refactor: extract gas buffer helpers into public custody functions

[maxpushka]

Summary by CodeRabbit

• New Features

  • Added automatic gas buffering for Ethereum withdrawal transactions with 75% buffer applied to gas limit and 30% buffer applied to gas price.

• Refactor

  • Consolidated gas buffer logic into a dedicated utility module, eliminating duplication across withdrawal operations for improved maintainability.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: bc1bd6a0-b332-40d1-bf10-a879dc4803c1

📥 Commits

Reviewing files that changed from the base of the PR and between b14002d and f6b8850.

📒 Files selected for processing (2)

• custody/gas_buffer.go
• service/service.go

---

📝 Walkthrough

Walkthrough

A new GasBuffer utility is introduced in the custody package with constants and functions for gas buffering Ethereum transactions. The service package is refactored to use these new custody utilities instead of maintaining its own gas buffering logic.

Changes

Cohort / File(s)	Summary
Gas Buffer Utilities custody/gas_buffer.go	New file adding gas buffering constants (75% for gas limit, 30% for price) and four public functions: ApplyGasPriceBuffer, StartWithdrawWithGasBuffer, FinalizeWithdrawWithGasBuffer, and RejectWithdrawWithGasBuffer. Each operation performs a dry-run, applies buffers, and executes the transaction.
Service Refactoring service/service.go	Removed local gas buffer constant and replaced manual buffer logic in finalization and rejection functions with calls to custody.FinalizeWithdrawWithGasBuffer and custody.RejectWithdrawWithGasBuffer.

Sequence Diagram

sequenceDiagram
    actor Caller
    participant Service as Service
    participant Custody as Custody Package
    participant Contract as IWithdraw Contract
    participant EthBackend as Ethereum Backend
    
    Caller->>Service: Call withdraw operation
    Service->>Custody: Call buffered operation
    Custody->>Contract: Dry-run transaction (estimate gas)
    Contract->>EthBackend: Execute dry-run
    EthBackend-->>Contract: Gas estimation result
    Contract-->>Custody: Gas estimate returned
    Custody->>EthBackend: Fetch suggested gas price
    EthBackend-->>Custody: Gas price + apply buffers
    Custody->>Contract: Execute actual operation<br/>(with buffered gas limit & price)
    Contract->>EthBackend: Submit transaction
    EthBackend-->>Contract: Transaction confirmation
    Contract-->>Custody: Transaction result
    Custody-->>Service: Return transaction
    Service-->>Caller: Return result

Loading

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~22 minutes

Possibly related PRs

• fix(service): increase gas buffer to 50%, add race condition test #24: Introduces similar gas-buffering modifications for withdrawal finalization and rejection operations that are now being centralized into custody package helpers.

Poem

🐰 Hop, hop, buffering flows,
Gas prices rise, our safety grows!
Custody guards with seventy-five,
Thirty percent keeps us all alive!
🌟 Sweet protection, transaction-wise.

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'refactor: extract gas buffer helpers into public custody functions' accurately describes the main change: moving gas buffer logic from service.go into public functions in the custody package.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}