Add current_slot to fast_confirmation event - #616
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Co-authored-by: Nico Flaig <nflaig@protonmail.com>
nflaig
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Co-authored-by: Nico Flaig <nflaig@protonmail.com>
mkalinin
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- Wires the new `fast_confirmation` Server-Sent Event from beacon-APIs PR [#598](ethereum/beacon-APIs#598). The event fires once per slot whenever the Fast Confirmation Rule executes and carries `{block, slot}`, where `slot` is the slot of the confirmed beacon block. - Crosses the fork-choice ↔ beacon-node boundary via a new optional `onFastConfirmation` callback on `ForkChoiceStore`, mirroring the existing `onJustified` / `onFinalized` plumbing. The emit is invoked from `ForkChoice.runFastConfirmation()` after the rule succeeds. - Removes the now-redundant Lodestar-namespace endpoint `GET /eth/v1/lodestar/fast_confirmation_info` (and its `getConfirmedBlock` helper) — the standard SSE event supersedes it, and the head/checkpoint fields it bundled are already available via standard beacon-API endpoints. This PR is aligned with the changes proposed in ethereum/beacon-APIs#616 ### Architecture ``` Chain.onClockSlot → forkChoice.updateTime └── (per tick) runFastConfirmation └── fcStore.notifyFastConfirmation({block, slot}) └── ChainEventEmitter.emit(EventType.fastConfirmation, {block, slot}) └── SSE subscribers via /eth/v1/events?topics=fast_confirmation ``` `ApiEvents` in `ChainEventEmitter` is derived from `routes.events.EventType`, so adding the new variant flows through automatically — no per-event boilerplate in the chain or events API layers. ### Edge cases | Scenario | Behavior | |---|---| | `--chain.fastConfirmation` disabled (default) | No emit (FCR doesn't run) | | FCR rule throws | No emit; existing warn-and-continue catch is unchanged | | Confirmed root not in `protoArray` (defensive) | Warn log with `slot`+`confirmedRoot`, skip emit | | `updateTime` advances multiple slots | One emit per tick |
dapplion
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Subscribe to the fast_confirmation beacon event stream topic (fast confirmation rule, see ethereum/beacon-APIs#616) as an optional ancillary SSE stream. Nodes that don't support the topic reject the subscription with a 4xx response, in which case the stream silently gives up, so the feature auto-activates only on FCR-enabled nodes. The most recent fast confirmed (safe) block is tracked per client and network-wide in the chain state, and visualized in the frontend: - index page: safe slot next to the current slot in the network overview, and a shield marker on fast confirmed slots in the recent slots list - consensus clients page: sortable "Safe Slot" column (only shown when at least one node reports fast confirmations) - /v1/clients/consensus API: fcr_enabled, safe_slot and safe_root fields
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Summary
current_slot(wall-clock slot at execution time) to thefast_confirmationevent payload, alongside the existingblockandslotof the most recent confirmed block.Motivation
Without
current_slot, consumers cannot distinguish a fresh FCR run that re-confirmed the same block from a stale or missed emission. Making the emission cadence explicit in the spec removes ambiguity about whether implementations may suppress unchanged results.