runtime/accounts: Include nonce in API response

Author: ptrus

api/spec/v1.yaml

@@ -3722,12 +3722,17 @@ components:
 
     RuntimeAccount:
       type: object
-      required: [address, balances, evm_balances, stats]
+      required: [address, nonce, balances, evm_balances, stats]
       properties:
         address:
           type: string
           description: The staking address for this account.
           example: *staking_address_1
+        nonce:
+          type: integer
+          format: int64
+          description: The expected nonce for the next transaction (= last used nonce + 1)
+          example: 0
         address_preimage:
           allOf: [$ref: '#/components/schemas/AddressPreimage']
         balances:

storage/client/client.go

@@ -2057,6 +2057,17 @@ func (c *StorageClient) RuntimeAccount(ctx context.Context, runtime common.Runti
 		return nil, wrapError(err)
 	}
 
+	// Get the next expected nonce for this account.
+	err = c.db.QueryRow(
+		ctx,
+		queries.RuntimeAccountNonce,
+		runtime,
+		address.String(),
+	).Scan(&a.Nonce)
+	if err != nil {
+		return nil, wrapError(err)
+	}
+
 	return &a, nil
 }
 

storage/client/queries/queries.go

@@ -882,6 +882,13 @@ const (
 			(runtime = $1) AND
 			(address = $2::text)`
 
+	RuntimeAccountNonce = `
+		SELECT COALESCE(MAX(nonce) + 1, 0)
+		FROM chain.runtime_transaction_signers
+		WHERE
+			(runtime = $1) AND
+			(signer_address = $2::text)`
+
 	RuntimeDelegations = `
 		SELECT delegatee, shares, escrow_balance_active, escrow_total_shares_active
 			FROM chain.runtime_accounts_delegations