Principle Encode Lessons In Structure

---
name: principle-encode-lessons-in-structure
description: "Apply when a repeated instruction should become enforceable in tests, lint, metadata, or tools."
license: MIT
metadata:
  author: jstack-maintainers
  source: michael-denyer/pstack-claude
  source-version: "0.9.30"
  source-commit: 45f768349a6d7d7e71509fee3f5bccfad54b3bad
  owner: software-factory
  risk: low
  capabilities: jstack,engineering-principle
user-invocable: false
---

# Encode Lessons in Structure

Encode recurring fixes in mechanisms (tools, code, metadata, automation) instead of textual instructions. Every error, human correction, and unexpected outcome is a learning signal. Capture it, route it, and close the loop.

**Why:** Textual instructions are easy to miss. They require the reader to notice, remember, and comply. Structural mechanisms (lint rules, metadata flags, runtime checks, automation scripts) enforce the rule without cooperation.

**Pattern:**
When you catch yourself writing the same instruction a second time:
1. Ask: can this be a lint rule, a metadata flag, a runtime check, or a script?
2. If yes, encode it. Delete the instruction
3. If no (requires judgment), make the instruction more prominent and add an example of the failure mode

**Pick the strongest mechanism.** When more than one mechanism would work, choose the strongest the situation allows (an unrepresentable state that cannot compile, then a lint or banned API that fails CI, then a canonical helper, then a runtime check), because agents copy whatever the surrounding code already does and a weaker guard becomes the next template.

**Corollary:** If the fix is structural, only use the structural fix. The instruction is the symptom.

**Feedback loop:**
- **Capture every correction.** When the human intervenes or tests fail, decide if it's a one-off or a pattern.
- **Route to the right layer.** One-off -> brain note. Recurring fix -> skill or lint rule. Systemic issue -> principle.
- **Close the loop.** Don't just record. Apply now or create a concrete todo.

**Anti-patterns:**
- Acknowledging without recording ("I'll keep that in mind" does not persist)
- Recording without routing (a brain note about a lint rule that should exist is wasted unless the lint rule gets implemented)
- Fixing without generalizing (fixing one instance while leaving the recurring pattern intact)