---
name: principle-encode-lessons-in-structure
description: "Apply when you catch yourself writing the same instruction a second time, or notice a recurring correction. Encode the rule as a lint, metadata flag, runtime check, or script instead of more text."
disable-model-invocation: true
---

# 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)

## Session capabilities and authorization

Follow [session capability discovery](../../references/host-capabilities.md) for reads, writes, execution and durable persistence. Apply mechanisms within the authorized task. This principle does not authorize installation, global settings or external actions. Treat a brain note as an authorized durable record when persistence is available; claim it saved only after write and readback. If persistence is unavailable, state that limit and include the concrete todo in the current response.

If writes or execution are unavailable, provide a reduced proposal that names the check, its integration point and the remaining implementation or verification work. If the rule or source needed to select a mechanism is missing, identify the missing inputs and keep the proposal provisional. Delete a redundant instruction only once the structural fix enforces its rule. Preserve judgment-dependent guidance with a prominent failure example.

Preserve explicit-invocation metadata without assuming the host enforces it. Claim enforcement, implementation or verification only for observed operations.