Individual skill
ds-principles
Compact engineering principles for design, debugging, verification, and delegation, each with a trigger. Use when choosing structure or types, sizing a diff, debugging, writing tests, or when the user types /ds-principles.
skills/ds-principles/SKILL.md
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- agent-skills Repository topic
- claude-code Repository topic
- cline Repository topic
- deepseek Repository topic
- skills Repository topic
- engineering Derived category
- design Derived category
- writing Derived category
- testing Derived category
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SKILL.mdcore · 3,908 bytes
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# Engineering principles
If a trigger matches, apply the rule. Name principles that changed a decision.
## Design
1. **Subtract, then add little.** Remove dead code and stale checks first, then make the shortest diff that works. No abstraction with one user. Apply when sizing a diff or tempted to add a layer.
2. **Data shape first.** Choose the core types and structures before logic. Apply before writing new logic.
3. **Model the domain.** Put states in one structure, such as a typed union, state machine, or lookup table, not scattered conditionals. Apply when code branches a lot or repeats a shape across files.
4. **Redesign for the new need.** Fit a new requirement as if it existed from day one. Apply when an addition strains the design.
5. **Low reader load.** Inline one-caller wrappers and shrink mutable scope. Apply when code is hard to trace.
6. **Guards at boundaries.** Validate where input enters: CLI, config, network, files, external APIs. Trust types inside and keep core logic pure. Apply when adding validation or error handling.
7. **Idempotent steps.** Rerunning a step, even after a crash, reaches the same state. Apply to commands, setup, and retries.
8. **No shared writers.** Give each concurrent actor its own file, branch, or key before using locks. Apply when parallel work touches shared state.