manifest.json

{
  "manifest_version": 3,
  "name": "GitHub HTML Attachment Preview",
  "version": "0.1.0",
  "description": "Preview .html/.htm attachments in GitHub PR/Issue comments in an isolated sandbox, without downloading.",
  "permissions": ["storage", "tabs"],
  "host_permissions": [
    "https://github.com/*",
    "https://*.githubusercontent.com/*"
  ],
  "background": {
    "service_worker": "src/background.ts",
    "type": "module"
  },
  "content_scripts": [
    {
      "matches": [
        "https://github.com/*/*/pull/*",
        "https://github.com/*/*/issues/*"
      ],
      "js": ["src/content.ts"],
      "run_at": "document_idle"
    }
  ],
  "sandbox": {
    "pages": ["src/sandbox.html"]
  },
  "content_security_policy": {
    "sandbox": "sandbox allow-scripts; default-src 'none'; script-src 'self' 'unsafe-inline'; style-src 'unsafe-inline'; img-src data: blob:; font-src data:; media-src data: blob:; connect-src 'none'; frame-src 'none'; child-src 'none'; object-src 'none'; base-uri 'none'; form-action 'none';"
  }
}