feat(events): add chain_reorg and safe_target chain events#533
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feat(events): add chain_reorg and safe_target chain events#533MegaRedHand wants to merge 1 commit into
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Extend the /lean/v0/events stream with two cheap follow-up topics derived from the actor-layer snapshot diff. chain_reorg: fork choice switched to a head off the old head's chain. Reuses store::reorg_depth (widened to pub(crate) so the actor diff and block processing share one definition of "reorg"); recency-gated like head and emitted just before it. Mirrors the beacon chain_reorg payload minus epoch/execution_optimistic. safe_target: the interval-3 fork-choice safe attestation target advanced. Ungated since it coalesces to the latest value, the only one that matters; an ethlambda extension with no beacon analog.
This was referenced Jul 21, 2026
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Continues the chain-event pub-sub series (#516 / #517 / #518, all merged). Adds the beacon `block_gossip` analog. ## Event added | Topic | Payload | Emitted when | |-------|---------|--------------| | `block_gossip` | `{ slot, block }` | A block is seen on the network, before import | ## Notes - Emitted from the blockchain actor's `NewBlock` handler, **not** a second P2P-side publisher, so the actor stays the sole event publisher and the write flow stays one-directional (a core requirement of the series' design). - Fires for both gossip'd and by-root-fetched blocks, since both re-enter through `NewBlock`. Import may pend the block while its parent chain is fetched, so this precedes import. - Ungated like `block` (not recency-gated), so subscribers can watch sync progress. Low-rate (one per block), so the payload is built unconditionally behind `emit`'s no-subscriber guard. ## Testing `cargo fmt`, `cargo clippy -p ethlambda-blockchain -p ethlambda-rpc` (clean), blockchain lib + rpc events tests pass. --- **Independent PR, based off `main`.** One of three sibling PRs continuing the series — alongside #533 (`chain_reorg`/`safe_target`) and #534 (`attestation`/`aggregate`), each independently based off `main`. They touch overlapping regions of `events.rs` / `docs/rpc.md`, so whichever two merge later will each need a small conflict rebase. Opened as draft.
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Closing this until the events become relevant |
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Continues the chain-event pub-sub series (#516 / #517 / #518, all merged). Adds the two high-rate topics. ## Events added | Topic | Payload | Emitted when | |-------|---------|--------------| | `attestation` | `{ validator_id, data: AttestationData }` | A single validator vote passes gossip validation (signature omitted) | | `aggregate` | `{ participants: [u64], data: AttestationData }` | A committee-signature aggregate is produced locally or accepted from gossip (proof omitted) | Both fire only for messages the store **accepted** (data + signature validation), so subscribers see the same votes fork choice does. A node never receives its own aggregate back over gossip, so `aggregate` fires at two sites: the locally produced `AggregateProduced` path and the gossip-received path. ## Design points - The ~3 KB XMSS signature and the SNARK proof bytes are deliberately **omitted** — too heavy for a high-rate stream. - The shared broadcast channel capacity is bumped **256 → 8192**. All topics share one ring buffer, so a subscriber's tolerable stall is `capacity / total_event_rate` (dominated by the attestation rate), not per-topic. A per-topic split behind the `EventBus` facade remains the escape hatch if real devnet rates show the shared window biting — see the note in `docs/rpc.md`. - Emission uses the plain, no-subscriber-guarded `emit`. Consequence: the per-vote `AttestationData` is cloned even when nobody is subscribed (the guard only skips the send). If that actor-hot-path cost proves material, a payload-deferral helper can be added in a follow-up. ## Testing `cargo fmt`, `cargo clippy -p ethlambda-blockchain -p ethlambda-rpc` (clean), blockchain + rpc lib tests pass, including `events_streams_attestation_with_nested_data` (verifies the untagged `data:` nesting over the wire). --- **Independent PR, based off `main`.** One of three sibling PRs continuing the series — alongside #533 (`chain_reorg`/`safe_target`) and #535 (`block_gossip`), each independently based off `main`. They touch overlapping regions of `events.rs` / `docs/rpc.md`, so whichever two merge later will each need a small conflict rebase.
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Continues the chain-event pub-sub series (#516 / #517 / #518, all merged). Adds the two cheap follow-up topics, both derived from the existing actor-layer snapshot diff.
Events added
chain_reorg{ slot, depth, old_head_block, old_head_state, new_head_block, new_head_state }head)safe_target{ slot, block }Notes
chain_reorgreusesstore::reorg_depth, widened topub(crate)so the actor diff and block processing share one definition of "reorg". Recency-gated likehead(HEAD_EVENT_RECENCY_SLOTS) and emitted just before it, matching beacon ordering; payload mirrors the beaconchain_reorgshape minusepoch/execution_optimistic.safe_targetis an ethlambda extension with no beacon analog; ungated since it coalesces to the latest value (the only one that matters).Testing
cargo fmt,cargo clippy -p ethlambda-blockchain(clean), blockchain lib tests pass, including two new unit tests:chain_event_diff_emits_chain_reorg_before_headandchain_event_diff_emits_safe_target.Independent PR, based off
main. One of three sibling PRs continuing the series — alongside #534 (attestation/aggregate) and #535 (block_gossip), each independently based offmain. They touch overlapping regions ofevents.rs/docs/rpc.md, so whichever two merge later will each need a small conflict rebase. Opened as draft.