/incremental-coding

name: incremental-coding
description: Build in verifiable increments. Never implement more than can be tested right now. Ship partial working systems over complete broken ones.
category: build
applies-to: [claude, gemini, cursor, copilot, any]
version: 1.0.0

Overview

The biggest risk in software development is building a lot of code that doesn't work. Incremental coding limits this risk: build a little, verify it works, build more. At every step, the system is in a known-good state.

When to Use

• Any implementation that will take more than 2 hours
• When building in a complex domain you're uncertain about
• When multiple components need to integrate

Process

Step 1: Define the First Increment

1. What is the smallest possible thing you can build that provides value and can be verified? 2. It doesn't have to be feature-complete — just correct and verifiable. 3. Example: "Add the endpoint skeleton with hardcoded response" before adding business logic.

**Verify:** The first increment can be verified in under 5 minutes.

Step 2: Build → Verify → Commit

4. Build only the first increment. 5. Run tests. Verify manually if needed. Confirm it works. 6. Commit this working state. 7. Repeat for the next increment.

**Verify:** There is a working commit after each increment.

Step 3: Integration Continuously

8. Integrate with the real system as early as possible — not at the end. 9. Test against real dependencies (DB, API, etc.) as early as possible. 10. Fake integrations (mocks) should be replaced with real ones by the end.

**Verify:** By completion, all mocks replaced with real integration.

Common Rationalizations (and Rebuttals)

| Excuse | Rebuttal | |--------|----------| | "I need to build it all to know if it works" | No. Build the first piece and test it. Uncertainty is always reducible. | | "Integration is at the end" | Integration pain is proportional to time since last integration. Integrate continuously. |

Verification

• [ ] Implementation built in verifiable increments
• [ ] Working commit exists after each increment
• [ ] No long stretches of "broken" state in git history
• [ ] All mocks replaced with real integrations by completion

References

• [test-driven-development skill](../test-driven-development/SKILL.md)
• [task-decomposition skill](../task-decomposition/SKILL.md)