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Do You Know Why This Design Exists?

Type: Structure
Category: Common
Audience: Reviewer / Lead Architect / Any Engineer Who Has Ever Said “It Works, I Guess”

✅ This Isn’t About Best Practices

Every system is a graveyard of decisions.
What worked once may break tomorrow—and what breaks may never be blamed on the real cause.

This isn’t a checklist item.
It’s a survival instinct.

🔍 What We’re Really Asking

  • Why this approach, and not the others?
  • What trade-offs did you consciously accept?
  • If someone replaces this tomorrow, will they know what not to break?

🧠 Patterns That Save You Later

  • You wrote: “This design minimizes write amplification at the cost of occasional staleness.”
    → That one sentence just saved someone 3 days of debugging.
  • You noted the alternative: “We didn’t go with Option B due to memory constraints in multi-tenant scaling.”
    → That tells ops, PM, and future-you something valuable.

⚠️ When It’s Missing

  • Design becomes cargo culted. No one knows why it exists, so no one knows when it can die.
  • Reviewers can’t give meaningful feedback. There’s no context to push against.
  • The system survives—but its reasons rot away.

❓ FAQ

  • Q: Isn’t this just documentation?
    A: No. Documentation explains what. This explains why. Different species.

  • Q: Can’t people figure it out from code?
    A: Not when they’re stressed. Or new. Or not you.

  • [All perspectives are expected to reference design justification.]