feat: implement flashblock sync over p2p

[noot]

📝 Summary

• implement sync and execution of flashblocks received over p2p

instructions for local testing with builder-playground, 1 builder building and 1 builder syncing:

1. checkout modified builder-playground branch: cd builder-playground && git checkout noot/multi-builder
2. checkout and build this branch: cd op-rbuilder && git checkout noot/p2p-sync && cargo build
3. run builder-playground:

sudo rm -rf ~/.playground ~/.local/share/reth && go run main.go cook opstack --flashblocks --external-builder http://host.docker.internal:4444 --flashblocks-builder ws://host.docker.internal:1111 --base-overlay

4. check that the sync-only node has started: docker logs devnet-op-rbuilder-sync-only-1 -f
5. run builder that will build:

./target/debug/op-rbuilder node --chain $HOME/.playground/devnet/l2-genesis.json --http --http.port 2222 --authrpc.port 4444 --authrpc.jwtsecret $HOME/.playground/devnet/jwtsecret --port 30333 --disable-discovery --rollup.builder-secret-key 59c6995e998f97a5a0044966f0945389dc9e86dae88c7a8412f4603b6b78690d --trusted-peers enode://79be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8@127.0.0.1:30304 --authrpc.addr 0.0.0.0 --flashblocks.enabled --flashblocks.addr 172.17.0.1 --flashblocks.port 1111 --rollup.chain-block-time 2000 --flashblocks.p2p_enabled

you should see logs showing that the nodes connected and that flashblocks are syncing and successfully executing and being added to the canonical chain:

2025-10-15T18:52:31.442158Z  INFO executing flashblock header=Header { parent_hash: 0x70285e5ea71a4e7a3f8201ad26f3e9d56fa7c107b829577ed62f81e50134dcaf, ommers_hash: 0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347, beneficiary: 0x4200000000000000000000000000000000000011, state_root: 0x468f6ad3315f8435ef691e752eb3420313c0709d9c10cd5231d069e61ec4c36f, transactions_root: 0xa0ba654a54295a9730299eccbdbda4e485729cac1020d47e63ed7322f61455d9, receipts_root: 0x078cb07a71cd0774760b0d2ef9d538699f8a5a90269eb293f79e6978968225ad, logs_bloom: 0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000, difficulty: 0, number: 25, gas_limit: 60000000, gas_used: 73498, timestamp: 1760554353, extra_data: 0x00000000fa00000006, mix_hash: 0x0130f5ed8cefc24088a9b58715b709e975ce4fd6e4c53d5fefb2a0435b1e9cfc, nonce: 0x0000000000000000, base_fee_per_gas: Some(905213509), withdrawals_root: Some(0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421), blob_gas_used: Some(0), excess_blob_gas: Some(0), parent_beacon_block_root: Some(0x59fe6ce059192b2ce5d0e83a5b149f88d5d10e3d5d69713da1784eccbd6c2d9d), requests_hash: None }
2025-10-15T18:52:31.442901Z  INFO successfully executed flashblock header=Header { parent_hash: 0x70285e5ea71a4e7a3f8201ad26f3e9d56fa7c107b829577ed62f81e50134dcaf, ommers_hash: 0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347, beneficiary: 0x4200000000000000000000000000000000000011, state_root: 0x468f6ad3315f8435ef691e752eb3420313c0709d9c10cd5231d069e61ec4c36f, transactions_root: 0xa0ba654a54295a9730299eccbdbda4e485729cac1020d47e63ed7322f61455d9, receipts_root: 0x078cb07a71cd0774760b0d2ef9d538699f8a5a90269eb293f79e6978968225ad, logs_bloom: 0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000, difficulty: 0, number: 25, gas_limit: 60000000, gas_used: 73498, timestamp: 1760554353, extra_data: 0x00000000fa00000006, mix_hash: 0x0130f5ed8cefc24088a9b58715b709e975ce4fd6e4c53d5fefb2a0435b1e9cfc, nonce: 0x0000000000000000, base_fee_per_gas: Some(905213509), withdrawals_root: Some(0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421), blob_gas_used: Some(0), excess_blob_gas: Some(0), parent_beacon_block_root: Some(0x59fe6ce059192b2ce5d0e83a5b149f88d5d10e3d5d69713da1784eccbd6c2d9d), requests_hash: None }
2025-10-15T18:52:31.443200Z  INFO Block added to canonical chain number=25 hash=0x17daba1d7d7386a5af8cb0cff6dac93b4ef310c9ffc88df6ce9af04b59568700 peers=1 txs=2 gas_used=73.50Kgas gas_throughput=5.57Ggas/second gas_limit=60.00Mgas full=0.1% base_fee=0.91Gwei blobs=0 excess_blobs=0 elapsed=13.19µs

💡 Motivation and Context

--- see #275

✅ I have completed the following steps:

• Run make lint
• Run make test
• Added tests (if applicable)

[avalonche]

please test with load with contender just to make sure there's no regression in the caching (notably the latencies for get payload, new payload etc are not affected under load)

[SozinM]

maybe debug?

[SozinM]

same

[SozinM]

debug?

[Copilot]

Pull Request Overview

This PR implements peer-to-peer synchronization and execution of flashblocks, allowing builder nodes to receive and execute flashblocks from other builders in addition to building their own.

Key changes:

• Added flashblock execution logic for synced blocks with validation against expected block hashes
• Enhanced P2P behavior to automatically dial discovered mDNS peers and prevent duplicate connections
• Added new metrics to distinguish between built and synced flashblocks

Reviewed Changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
crates/p2p/src/outgoing.rs	Enhanced error handling for message broadcasting and changed logging level from debug to info
crates/p2p/src/lib.rs	Added automatic dialing of mDNS discovered peers and updated event handling to pass swarm reference
crates/p2p/src/behaviour.rs	Modified mDNS event handling to dial discovered peers if not already connected
crates/op-rbuilder/src/tests/flashblocks.rs	Reformatted test configuration structs (whitespace changes only)
crates/op-rbuilder/src/metrics.rs	Added metrics for synced blocks and separated invalid block counters for built vs synced blocks
crates/op-rbuilder/src/builders/flashblocks/service.rs	Created syncer context and integrated it with payload handler
crates/op-rbuilder/src/builders/flashblocks/payload_handler.rs	Implemented complete flashblock execution and validation logic for synced payloads
crates/op-rbuilder/src/builders/flashblocks/payload.rs	Updated metrics initialization and reference to use shared instance
crates/op-rbuilder/src/builders/flashblocks/mod.rs	Added ctx module declaration
crates/op-rbuilder/src/builders/flashblocks/ctx.rs	New file defining syncer context for flashblock execution

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[Copilot]

Pull Request Overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated 3 comments.

Comments suppressed due to low confidence (1)

crates/op-rbuilder/src/builders/flashblocks/payload_handler.rs:1

• The TODO comment indicates uncertainty about cancellation token usage. If the token is truly unused due to reth's task_executor, consider documenting why it's still being created and passed through the system, or evaluate if it should be removed.

use crate::{

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[SozinM]

looks good