refactor: remove the ECharts renderer

CHANGELOG.md

@@ -31,13 +31,18 @@ independently. `flexviz` pins a compatible `flexviz-polars` range.
 
 - A notebook `show()` displays the server's own `/view` page in its iframe,
   like the browser path, instead of a `data:` page that called the server from
-  another origin. For the deprecated ECharts renderer, `height` now sets only
-  the iframe height.
+  another origin.
 
 ### Removed
 
 - `flexviz.server.show_server`. Use `Figure.show()`, `Dashboard.show()` or
   `flexviz serve`.
+- The deprecated ECharts renderer. `renderer="echarts"` now raises a
+  `ValueError`. A share URL or `flexviz history` entry with
+  `renderer=echarts` returns HTTP 400 at `/view` and `/h/{n}`. The renderer
+  name must now be exactly `"plotly"`, so `renderer="Plotly"` also raises.
+- `flexviz.cache.set_cache_backend` and `flexviz.cache.set_cube_cache_backend`,
+  which replaced the server-side delta cache and cube cache.
 
 ## [0.1.0b5] - 2026-09-27
 

docs/guides/cross-filtering.md

@@ -117,4 +117,3 @@ Rules and limits:
   [shared URLs](sharing.md), export and import. A spec whose linked axes hold
   different ranges is rejected, so an agent that patches the viewport with
   `flexvizApply` must set every key of a group.
-- The deprecated ECharts renderer does not support linked axes.

docs/guides/customizing.md

@@ -73,10 +73,6 @@ a log scale. A replacing merge would erase the label.
 Every key comes from the
 [Plotly layout reference](https://plotly.com/python/reference/layout/).
 
-!!! warning "Plotly only"
-    ECharts is deprecated and reads `title`, `xlabel`, `ylabel` and legend
-    visibility only. Every other `update_layout()` key is ignored there.
-
 ### Colors
 
 Pass `color` for a single trace and `color_map` for a grouped one. See

flexviz/adapters/__init__.py

@@ -1,14 +1,13 @@
 """Adapter base class and helpers.
 
-Renderer-specific adapters (PlotlyAdapter, EchartsAdapter) are imported lazily
+Renderer-specific adapters (PlotlyAdapter) are imported lazily
 to avoid hard dependencies on optional libraries.
 """
 
 from .base import AbstractAdapter
 from .registry import (
     build_adapter,
     get_renderer_definition,
-    normalize_renderer_name,
     supported_renderers,
     validate_dashboard_renderer,
 )
@@ -17,7 +16,6 @@
     "AbstractAdapter",
     "build_adapter",
     "get_renderer_definition",
-    "normalize_renderer_name",
     "supported_renderers",
     "validate_dashboard_renderer",
 ]