Per-layer styling, picker toggle, resizable panel, dark-mode icon fix (#3)

* Add per-layer styling, picker toggle, panel resize, dark-mode icon fix

- Each theme now expands to its individual source layers; every layer has
  its own visibility checkbox, color picker, and opacity slider, with a
  theme master checkbox that reflects indeterminate state. State moves to
  a per-layer model (OvertureLayerState) and new setLayer*/setThemeExpanded
  methods drive the map sources/layers
- Add an "Inspect features on click" checkbox to enable/disable the picker
  at runtime (setInspect); inspect state is part of OvertureMapsState
- Make the panel width drag-resizable; the handle sits on the edge away
  from the anchored corner so it works at top-left and top-right alike
- Fix the toggle icon contrast in dark mode by raising the control
  background specificity above maplibre's default white control group

* Reorder themes and replace the plugin icon

- Reorder the theme panel to Addresses, Places, Transportation, Buildings,
  Divisions, Base (top to bottom). Layers are inserted with a beforeId so
  the first listed theme always draws on top of the map regardless of the
  order layers are toggled, keeping detail themes above the base background.
- Replace the stacked-layers toggle icon with a folded-map icon to avoid
  visual confusion with other layer controls.

* Use overlapping-circles icon for the plugin toggle

Replace the folded-map icon (which collided with other plugins) with three
overlapping ring outlines echoing the Overture Maps brand motif. Distinct
from the default MapLibre layer, globe, and compass controls, with good
contrast in light and dark modes.

* Add a per-layer style editor button (color, size, opacity)

Replace the fixed per-layer color swatch with a style button that opens an
inline editor exposing the layer's color, size (circle radius for points,
line width for lines and polygon outlines), and opacity. Adds a `size`
field to the layer state, threads it through the spec builders, and adds
`setLayerSize` plus `sizePropertyForLayerType` / `defaultSizeForGeometry`
helpers. A small read-only color swatch stays on the collapsed row as a
preview.

* Address CodeRabbit review feedback

- Clarify the exported-types list in the README: ReleasesResponse is main
  entry only and OvertureMapsControlReactProps is React entry only, rather
  than implying every type is exported from both
- Add a :focus-visible outline to the per-layer color input so keyboard
  users get a visible focus ring

* Add per-layer GeoJSON export of features in the current view

Add a download button to each layer row that exports the features rendered
in the current map view to a GeoJSON file. The export is gated by a new
exportMinZoom option (default 12) so it only ever covers a small area, and
the button is disabled when the layer is hidden. Features are deduplicated
across tile boundaries. Adds public exportLayer and getRenderedLayerGeoJSON
methods and a transient panel notice for export feedback.

* Follow the system color scheme live in auto theme mode

In auto mode, resolve the color scheme from prefers-color-scheme and apply
it as an explicit ovt-theme-light/dark class, and subscribe to a matchMedia
listener so the panel, container, and newly created popups adapt live when
the OS theme changes (not just at load). The CSS media query remains as a
fallback.

* Address CodeRabbit review feedback

- Lowercase the SVG stroke keyword (currentColor -> currentcolor) for the
  style/export buttons to satisfy stylelint value-keyword-case
- Make the export notice an aria-live region (role=status, aria-live,
  aria-atomic) and hide it via a CSS :empty rule instead of display
  toggling so screen readers announce export feedback
- Coalesce exportMinZoom against the default in exportLayer so passing
  exportMinZoom: undefined cannot bypass the zoom gate
- Align the exportMinZoom README description with the feature list wording

Author: giswqs

README.md

@@ -11,8 +11,10 @@ A [MapLibre GL JS](https://maplibre.org/) plugin for visualizing [Overture Maps]
 
 - **All six Overture themes** - Addresses, base, buildings, divisions, places, and transportation, each loaded from the official Overture PMTiles distribution
 - **Dynamic releases** - Fetches the latest [Overture release list](https://labs.overturemaps.org/data/releases.json) at runtime, with a dropdown to switch releases and an option to pin one
-- **Theme controls** - Checkbox, color swatch, and opacity slider per theme
-- **Feature inspection** - Click any rendered Overture feature to see its properties in a popup (can be disabled)
+- **Per-layer styling** - Expand a theme to toggle each source layer individually; a style button opens an inline editor for the layer's color, size (point radius / line width), and opacity
+- **GeoJSON export** - A download button on each layer exports the features rendered in the current map view to a GeoJSON file. Gated by a minimum zoom (`exportMinZoom`) so exports stay limited to a small area
+- **Feature inspection** - Click any rendered Overture feature to see its properties in a popup; toggle the picker on or off from the panel
+- **Resizable panel** - Drag the panel edge to resize its width; the handle adapts to whichever corner the control sits in
 - **Dark and light mode** - The control UI follows `prefers-color-scheme` by default and can be forced light or dark
 - **Small-screen friendly** - The panel stays within the viewport and scrolls vertically when space is tight
 - **TypeScript Support** - Full TypeScript support with exported type definitions
@@ -135,6 +137,7 @@ The main control class implementing MapLibre's `IControl` interface.
 | `releasesUrl`   | `string`                      | Overture labs releases.json                   | Endpoint listing available releases                                       |
 | `tilesBaseUrl`  | `string`                      | Official Overture S3 tiles URL                | Base URL of the PMTiles distribution                                      |
 | `inspect`       | `boolean`                     | `true`                                        | Click a rendered feature to open a properties popup                       |
+| `exportMinZoom` | `number`                      | `12`                                          | Minimum zoom required to export a layer to GeoJSON (keeps exports limited to a small area)  |
 | `visibleThemes` | `OvertureTheme[]`             | `['buildings', 'transportation', 'places']`   | Themes that start visible                                                 |
 | `themeColors`   | `Partial<Record<OvertureTheme, string>>` | x-ray palette                       | Per-theme color overrides                                                 |
 | `themeOpacity`  | `Partial<Record<OvertureTheme, number>>` | `0.8`                               | Per-theme initial opacity (0..1)                                          |
@@ -144,8 +147,16 @@ The main control class implementing MapLibre's `IControl` interface.
 - `toggle()` / `expand()` / `collapse()` - Control the panel
 - `getState()` / `setState(state)` - Read or update the state
 - `setRelease(release)` - Switch the active Overture release
-- `setThemeVisible(theme, visible)` - Show or hide a theme
-- `setThemeOpacity(theme, opacity)` - Set a theme's opacity (0..1)
+- `setThemeVisible(theme, visible)` - Show or hide every layer of a theme
+- `setThemeOpacity(theme, opacity)` - Set the opacity of every layer of a theme (0..1)
+- `setThemeExpanded(theme, expanded)` - Expand or collapse a theme's layer list
+- `setLayerVisible(theme, sourceLayer, visible)` - Show or hide a single source layer
+- `setLayerOpacity(theme, sourceLayer, opacity)` - Set a single layer's opacity (0..1)
+- `setLayerColor(theme, sourceLayer, color)` - Set a single layer's color
+- `setLayerSize(theme, sourceLayer, size)` - Set a single layer's size (point radius / line width)
+- `setInspect(enabled)` - Enable or disable the feature inspection picker
+- `exportLayer(theme, sourceLayer)` - Download the layer's in-view features as GeoJSON (gated by `exportMinZoom`); returns the FeatureCollection or null
+- `getRenderedLayerGeoJSON(theme, sourceLayer)` - Get the layer's in-view features as a GeoJSON FeatureCollection without downloading
 - `refreshReleases()` - Re-fetch the release list
 - `on(event, handler)` / `off(event, handler)` - Manage event handlers
 - `getMap()` / `getContainer()` - Access the map and container
@@ -191,7 +202,9 @@ const {
 
 ### Exported Types
 
-`OvertureMapsControlOptions`, `OvertureMapsState`, `OvertureThemeState`, `OvertureMapsControlReactProps`, `OvertureMapsEvent`, `OvertureMapsEventHandler`, `OvertureTheme`, `OvertureGeometry`, `OvertureLayerDef`, `ThemeDefinition`, `ControlColorScheme`, and `ReleasesResponse` are exported from both entry points (React-specific types from `/react`).
+Exported from both entry points: `OvertureMapsControlOptions`, `OvertureMapsState`, `OvertureThemeState`, `OvertureLayerState`, `OvertureMapsEvent`, `OvertureMapsEventHandler`, `OvertureTheme`, `OvertureGeometry`, `OvertureLayerDef`, `ThemeDefinition`, and `ControlColorScheme`.
+
+Main entry only (`.`): `ReleasesResponse`. React entry only (`/react`): `OvertureMapsControlReactProps`.
 
 Helpers are also exported: `THEMES`, `THEME_IDS`, `buildLayerSpecs`, `layerIdsForTheme`, `sourceIdForTheme`, `tileUrlForTheme`, `fetchReleases`, `ensurePmtilesProtocol`, and more.
 

src/index.ts

@@ -9,10 +9,15 @@ export {
   THEMES,
   THEME_IDS,
   buildLayerSpecs,
+  buildSourceLayerSpecs,
   layerIdsForTheme,
+  layerIdsForSourceLayer,
   sourceIdForTheme,
   tileUrlForTheme,
   opacityPropertyForLayerType,
+  colorPropertyForLayerType,
+  sizePropertyForLayerType,
+  defaultSizeForGeometry,
 } from './lib/core/themes';
 
 // Releases helpers
@@ -31,6 +36,7 @@ export type {
   OvertureMapsControlOptions,
   OvertureMapsState,
   OvertureThemeState,
+  OvertureLayerState,
   OvertureMapsEvent,
   OvertureMapsEventHandler,
   ControlColorScheme,