Agent skill

Phoenix Contexts

by oliver-kriska in oliver-kriska/claude-elixir-phoenix

Phoenix context design — creating/splitting contexts, Scope (1.8+), Ecto.Multi, PubSub, routers, plugs, controllers.

MITAuto-check passedAI & LLM Engineering

Install Phoenix Contexts

skills CLI

$ npx skills add oliver-kriska/claude-elixir-phoenix --skill phoenix-contexts -a claude-code

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

GitHub CLI

$ gh skill install oliver-kriska/claude-elixir-phoenix phoenix-contexts --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/oliver-kriska/claude-elixir-phoenix.git skills-src && mkdir -p .claude/skills && cp -r skills-src/targets/pi/skills/phoenix-contexts .claude/skills/phoenix-contexts && 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 "phoenix-contexts" agent skill from https://github.com/oliver-kriska/claude-elixir-phoenix/tree/main/targets/pi/skills/phoenix-contexts into .claude/skills/phoenix-contexts/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "phoenix-contexts", 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/oliver-kriska/claude-elixir-phoenix/tree/main/targets/pi/skills/phoenix-contexts

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 oliver-kriska/claude-elixir-phoenix --skill phoenix-contexts -a codex

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

GitHub CLI

$ gh skill install oliver-kriska/claude-elixir-phoenix phoenix-contexts --agent codex

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

Manual copy

$ git clone --depth 1 https://github.com/oliver-kriska/claude-elixir-phoenix.git skills-src && mkdir -p .agents/skills && cp -r skills-src/targets/pi/skills/phoenix-contexts .agents/skills/phoenix-contexts && 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 "phoenix-contexts" agent skill from https://github.com/oliver-kriska/claude-elixir-phoenix/tree/main/targets/pi/skills/phoenix-contexts into .agents/skills/phoenix-contexts/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "phoenix-contexts", 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 oliver-kriska/claude-elixir-phoenix --skill phoenix-contexts -a cursor

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

GitHub CLI

$ gh skill install oliver-kriska/claude-elixir-phoenix phoenix-contexts --agent cursor

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

Manual copy

$ git clone --depth 1 https://github.com/oliver-kriska/claude-elixir-phoenix.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/targets/pi/skills/phoenix-contexts .cursor/skills/phoenix-contexts && 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 "phoenix-contexts" agent skill from https://github.com/oliver-kriska/claude-elixir-phoenix/tree/main/targets/pi/skills/phoenix-contexts into .cursor/skills/phoenix-contexts/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "phoenix-contexts", 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/oliver-kriska/claude-elixir-phoenix.git --path targets/pi/skills/phoenix-contexts

--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 oliver-kriska/claude-elixir-phoenix --skill phoenix-contexts -a gemini-cli

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

GitHub CLI

$ gh skill install oliver-kriska/claude-elixir-phoenix phoenix-contexts --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/oliver-kriska/claude-elixir-phoenix.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/targets/pi/skills/phoenix-contexts .gemini/skills/phoenix-contexts && 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 "phoenix-contexts" agent skill from https://github.com/oliver-kriska/claude-elixir-phoenix/tree/main/targets/pi/skills/phoenix-contexts into .gemini/skills/phoenix-contexts/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "phoenix-contexts", 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 oliver-kriska/claude-elixir-phoenix phoenix-contexts

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 oliver-kriska/claude-elixir-phoenix --skill phoenix-contexts -a github-copilot

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

Manual copy

$ git clone --depth 1 https://github.com/oliver-kriska/claude-elixir-phoenix.git skills-src && mkdir -p .github/skills && cp -r skills-src/targets/pi/skills/phoenix-contexts .github/skills/phoenix-contexts && 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 "phoenix-contexts" agent skill from https://github.com/oliver-kriska/claude-elixir-phoenix/tree/main/targets/pi/skills/phoenix-contexts into .github/skills/phoenix-contexts/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "phoenix-contexts", 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 oliver-kriska/claude-elixir-phoenix --skill phoenix-contexts -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 oliver-kriska/claude-elixir-phoenix phoenix-contexts --agent opencode

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

Manual copy

$ git clone --depth 1 https://github.com/oliver-kriska/claude-elixir-phoenix.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/targets/pi/skills/phoenix-contexts .opencode/skills/phoenix-contexts && 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 "phoenix-contexts" agent skill from https://github.com/oliver-kriska/claude-elixir-phoenix/tree/main/targets/pi/skills/phoenix-contexts into .opencode/skills/phoenix-contexts/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "phoenix-contexts", 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: phoenix-contexts
GitHub stars: 565
Token cost: ~841 tokens
SKILL.md length: 251 words
Files: 6 (incl. references)
Skills in repo: 111
Repo updated: Oct 5, 2026
First seen: Oct 7, 2026
Licence: MIT

At a glance

Phoenix context design — creating/splitting contexts, Scope (1.8+), Ecto.Multi, PubSub, routers, plugs, controllers.

Works in 4 steps: CONTEXTS OWN THEIR DATA — Never query… → SCOPES ARE MANDATORY (Phoenix 1.8+) —… → THIN CONTROLLERS/LIVEVIEWS — Controllers… → …
Editing contexts
SKILL.md covers Iron Laws — Never Violate These, Context Structure, Phoenix 1.8+ Scopes (CRITICAL) and Quick Decisions, plus 3 more sections
Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Phoenix Contexts is an agent skill from oliver-kriska/claude-elixir-phoenix. Phoenix context design — creating/splitting contexts, Scope (1.8+), Ecto.Multi, PubSub, routers, plugs, controllers. Use when editing contexts, routers, or designing boundaries.

Its SKILL.md is about 840 tokens, which your agent loads only when the skill is triggered. The skill folder holds 6 other files, including reference files (for example `references/context-patterns.md`, `references/json-api-patterns.md` and `references/plug-patterns.md`).

It sits in AI & LLM Engineering, covering LLM observability and Event-driven systems. The repository describes itself as: Claude Code plugin for Elixir/Phoenix/LiveView — 26 specialist agents, Iron Laws enforcement, and Tidewave MCP integration. Plan features with parallel research agents, execute… The licence is MIT.

When your agent uses it

Editing contexts
Designing boundaries

Example prompts

“/phoenix-contexts”

Workflow steps

4 steps, taken from the first numbered list in SKILL.md.

CONTEXTS OWN THEIR DATA — Never query another context's schema directly via Repo
SCOPES ARE MANDATORY (Phoenix 1.8+) — Every context function MUST accept scope as first parameter
THIN CONTROLLERS/LIVEVIEWS — Controllers translate HTTP, business logic stays in contexts
NO SIDE EFFECTS IN SCHEMAS — Use Ecto.Multi for transactions with side effects

What it can do on your machine

Read from SKILL.md and the folder at commit 9767a82. 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 elixir).
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

Phoenix Contexts loads about 841 tokens when it runs, and up to ~7k if it reads all its reference files. Until then it costs about 49 tokens; SKILL.md has 251 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~49
When it runs · the whole SKILL.md, loaded when a task matches: ~841
With references · SKILL.md plus every file in references/, read only if the agent opens them: ~7k

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 oliver-kriska/claude-elixir-phoenix at commit 9767a82, republished under its MIT licence (© oliver-kriska). 251 words, ~841 tokens.

Download SKILL.mdSave it as .claude/skills/phoenix-contexts/SKILL.md (or your agent's skills folder). This skill also uses 5 other files; get the full folder from GitHub.

name: phoenix-contexts
description: Phoenix context design — creating/splitting contexts, Scope (1.8+), Ecto.Multi, PubSub, routers, plugs, controllers. Use when editing contexts, routers, or designing boundaries.

Phoenix Contexts Reference

Ash projects: Ash.Domain replaces Phoenix contexts for data access — use the ash-framework skill. Context boundary and PubSub patterns still apply.

Reference for designing and implementing Phoenix contexts (bounded contexts).

Iron Laws — Never Violate These

CONTEXTS OWN THEIR DATA — Never query another context's schema directly via Repo
SCOPES ARE MANDATORY (Phoenix 1.8+) — Every context function MUST accept scope as first parameter
THIN CONTROLLERS/LIVEVIEWS — Controllers translate HTTP, business logic stays in contexts
NO SIDE EFFECTS IN SCHEMAS — Use Ecto.Multi for transactions with side effects

Context Structure

lib/my_app/
├── accounts/           # Context directory
│   ├── user.ex         # Schema
│   ├── scope.ex        # Scope struct (Phoenix 1.8+)
├── accounts.ex         # Context module (public API)

Phoenix 1.8+ Scopes (CRITICAL)

Context functions take the scope as their first parameter, so queries are filtered to the caller:

elixir

def list_posts(%Scope{} = scope) do
  from(p in Post, where: p.user_id == ^scope.user.id)
  |> Repo.all()
end

def create_post(%Scope{} = scope, attrs) do
  %Post{user_id: scope.user.id}
  |> Post.changeset(attrs)
  |> Repo.insert()
  |> broadcast(scope, :created)
end

Quick Decisions

When to SPLIT contexts?

Module exceeds ~400 lines
Functions don't share domain language
Could theoretically be a separate microservice
Team member could own it independently

When to KEEP together?

Resources share vocabulary and domain concepts
Functions frequently operate on same data together
Splitting would create excessive cross-context calls

Cross-Context References

elixir

# ✅ Reference by ID, convert at boundary
def create_order(%Scope{} = scope, user_id, product_ids) do
  with {:ok, user} <- Accounts.fetch_user(scope, user_id) do
    do_create_order(scope, user.id, product_ids)
  end
end

# ❌ Reaching into other context's internals
alias MyApp.Accounts.User  # Don't do this
Repo.all(from o in Order, join: u in User, ...)  # Don't query other schemas

Anti-patterns

Wrong	Right
Service objects (`UserCreationService`)	Context functions (`Accounts.create_user/2`)
Repository pattern wrapping Repo	Repo IS the repository
Direct Repo calls in controllers	Delegate to context
Schema callbacks with side effects	Use Ecto.Multi

Version Notes

Phoenix 1.8+: Uses built-in %Scope{} struct for authorization context
Phoenix 1.7: Requires manual authorization context (see references/scopes-auth.md "Pre-Scopes Patterns")

References

For detailed patterns, see:

references/context-patterns.md - Full context module, PubSub, Multi, cross-boundary
references/scopes-auth.md - Scope struct, multi-tenant, authorization, plugs
references/routing-patterns.md - Verified routes, pipelines, API auth
references/plug-patterns.md - Function/module plugs, placement, guards
references/json-api-patterns.md - JSON controllers, FallbackController, API auth

Files

SKILL.md and 5 other files (references) in targets/pi/skills/phoenix-contexts of oliver-kriska/claude-elixir-phoenix.

SKILL.md
references/context-patterns.md
references/json-api-patterns.md
references/plug-patterns.md
references/routing-patterns.md
references/scopes-auth.md

Open the folder on GitHubat commit 9767a82

Compare with similar skills

Phoenix Contexts 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.

Phoenix Contexts compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Phoenix Contexts this skilloliver-kriska/claude-elixir-phoenix	565	—	~841	Automated safety check: Pass	MIT	4 days ago
Phoenixericrisco/rsc-harness	174	—	~2.9k	Automated safety check: Notes	MIT	2 days ago
Phoenix Pubsub Patternsj-morgan6/elixir-phoenix-guide	166	—	~1.8k	Automated safety check: Pass	MIT	3 mo ago
Elixir Expertpass-agent/loomkin	181	1 repos	~796	Automated safety check: Pass	MIT	4 mo ago
Hex Docs Searchbradleygolden/claude-marketplace-elixir	176	—	~4.1k	Automated safety check: Notes	MIT	9 mo ago
Absinthe SubscriptionsTheBushidoCollective/han	198	—	~875	Automated safety check: Pass	Custom licence	1 mo ago

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Questions about Phoenix Contexts

What does Phoenix Contexts do?

Phoenix context design — creating/splitting contexts, Scope (1.8+), Ecto.Multi, PubSub, routers, plugs, controllers. Phoenix Contexts is an agent skill from oliver-kriska/claude-elixir-phoenix.Multi, PubSub, routers, plugs, controllers.

When should I use Phoenix Contexts?

Phoenix Contexts fits situations like: editing contexts; designing boundaries.

How do I install Phoenix Contexts in Claude Code?

Run `npx skills add oliver-kriska/claude-elixir-phoenix --skill phoenix-contexts -a claude-code`. Or copy the skill folder (targets/pi/skills/phoenix-contexts in oliver-kriska/claude-elixir-phoenix) into .claude/skills/phoenix-contexts in your project. Claude Code loads it when a task matches its description.

How do I install Phoenix Contexts in Codex?

Run `npx skills add oliver-kriska/claude-elixir-phoenix --skill phoenix-contexts -a codex`. Or copy the skill folder (targets/pi/skills/phoenix-contexts in oliver-kriska/claude-elixir-phoenix) into .agents/skills/phoenix-contexts in your project. Codex loads it when a task matches its description.

Can I use Phoenix Contexts 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 oliver-kriska/claude-elixir-phoenix --skill phoenix-contexts -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/phoenix-contexts, .gemini/skills/phoenix-contexts, .github/skills/phoenix-contexts and .opencode/skills/phoenix-contexts in your project.

What does Phoenix Contexts need to run?

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

Does Phoenix Contexts 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 Phoenix Contexts 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 Phoenix Contexts use?

Phoenix Contexts is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Phoenix Contexts use?

About 841 tokens (SKILL.md is roughly 3.4k 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 6.2k tokens, read only when the agent opens those files.

What are the alternatives to Phoenix Contexts?

Skills that share tags, products or a category with Phoenix Contexts: Phoenix (ericrisco/rsc-harness, 174 stars), Phoenix Pubsub Patterns (j-morgan6/elixir-phoenix-guide, 166 stars), Elixir Expert (pass-agent/loomkin, 181 stars) and Hex Docs Search (bradleygolden/claude-marketplace-elixir, 176 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Phoenix Contexts?

oliver-kriska (a GitHub user) maintains it in oliver-kriska/claude-elixir-phoenix, which has 565 GitHub stars. The repository holds 111 skills in this directory. The repository was last updated on October 5, 2026.

Source: oliver-kriska/claude-elixir-phoenix on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Install Phoenix Contexts

Facts

At a glance

What it does

When your agent uses it

Example prompts

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Phoenix Contexts Reference

Iron Laws — Never Violate These

Context Structure

Phoenix 1.8+ Scopes (CRITICAL)

Quick Decisions

When to SPLIT contexts?

When to KEEP together?

Cross-Context References

Anti-patterns

Version Notes

References

Files

Compare with similar skills

Similar skills

More from oliver-kriska/claude-elixir-phoenix

Related

Questions about Phoenix Contexts