BMAD-METHOD/expansion-packs/bmad-javascript-fullstack/data/core-principles-modular/essential-principles.md

Essential Development Principles

Core philosophy for all JavaScript/TypeScript agents. These are non-negotiable.

Universal Principles

Type Safety First: Catch errors at compile time. Use TypeScript strict mode.

Security First: Authenticate endpoints. Validate inputs. Sanitize outputs. Never trust client.

Developer Experience: Fast feedback. Clear errors. Intuitive APIs. Good docs.

Performance Matters: Optimize perceived performance first. Measure before optimizing.

Maintainability: Clean code. Consistent patterns. Automated tests. Documentation.

YAGNI: Don't over-engineer. Build for 2x scale, not 100x. Use boring, proven tech.

Component-First: Everything is reusable, testable, composable.

Clean Architecture: Separate concerns. Dependency injection. Controllers handle I/O, services handle logic.

Observability: Log, monitor, track errors. Can't improve what you don't measure.

Context Efficiency Philosophy

Reference, Don't Repeat: Point to file paths, don't duplicate content.

• ✅ "Implementation in src/auth.service.ts"
• ❌ Pasting entire file

Provide Summaries: After creating artifacts, give 2-3 sentence overview.

• ✅ "Created JWT auth. See src/auth.service.ts"
• ❌ Explaining every line

Progressive Detail: High-level first, details when implementing.

Archive Verbose: Keep implementations in files, reference them.

Checkpoint at Transitions: Compress to max 100-line summaries with:

• Final decisions
• File paths
• Critical constraints
• Next steps

JIT Context Loading

Start Minimal: Load role + essential-principles + task ONLY

Load on Decision: Load guides ONLY when making specific decision

Question Before Loading:

1. Making THIS decision NOW?
2. My role's responsibility?
3. Not in checkpoint already?
4. Can't use role knowledge?

If any NO → Don't load

Token Budget Awareness

Targets:

• Simple task: <1,000 tokens
• Medium task: 1,000-2,000 tokens
• Complex task: 2,000-4,000 tokens
• Use checkpoints when >3,000

Status Levels:

• 🟢 0-50%: Continue normally
• 🟡 50-75%: Be selective
• 🟠 75-90%: Stop loading
• 🔴 >90%: Checkpoint NOW

Working Philosophy

Start Simple: MVP first. Monolith before microservices.

Fail Fast: Validate early. Catch at compile time.

Iterate Quickly: Ship small. Get feedback. Improve.

Automate Everything: Testing, linting, deployment.

Monitor and Learn: Track metrics. Analyze errors. Improve.