Circuit-Controlled Quality Filters

This mod allows you to set generic quality filters (no specific item selected) on inserters and splitters using circuits.

TLDR how to use:

Open an inserter or splitter
Enable "Set filters with quality signals"
Send quality + (optional) comparator + (optional) item signals on the connected circuit network.

longer boring description:

When opening an inserter or splitter interface you will see a new option: "Set filters with quality signals".

Setting this option will allow the entity to read quality signals from connected circuit networks and set its filters to match. This mod adds quality signals to the Signals tab for convenience, but you can also use the ones found in the Unsorted tab.

Comparator signals are also supported (>, <, =, ≥, ≤, ≠). For example, if you want to set the filter for qualities greater than rare, you can send both the "Rare" and "Greater than" signals. If no comparator signal is present the filter will default to "=". If multiple comparator signals are present, the highest-value one wins.

You can also set filters for specific items (instead of generic quality-only filters). If multiple quality and/or item signals are sent, the mod creates a filter for each quality × item combination, ordered by highest quality tier and highest item signal value (limited by available filter slots).

Other Notes

This mod should automatically support qualities added by other mods.
Currently inserters and splitters are supported. Additional entity types may be added later.
This is a beta release, expect to run into bugs and backup your save before installing/updating.

Known Issues/Limitations:

The vanilla circuit-controlled "Set filters" option doesn't support generic quality filters, so it is disabled while this mod's setting is active. When "Set filters with quality signals" is enabled, this mod takes control of the filter settings ("Use filters" ON, "Whitelist", "Set filters" OFF).
Removing an entity with "Set filters with quality signals" enabled then restoring it with the Undo action does not keep its setting.
Some modded entities have the "Set filters with quality signals" option but don't currently function