Agent skill

Define Domains

Create and manipulate domains for PINA physics-driven problems.

MITAuto-check passedAI & LLM Engineering

Install Define Domains

skills CLI

$ npx skills add PINA-org/PINA --skill define-domains -a claude-code

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

GitHub CLI

$ gh skill install PINA-org/PINA define-domains --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/PINA-org/PINA.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.opencode/skills/define-domains .claude/skills/define-domains && 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/

Paste into Claude Code

Install the "define-domains" agent skill from https://github.com/PINA-org/PINA/tree/master/.opencode/skills/define-domains into .claude/skills/define-domains/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "define-domains", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/PINA-org/PINA/tree/master/.opencode/skills/define-domains

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add PINA-org/PINA --skill define-domains -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install PINA-org/PINA define-domains --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/PINA-org/PINA.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.opencode/skills/define-domains .agents/skills/define-domains && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "define-domains" agent skill from https://github.com/PINA-org/PINA/tree/master/.opencode/skills/define-domains into .agents/skills/define-domains/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "define-domains", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add PINA-org/PINA --skill define-domains -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install PINA-org/PINA define-domains --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/PINA-org/PINA.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.opencode/skills/define-domains .cursor/skills/define-domains && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "define-domains" agent skill from https://github.com/PINA-org/PINA/tree/master/.opencode/skills/define-domains into .cursor/skills/define-domains/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "define-domains", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/PINA-org/PINA.git --path .opencode/skills/define-domains

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add PINA-org/PINA --skill define-domains -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install PINA-org/PINA define-domains --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/PINA-org/PINA.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.opencode/skills/define-domains .gemini/skills/define-domains && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "define-domains" agent skill from https://github.com/PINA-org/PINA/tree/master/.opencode/skills/define-domains into .gemini/skills/define-domains/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "define-domains", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install PINA-org/PINA define-domains

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add PINA-org/PINA --skill define-domains -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/PINA-org/PINA.git skills-src && mkdir -p .github/skills && cp -r skills-src/.opencode/skills/define-domains .github/skills/define-domains && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "define-domains" agent skill from https://github.com/PINA-org/PINA/tree/master/.opencode/skills/define-domains into .github/skills/define-domains/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "define-domains", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add PINA-org/PINA --skill define-domains -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install PINA-org/PINA define-domains --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/PINA-org/PINA.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.opencode/skills/define-domains .opencode/skills/define-domains && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "define-domains" agent skill from https://github.com/PINA-org/PINA/tree/master/.opencode/skills/define-domains into .opencode/skills/define-domains/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "define-domains", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: define-domains
GitHub stars: 798
Token cost: ~1.1k tokens
SKILL.md length: 268 words
Files: 1
Skills in repo: 10
Repo updated: Oct 6, 2026
First seen: Oct 7, 2026
Licence: MIT

At a glance

Create and manipulate domains for PINA physics-driven problems.

Works in 3 steps: Create domains → Domain methods for problem setup → Discretise domains (sampling)
Tasks that involve Deep learning
SKILL.md covers Step 1 — Create domains, Step 2 — Domain methods for…, Step 3 — Discretise domains… and Checklist
Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Define Domains is an agent skill from PINA-org/PINA. Create and manipulate domains for PINA physics-driven problems. Covers domain types (Cartesian, Ellipsoid, Simplex), set operations, partial/update methods, and domain discretisation.

Its SKILL.md is about 1.1k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts. Compatibility notes: opencode, codex, claude

It sits in AI & LLM Engineering, covering Deep learning. The repository describes itself as: Physics-Informed Neural networks for Advanced modeling. The licence is MIT.

When your agent uses it

Tasks that involve Deep learning

Example prompts

“/define-domains”

Requirements

Python 3
Compatibility (from SKILL.md): opencode, codex, claude

Workflow steps

3 steps, taken from the step headings in SKILL.md.

Create domains
Domain methods for problem setup
Discretise domains (sampling)

What it can do on your machine

Read from SKILL.md and the folder at commit 0cd8afb. 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 python).
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.
Compatibility
opencode, codex, claude
From compatibility in the SKILL.md frontmatter.

Context cost

Define Domains loads about 1.1k tokens when it runs. Until then it costs about 50 tokens; SKILL.md has 268 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~50
When it runs · the whole SKILL.md, loaded when a task matches: ~1.1k

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 PINA-org/PINA at commit 0cd8afb, republished under its MIT licence (© PINA-org). 268 words, ~1,072 tokens.

Download SKILL.mdSave it as .claude/skills/define-domains/SKILL.md (or your agent's skills folder).

name: define-domains
description: Create and manipulate domains for PINA physics-driven problems. Covers domain types (Cartesian, Ellipsoid, Simplex), set operations, partial/update methods, and domain discretisation.
compatibility: opencode, codex, claude
license: MIT
metadata.audience: users
metadata.workflow: problem-creation

Define Domains for a PINA Problem

[!IMPORTANT] Read RULES.md before using this skill — it applies to all skills. This is a sub-skill of create-problem. Load the entry-point skill first.

Use this skill to create spatial, temporal, and parameter domains, and to discretise them for training.

Step 1 — Create domains

For each domain type, ask:

What are the variable names and their ranges?

If the user does not specify a domain, ask for:

Variable name (e.g. x)
Lower bound (e.g. 0)
Upper bound (e.g. 1)

Domain types available

python

from pina.domain import CartesianDomain, EllipsoidDomain, SimplexDomain

Domain type	Description	Example
`CartesianDomain`	Hyperrectangle (most common)	`CartesianDomain({"x": [0, 1], "y": [0, 1]})`
`EllipsoidDomain`	Hyperellipsoid	`EllipsoidDomain({"x": [0, 1], "y": [0, 1]})`
`SimplexDomain`	Simplex defined by vertices	`SimplexDomain(vertices=[...])`

CartesianDomain supports sampling modes: random, grid, chebyshev, latin/lh.

Set operations on domains

python

from pina.domain import Union, Intersection, Difference, Exclusion

combined = Union(domain_a, domain_b)
overlap = Intersection(domain_a, domain_b)
subtracted = Difference(domain_a, domain_b)
excluded = Exclusion(domain_a, domain_b)

Step 2 — Domain methods for problem setup

`partial()` — extract boundary

Creates a sub-domain representing the boundary of the parent domain:

python

spatial_domain = CartesianDomain({"x": [0, 1], "y": [0, 1]})
boundary = spatial_domain.partial()  # boundary of the square

`update()` — combine domains (space + time)

Creates the Cartesian product of two domains. Essential for space-time problems:

python

spatial_domain = CartesianDomain({"x": [-1, 1]})
temporal_domain = CartesianDomain({"t": [0, 1]})

interior = spatial_domain.update(temporal_domain)
# Equivalent to CartesianDomain({"x": [-1, 1], "t": [0, 1]})

Common patterns:

python

domains = {
    "D": spatial_domain.update(temporal_domain),   # space-time interior
    "ic": spatial_domain.update(CartesianDomain({"t": 0})),  # initial condition
    "boundary": spatial_domain.partial().update(temporal_domain),  # moving boundary
}

Step 3 — Discretise domains (sampling)

After the problem class is fully defined, sample points from each domain:

python

problem.discretise_domain(n=5000, mode="random", domains=["D"])
problem.discretise_domain(n=500, mode="random", domains=["boundary"])

Mode	Description
`"random"`	Uniform random sampling (default)
`"latin"`/`"lh"`	Latin hypercube sampling
`"grid"`	Regular grid points
`"chebyshev"`	Chebyshev nodes (good for polynomials)

After all domains are discretised:

python

problem.move_discretisation_into_conditions()
assert problem.are_all_domains_discretised

Checklist

All required domains are defined (spatial_domain, temporal_domain, parameter_domain, or unknown_parameter_domain as appropriate)
domains dict contains a key for every domain referenced in conditions
For space-time problems: spatial_domain.update(temporal_domain) used to build the interior domain
For boundary conditions: spatial_domain.partial() used correctly
problem.discretise_domain(n=..., mode=..., domains=...) called for each physics domain
problem.move_discretisation_into_conditions() called before training
problem.are_all_domains_discretised is True after discretisation

Files

Just SKILL.md in .opencode/skills/define-domains of PINA-org/PINA.

Open the folder on GitHubat commit 0cd8afb

Compare with similar skills

Define Domains 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.

Define Domains compared with similar skills
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Define Domains this skillPINA-org/PINA	798	—	~1.1k	Automated safety check: Pass	MIT	4 days ago
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Segment Anything Model GuideOrchestra-Research/AI-Research-SKILLs	13k	8 repos	~3.3k	Automated safety check: Pass	MIT	3 mo ago
Add Oponnx/onnx	22k	—	~1.2k	Automated safety check: Pass	Apache-2.0	today
CLIP Image-Text MatchingOrchestra-Research/AI-Research-SKILLs	13k	7 repos	~1.7k	Automated safety check: Pass	MIT	3 mo ago
Add Function Bodyonnx/onnx	22k	—	~1.1k	Automated safety check: Pass	Apache-2.0	today

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Questions about Define Domains

What does Define Domains do?

Create and manipulate domains for PINA physics-driven problems. Define Domains is an agent skill from PINA-org/PINA. Create and manipulate domains for PINA physics-driven problems.

When should I use Define Domains?

Define Domains fits situations like: tasks that involve Deep learning.

How do I install Define Domains in Claude Code?

Run `npx skills add PINA-org/PINA --skill define-domains -a claude-code`. Or copy the skill folder (.opencode/skills/define-domains in PINA-org/PINA) into .claude/skills/define-domains in your project. Claude Code loads it when a task matches its description.

How do I install Define Domains in Codex?

Run `npx skills add PINA-org/PINA --skill define-domains -a codex`. Or copy the skill folder (.opencode/skills/define-domains in PINA-org/PINA) into .agents/skills/define-domains in your project. Codex loads it when a task matches its description.

Can I use Define Domains 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 PINA-org/PINA --skill define-domains -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/define-domains, .gemini/skills/define-domains, .github/skills/define-domains and .opencode/skills/define-domains in your project.

What does Define Domains need to run?

SKILL.md names no scripts, command-line tools or credentials: Define Domains is instructions for the agent only. Our summary lists: Python 3. Compatibility (from SKILL.md): opencode, codex, claude.

Does Define Domains 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 Define Domains 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 Define Domains use?

Define Domains is published under the MIT licence (declared in SKILL.md). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Define Domains use?

About 1.1k tokens (SKILL.md is roughly 4.3k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Define Domains?

Skills that share tags, products or a category with Define Domains: Add Uint Support (pytorch/pytorch, 104k stars), Segment Anything Model Guide (Orchestra-Research/AI-Research-SKILLs, 13k stars), Add Op (onnx/onnx, 22k stars) and CLIP Image-Text Matching (Orchestra-Research/AI-Research-SKILLs, 13k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Define Domains?

PINA-org (a GitHub organization) maintains it in PINA-org/PINA, which has 798 GitHub stars. The repository holds 10 skills in this directory. The repository was last updated on October 6, 2026.

Source: PINA-org/PINA on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Install Define Domains

Facts

At a glance

What it does

When your agent uses it

Example prompts

Requirements

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Compatibility

Context cost

Safety

SKILL.md

Define Domains for a PINA Problem

Step 1 — Create domains

Domain types available

Set operations on domains

Step 2 — Domain methods for problem setup

partial() — extract boundary

update() — combine domains (space + time)

Step 3 — Discretise domains (sampling)

Checklist

Files

Compare with similar skills

Similar skills

More from PINA-org/PINA

Related

Questions about Define Domains

`partial()` — extract boundary

`update()` — combine domains (space + time)