principle-foundational-thinking

principle-foundational-thinking is a skill for Claude Code, Codex from minghinmatthewlam/agent-guards. It costs 42 tokens per session (289 once invoked), scanned A, a copy of principle-foundational-thinking, MIT.

A software design method that chooses data shapes, shared types, and work order before writing most of the logic. It asks how data is accessed and what happens when multiple actors change shared state at once.

In plain words
What is it for?
Use it when starting a project, choosing data structures, designing concurrent code, or deciding whether tests, continuous integration, linting, or shared types should come first.
Why use it?
Early structural choices affect every later feature. A suitable data model and basic project setup can prevent complicated special cases and unsafe coordination.

Skill for Claude CodeCodex

Written for Claude Code and Codex: user-invocable in frontmatter, but also agents/openai.yaml present.

Part of the pstack plugin — 55 skills, 2 agents shipped together

Good fit Use it when starting a project, choosing data structures, designing concurrent code, or deciding whether tests, continuous integration, linting, or shared types should come first.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/minghinmatthewlam/agent-guards/principle-foundational-thinking
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 minghinmatthewlam/agent-guards --skill principle-foundational-thinking
Clone the repo
git clone --depth 1 https://github.com/minghinmatthewlam/agent-guards

Made for: Claude Code, Codex.

Or install pstack, the plugin that ships this one along with the rest of its 55 skills, 2 agents.

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 principle-foundational-thinking

README.md
[![agentmods](https://agentmods.dev/badge/skills/minghinmatthewlam/agent-guards/principle-foundational-thinking/github.svg)](https://agentmods.dev/skills/minghinmatthewlam/agent-guards/principle-foundational-thinking)
Your own site
<a href="https://agentmods.dev/skills/minghinmatthewlam/agent-guards/principle-foundational-thinking"><img src="https://agentmods.dev/badge/skills/minghinmatthewlam/agent-guards/principle-foundational-thinking/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 principle-foundational-thinking

Your own site · 80×15
<a href="https://agentmods.dev/skills/minghinmatthewlam/agent-guards/principle-foundational-thinking"><img src="https://agentmods.dev/badge/skills/minghinmatthewlam/agent-guards/principle-foundational-thinking.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 42 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 289 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.
Origin 100% copy Near-identical to another mod 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 $0.00042 $0.00289
Opus 5.5 $0.00017 $0.00116
Sonnet 5.5 $0.00008 $0.00058
Haiku 4.5 $0.00004 $0.00029

Measured 2d ago against content hash a3d9bf77ebb9, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

principle-foundational-thinking 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 2d 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.

Origin

This is a copy

100% identical to principle-foundational-thinking — 2 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

plugins/pstack/skills/principle-foundational-thinking/SKILL.md · 22 lines

What it actually says

Foundational Thinking

Structural decisions protect option value. Code-level decisions protect simplicity.

Data structures first. Get the data shape right before writing logic. Define core types early, trace every access pattern, and choose structures that match the dominant paths.

At code level, DRY the structure, not every line. Types and data models should converge. Three similar statements still beat a premature abstraction. Prefer explicit over clever. Test behavior and edge cases, not line counts.

Concurrency corollary. Before sharing state between actors, ask "what happens if another actor modifies this concurrently?" If not "nothing", isolate.

Scaffold first. If something helps every later phase, do it first. Ask "does every subsequent phase benefit from this existing?" CI, linting, test infrastructure, and shared types are scaffold. Sequence for option value: setup before features, tests before fixes. Keep commits small and single-purpose.

Each increment should land a coherent abstraction or deepen one that exists. Do not spread a new capability across callers as special-case coordination.

Subtraction comes before scaffolding. Remove dead code first, then lay foundations.

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 2d ago First seen · 22 lines · 42 tokens per session scan A a3d9bf77ebb9

Subscribe to this mod's changes

principle-foundational-thinking is a skill published in the GitHub repository minghinmatthewlam/agent-guards (47 stars, last pushed 2d ago), licensed MIT. It adds 42 tokens to every session and 289 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 100% identical to principle-foundational-thinking, differing in 2 lines, and is treated as a copy.

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