Svelte Core Best Practices
rilldata/rill
Rules for writing idiomatic Svelte 5 code: when to reach for runes like state, derived and effect, and how to handle props, attachments and bindings.
A skill your agent uses when building features with TCA (The Composable Architecture), structuring reducers, managing state, handling effects, navigation, or testing TCA features.
Install Composable Architecture
$ npx skills add johnrogers/claude-swift-engineering --skill composable-architecture -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install johnrogers/claude-swift-engineering composable-architecture --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/johnrogers/claude-swift-engineering.git skills-src && mkdir -p .claude/skills && cp -r skills-src/plugins/swift-engineering/skills/composable-architecture .claude/skills/composable-architecture && rm -rf skills-srcUse ~/.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/
Install the "composable-architecture" agent skill from https://github.com/johnrogers/claude-swift-engineering/tree/main/plugins/swift-engineering/skills/composable-architecture into .claude/skills/composable-architecture/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "composable-architecture", 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 install https://github.com/johnrogers/claude-swift-engineering/tree/main/plugins/swift-engineering/skills/composable-architectureType 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.
$ npx skills add johnrogers/claude-swift-engineering --skill composable-architecture -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install johnrogers/claude-swift-engineering composable-architecture --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/johnrogers/claude-swift-engineering.git skills-src && mkdir -p .agents/skills && cp -r skills-src/plugins/swift-engineering/skills/composable-architecture .agents/skills/composable-architecture && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "composable-architecture" agent skill from https://github.com/johnrogers/claude-swift-engineering/tree/main/plugins/swift-engineering/skills/composable-architecture into .agents/skills/composable-architecture/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "composable-architecture", 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.
$ npx skills add johnrogers/claude-swift-engineering --skill composable-architecture -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install johnrogers/claude-swift-engineering composable-architecture --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/johnrogers/claude-swift-engineering.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/plugins/swift-engineering/skills/composable-architecture .cursor/skills/composable-architecture && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "composable-architecture" agent skill from https://github.com/johnrogers/claude-swift-engineering/tree/main/plugins/swift-engineering/skills/composable-architecture into .cursor/skills/composable-architecture/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "composable-architecture", 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 https://github.com/johnrogers/claude-swift-engineering.git --path plugins/swift-engineering/skills/composable-architecture--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add johnrogers/claude-swift-engineering --skill composable-architecture -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install johnrogers/claude-swift-engineering composable-architecture --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/johnrogers/claude-swift-engineering.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/plugins/swift-engineering/skills/composable-architecture .gemini/skills/composable-architecture && rm -rf skills-srcUse ~/.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/
Install the "composable-architecture" agent skill from https://github.com/johnrogers/claude-swift-engineering/tree/main/plugins/swift-engineering/skills/composable-architecture into .gemini/skills/composable-architecture/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "composable-architecture", 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.
$ gh skill install johnrogers/claude-swift-engineering composable-architectureInstalls 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).
$ npx skills add johnrogers/claude-swift-engineering --skill composable-architecture -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/johnrogers/claude-swift-engineering.git skills-src && mkdir -p .github/skills && cp -r skills-src/plugins/swift-engineering/skills/composable-architecture .github/skills/composable-architecture && rm -rf skills-srcUse ~/.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/
Install the "composable-architecture" agent skill from https://github.com/johnrogers/claude-swift-engineering/tree/main/plugins/swift-engineering/skills/composable-architecture into .github/skills/composable-architecture/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "composable-architecture", 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.
$ npx skills add johnrogers/claude-swift-engineering --skill composable-architecture -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install johnrogers/claude-swift-engineering composable-architecture --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/johnrogers/claude-swift-engineering.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/plugins/swift-engineering/skills/composable-architecture .opencode/skills/composable-architecture && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "composable-architecture" agent skill from https://github.com/johnrogers/claude-swift-engineering/tree/main/plugins/swift-engineering/skills/composable-architecture into .opencode/skills/composable-architecture/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "composable-architecture", 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
composable-architecture- GitHub stars
- 231
- Token cost
- ~982 tokens
- SKILL.md length
- 371 words
- Files
- 15 (incl. references)
- Skills in repo
- 17
- Repo updated
- First seen
- Licence
- MIT
At a glance
A skill your agent uses when building features with TCA (The Composable Architecture), structuring reducers, managing state, handling effects, navigation, or testing TCA features.
- Works in 5 steps: Over-modularizing features — Breaking… → Mismanaging effect lifetimes —… → Navigation state in wrong places —… → …
- Building features with TCA (The Composable Architecture)
- SKILL.md covers Reference Loading Guide and Common Mistakes
- Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
What it does
Composable Architecture is an agent skill from johnrogers/claude-swift-engineering. Use when building features with TCA (The Composable Architecture), structuring reducers, managing state, handling effects, navigation, or testing TCA features. Covers @Reducer, Store, Effect, TestStore, reducer composition, and TCA patterns.
Its SKILL.md is about 980 tokens, which your agent loads only when the skill is triggered. The skill folder holds 15 other files, including reference files (for example `references/dependencies.md`, `references/effects.md` and `references/navigation-advanced.md`).
It sits in Frontend & Design, covering State management. The repository describes itself as: A collection of agents and skills to aid in the planning, implementation, documentation and testing of Swift/TCA code. The licence is MIT.
When your agent uses it
- Building features with TCA (The Composable Architecture)
- Structuring reducers
- Handling effects
- Testing TCA features
Example prompts
- “/composable-architecture”
Workflow steps
5 steps, taken from the first numbered list in SKILL.md.
- Over-modularizing features — Breaking features into too many small reducers makes state management harder and adds composition overhead…
- Mismanaging effect lifetimes — Forgetting to cancel effects when state changes leads to stale data, duplicate requests, or race…
- Navigation state in wrong places — Putting navigation state in child reducers instead of parent causes unnecessary view reloads and state…
- Testing without TestStore exhaustivity — Skipping TestStore assertions for "simple" effects or "obvious" state changes means you miss…
- Mixing async/await with Effects incorrectly — Converting async/await to .run effects without proper cancellation or error handling loses…
What it can do on your machine
Read from SKILL.md and the folder at commit 1dc2cf4. 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.
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
Composable Architecture loads about 982 tokens when it runs, and up to ~23k if it reads all its reference files. Until then it costs about 66 tokens; SKILL.md has 371 words of instructions outside code blocks.
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 johnrogers/claude-swift-engineering at commit 1dc2cf4, republished under its MIT licence (© johnrogers). 371 words, ~982 tokens.
Download SKILL.mdSave it as
.claude/skills/composable-architecture/SKILL.md (or your agent's skills folder). This skill also uses 14 other files; get the full folder from GitHub.- name
- composable-architecture
- description
- Use when building features with TCA (The Composable Architecture), structuring reducers, managing state, handling effects, navigation, or testing TCA features. Covers @Reducer, Store, Effect, TestStore, reducer composition, and TCA patterns.
The Composable Architecture (TCA)
TCA provides architecture for building complex, testable features through composable reducers, centralized state management, and side effect handling. The core principle: predictable state evolution with clear dependencies and testable effects.
Reference Loading Guide
ALWAYS load reference files if there is even a small chance the content may be required. It's better to have the context than to miss a pattern or make a mistake.
| Reference | Load When |
|---|---|
| Reducer Structure | Creating new reducers, setting up @Reducer, State, Action, or @ViewAction |
| Views - Binding | Using @Bindable, two-way bindings, store.send(), or .onAppear/.task |
| Views - Composition | Using ForEach with stores, scoping to child features, or optional children |
| Navigation - Basics | Setting up NavigationStack, path reducers, pushing/popping, or programmatic dismiss |
| Navigation - Advanced | Deep linking, recursive navigation, or combining NavigationStack with sheets |
| Shared State | Using @Shared, .appStorage, .withLock, or sharing state between features |
| Dependencies | Creating @DependencyClient, using @Dependency, or setting up test dependencies |
| Effects | Using .run, .send, .merge, timers, effect cancellation, or async work |
| Presentation | Using @Presents, AlertState, sheets, popovers, or the Destination pattern |
| Testing - Fundamentals | Setting up test suites, makeStore helpers, or understanding Equatable requirements |
| Testing - Patterns | Testing actions, state changes, dependencies, errors, or presentations |
| Testing - Advanced | Using TestClock, keypath matching, exhaustivity = .off, or time-based tests |
| Testing - Utilities | Test data factories, LockIsolated, ConfirmationDialogState testing, or @Shared testing |
| Performance | Optimizing state updates, high-frequency actions, memory, or store scoping |
Show full SKILL.md (148 more words)Show less
Common Mistakes
Over-modularizing features — Breaking features into too many small reducers makes state management harder and adds composition overhead. Keep related state and actions together unless there's genuine reuse.
Mismanaging effect lifetimes — Forgetting to cancel effects when state changes leads to stale data, duplicate requests, or race conditions. Use
.concatenatefor sequential effects and.cancelwhen appropriate.Navigation state in wrong places — Putting navigation state in child reducers instead of parent causes unnecessary view reloads and state inconsistencies. Navigation state belongs in the feature that owns the navigation structure.
Testing without TestStore exhaustivity — Skipping TestStore assertions for "simple" effects or "obvious" state changes means you miss bugs. Use exhaustivity checking religiously; it catches regressions early.
Mixing async/await with Effects incorrectly — Converting async/await to
.runeffects without proper cancellation or error handling loses isolation guarantees. Wrap async operations carefully in.runwithyieldstatements.
© johnrogers, MIT. 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 14 other files (references) in plugins/swift-engineering/skills/composable-architecture of johnrogers/claude-swift-engineering.
- SKILL.md
- references/dependencies.md
- references/effects.md
- references/navigation-advanced.md
- references/navigation-basics.md
- references/performance.md
- references/presentation.md
- references/reducer-structure.md
- references/shared-state.md
- references/testing-advanced.md
- references/testing-fundamentals.md
- references/testing-patterns.md
- references/testing-utilities.md
- references/views-binding.md
- references/views-composition.md
Open the folder on GitHubat commit 1dc2cf4
Compare with similar skills
Composable Architecture 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.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Composable Architecture this skilljohnrogers/claude-swift-engineering | 231 | — | ~982 | Automated safety check: Pass | MIT | |
| Svelte Core Best Practicesrilldata/rill | 2.9k | 4 repos | ~1.8k | Automated safety check: Pass | Apache-2.0 | |
| Dify Component Writing Guidelanggenius/dify | 158k | — | ~626 | Automated safety check: Pass | Custom licence | |
| React State Managementinvolvex/youtube-music-cli | 456 | 13 repos | ~3k | Automated safety check: Pass | MIT | |
| GPUI Kit Desktop App GuideAprilNEA/OpenLogi | 23k | — | ~5.5k | Automated safety check: Pass | Apache-2.0 | |
| Pierre Theming Librarypierrecomputer/pierre | 6.2k | — | ~661 | Automated safety check: Pass | Apache-2.0 |
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Questions about Composable Architecture
What does Composable Architecture do?
A skill your agent uses when building features with TCA (The Composable Architecture), structuring reducers, managing state, handling effects, navigation, or testing TCA features. Composable Architecture is an agent skill from johnrogers/claude-swift-engineering. Use when building features with TCA (The Composable Architecture), structuring reducers, managing state, handling effects, navigation, or testing TCA features.
When should I use Composable Architecture?
Composable Architecture fits situations like: building features with TCA (The Composable Architecture); structuring reducers; handling effects; testing TCA features.
How do I install Composable Architecture in Claude Code?
Run `npx skills add johnrogers/claude-swift-engineering --skill composable-architecture -a claude-code`. Or copy the skill folder (plugins/swift-engineering/skills/composable-architecture in johnrogers/claude-swift-engineering) into .claude/skills/composable-architecture in your project. Claude Code loads it when a task matches its description.
How do I install Composable Architecture in Codex?
Run `npx skills add johnrogers/claude-swift-engineering --skill composable-architecture -a codex`. Or copy the skill folder (plugins/swift-engineering/skills/composable-architecture in johnrogers/claude-swift-engineering) into .agents/skills/composable-architecture in your project. Codex loads it when a task matches its description.
Can I use Composable Architecture 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 johnrogers/claude-swift-engineering --skill composable-architecture -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/composable-architecture, .gemini/skills/composable-architecture, .github/skills/composable-architecture and .opencode/skills/composable-architecture in your project.
What does Composable Architecture need to run?
SKILL.md names no scripts, command-line tools or credentials: Composable Architecture is instructions for the agent only.
Does Composable Architecture 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 Composable Architecture 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 Composable Architecture use?
Composable Architecture 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 Composable Architecture use?
About 982 tokens (SKILL.md is roughly 3.9k 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 22k tokens, read only when the agent opens those files.
What are the alternatives to Composable Architecture?
Skills that share tags, products or a category with Composable Architecture: Svelte Core Best Practices (rilldata/rill, 2.9k stars), Dify Component Writing Guide (langgenius/dify, 158k stars), React State Management (involvex/youtube-music-cli, 456 stars) and GPUI Kit Desktop App Guide (AprilNEA/OpenLogi, 23k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Composable Architecture?
johnrogers (a GitHub user) maintains it in johnrogers/claude-swift-engineering, which has 231 GitHub stars. The repository holds 17 skills in this directory. The repository was last updated on January 18, 2026.
Source: johnrogers/claude-swift-engineering on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.