Unpacked build of the extension. Download the zip, unpack it somewhere permanent, then open chrome://extensions/, turn on Developer mode, click "Load unpacked" and pick the unpacked folder.
Keep the folder where it is. Chrome loads an unpacked extension from that path on every start, so moving or deleting it disables the extension.
What is in this build
Downstream of dexterouslogic/super-simple-highlighter (GPL-3.0), via emersonding's Manifest V3 migration and selection toolbar.
Added here: saved selections are now found through a per-page index held in _local documents and maintained from PouchDB's changes feed, in place of reading the whole database on every page load. On a database of 20,000 saved selections across 400 pages, the two queries that run on every navigation went from 788 ms and 789 ms to 2 ms and 4 ms, and the page list went from 808 ms to 25 ms. The index stays out of backups and exports, and is rebuilt by itself if it is ever lost.
Also fixed: the About page logo, which had been broken since the project was reorganised into src/.
Verified by 20 unit tests and 41 end-to-end tests that drive the extension in a real Chromium.
Zip contents
manifest.json, src/, assets/, _locales/, plus LICENSE and README.md. Tests, docs and development configuration are not included.