One Diff, One Thesis

In this segment, we focus on the powerful practice of “One Diff, One Thesis”, along with a recap of three foundational principles for writing high-quality diffs. These habits dramatically improve your velocity, code quality, and perceived maturity as an engineer—especially early in your career.

Key Takeaways:

• We follow the “One Diff, One Thesis” principle: Each code change should focus on a single, clearly defined purpose. Large, unfocused diffs (e.g., 5,000+ lines) dilute review quality and lead to blind approvals or unclear feedback.
• We break big features into smaller, stackable diffs: By submitting changes in 50–250 line chunks with logical dependencies, we keep discussions focused, reduce cognitive load for reviewers, and maintain a clear project history.
• We pay the “20-minute tax” for high-quality diffs: Investing time in writing strong context, test plans, and clear, focused diffs pays off by dramatically speeding up approvals and reducing iteration cycles.
• We see these habits as promotion-worthy: The most common reason junior engineers struggle during performance reviews is neglecting these basics. Conversely, those who consistently apply them stand out and accelerate their growth.
• We optimize for long-term velocity and trust: Thoughtful, well-structured diffs help reviewers engage more quickly and confidently, enabling faster delivery and demonstrating leadership-level attention to detail.

These three practices—providing strong context, writing solid test plans, and submitting focused diffs—are low-effort, high-return habits that every engineer, especially early in their career, should master.