engineering-principles

engineering-principles is a skill for Claude Code, Codex from J-StaR-Films-Studios/VibeCode-Protocol-Suite. It costs 30 tokens per session (1,666 once invoked), scanned A, original, ISC.

A set of general software engineering rules for designing systems, organising code, reviewing changes, and handling application state.

In plain words
What is it for?
Use it during system design, code reviews, state management, and other decisions about how software should be structured.
Why use it?
It provides consistent guidance for making code easier to reason about and reducing avoidable design and maintenance problems.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions subagents.

Good fit Use it during system design, code reviews, state management, and other decisions about how software should be structured.

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Install with agentmods
npx agentmods add skills/j-star-films-studios/vibecode-protocol-suite/engineering-principles
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add J-StaR-Films-Studios/VibeCode-Protocol-Suite --skill engineering-principles
Clone the repo
git clone --depth 1 https://github.com/J-StaR-Films-Studios/VibeCode-Protocol-Suite

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for engineering-principles

README.md
[![agentmods](https://agentmods.dev/badge/skills/j-star-films-studios/vibecode-protocol-suite/engineering-principles/github.svg)](https://agentmods.dev/skills/j-star-films-studios/vibecode-protocol-suite/engineering-principles)
Your own site
<a href="https://agentmods.dev/skills/j-star-films-studios/vibecode-protocol-suite/engineering-principles"><img src="https://agentmods.dev/badge/skills/j-star-films-studios/vibecode-protocol-suite/engineering-principles/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for engineering-principles

Your own site · 80×15
<a href="https://agentmods.dev/skills/j-star-films-studios/vibecode-protocol-suite/engineering-principles"><img src="https://agentmods.dev/badge/skills/j-star-films-studios/vibecode-protocol-suite/engineering-principles.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 30 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,666 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00030 $0.01666
Opus 5 $0.00015 $0.00833
Sonnet 5 $0.00006 $0.00333
Haiku 4.5 $0.00003 $0.00167

Measured 7d ago against content hash 8050fcac9b94, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

engineering-principles scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 7d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

assets/.agent/skills/engineering-principles/SKILL.md · 40 lines

How it starts

The opening of the file, as written. The whole thing — 40 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Engineering Principles Suite

A catalogue of 21 foundational principles for software architecture, code quality, state management, and agentic workflows.

Principles Catalog

Read the specific principle file via view_file on demand when applying its rule:

Principle When to Apply File Path
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. boundary-discipline/SKILL.md
build-the-lever Apply to any non-trivial work, not just bulk work: edits, migrations, analyses, checks. Build the tool that does it or proves it (codemod, script, generator, or a skill your subagents follow) instead of working by hand. The tool is the artifact a reviewer can rerun. build-the-lever/SKILL.md
encode-lessons-in-structure 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. encode-lessons-in-structure/SKILL.md
exhaust-the-design-space Apply when facing a novel UI interaction or architectural decision with no precedent in the codebase. Build 2-3 competing prototypes and compare side by side before committing. exhaust-the-design-space/SKILL.md
experience-first Apply when product, UX, or feature-scope tradeoffs come up. Choose user delight over implementation convenience; ship fewer polished features over more rough ones. experience-first/SKILL.md
fix-root-causes Apply when debugging. Trace each symptom to its root cause and fix it there; reproduce first, ask why until you reach it, resist nil-check guards that silence crashes. fix-root-causes/SKILL.md
foundational-thinking Apply before writing logic: choosing core types and data structures, sequencing scaffold-vs-feature work, asking what concurrent actors share. Get the data structures right so downstream code becomes obvious. foundational-thinking/SKILL.md
guard-the-context-window Apply when context is filling up: large outputs, long files, repeated reads, fan-out planning. Route bulk to subagents; keep summaries in the main thread, not raw payloads. guard-the-context-window/SKILL.md
laziness-protocol Apply when refactoring, evaluating diff size, or tempted to add abstractions, layers, or signal threading. Bias toward deletion and the smallest change that solves the problem. laziness-protocol/SKILL.md
make-operations-idempotent Apply when designing commands, lifecycle steps, or processing loops that run amid crashes, restarts, and retries. Converge to the same end state regardless of partial prior runs. make-operations-idempotent/SKILL.md
migrate-callers-then-delete-legacy-apis Apply when introducing a new internal API while old callers still exist. Migrate callers and delete the old API in the same wave instead of preserving compatibility layers. migrate-callers-then-delete-legacy-apis/SKILL.md
minimize-reader-load Apply when reviewing or shaping code that's hard to trace. Count layers between question and answer, and hidden state in the reader's head; collapse one-caller wrappers and shrink mutable scope. minimize-reader-load/SKILL.md
model-the-domain Apply when writing stateful logic, or when code branches a lot or repeats a shape assumption across files. Encode the domain in a structure instead of scattered conditionals. model-the-domain/SKILL.md
never-block-on-the-human Apply when tempted to ask 'should I do X?' on reversible work. Proceed, present the result, let the human course-correct after the fact; reserve confirmation for irreversible actions. never-block-on-the-human/SKILL.md
outcome-oriented-execution Apply during planned rewrites and migrations with explicit phase boundaries. Converge on the target architecture; don't preserve smooth intermediate states with throwaway compatibility code. outcome-oriented-execution/SKILL.md
prove-it-works Apply after completing a task, before declaring done. Verify against the real artifact (run the feature, read the actual value, inspect the diff), not a proxy, self-report, or 'it compiles.' prove-it-works/SKILL.md
redesign-from-first-principles Apply when integrating a new requirement into an existing design. Redesign as if the requirement had been a foundational assumption from day one, instead of bolting it on. redesign-from-first-principles/SKILL.md
separate-before-serializing-shared-state Apply when concurrent actors might write to the same file, branch, key, or state object. Eliminate the sharing first; serialize structurally only when one shared writer is a real invariant. separate-before-serializing-shared-state/SKILL.md
sequence-verifiable-units Apply to multi-step work (sweeps, migrations, runs of similar edits) and to how you stack commits and PRs. Break work into small units that each end in a verifiable state, check each before the next, and order delivery so the sequence proves itself to a reviewer. sequence-verifiable-units/SKILL.md
subtract-before-you-add Apply when sequencing an addition, refactor, or rewrite. Remove dead weight, redundant validators, and stub references first, then build on the simpler base. subtract-before-you-add/SKILL.md
type-system-discipline Apply when designing types, reviewing a function signature, or writing code in any statically-typed language. Make illegal states unrepresentable, brand semantic primitives, parse external data at boundaries, refuse to lie to the compiler, exhaust variants, derive from authoritative schemas. type-system-discipline/SKILL.md

Read the full file on GitHub · 40 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 7d ago First seen · 40 lines · 30 tokens per session scan A 8050fcac9b94

Subscribe to this mod's changes

engineering-principles is a skill published in the GitHub repository J-StaR-Films-Studios/VibeCode-Protocol-Suite (24 stars, last pushed today), licensed ISC. It adds 30 tokens to every session and 1,666 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.