The Apps development server appends every decoded MCP request, response, and AppBridge message to an in-memory list. The list has no entry-count or byte limit and is cleared only by an explicit request.
Capture continues when the log panel is disabled. In a local Starlette `TestClient` reproduction with `log_panel=False`, the page had no panel markup, but three proxy requests left six full request/response entries available from `/api/logs`. A separate run of the log class retained about 36.5 MB of traced Python allocations after 2,000 request/response pairs with 8-KiB payloads on each side.
Long-running previews or repeated large tool results can therefore increase memory use for the lifetime of the dev server. Could the server bound retained log data and skip capture when the panel is disabled? This is related to #4121, which added the option to show or hide the log panel.
### Example Code
```Python
```
### Version Information
```Text
- FastMCP main: `5baeacfe20eca735cb949564b4915f93a622b916`
- Python: 3.12.15
- OS: macOS 15.0.1 arm64
```
What happened?