chrome-extension

chrome-extension is a skill for Claude Code from samber/cc-skills. It costs 143 tokens per session (3,916 once invoked), scanned A, original, MIT.

A development guide for Chrome browser extensions using Manifest V3, the current extension format. It covers extension configuration, background code, page-injected code, communication, storage, and user-interface surfaces.

In plain words
What is it for?
Use it when building, changing, debugging, or publishing a Chrome extension. It covers manifests, service workers, content scripts, messaging, popups, side panels, storage, network rules, and related extension features.
Why use it?
Chrome extensions run in several separate parts, such as a popup, background service worker, and code added to web pages. The guide helps choose how those parts should be connected and managed.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: names the AskUserQuestion tool; mentions Claude Code; mentions Codex.

Part of the cc-skills plugin — 21 skills shipped together

Good fit Use it when building, changing, debugging, or publishing a Chrome extension. It covers manifests, service workers, content scripts, messaging, popups, side panels, storage, network rules, and related extension features.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/samber/cc-skills/chrome-extension
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add samber/cc-skills --skill chrome-extension
Clone the repo
git clone --depth 1 https://github.com/samber/cc-skills

Made for: Claude Code.

Or install cc-skills, the plugin that ships this one along with the rest of its 21 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for chrome-extension

README.md
[![agentmods](https://agentmods.dev/badge/skills/samber/cc-skills/chrome-extension/github.svg)](https://agentmods.dev/skills/samber/cc-skills/chrome-extension)
Your own site
<a href="https://agentmods.dev/skills/samber/cc-skills/chrome-extension"><img src="https://agentmods.dev/badge/skills/samber/cc-skills/chrome-extension/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for chrome-extension

Your own site · 80×15
<a href="https://agentmods.dev/skills/samber/cc-skills/chrome-extension"><img src="https://agentmods.dev/badge/skills/samber/cc-skills/chrome-extension.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 143 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,916 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • Socket pass 11 Apr 2026
  • Snyk warn 11 Apr 2026
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00143 $0.03916
Opus 5 $0.00072 $0.01958
Sonnet 5 $0.00029 $0.00783
Haiku 4.5 $0.00014 $0.00392

Measured 4d ago against content hash 1465c8c9fc7a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

chrome-extension scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

const res = await fetch(msg.url);
Origin

Copies of this mod

1 near-identical copy found in the catalogue:

skills/chrome-extension/SKILL.md · 341 lines

How it starts

The opening of the file, as written. The whole thing — 341 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Chrome Extension Development (Manifest V3)

This skill covers everything needed to build, debug, and publish Chrome extensions with MV3. It is organized as a routing document: read this file first to understand the architecture and decision points, then load the relevant reference file for implementation details.

Reference files

Read only the reference files relevant to the current task. Each file is self-contained.

File When to read
references/manifest-v3.md Setting up or modifying manifest.json, configuring icons, versioning
references/service-worker.md Background logic, lifecycle, state persistence, alarms, events
references/content-scripts.md Injecting code into pages, isolated/main world, dynamic injection, SPA handling, orphaning
references/messaging-rpc.md Communication between any contexts, typed protocols, RPC layer, async handler patterns
references/ui-surfaces.md Popup, options page, side panel, context menus, commands, notifications, omnibox, devtools panel
references/storage.md chrome.storage (local/sync/session), quotas, reactive patterns, framework hooks
references/network-csp.md HTTP requests from content scripts, CSP bypass relay, declarativeNetRequest, offscreen docs, CORS
references/permissions.md Required/optional permissions, host permissions, activeTab, runtime request flow
references/web-accessible-resources.md Exposing extension files to web pages, security implications
references/typescript-build.md TypeScript setup, project structure, build tools comparison, bundling
references/publishing.md Chrome Web Store submission, review process, rejection reasons, updates, privacy policy
references/execution-contexts.md Communication flow diagrams, per-context capabilities/limits, choosing the right messaging method
references/debugging-mistakes.md DevTools for extensions, testing SW termination, common gotchas, error patterns

Read the full file on GitHub · 341 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 4d ago Changed · +6 tokens per session 1465c8c9fc7a
  2. 10d ago First seen · 341 lines · 137 tokens per session scan A 9c4e156b5eba

Subscribe to this mod's changes

chrome-extension is a skill published in the GitHub repository samber/cc-skills (207 stars, last pushed 2d ago), licensed MIT. It adds 143 tokens to every session and 3,916 once invoked, about $0.0007 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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