avoid usage of mosaic_def document (#1270)

* avoid usage of mosaic_def document

* fix

Author: vincentsarago

CHANGES.md

@@ -7,6 +7,10 @@
 * add `/validate` endpoint via `ValidateExtension` extension
 * add `Latitude` and `Longitude` as compatible spatial dimensions (@abarciauskas-bgse, https://github.com/developmentseed/titiler/pull/1268)
 
+### titiler.mosaic
+
+* remove usage of `mosaic_def.center` and calculate from bounds
+
 ## 0.25.0 (2025-11-07)
 
 ### Misc 

src/titiler/application/tests/routes/test_mosaic.py

@@ -82,7 +82,6 @@ def test_tilejson(app):
     assert body["minzoom"] == mosaicjson["minzoom"]
     assert body["maxzoom"] == mosaicjson["maxzoom"]
     assert body["bounds"] == mosaicjson["bounds"]
-    assert body["center"] == mosaicjson["center"]
 
 
 def test_point(app):

src/titiler/mosaic/titiler/mosaic/factory.py

@@ -696,15 +696,19 @@ def tilejson(
                     reader_options=reader_params.as_dict(),
                     **backend_params.as_dict(),
                 ) as src_dst:
-                    center = list(src_dst.mosaic_def.center)
-                    if minzoom is not None:
-                        center[-1] = minzoom
-
+                    bounds = src_dst.get_geographic_bounds(tms.rasterio_geographic_crs)
+                    minzoom = minzoom if minzoom is not None else src_dst.minzoom
+                    maxzoom = maxzoom if maxzoom is not None else src_dst.maxzoom
+                    center = (
+                        (bounds[0] + bounds[2]) / 2,
+                        (bounds[1] + bounds[3]) / 2,
+                        minzoom,
+                    )
                     return {
-                        "bounds": src_dst.bounds,
+                        "bounds": bounds,
                         "center": tuple(center),
-                        "minzoom": minzoom if minzoom is not None else src_dst.minzoom,
-                        "maxzoom": maxzoom if maxzoom is not None else src_dst.maxzoom,
+                        "minzoom": minzoom,
+                        "maxzoom": maxzoom,
                         "tiles": [tiles_url],
                         "attribution": os.environ.get("TITILER_DEFAULT_ATTRIBUTION"),
                     }