trigger recovery hardening

[AdoAdoAdo]

Reasoning behind the pull request

Proposed changes

Testing procedure

Pre-requisites

Based on the Contributing Guidelines the PR author and the reviewers must check the following requirements are met:

• was the PR targeted to the correct branch?
• if this is a larger feature that probably needs more than one PR, is there a feat branch created?
• if this is a feat branch merging, do all satellite projects have a proper tag inside go.mod?

[Copilot]

Pull request overview

This PR hardens epoch-start trigger recovery by shifting shard-block epoch mismatch handling to the epoch start trigger, introducing Supernova-specific recovery tracking (candidates + generation), and extending request handling to support epoch-stamped meta-header requests.

Changes:

• Delegate epoch mismatch remediation from shardProcessor.checkEpochCorrectness to EpochStartTrigger.RequestEpochStartIfNeeded.
• Add Supernova epoch-start recovery state machine (candidates/pending data + generation gating + close/reset behavior) and broaden related test coverage.
• Extend the epochStart RequestHandler API to support epoch-aware meta-header-by-hash/nonce requests and update callers/tests accordingly.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
process/mock/endOfEpochTriggerStub.go	Extends the epoch start trigger stub to allow observing RequestEpochStartIfNeeded calls in tests.
process/block/shardblock.go	Replaces local “evict + request” logic with trigger notification on epoch mismatch.
process/block/shardblock_test.go	Updates tests to assert trigger notification instead of header eviction/request side effects.
epochStart/shardchain/triggerRegistry.go	Resets pending recovery state after loading trigger state.
epochStart/shardchain/triggerRegistry_test.go	Adjusts cloning/equality logic to account for new recovery fields/generation.
epochStart/shardchain/trigger.go	Implements Supernova recovery tracking, generation-based stale-state protection, and epoch-stamped neighbor requests.
epochStart/shardchain/trigger_test.go	Adds targeted tests for Supernova recovery flows and generation/close behavior.
epochStart/mock/validatorInfoSyncerStub.go	Makes the syncer stub callbacks configurable for new recovery tests.
epochStart/interface.go	Extends request handler interface with epoch-aware meta-header request methods.

Suppressed comments (2)

epochStart/shardchain/trigger_test.go:754

• Using a fixed time.Sleep(50ms) to assert that no second sync happens can make the test nondeterministic (it may pass/fail depending on timing). It’s more robust to assert the invariants hold for a short bounded interval.

		tr.RequestEpochStartIfNeeded(header)
		time.Sleep(50 * time.Millisecond)
		require.Equal(t, int32(1), syncCalls.Load())
		require.Equal(t, 1, numRecoveryCandidates(tr))

epochStart/shardchain/trigger_test.go:799

• Same flakiness concern here: a single time.Sleep(50ms) doesn’t reliably prove no second async call occurs. Consider checking the counters remain stable over a bounded interval instead.

		tr.RequestEpochStartIfNeeded(header)
		time.Sleep(50 * time.Millisecond)
		require.Equal(t, int32(1), syncCalls.Load())
		require.Equal(t, 1, numRecoveryCandidates(tr))

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[Copilot]

Pull request overview

Copilot reviewed 20 out of 20 changed files in this pull request and generated 1 comment.