proof: improve re-org proof replacement, strengthen error handling, expand test coverage

[ffranr]

This PR tightens the proof replacement path used during block re-org handling. It explicitly ensures that we no longer ignore errors that should be surfaced, giving more reliable behaviour during re-org updates.

Key changes

• Refactor replacement to a pure ReplaceProofInFiles function that updates supplied proof files and validates asset IDs.
• Remove implicit side effects. Callers now fetch candidate proofs and import updates explicitly during re-org handling.
• Strengthen error handling across proof encoding, decoding, lookup, and file validation. All errors are now surfaced instead of being ignored.
• Add unit tests covering multiple proof-replacement scenarios triggered by re-org events.

[gemini-code-assist]

Summary of Changes

Hello @ffranr, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the robustness and clarity of proof replacement mechanisms, particularly during blockchain re-organizations. By introducing a pure function for proof replacement and enforcing explicit error handling, it ensures that the system behaves more reliably and predictably when updating proofs, preventing critical errors from being overlooked.

Highlights

• Refactored Proof Replacement: The core logic for replacing proofs during re-organizations has been refactored into a new, pure function ReplaceProofInFiles, improving modularity and testability.
• Explicit Side Effects: Implicit side effects have been removed from the proof replacement process. Callers are now responsible for explicitly fetching candidate proofs and importing updates, leading to clearer control flow.
• Strengthened Error Handling: Error handling has been significantly improved across proof encoding, decoding, lookup, and file validation. All errors are now properly surfaced and wrapped, preventing silent failures.
• Expanded Test Coverage: New unit tests have been added to cover various proof-replacement scenarios, including successful updates, skipping non-matching proofs, and handling mismatched asset IDs.

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[gemini-code-assist]

Code Review

This pull request is a great improvement. It refactors the proof replacement logic into a pure function, which improves testability and separation of concerns. The error handling has been significantly strengthened by adding more context to error messages, which will make debugging much easier. The new unit tests are also a welcome addition, ensuring the new functionality is well-covered.

I've found one minor style issue that I've commented on. Otherwise, the changes look solid.

[coveralls]

Pull Request Test Coverage Report for Build 19935475562

Details

• 89 of 136 (65.44%) changed or added relevant lines in 4 files are covered.
• 82 unchanged lines in 20 files lost coverage.
• Overall coverage remained the same at 56.62%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
tapgarden/planter.go	22	27	81.48%
tapgarden/re-org_watcher.go	25	32	78.13%
proof/archive.go	32	42	76.19%
proof/file.go	10	35	28.57%

Files with Coverage Reduction	New Missed Lines	%
commitment/tap.go	1	85.65%
asset/group_key.go	2	72.15%
mssmt/compacted_tree.go	2	77.19%
rfqmsg/records.go	2	70.8%
tapchannel/aux_leaf_signer.go	2	43.18%
tapdb/mssmt.go	2	89.55%
tapdb/sqlc/mssmt.sql.go	2	48.34%
tapdb/sqlc/transfers.sql.go	2	83.33%
tapdb/sqlc/universe.sql.go	2	73.71%
tapdb/universe.go	2	81.04%

Totals
Change from base Build 19933051412:	0.0%
Covered Lines:	64877
Relevant Lines:	114584

---

💛 - Coveralls

[jtobin]

- The replacement logic is now side-effect free and focused on
  transformation, making it easier to unit test.
- Fetching and importing responsibilities are explicit at call sites,
  improving clarity and making state changes easier to reason about.

😍