chrome-extension-mv3
Skill2 starsChanged 41 days agoMITView on GitHub
Manifest V3 Chrome extension development — service worker lifecycle, message passing (popup ↔ service worker ↔ content script), content script injection, and host_permissions fetch patterns. Use when editing manifest.json, background/service worker, popup, content scripts, chrome.runtime.sendMessage, or extension permissions.
In this repository49 other files it gives its agents.
- AGENTS.mdAGENTS.md
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The file
We split this skill into the rules it gives an agent
5 rules. About 0 are common, 0 are distinctive, and 5 are very specific to this project.
≈0
Common · estimate
Many files like this have a rule of this kind.
≈0
Distinctive · estimate
This author's own choices. Worth a look.
5
Very specific
Tied to their project's names, files or tools. Probably skip.
- Common
- Distinctive
- Very specific
- Very specific: line 22
Read the project's overlay or TECH_DETAILS*.md / AGENTS.md for exact filenames.
- Very specific: line 28
Service worker state: no globals — use chrome.storage / IndexedDB.
- Very specific: line 30
Manifest assets: only reference icons/paths that exist.
- Very specific: line 51
Search guides: npx -y modern-web-guidance@latest search "…" — do not copy the full guide tree into your repo.
- Very specific: line 55
If the repo ships a file map, message action table, or domain-specific fetch rules, load it from …
≈ “Common” is an estimate: at least 1 in 5 of the 350,495 skill files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.
Files
Chrome extension (Manifest V3)
Vanilla MV3 patterns for extensions without a bundler/framework in the active path. Pair with project overlays for app-specific file maps and message action names (examples/overlays/).
Architecture (typical three-layer)
| Layer | Runs in | Typical files | Responsibilities |
| Popup / UI | Extension page | popup.html, popup.js | User input, display, orchestrates messages to SW |
| Service worker | Background (ephemeral) | background.js, event.js, sw.js | Network fetch needing host_permissions, relay, durable cache |
| Content script | Isolated world on web pages | content.js | DOM/selection access, page context, no extension APIs for cross-origin fetch |
Read the project's overlay or TECH_DETAILS*.md / AGENTS.md for exact filenames.
Rules for changes
- Async
sendResponse: async work in message handlers → IIFE +return true, or return a Promise (Chrome 99+ only). See references/message-passing.md. - Cross-origin fetch: pages and popups cannot bypass host restrictions — fetch from the service worker when
host_permissionsare declared; never duplicate fetch in popup if SW already owns that origin. - Service worker state: no globals — use
chrome.storage/ IndexedDB; listeners registered at top level. See references/service-worker.md. - Selection: cache selection in the content script; popup open often clears live
window.getSelection(). - Manifest assets: only reference icons/paths that exist; MV3 requires
service_workernotbackground.scripts. - Content scripts: isolated world — use messaging for SW coordination. See references/content-scripts.md.
Message passing checklist
- [ ] Action/type names match across popup, SW, and content script
- [ ] Async handlers: return true (IIFE) or return Promise — not both
- [ ] tabs.sendMessage: handle "receiving end does not exist" (script not injected yet)
- [ ] Only one listener should sendResponse per message typeMV3 references (this skill)
- message-passing.md — popup ↔ service worker ↔ content script
- service-worker.md — lifecycle, storage, alarms
- content-scripts.md — injection, DOM, messaging
Upstream (do not vendor)
- GoogleChrome/modern-web-guidance — chrome-extensions
- Search guides:
npx -y modern-web-guidance@latest search "…"— do not copy the full guide tree into your repo.
Project overlay
If the repo ships a file map, message action table, or domain-specific fetch rules, load it from .agents/skills/chrome-extension-mv3/references/ or examples/overlays/sorkalam-mv3-extension.md (Sorkalam dictionary extension).
Example provenance: sorkalam-extension.
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