Carson Sievert cpsievert

Session Persistence: Eliminating the Gray Screen of Death

Problem

When a Shiny app's WebSocket connection drops — whether from a network blip, laptop sleep, server error, or any other cause — the user sees a semi-transparent gray overlay with no recovery path (the "gray screen of death"). The session is permanently destroyed server-side, and all state is lost.

An existing session$allowReconnect() mechanism exists but is off by default, only works on certain hosting platforms, and performs a cold restart (new session, server function re-runs, all server-side state lost).

Goal

This gist contains a minimal reprex for this CS ticket

The app.py was deployed here. If you visit there, and repeatedly refresh, you should (eventually) see this error:

Note that the reprex needs this branch of shinywidgets, which switches the order of the libembed-amd.js and output.js scripts in the head of the document.

For some reason, quarto serve seems to be ordering these `

	from chatlas import ChatAnthropic
	from faicons import icon_svg
	from shiny import reactive
	from shiny.express import input, render, ui

	chat_model = ChatAnthropic(
	system_prompt="""
	You are a helpful AI fitness coach.
	Give detailed workout plans to users based on their fitness goals and experience level.
	Before getting into details, give a brief introduction to the workout plan.

	import numpy as np
	from chatlas import ChatAnthropic
	from sentence_transformers import SentenceTransformer

	# Initialize the SentenceTransformer model and chat client
	embed_model = SentenceTransformer("sentence-transformers/all-MiniLM-L6-v2")
	chat = ChatAnthropic(
	system_prompt="""
	You are a helpful AI assistant. Using the provided context,
	answer the user's question. If you cannot answer the question based on the

	import pandas as pd
	import plotly.express as px
	import plotly.graph_objects as go
	from shinywidgets import render_plotly

	from shiny import reactive
	from shiny.express import render

	num_rows = 10
	x_points = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

	# Example adapted from https://plotly.com/python/mapbox-county-choropleth/

	import json
	from urllib.request import urlopen

	import pandas as pd
	import plotly.express as px
	import plotly.graph_objects as go
	from shinywidgets import render_plotly

	# ------------------------------------------------------------------------
	# Learn more about bslib::tooltip() and bslib::popover() at
	# https://rstudio.github.io/bslib/articles/tooltips-popovers/index.html
	# ------------------------------------------------------------------------

	library(shiny)
	library(bslib)
	library(palmerpenguins)
	library(ggplot2)

	library(bslib)
	library(htmltools)
	library(crosstalk)
	library(plotly)
	library(leaflet)

	# Create Diamonds view
	dat <- SharedData$new(dplyr::sample_n(diamonds, 1000))

	sidebar_diamonds <- layout_sidebar(

	library(bslib)
	library(bsicons)
	library(crosstalk)
	library(plotly)

	dat <- SharedData$new(dplyr::sample_n(diamonds, 1000))

	accordion_filters <- accordion(
	accordion_panel(
	"Dropdowns", icon = bs_icon("menu-app"),