fix(consensus/XDPoS,core): stop fabricating verify batch blocks, close #2253

[gzliudan]

Proposed changes

Avoid exposing in-flight verify batch headers as empty placeholder blocks. Wire real batch blocks into full block imports while keeping header-only verification limited to header lookups, so consensus code cannot observe fabricated bodies during VerifyHeaders.

Add unit coverage for verifyChainReader and an engine v2 regression test for block lookups during batch verification.

fix #2253

test: sync testnet from genesis block, passed all blocks

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• refactor: A code change that neither fixes a bug nor adds a feature
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• test: Adding missing tests or correcting existing tests

Impacted Components

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• Consensus
• Account
• Network
• Geth
• Smart Contract
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Checklist

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• This PR has sufficient test coverage (unit/integration test) OR I have provided reason in the PR description for not having test coverage
• Tested on a private network from the genesis block and monitored the chain operating correctly for multiple epochs.
• Provide an end-to-end test plan in the PR description on how to manually test it on the devnet/testnet.
• Tested the backwards compatibility.
• Tested with XDC nodes running this version co-exist with those running the previous version.
• Relevant documentation has been updated as part of this PR
• N/A

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[Copilot]

Pull request overview

Fixes XDPoS header-batch verification so consensus code can’t observe “fabricated” empty blocks for in-flight headers during VerifyHeaders, while still allowing full block imports to provide real batch blocks for GetBlock lookups.

Changes:

• Introduces an XDPoS verify-batch ChainReader wrapper that shadows headers but does not fabricate placeholder blocks (unless real blocks are explicitly provided).
• Wires the wrapper into header-only verification (HeaderChain.ValidateHeaderChain) and full block imports (BlockChain.insertChain) with engine-specific handling for XDPoS.
• Adds unit tests for the verify-batch reader and an engine v2 regression test to ensure GetBlock doesn’t return fabricated batch blocks during header verification (HookPenalty path).

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
core/headerchain.go	Uses an XDPoS-specific verify-batch ChainReader when validating header chains.
core/blockchain.go	Passes real batch blocks to the verify-batch ChainReader during full block imports.
consensus/XDPoS/XDPoS.go	Switches to the new exported verify-batch reader constructor.
consensus/XDPoS/verify_chain_reader.go	Stops creating header-only placeholder blocks; optionally exposes real blocks when provided.
consensus/XDPoS/verify_chain_reader_test.go	Expands unit coverage for header shadowing and block lookup behavior.
consensus/tests/engine_v2_tests/verify_header_test.go	Adds regression coverage ensuring batch GetBlock lookups don’t see fabricated blocks during verification.

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