Make metadata sync safer

[tompro]

📝 Description

Keep chain metadata up to immediately before replacement.

Fixes #908

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✅ Checklist

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• My code adheres to the coding guidelines of this project.
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🚀 Changes Made

• Bug Fixes:
  • Preserve chain metadata as long as possible

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📋 Review Guidelines

Please focus on the following while reviewing:

• Does the code follow the repository's contribution guidelines?
• Are there any potential bugs or performance issues?
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[Copilot]

Pull request overview

This PR adjusts chain resync logic in the transport layer so that stored chain event metadata is preserved until immediately before a validated remote chain candidate is actually applied, addressing the “missing previous block” failure mode described in #908.

Changes:

• Move chain_event_store.remove_chain_events(...) to occur only after a preferred remote chain has been validated and successfully applied (identity/company/bill resync paths).
• Keep existing chain event metadata intact during candidate evaluation to avoid leaving local state without metadata if validation fails.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
crates/bcr-ebill-transport/src/handler/identity_chain_event_processor.rs	Defers invalidation of identity chain events until after a validated chain replacement is applied.
crates/bcr-ebill-transport/src/handler/company_chain_event_processor.rs	Defers invalidation of company chain events until after a validated chain replacement is applied.
crates/bcr-ebill-transport/src/handler/bill_chain_event_processor.rs	Defers invalidation of bill chain events until after a validated chain replacement is applied.

[Copilot]

remove_chain_events is now only invoked after a preferred remote chain has been validated and applied. There is an existing unit test (test_resync_chain_skips_non_preferred_chain) that currently sets an expectation that remove_chain_events is called even when no chain candidate is accepted; with this new control flow, that expectation should be updated (e.g., expect 0 calls, or explicitly assert it is not called).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 70.58%. Comparing base (e90a5b4) to head (28204b7).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #909      +/-   ##
==========================================
+ Coverage   70.57%   70.58%   +0.01%     
==========================================
  Files         139      139              
  Lines       27708    27708              
==========================================
+ Hits        19554    19557       +3     
+ Misses       8154     8151       -3     

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[zupzup]

LGTM 👍 Also tested locally with the frontend client and seems to fix the issue