fix(wallet): save complete burn proof in file

[sdbondi]

Description

fix(wallet): save complete burn proof in file

Motivation and Context

Use a shared file location for burn proofs, this allows L2 wallets to pick up burns for claiming

How Has This Been Tested?

Manually

What process can a PR reviewer use to test or verify this change?

Breaking Changes

• None
• Requires data directory on base node to be deleted
• Requires hard fork
• Other - Please specify

[gemini-code-assist]

Summary of Changes

Hello, 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 refactors the handling of burn proofs within the wallet, moving from a manual file path input to an automated system that saves complete burn proofs to a designated shared directory. This change aims to improve interoperability with L2 wallets by providing a standardized and accessible location for burn claim data. The console wallet's user interface has been simplified as a result, and the underlying transaction service now emits events upon successful burn proof confirmation and persistence.

Highlights

• Burn Proof Persistence: Burn proofs are now automatically saved to a shared file location after a burn transaction completes, enabling L2 wallets to easily access them for claiming.
• Console Wallet UI Simplification: The console wallet UI has been streamlined by removing the manual input field for the burn proof filepath, as proofs are now automatically managed.
• Configuration and Dependencies: New dependencies (dirs-next, tempfile) were added to facilitate cross-platform directory handling and temporary file operations. A new CLI argument (--burn-proof-out) was introduced for the console wallet to specify the output directory for burn proofs.
• Transaction Eventing: A new TransactionBurnConfirmed event has been added to the transaction service, providing a clear signal when a burn transaction has been confirmed and its proof saved.
• Complete Burn Proof Structure: A new CompleteClaimBurnProof struct was introduced to encapsulate all necessary data for a burn claim, including the claim proof, merkle proof, encrypted data, kernel, and value.

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[gemini-code-assist]

Code Review

This pull request refactors the burn proof saving mechanism to use a shared directory, which is a solid improvement for interoperability with L2 wallets. The logic has been moved to a more appropriate place in the transaction lifecycle. The changes are mostly clean and correct. I have a few suggestions to improve robustness and code style.

[gemini-code-assist]

The code writes a file but doesn't ensure the directory exists. This could lead to an error if the directory hasn't been created yet. It's safer to create the directory before attempting to write the file.

    if let Some(parent) = final_path.parent() {
        fs::create_dir_all(parent).await?;
    }
    fs::write(&final_path, serde_json::to_vec_pretty(&complete_proof)?).await?;

[gemini-code-assist]

CompressedCommitment is a small, 32-byte Copy type. Boxing it with Box<CompressedCommitment> is unnecessary and introduces a heap allocation. It's better to store it directly. This also allows restoring the Hash derive on the TransactionEvent enum, which was removed in this PR.

This would also simplify the event creation in fetch_claim_burn_merkle_proofs.rs to commitment: burn.burn_proof.commitment.

Suggested change

	commitment: Box<CompressedCommitment>,
	commitment: CompressedCommitment,

[gemini-code-assist]

These ok_or_else calls can be made more idiomatic by using the Context trait from anyhow. This improves readability. You'll need to add use anyhow::Context; to the file.

Suggested change

	fs::create_dir_all(&burn_proofs_dir).await?;
	let kernel_merkle_proof = proof
	.kernel_merkle_proof
	.ok_or_else(|| anyhow!("No kernel_merkle_proof"))?;
	let encrypted_data = proof.encrypted_data.ok_or_else(|| anyhow!("No encrypted_data"))?;
	let kernel_merkle_proof = proof.kernel_merkle_proof.context("No kernel_merkle_proof")?;
	let encrypted_data = proof.encrypted_data.context("No encrypted_data")?;
	let value = proof.value.context("No value")?;