Report renderer progress and detect stalled jobs

docs/server-plugin.md

@@ -48,6 +48,10 @@ Upload sends the latest **completed** export. It does not generate an export. Th
 
 The worker renders the map and panoramas. Open the private draft in your dashboard; the page updates while processing. Inspect the result, choose at least five locations, and submit for moderation. Once a moderator approves it, players can select it in the catalog.
 
+Both the dashboard and draft show completed-work progress: downloading, reading/indexing terrain, loading models, building geometry, rendering panorama faces, rendering the surface map, and saving images. Percentages are not a time estimate. The terminal reports block/face counts as work advances. A large export can take longer on a Mac using software rendering.
+
+If the worker stops renewing its lease, the page warns that it has stopped reporting. Renderer cancellation closes its browser, and `MINEGEO_RENDER_IDLE_SECONDS` (default 600) fails a renderer that reports no progress for that period. This is an inactivity limit, not a limit on total rendering time. Use a smaller export area or lower `MINEGEO_FACE_SIZE` if rendering one face exceeds it.
+
 ## Retry, cancel, and configure
 
 - An interrupted transfer resumes with `minegeo upload`. Progress is saved in `.upload-state.json` beside the export. Already received exports are not submitted twice.