# Principle Boundary Discipline

Apply when wiring validation, error handling, or framework adapters.

- Repository: https://github.com/nightly-labs/openbot (4509 stars)
- Category: Business
- License: see repository
- Last updated: 2026-11-01
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add nightly-labs/openbot --skill principle-boundary-discipline -g -a claude-code -y`
Codex: `npx skills add nightly-labs/openbot --skill principle-boundary-discipline -g -a codex -y`
Cursor: `npx skills add nightly-labs/openbot --skill principle-boundary-discipline -g -a cursor -y`
Gemini CLI: `npx skills add nightly-labs/openbot --skill principle-boundary-discipline -g -a gemini-cli -y`

## Description

Apply when wiring validation, error handling, or framework adapters. Concentrate guards at system boundaries (CLI, config, network, external APIs); trust internal types and keep business logic in pure functions.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# Boundary Discipline

Place validation, type narrowing, and error handling at system boundaries. Trust internal code unconditionally. Business logic lives in pure functions. The shell is thin and mechanical.

**Why:** Scattered validation is noisy, redundant, and gives a false sense of safety. Keep logic out of framework wiring so it can be tested without the framework.

**The pattern:**
- **At boundaries** (CLI args, config files, external APIs, network protocols): validate, return errors, handle defensively.
- **Inside the system:** typed data, error propagation, no re-validation. Trust the types.
- **Across the boundary.** Expose domain concepts, not the boundary's private representation. Keep general-purpose mechanism inside and special-purpose policy at the edge.

**Applications:**

Validation and error handling:
- Validate config at parse time (the boundary), not inside business logic
- Parse raw data into domain types at the boundary
- Do not re-export transport, storage, framework, or wire types through the public surface
- No redundant nil checks deep in call chains if the boundary already validated

Code organization:
- Business logic in pure functions with no framework dependencies
- Parse functions: pure transforms from raw bytes to typed state
- Prompt construction: structured state in, string out
- Scoring and assessment: pure transforms from state to results

**The tests:**
- "Is this data crossing a system boundary right now?" If not, validation is redundant.
- "Can this be a pure function that the shell just calls?" If yes, extract it.