Banksalad Establishes Code Review Culture with 'Small PRs' and 'Pn Rules'

Banksalad's iOS team systematized its code review process to respond to organizational scale-up and increasing service complexity. The core goal is to pursue asynchronous communication, making reviewer expressions clear and reducing review burden based on GitHub PRs.

Small PRs and Experiment Platform

To resolve review bottlenecks and minimize deployment complexity, the small PR principle was introduced. Features are broken down into minimal units to keep each PR under 1,000 lines, allowing reviewers to examine code with focus. In particular, the Banksalad 2.0 project used an experiment platform to distinguish experimental and control groups based on OS and app version. The development process was subdivided into approximately 8,000 commits, and even incomplete features were merged into the main branch immediately once the minimal-unit PR review was complete, preventing conflicts.

Clear Communication Rules

For low-context communication, the Pn rule and D-n rule were introduced. The Pn rule reduces misunderstandings by classifying the emphasis level of review comments into 5 stages from P1 (must fix) to P5 (minor opinion). The D-n rule specifies the required merge timeline when requesting a review, from D-0 (urgent) to D-N (within N days), helping reviewers determine priority. Additionally, the PR template requires attaching product planning, technical plans, and design links, minimizing the prior knowledge reviewers need.

Resource Savings Through Automation

Coding style and unit tests were automated to reduce labor costs. SwiftFormat was integrated into the build stage to automatically apply coding conventions, allowing reviewers to focus only on logic and architecture. The CI pipeline was optimized considering the unit test execution time (about 10 minutes), achieving efficiency equivalent to hiring about 1 additional iOS developer. These efforts reflect Banksalad's development culture of uncompromising 'sullri' (natural order) and reducing communication costs.