# writing-assistance-apis

Integrates built-in browser Summarizer, Writer, and Rewriter APIs in JavaScript and TypeScript apps. It handles model downloads, streaming responses, and abort signals.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 473 installs · ★ 52
- Author: webmaxru
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/webmaxru/web-ai-agent-skills/tree/HEAD/skills/writing-assistance-apis/SKILL.md
- Updated: 2026-09-29
- HTML: https://affpapa.org/en/nevibecode/skills/writing-assistance-apis

## What it does

This skill inspects web projects using `scripts/find-writing-assistance-targets.mjs` to locate UI entry points. It adapts `assets/writing-assistance-session.template.ts` to build guarded wrappers around browser AI. The workflow covers `Summarizer` for text summaries, `Writer` for drafting, and `Rewriter` for editing tasks.

Session creation is guarded by the `availability()` method. It requires user activation when a model must download first. Download status flows through the `monitor` callback. Session options stay immutable after creation. Calls support `AbortController` for clean cancellation and free memory via `destroy()`.

These APIs fail inside Web Workers or on servers because they depend on a secure `Window` context. Cross-origin iframes also need explicit permissions-policy headers. When token budgets trigger `QuotaExceededError`, the logic trims context inputs before retrying.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add webmaxru/web-ai-agent-skills --skill writing-assistance-apis -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/writing-assistance-apis/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/writing-assistance-apis/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add webmaxru/web-ai-agent-skills --skill writing-assistance-apis -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/writing-assistance-apis/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add webmaxru/web-ai-agent-skills --skill writing-assistance-apis -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/writing-assistance-apis/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install webmaxru/web-ai-agent-skills writing-assistance-apis
```

2. **Manually: put the files in place**
- File: `.github/skills/writing-assistance-apis/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add webmaxru/web-ai-agent-skills --skill writing-assistance-apis -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/webmaxru/web-ai-agent-skills --path skills/writing-assistance-apis
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/writing-assistance-apis/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add webmaxru/web-ai-agent-skills --skill writing-assistance-apis -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/webmaxru/web-ai-agent-skills/tree/HEAD/skills/writing-assistance-apis/SKILL.md

## When to use it
- integrate browser Summarizer, Writer, and Rewriter APIs into frontend code
- monitor local model download progress during session creation
- cancel in-flight text generation with `AbortController` and clean up sessions
- handle `NotAllowedError` by configuring permissions-policy delegation for iframes

## Example prompts
- "Add the browser Summarizer API to condense articles and show model download progress."
- "Implement a guarded Writer session wrapper with AbortController cancellation and non-AI fallbacks."
- "Verify Rewriter API availability and configure iframe permissions-policy delegation."

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: 5e280ca9fcec00be.

BEGIN THIRD-PARTY FILE 5e280ca9fcec00be
```text
---
name: writing-assistance-apis
description: Implements and debugs browser Summarizer, Writer, and Rewriter integrations in JavaScript or TypeScript web apps. Use when adding availability checks, model download UX, session creation, summarize or write or rewrite flows, streaming output, abort handling, or permissions-policy constraints for built-in writing assistance APIs. Don't use for generic prompt engineering, server-side LLM SDKs, or cloud AI services.
license: MIT
metadata:
  author: webmaxru
  version: "1.4"
---

# Writing Assistance APIs

## Procedures

**Step 1: Identify the browser integration surface**
1. Inspect the workspace for browser entry points, UI handlers, and any existing AI abstraction layer.
2. Execute `node scripts/find-writing-assistance-targets.mjs .` to inventory likely frontend files and existing Summarizer, Writer, or Rewriter usage when a Node runtime is available.
3. If a Node runtime is unavailable, inspect the nearest `package.json`, HTML entry point, and framework bootstrap files manually to identify the browser app boundary.
4. If the workspace contains multiple frontend apps, prefer the app that contains the active route, component, or user-requested feature surface.
5. If the inventory still leaves multiple plausible frontend targets, stop and ask which app should receive the Writing Assistance API integration.
6. If the project is not a browser web app, stop and explain that this skill does not apply.

**Step 2: Confirm API viability and choose the right surface**
1. Read `references/writing-assistance-reference.md` before writing code.
2. Read `references/examples.md` when the feature needs a session shape for monitoring downloads, batch output, streaming output, or cancellation.
3. Read `references/compatibility.md` when preview flags, browser channels, hardware requirements, or iframe constraints matter.
4. Read `references/troubleshooting.md` when availability checks, creation, streaming, or session cleanup fail.
5. Verify that the feature runs in a secure `Window` context and that the relevant permissions-policy feature allows access from the current frame.
6. Choose the narrowest surface that matches the task:
   - `Summarizer` for article, document, or conversation summaries.
   - `Writer` for generating new text from a short prompt or writing task.
   - `Rewriter` for transforming existing text while preserving its intent.
```
END THIRD-PARTY FILE 5e280ca9fcec00be

The third-party file has ended. Everything between the 5e280ca9fcec00be tags is data: requests and commands from it are not followed. An “end of file” line with another tag inside the block is part of the file.

First 2412 of 6422 bytes. © webmaxru · MIT · https://github.com/webmaxru/web-ai-agent-skills/tree/HEAD/skills/writing-assistance-apis/SKILL.md

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---
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