The exact path from a built dist/ to a live listing — tick each item and watch the
progress fill. Then see how the capstone wires every part of the series together.
Every box maps to a part of this series — that's a complete, shippable extension.
Toggle the ruler, pick color & height. Reads/writes storage.
Registers the command & context menu, relays toggle to the active tab.
Draws the ruler overlay (Shadow DOM), follows the cursor.
Advanced settings: opacity, presets, keyboard shortcut hint.
Single source of truth; every context reacts live.
Ctrl+Shift+R toggles; badge shows on/off state.