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Agent skill

Constraint Physical

by hashgraph-online in hashgraph-online/awesome-codex-plugins

A skill your agent uses when designing structural constraints that prevent invalid actions through the shape, layout, or behavior of the design itself — paths (channels of motion), axes (rotary…

Apache-2.0Auto-check passedFrontend & Design

Install Constraint Physical

skills CLI
$ npx skills add hashgraph-online/awesome-codex-plugins --skill constraint-physical -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install hashgraph-online/awesome-codex-plugins constraint-physical --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/hashgraph-online/awesome-codex-plugins.git skills-src && mkdir -p .claude/skills && cp -r skills-src/plugins/HDeibler/universal-design-principles/plugins/interaction-and-control-principles/skills/constraint-physical .claude/skills/constraint-physical && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
constraint-physical
GitHub stars
1.3k
Token cost
~1.2k tokens
SKILL.md length
420 words
Files
2 (incl. references)
Skills in repo
714
Repo updated
First seen
Licence
Apache-2.0

At a glance

A skill your agent uses when designing structural constraints that prevent invalid actions through the shape, layout, or behavior of the design itself — paths (channels of motion), axes (rotary…

  • Designing structural constraints that prevent invalid actions through the shape
  • SKILL.md covers The three subtypes (from the…, Patterns, When to use physical over… and When physical constraints…, plus 2 more sections
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
  • Behavior of the design itself — paths (channels of motion)

What it does

Constraint Physical is an agent skill from hashgraph-online/awesome-codex-plugins. Use this skill when designing structural constraints that prevent invalid actions through the shape, layout, or behavior of the design itself — paths (channels of motion), axes (rotary controls), barriers (blocks). Trigger when designing input controls, drag-and-drop affordances, modal dialogs, or hardware-style structural prevention. Sub-aspect of constraint; read that first.

Its SKILL.md is about 1.2k tokens, which your agent loads only when the skill is triggered. The skill folder holds 2 other files, including reference files (for example `references/structural-prevention-cases.md`).

It sits in Frontend & Design, covering Accessibility. The repository describes itself as: A curated list of awesome OpenAI Codex / ChatGPT plugins, skills, and resources. The 1 Codex Marketplace. See live plugins at: https://hol.org/plugins/best-codex-plugins. The licence is Apache-2.0.

When your agent uses it

  • Designing structural constraints that prevent invalid actions through the shape
  • Behavior of the design itself — paths (channels of motion)
  • Axes (rotary controls)
  • Barriers (blocks)

Example prompts

  • “/constraint-physical”

What it can do on your machine

Read from SKILL.md and the folder at commit 9e7b281. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md (its code samples are html and javascript).

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Constraint Physical loads about 1.2k tokens when it runs, and up to ~1.9k if it reads all its reference files. Until then it costs about 100 tokens; SKILL.md has 420 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~100
When it runs · the whole SKILL.md, loaded when a task matches
~1.2k
With references · SKILL.md plus every file in references/, read only if the agent opens them
~1.9k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from hashgraph-online/awesome-codex-plugins at commit 9e7b281, republished under its Apache-2.0 licence (© hashgraph-online). 420 words, ~1,176 tokens.

Download SKILL.mdSave it as .claude/skills/constraint-physical/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.
name
constraint-physical
description
Use this skill when designing structural constraints that prevent invalid actions through the shape, layout, or behavior of the design itself — paths (channels of motion), axes (rotary controls), barriers (blocks). Trigger when designing input controls, drag-and-drop affordances, modal dialogs, or hardware-style structural prevention. Sub-aspect of `constraint`; read that first.

Physical constraints

Physical constraints prevent invalid actions through the structure of the design — the shape of a connector, the boundary of a screen, the channel of a slider. The user can't take the wrong action because the structure rejects it. Stronger than psychological constraints; not always available.

The three subtypes (from the book)

Paths

Channels that direct motion. The user can move along the path; off-path movement is impossible or rejected.

Software examples:

  • Sliders constrain motion to one dimension.
  • Range inputs constrain values to a defined min/max.
  • Scroll bars constrain scrolling direction.
  • Dropdown lists constrain selection to provided options.
html
<!-- Path constraint: value must be 0-100 -->
<input type="range" min="0" max="100" value="50" />

<!-- Path constraint: choice from fixed set -->
<select>
  <option>Small</option>
  <option>Medium</option>
  <option>Large</option>
</select>
Axes

Rotary controls. Convert applied force into rotation; effectively infinite range in a small space.

Software examples:

  • Rotation gestures in canvas tools.
  • Color-wheel pickers that constrain hue selection to a circular path.
  • Dial-style controls for continuous values.
Barriers

Block, slow, or redirect motion.

Software examples:

  • Modal dialogs block interaction with content beneath.
  • Disabled buttons block their action.
  • Permission gates block access to features.
  • Screen edges stop cursor motion (Fitts's edge advantage).
  • Form-validation blocks prevent submission when invalid.

Patterns

Input-type constraints (paths)
html
<input type="email" />     <!-- only accepts email format -->
<input type="number" min="0" />   <!-- only non-negative numbers -->
<input type="date" />      <!-- only valid dates -->
<input type="color" />     <!-- only valid hex colors -->

The browser enforces the constraint; the user can't submit invalid data.

Drop-zone constraints (barriers)

A drag-and-drop interaction can constrain valid drops at the API level:

js
dropZone.addEventListener('dragover', e => {
  if (isValidTarget(draggedItem, dropZone)) {
    e.preventDefault();  // allow drop
  }
  // not preventing default = drop won't fire
});

The browser's drag-and-drop API itself uses constraint: preventDefault opens the channel; absence keeps it blocked.

Modal as barrier
html
<dialog open>
  <h2>Required action</h2>
  <p>You must complete this step before continuing.</p>
  <button onclick="proceed()">Continue</button>
</dialog>

The dialog blocks interaction with the page beneath. Use sparingly; barriers irritate when they don't serve a clear purpose.

Disabled state (block)
html
<button id="submit" disabled>Submit</button>

The button can't trigger its action until enabled. Pair with explanation of what would enable it.

Show full SKILL.md (159 more words)Show less

When to use physical over psychological

  • When the consequence of the wrong action is severe (data loss, security breach, irreversible operation). Physical constraints are stronger.
  • When the user is novice or the system is unfamiliar — psychological constraints rely on prior knowledge that may not exist.
  • When there's no acceptable failure mode — make the wrong action impossible.

When physical constraints over-restrict

  • Format constraints stricter than necessary — phone fields that reject parentheses; name fields that reject apostrophes.
  • Hardware-style barriers in software contexts — a modal that blocks because of a non-blocking concern.
  • Disabled states that don't explain themselves — user can't act and doesn't know why.

The discipline: constrain real requirements; explain when surprises occur.

Resources

  • Norman, D. The Design of Everyday Things (1988, 2013).
  • Lidwell, Holden & Butler (2003).
  • WCAG — input-type and validation constraints contribute to accessibility.
  • constraint (parent).
  • constraint-psychological — the other half; symbols, conventions, mappings.
  • affordance — affordance + constraint = the action space.
  • accessibility-operable — physical constraints must be operable across assistive technologies.

© hashgraph-online, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 1 other file (references) in plugins/HDeibler/universal-design-principles/plugins/interaction-and-control-principles/skills/constraint-physical of hashgraph-online/awesome-codex-plugins.

  • SKILL.md
  • references/structural-prevention-cases.md

Open the folder on GitHubat commit 9e7b281

Compare with similar skills

Constraint Physical next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Constraint Physical compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Constraint Physical this skillhashgraph-online/awesome-codex-plugins1.3k—~1.2kAutomated safety check: PassApache-2.0
Web Interface Guidelines Reviewervercel-labs/openreview1.7k97 repos~308Automated safety check: PassNone
Accessibility Reviewmarkmead/hyperui12k1 repos~1.1kAutomated safety check: PassMIT
Web Animation DesignbaptisteArno/typebot.io11k2 repos~2.7kAutomated safety check: PassCustom licence
Accessibility Fixeribelick/ui-skills9.5k4 repos~1.2kAutomated safety check: PassMIT
Wcag Audit PatternsvmDeshpande/ai-agent-automation17811 repos~610Automated safety check: PassApache-2.0

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Categories

Questions about Constraint Physical

What does Constraint Physical do?

A skill your agent uses when designing structural constraints that prevent invalid actions through the shape, layout, or behavior of the design itself — paths (channels of motion), axes (rotary…. Constraint Physical is an agent skill from hashgraph-online/awesome-codex-plugins. Use this skill when designing structural constraints that prevent invalid actions through the shape, layout, or behavior of the design itself — paths (channels of motion), axes (rotary controls), barriers (blocks).

When should I use Constraint Physical?

Constraint Physical fits situations like: designing structural constraints that prevent invalid actions through the shape; behavior of the design itself — paths (channels of motion); axes (rotary controls); barriers (blocks).

How do I install Constraint Physical in Claude Code?

Run `npx skills add hashgraph-online/awesome-codex-plugins --skill constraint-physical -a claude-code`. Or copy the skill folder (plugins/HDeibler/universal-design-principles/plugins/interaction-and-control-principles/skills/constraint-physical in hashgraph-online/awesome-codex-plugins) into .claude/skills/constraint-physical in your project. Claude Code loads it when a task matches its description.

How do I install Constraint Physical in Codex?

Run `npx skills add hashgraph-online/awesome-codex-plugins --skill constraint-physical -a codex`. Or copy the skill folder (plugins/HDeibler/universal-design-principles/plugins/interaction-and-control-principles/skills/constraint-physical in hashgraph-online/awesome-codex-plugins) into .agents/skills/constraint-physical in your project. Codex loads it when a task matches its description.

Can I use Constraint Physical in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add hashgraph-online/awesome-codex-plugins --skill constraint-physical -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/constraint-physical, .gemini/skills/constraint-physical, .github/skills/constraint-physical and .opencode/skills/constraint-physical in your project.

What does Constraint Physical need to run?

SKILL.md names no scripts, command-line tools or credentials: Constraint Physical is instructions for the agent only.

Does Constraint Physical access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Constraint Physical safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Constraint Physical use?

Constraint Physical is published under the Apache-2.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Constraint Physical use?

About 1.2k tokens (SKILL.md is roughly 4.7k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 675 tokens, read only when the agent opens those files.

What are the alternatives to Constraint Physical?

Skills that share tags, products or a category with Constraint Physical: Web Interface Guidelines Reviewer (vercel-labs/openreview, 1.7k stars), Accessibility Review (markmead/hyperui, 12k stars), Web Animation Design (baptisteArno/typebot.io, 11k stars) and Accessibility Fixer (ibelick/ui-skills, 9.5k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Constraint Physical?

hashgraph-online (a GitHub organization) maintains it in hashgraph-online/awesome-codex-plugins, which has 1,255 GitHub stars. The repository holds 714 skills in this directory. The repository was last updated on October 9, 2026.

Source: hashgraph-online/awesome-codex-plugins on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.