Coding Guideline

Core Strategy

The project optimizes for confidence through type checking, testability, and low-fake tests.

• Model domain and UI states with ADTs, discriminated unions, and exhaustive handling.
• Prefer functional, pure logic at the center and stateful I/O at boundaries.
• Keep invalid states unrepresentable whenever practical.
• Test pure rules without I/O and orchestration with the narrowest realistic dependency.
• Avoid mocks when a fast real boundary is available. Use memory routers, in-memory DBs, and typed clients before mocking framework hooks or persistence.
• Prefer high-quality libraries over local framework code or one-off utilities.
• Avoid generic architecture patterns unless they solve a concrete project problem.

Troubleshooting Boundaries

Do not weaken project checks as a troubleshooting shortcut.

• tsconfig.json: Do not change type-checking options unless explicitly instructed. Adding include/exclude entries is allowed when new files require it.
• oxlint.config.ts: Do not change lint rules to silence errors unless explicitly instructed. Prefer the smallest local oxlint-disable / oxlint-ignore comment when a rule must be bypassed intentionally.

Required References

Read the relevant reference before editing code in that area:

• Backend/server code: references/backend/guideline.md
• Frontend/web code: references/frontend/guideline.md

If a change crosses both areas, read both references.