Switching to a domestic basemap: what actually has to change

• Tiles stay entirely grey because the key is refused or not bound to the current domain.
• The basemap loads but points sit a few hundred metres off because the GCJ-02 conversion is missing.
• Only vec or img is added, so the imagery appears without any labels.

1. Confirm the provider's CRS: Tianditu is CGCS2000 and close to WGS84, while Amap and Tencent are GCJ-02.
2. Paste the full tile URL into the address bar first; Tianditu is WMTS with TILEMATRIX, TILEROW and TILECOL rather than {z}/{x}/{y}.png.
3. Check the key whitelist: working on localhost but 403 in production points at the bound domain.
4. Check maxZoom against the service's real upper level.
5. Check whether y must be flipped for a TMS source.
6. Verify that the data pipeline converts WGS84 to GCJ-02 once, at display time.

Keep raw data in WGS84 and convert once before rendering on a GCJ-02 basemap with wgs84ToGcj02, and build the Tianditu URL with SERVICE=WMTS, REQUEST=GetTile, VERSION=1.0.0, LAYER=vec, STYLE=default, TILEMATRIXSET=w, FORMAT=tiles, TILEMATRIX={z}, TILEROW={y}, TILECOL={x} and tk, using subdomains 0 to 7.

L.tileLayer(
  'https://t{s}.tianditu.gov.cn/vec_w/wmts?SERVICE=WMTS&REQUEST=GetTile' +
  '&VERSION=1.0.0&LAYER=vec&STYLE=default&TILEMATRIXSET=w' +
  '&FORMAT=tiles&TILEMATRIX={z}&TILEROW={y}&TILECOL={x}&tk=你的KEY',
  { subdomains: '01234567', maxZoom: 18 }
).addTo(map);

L.tileLayer(
  'https://webrd0{s}.is.autonavi.com/appmaptile?lang=zh_cn&size=1' +
  '&scale=1&style=8&x={x}&y={y}&z={z}',
  { subdomains: '1234', maxZoom: 18 }
).addTo(map);

• Converting coordinates during import and storing GCJ-02, after which the data can never be used with Tianditu or in GIS analysis again.
• Hardcoding Amap style=8 tiles as a production dependency: there is no key check and no stability guarantee, so the official API is the right path.