                "CheckWeight",
+                "ChargeTransactionPayment"
+            ],
+            "version": 4
+        }
+    }
+}
+
+// Result
+{
+    "id": 1,
+    "jsonrpc": "2.0",
+    "result": {
+        "signature": "0x01234567..."
+    }
+}
+```
+
+<Note>
+  The `method` field in the transaction payload contains the SCALE encoded call data specific to the
+  transaction being signed. This typically includes the pallet name, function name and any
+  parameters required for that specific transaction.
+</Note>
+
+## polkadot_signMessage
+
+This method returns a signature for the provided message payload. It will be signed by a keypair corresponding to the requested signer address.
+
+### Parameters
+
+1. `Object` - As per Polkadot type `SignerPayloadRaw` containing:
+   - `address`: `string` - SS58 encoded address
+   - `data`: `string` - The hex-encoded data for this request
+   - `type`: `'bytes' | 'payload'` - (optional) Identifies if the message is arbitrary bytes or a transaction payload
+
+<Note type="warning">
+`polkadot_signMessage` can potentially be used to sign arbitrary transactions blindly. To mitigate this security risk:
+
+1. Always wrap messages in `<Bytes>message</Bytes>` tags before hex encoding when message `type` is `'bytes'` or not specified
+2. If the type is not `'payload'`, signers MUST verify that messages are properly wrapped
+3. Use `type: 'payload'` only when signing transaction-like data that should be possible to decrypt
+
+This convention helps prevent malicious applications from using `polkadot_signMessage` for blind transaction signing while maintaining compatibility with widely-used Polkadot signing implementations.
+
+</Note>
+
+### Returns
+
+1. `Object` - Signature result:
+   - `signature`: `string` - Hex-encoded signature
+
+### Example
+
+```javascript
+// Request
+{
+    "id": 1,
+    "jsonrpc": "2.0",
+    "method": "polkadot_signMessage",
+    "params": {
+        "address": "15UyNqZ7NB1QQVpY9xv7VGwkxtvXePKihFHx8kH4VgEcS1gU",
+        "data": "0x3c42797465733e68656c6c6f20776f726c643c2f42797465733e", // "<Bytes>hello world</Bytes>" hex encoded
+        "type": "bytes"
+    }
+}
+
+// Result
+{
+    "id": 1,
+    "jsonrpc": "2.0",
+    "result": {
+        "signature": "0x6a98517e159dcaef1855cda5f5e5a61387ac3b63212b0f82642f5599502fc9eb1ea134e2db5dfbe0ec4530c6e7e576b177ad0618f68eaec37a3ac6dce819a30a"
+    }
+}
+```
+
+## Additional Resources
+
+For more information about Polkadot RPC methods and integration details, please refer to:
+
+- [Polkadot Transaction Construction](https://docs.polkadot.com/develop/toolkit/integrations/transaction-construction/)
+- [Polkadot.js Extrinsic Types](https://github.com/polkadot-js/api/blob/master/packages/types/src/types/extrinsic.ts#L32)

docs.json

@@ -142,6 +142,7 @@
                       "advanced/multichain/rpc-reference/ethereum-rpc",
                       "advanced/multichain/rpc-reference/solana-rpc",
                       "advanced/multichain/rpc-reference/sui-rpc",
+                      "advanced/multichain/rpc-reference/polkadot-rpc",
                       "advanced/multichain/rpc-reference/stacks-rpc",
                       "advanced/multichain/rpc-reference/tron-rpc",
                       "advanced/multichain/rpc-reference/near-rpc",