Add EIP: eth_sendRawTransactionSync Method

EIPS/eip-7966.md

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+---
+eip: 7966
+title: eth_sendRawTransactionSync Method
+description: A JSON-RPC method to reduce transaction submission latency by allowing synchronous receipt of transaction hash and block inclusion.
+author: Sam Battenally (@SmoothBot), Hai Nguyen (@hai-rise), Thanh Nguyen (@LampardNguyen234)
+discussions-to: https://ethereum-magicians.org/t/eip-7966-eth-sendrawtransactionsync-method/24640
+status: Draft
+type: Standards Track
+category: Interface
+created: 2025-06-11
+---
+
+## Abstract
+
+This EIP proposes a new JSON-RPC method, `eth_sendRawTransactionSync`, which submits a signed raw transaction and waits synchronously for the transaction receipt or a configurable timeout before returning. This method addresses the user experience gap in high-frequency applications by offering stronger delivery guarantees than `eth_sendRawTransaction`.
+
+## Motivation
+
+Currently, Ethereum clients submit signed transactions asynchronously using `eth_sendRawTransaction`. Clients receive a transaction hash immediately but must poll repeatedly for the transaction receipt, which increases latency and complicates client-side logic.
+
+This asynchronous approach is not efficient for high-frequency blockchains or Layer 2 solutions with fast block times and low latency, where rapid transaction throughput and quick confirmation feedback are critical. The need to separately poll for receipts results in increased network overhead, slower overall transaction confirmation feedback, and more complex client implementations.
+
+![Sync vs Async Transaction Sending](../assets/eip-7966/sync-vs-async.png)
+_In a low-latency blockchain, transaction receipts are often available right after the transactions land in the block producer’s mempool. Requiring an additional RPC call introduces unnecessary latency._
+
+`eth_sendRawTransactionSync` addresses these issues by combining transaction submission and receipt retrieval into a single RPC call. This helps:
+
+- reduce total transaction submission and confirmation latency by approximately 50%;
+- simplify client implementations by eliminating the need for separate polling loops;
+- improve user experience by enabling more responsive dApps and wallets;
+- align blockchain interactions closer to traditional Web2 request-response patterns;
+- maintain backward compatibility and optionality, preserving existing RPC methods and semantics.
+
+## Specification
+
+### Method Name
+
+`eth_sendRawTransactionSync`
+
+### Parameters
+
+The parameters of this method MUST be identical to the `eth_sendRawTransaction` method, which contain a signed transaction data.
+
+- `DATA`. The signed transaction data.
+
+### Returns
+
+- **On success**. Clients MUST return the transaction receipt object as defined by the `eth_getTransactionReceipt` method.
+- **On timeout error**. Clients MUST return an error code `-32002` with a timeout message.
+- **On standard error**. Clients MUST return a JSON-RPC error object consistent with existing RPC error formats.
+
+### Timeout Configuration
+
+- The handler function of this RPC MUST incorporate a configurable timeout when waiting for receipts (RECOMMENDED: 2 seconds).
+- Implementations MUST provide a way to configure the timeout duration.
+- Node operators MAY implement dynamic timeout adjustment based on real-time network conditions.
+
+### Behavior
+
+Upon receiving an `eth_sendRawTransactionSync` request, the handler function performs the following tasks.
+
+- The handler function MUST submit the signed transaction to the network as per the existing `eth_sendRawTransaction` semantics.
+- The handler function MUST wait for the transaction receipt until the timeout elapses.
+- If the receipt is found within the specified timeout, the handler function MUST return it immediately.
+- If the timeout expires without obtaining a receipt, the handler function MUST return an error message with a timeout message.
+- If the transaction submission fails (e.g., due to invalid transaction data), the handler function MUST return an error immediately.
+
+### Example Request
+
+```json
+{
+  "jsonrpc": "2.0",
+  "method": "eth_sendRawTransactionSync",
+  "params": [
+    "0xf86c808504a817c80082520894ab... (signed tx hex)"
+  ],
+  "id": 1
+}
+```
+
+### Example Response (Success)
+
+```json
+{
+  "jsonrpc": "2.0",
+  "id": 1,
+  "result": {
+    "transactionHash": "0x1234abcd...",
+    "blockHash": "0xabcd1234...",
+    "blockNumber": "0x10d4f",
+    "cumulativeGasUsed": "0x5208",
+    "gasUsed": "0x5208",
+    "contractAddress": null,
+    "logs": [],
+    "status": "0x1"
+  }
+}
+```
+
+### Example Response (Timeout)
+
+```json
+{
+  "jsonrpc": "2.0",
+  "id": 1,
+  "error": {
+    "code": -32002,
+    "message": "The transaction was added to the mempool but wasn't processed in 2s.",
+    "data": "0x1234abcd..."
+  }
+}
+```
+
+### Example Response (Error)
+
+```json
+{
+  "jsonrpc": "2.0",
+  "id": 1,
+  "error": {
+    "code": -32000,
+    "message": "Invalid transaction"
+  }
+}
+```
+
+## Rationale
+
+### Why Not Extend Existing RPC?
+
+Modifying `eth_sendRawTransaction` to support this behavior would risk compatibility issues and ambiguity. A separate method makes the semantics explicit and opt-in.
+
+### Blocking Behavior and Timeouts
+
+Clients SHOULD allow configuration of the timeout period, defaulting to 2 seconds (depending on the implementation). This balances responsiveness and propagation guarantees without creating excessive overhead in node clients.
+
+### Optionality
+
+This method is optional and does not replace or change existing asynchronous transaction submission methods. Clients and servers that do not implement this method will continue to operate normally using the standard asynchronous RPC methods.
+
+This RPC method is particularly suitable for EVM-compatible blockchains or L2 solutions with fast block times and low network latency, where synchronous receipt retrieval can significantly improve responsiveness. On high-latency or slower blockchains (e.g., Ethereum mainnet pre-sharding), the synchronous wait may cause longer RPC call durations or timeouts, making the method less practical.
+
+### Improved UX
+
+The synchronous receipt retrieval reduces the complexity of client applications by eliminating the need for separate polling logic.
+
+## Backwards Compatibility
+
+This EIP introduces a new RPC method and does not modify or deprecate any existing methods. Clients and servers that do not implement this method will continue operating normally. Existing applications using `eth_sendRawTransaction` are unaffected. Clients that do not support the method will simply return `method not found`.
+
+## Reference Implementation
+
+A minimal reference implementation can be realized by wrapping existing `eth_sendRawTransaction` submission with a polling loop that queries `eth_getTransactionReceipt` at short intervals until a receipt is found or a timeout occurs. Polling intervals and timeout values can be tuned by client implementations to optimize performance.
+
+For example, in `reth`, we can implement the handler for `eth_sendRawTransactionSync` as follows.
+
+```rust
+async fn send_raw_transaction_sync(&self, tx: Bytes) -> RpcResult<OpTransactionReceipt> {
+    const TIMEOUT_DURATION: Duration = Duration::from_secs(2);
+    const POLL_INTERVAL: Duration = Duration::from_millis(1);
+
+    let hash = self.inner.send_raw_transaction(tx).await?;
+
+    let start = Instant::now();
+    while start.elapsed() < TIMEOUT_DURATION {
+        if let Some(receipt) = self.pending_block.get_receipt(hash) {
+            return Ok(receipt);
+        }
+        tokio::time::sleep(POLL_INTERVAL).await;
+    }
+
+    Err(ErrorObject::owned(
+        -32002,
+        format!(
+            "The transaction was added to the mempool but wasn't processed in {TIMEOUT_DURATION:?}."
+        ),
+        Some(hash),
+    ))
+}
+```
+
+Other implementations such as `go-ethereum` can utilize a channel to signify receipt availability instead of polling.
+
+## Security Considerations
+
+- This method does not introduce new security risks beyond those inherent in transaction submission.
+- The timeout prevents indefinite blocking of RPC calls, protecting clients and servers from hanging requests.
+- Clients should handle timeout responses gracefully and continue monitoring transaction status as needed.
+- Servers must ensure that the implementation does not degrade node performance or cause denial-of-service.
+
+## Copyright
+
+Copyright and related rights waived via [CC0](../LICENSE.md).