Gossip topic format mismatch: spec fixtures use forkDigest hex, deployed clients use fixed network name

[dimka90]

Summary

The networking codec test vectors introduced in PR #608 define gossip topic strings using the hex-encoded forkDigest as the path segment:

/leanconsensus/0x12345678/block/ssz_snappy

However, all clients currently build gossip topics using a fixed network name string:

/leanconsensus/devnet0/block/ssz_snappy

This means every client fails all 8 gossip_topic test vectors. The mismatch is ecosystem-wide, not specific to any single client.

Evidence across clients

Verified in source code:

Client	Language	Topic format	Source
gean	Go	const NetworkName = "devnet0"	p2p/topics.go:6
ethlambda	Rust	pub const NETWORK_NAME: &str = "devnet0"	crates/net/p2p/src/gossipsub/messages.rs:13
zeam	Zig	chain_config.spec.name → "devnet0" from config	pkgs/network/src/interface.zig + pkgs/cli/src/node.zig:145
ream	Rust	LeanGossipTopic { fork: String } (generic)	crates/networking/p2p/src/gossipsub/lean/topics.rs — unit tests use "0x12345678" but runtime format is configurable

Switching any one client to the forkDigest format would break the gossip mesh.

Fixture test results (from gean's spec harness)

Running leanSpec PR #608 networking codec fixtures:

Codec	Passed	Failed
varint	13/13	0
gossip_message_id	8/8	0
enr	3/3	0
gossip_topic	0/8	8

All 8 gossip_topic failures are the same pattern:

got:  /leanconsensus/devnet0/block/ssz_snappy  
want: /leanconsensus/0x12345678/block/ssz_snappy

Question to delibrate on

Which format is canonical for devnet-4?

1. Fixed network name (devnet0) — what every client currently uses in production. Simple, no fork-awareness.
2. Hex forkDigest (0x12345678) — what the spec fixtures define. Fork-aware, supports multiple concurrent forks on the same network.

If option 2 is the direction, all client teams would need to coordinate the switch simultaneously to avoid breaking the live gossip mesh. If option 1, the fixtures in PR #608 should be updated to reflect the deployed reality.

Related

• leanSpec PR test(networking): add codec test vectors for varint, gossip topics, and message IDs #608: test(networking): add codec test vectors for varint, gossip topics, and message IDs

[tcoratger]

Closed by #622