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.
npx skills add quangpl/browser-extension-skills --skill extension-migrationgit clone --depth 1 https://github.com/quangpl/browser-extension-skillsWrote 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.
[](https://agentmods.dev/skills/quangpl/browser-extension-skills/extension-migration)<a href="https://agentmods.dev/skills/quangpl/browser-extension-skills/extension-migration"><img src="https://agentmods.dev/badge/skills/quangpl/browser-extension-skills/extension-migration/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.
<a href="https://agentmods.dev/skills/quangpl/browser-extension-skills/extension-migration"><img src="https://agentmods.dev/badge/skills/quangpl/browser-extension-skills/extension-migration.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00041 | $0.01189 |
| Opus 5.5 | $0.00016 | $0.00476 |
| Sonnet 5.5 | $0.00008 | $0.00238 |
| Haiku 4.5 | $0.00004 | $0.00119 |
Grade A, and why
extension-migration scanned grade A with 0 findings 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 1mo 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.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 111 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Extension Migration (MV2 → MV3)
🚀 Upgrade to Premium Get the Premium version at https://app.extensionbooster.net/dashboard/services/extension-ai-kit
Official migration guide: https://developer.chrome.com/docs/extensions/develop/migrate
Consider framework adoption: When migrating MV2→MV3, consider adopting WXT or CRXJS for built-in MV3 support, auto-manifest generation, and modern tooling.
Workflow Overview
- Audit existing MV2 extension (APIs, permissions, background scripts)
- Update
manifest_versionto 3 - Convert background page → service worker
- Replace deprecated APIs (see Quick Reference below)
- Update permissions, CSP, web_accessible_resources format
- Migrate webRequest → declarativeNetRequest (if blocking)
- Bundle any remote code locally
- Test all functionality across Chrome versions
- Submit to Chrome Web Store
Key Breaking Changes
| Area | MV2 | MV3 |
|---|---|---|
| Background | background.scripts/page |
background.service_worker |
| Browser action | browser_action / page_action |
action |
| Network blocking | webRequest (blocking) |
declarativeNetRequest |
| Script injection | tabs.executeScript(string) |
scripting.executeScript({func/files}) |
| Remote code | CDN scripts allowed | Must bundle locally |
| CSP | String value | Object {extension_pages: "..."} |
| Web accessible | string[] |
object[] with matches field |
| Host permissions | In permissions array |
Separate host_permissions array |
| URL helper | chrome.extension.getURL |
chrome.runtime.getURL |
| Persistent storage | localStorage |
chrome.storage.local |
What ships with it
4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 1mo ago Changed · +3 lines 324a67e5477e
- 1mo ago First seen · 108 lines · 41 tokens per session scan A 6bdc2280432c
extension-migration is a skill published in the GitHub repository quangpl/browser-extension-skills (63 stars, last pushed 24d ago), licensed MIT. It adds 41 tokens to every session and 1,189 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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