Fetch fees based on last chain exec header

[ssd04]

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?

[github-actions]

❌ Integration Tests completed with failures or errors.

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🔄 Build Details:

• mx-chain-go Commit Hash: e4f8c1dfdfc57629c82236f98bcea7c7800d1de4
• Current Branch: update-acc-fees-v3
• mx-chain-go Target Branch: rc/supernova
• mx-chain-simulator-go Target Branch: rc/supernova
• mx-chain-simulator-go Commit Hash: f10bde764d4770bd9c6caeac60f6b57020bc0bdc
• mx-chain-testing-suite Target Branch: rc/supernova
• mx-chain-testing-suite Commit Hash: 56ce8892aaafd0aa8420d821eac8a4bbf25f6d56

🚀 Environment Variables:

• TIMESTAMP: 2026_MAY_19__10_14_46
• PYTEST_EXIT_CODE: 1

[Copilot]

Pull request overview

This PR changes the source of accumulated epoch fees for V3 meta headers in getCurrentlyAccumulatedFees: instead of extracting them from the proposed header's embedded LastExecutionResult, they are now read from blockChain.GetLastExecutionResult() (the chain-level last execution result maintained by the async executor). Tests are updated to reflect the new source and to populate MetaExecutionResult.ExecutionResult where required by other paths.

Changes:

• In getCurrentlyAccumulatedFees, switch the V3 path to read fees from mp.blockChain.GetLastExecutionResult(); on nil chain result, return (0, 0, nil) instead of an error.
• Update Test_getCurrentlyAccumulatedFees to cover the new nil/zero-return behavior and the new fee source semantics; remove the obsolete "nil base execution result" test case.
• Update metablockProposal_test.go test setups to seed BlockChain with a MetaExecutionResult containing a populated BaseMetaExecutionResult (with fee fields where expectations changed).

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
process/block/metablock.go	Reads V3 last execution fees from the blockchain's last execution result instead of the proposed header; nil result yields zero fees.
process/block/metablock_test.go	Renames/rewrites V3 fee tests to drive BlockChain.GetLastExecutionResult; drops the now-unreachable "nil base execution result" case.
process/block/metablockProposal_test.go	Updates proposal/process tests to seed the chain's last execution result with nested BaseMetaExecutionResult and adjusts fee expectations to come from the chain rather than the header.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.57%. Comparing base (69d4de7) to head (d726fe6).
⚠️ Report is 10 commits behind head on feat/testnet-fixes.

Additional details and impacted files

@@                  Coverage Diff                   @@
##           feat/testnet-fixes    #7838      +/-   ##
======================================================
- Coverage               77.57%   77.57%   -0.01%     
======================================================
  Files                     884      884              
  Lines                  125210   125210              
======================================================
- Hits                    97135    97134       -1     
- Misses                  21622    21625       +3     
+ Partials                 6453     6451       -2     

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