principle-foundational-thinking

principle-foundational-thinking is a skill for Claude Code from chhoumann/t3-pstack. It costs 42 tokens per session (290 once invoked), scanned A, original, MIT.

A planning guideline for choosing data structures, sequencing work, and handling shared state. It recommends setting up foundations such as tests and continuous integration before features that depend on them.

In plain words
What is it for?
Use it before writing substantial logic to define core types, check concurrent access, remove dead code, and plan small, coherent changes.
Why use it?
It reduces rework caused by unsuitable data shapes, premature abstractions, unsafe shared state, or poorly ordered tasks.

Skill for Claude Code

Written for Claude Code: disable-model-invocation in frontmatter.

Part of the t3-pstack plugin — 62 skills, 4 agents, 1 hook shipped together

Good fit Use it before writing substantial logic to define core types, check concurrent access, remove dead code, and plan small, coherent changes.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/chhoumann/t3-pstack/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 chhoumann/t3-pstack --skill principle-foundational-thinking
Clone the repo
git clone --depth 1 https://github.com/chhoumann/t3-pstack

Made for: Claude Code.

Or install t3-pstack, the plugin that ships this one along with the rest of its 62 skills, 4 agents, 1 hook.

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/chhoumann/t3-pstack/principle-foundational-thinking/github.svg)](https://agentmods.dev/skills/chhoumann/t3-pstack/principle-foundational-thinking)
Your own site
<a href="https://agentmods.dev/skills/chhoumann/t3-pstack/principle-foundational-thinking"><img src="https://agentmods.dev/badge/skills/chhoumann/t3-pstack/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/chhoumann/t3-pstack/principle-foundational-thinking"><img src="https://agentmods.dev/badge/skills/chhoumann/t3-pstack/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 290 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 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 $0.00042 $0.00290
Opus 5.5 $0.00017 $0.00116
Sonnet 5.5 $0.00008 $0.00058
Haiku 4.5 $0.00004 $0.00029

Measured yesterday against content hash 864b827e8199, 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 yesterday.

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

Copies of this mod

2 near-identical copies found in the catalogue:

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.

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. yesterday Changed 864b827e8199
  2. 3d 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 chhoumann/t3-pstack (190 stars, last pushed yesterday), licensed MIT. It adds 42 tokens to every session and 290 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-10-13.

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