Individual skill
chrome-extension
Use when building or shipping a Manifest V3 browser extension and hitting its quirks — service worker dying and losing state, permission warnings, a Chrome Web Store rejection, content-script/worker/popup messaging, or an MV2-to-V3 migration. NOT a generic web app (that is `nextjs`), NOT a desktop shell (that is `electron`).
skills/chrome-extension/SKILL.md
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- Last checked
- Nov 6, 2026
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- 561
- Repository last updated
- Nov 4, 2026
- License
- MIT
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- chrome-extension Declared skill tag
- manifest-v3 Declared skill tag
- browser-extension Declared skill tag
- service-worker Declared skill tag
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SKILL.mdcore · 11,043 bytesSKILL.mdcore · 11,043 bytesSKILL.mdcore · 11,043 bytesevals/README.mddoc · 754 bytesevals/cases.yamlasset · 2,791 bytesreferences/store-and-migration.mddoc · 5,004 bytesscripts/verify.shruns · 2,111 bytes
Read excerpt
# Chrome extension (Manifest V3)
An MV3 extension is **three isolated JavaScript contexts that never share memory and only talk via messages**:
1. **Service worker** (`background.service_worker`) — the logic and lifecycle brain. Ephemeral: Chrome kills it when idle and restarts it on the next event. It has no DOM and no `window`.
2. **Content scripts** — run inside a web page, can read/write that page's DOM, live in an isolated JS world by default. No access to most `chrome.*` APIs except messaging and `storage`.
3. **UI surfaces** — popup (`action.default_popup`), options page, side panel. Normal web pages that load and unload as the user opens/closes them.
Internalize that picture first. Most extension bugs are someone treating one of these as if it shared state with another. They do not. The wire between them is `chrome.runtime` messaging and `chrome.storage`.
Manifest V3 is the only version the Chrome Web Store accepts; MV2 phase-out began June 2024 and is still rolling out. Build MV3 from the start.
## Pick a skeleton
