principle-foundational-thinking

A software-design principle for making foundational decisions before writing application logic. It emphasizes choosing core data structures, setting up shared scaffolding, and considering how concurrent actors may change shared state.

In plain words
What is it for?
Use it when choosing types or data structures, deciding the order of setup and feature work, designing tests or CI, or deciding whether shared state needs isolation under concurrent changes.
Why use it?
It reduces rewrites caused by poor data models and helps keep later code simpler, safer, and easier to extend.

Skill for Claude CodeCodex

Part of the pstack plugin — 41 skills, 2 agents shipped together

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.

agentmods
npx agentmods add skills/painhardcore/pstack/principle-foundational-thinking
Any agent
npx skills add painhardcore/pstack --skill principle-foundational-thinking
Clone the repo
git clone --depth 1 https://github.com/painhardcore/pstack

Made for: Claude Code, Codex.

Or install pstack, the plugin that ships this one along with the rest of its 41 skills, 2 agents.

Per session 42 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 331 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 88% 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 $0.00042 $0.00331
Opus 5 $0.00021 $0.00166
Sonnet 5 $0.00008 $0.00066
Haiku 4.5 $0.00004 $0.00033

Measured 2d ago against content hash 64aec61f4d1f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, 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

88% identical to principle-foundational-thinking — 1 line 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.

.opencode/skills/principle-foundational-thinking/SKILL.md · 21 lines

What it actually says

Foundational Thinking

Structural decisions protect option value. Code-level decisions protect simplicity. Over-engineering is often a premature decision that closes doors. The right foundational data structure keeps doors open.

Data structures first. Get the data shape right before writing logic. The right shape makes downstream code obvious. Define core types early, trace every access pattern, and choose structures that match the dominant paths. A data-structure change late is a rewrite. Early, it is often a one-line diff.

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 weight 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. 2d ago First seen · 21 lines · 42 tokens per session scan A 64aec61f4d1f

Subscribe to this mod's changes

principle-foundational-thinking is a skill published in the GitHub repository painhardcore/pstack (1 stars, last pushed 6d ago), licensed MIT. It adds 42 tokens to every session and 331 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 88% identical to principle-foundational-thinking, differing in 1 line, and is treated as a copy.

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