MCPInstall

principle-boundary-discipline

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.

Installs
832
Last 24h
+9
Trending rank
#9042
Security
Not audited

Install

Works with every agent the skills CLI supports.

npx skills add https://github.com/michael-denyer/pstack-claude --skill principle-boundary-discipline
  1. 01

    Install

    Run the command in your project. The CLI asks which agents to install for.

  2. 02

    Describe the task

    Ask your agent for something this skill covers. It loads principle-boundary-discipline automatically when relevant.

  3. 03

    Review the result

    The agent follows the SKILL.md steps, scripts and references bundled with the skill.

SKILL.md

The instructions your agent reads when the skill is triggered.

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.

FAQ

What does the principle-boundary-discipline skill do?

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.

How do I install principle-boundary-discipline?

Run npx skills add https://github.com/michael-denyer/pstack-claude --skill principle-boundary-discipline in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/principle-boundary-discipline/ (personal) or .claude/skills/principle-boundary-discipline/ (project).

Which AI agents can use principle-boundary-discipline?

Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.

Is principle-boundary-discipline safe to install?

No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.

Who maintains principle-boundary-discipline?

It is published by michael-denyer in michael-denyer/pstack-claude. It has 832 recorded installs.

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