Title:	Chat UI Component for 'shiny'
Version:	0.3.0
Description:	Provides a scrolling chat interface with multiline input, suitable for creating chatbot apps based on Large Language Models (LLMs). Designed to work particularly well with the 'ellmer' R package for calling LLMs.
License:	MIT + file LICENSE
URL:	https://posit-dev.github.io/shinychat/r/, https://github.com/posit-dev/shinychat
BugReports:	https://github.com/posit-dev/shinychat/issues
Imports:	base64enc, bslib, cli, coro, ellmer (≥ 0.3.0), fastmap, htmltools, jsonlite, lifecycle, promises (≥ 1.3.2), rlang (≥ 1.1.0), S7, shiny (≥ 1.10.0)
Suggests:	knitr, later, testthat (≥ 3.0.0), withr
Config/Needs/website:	tidyverse/tidytemplate, rmarkdown, weathR, gt, glue, bsicons
Config/testthat/edition:	3
Encoding:	UTF-8
RoxygenNote:	7.3.3
NeedsCompilation:	no
Packaged:	2025-11-20 13:44:36 UTC; garrick
Author:	Joe Cheng [aut], Carson Sievert [aut], Garrick Aden-Buie [aut, cre], Barret Schloerke [aut], Posit Software, PBC [cph, fnd]
Maintainer:	Garrick Aden-Buie <garrick@adenbuie.com>
Repository:	CRAN
Date/Publication:	2025-11-20 14:00:02 UTC

shinychat: Chat UI Component for 'shiny'

Description

Provides a scrolling chat interface with multiline input, suitable for creating chatbot apps based on Large Language Models (LLMs). Designed to work particularly well with the 'ellmer' R package for calling LLMs.

Author(s)

Maintainer: Garrick Aden-Buie garrick@adenbuie.com (ORCID)

Authors:

• Joe Cheng joe@posit.co

• Carson Sievert carson@posit.co

• Barret Schloerke barret@posit.co (ORCID)

Other contributors:

• Posit Software, PBC (ROR) [copyright holder, funder]

See Also

Useful links:

• https://posit-dev.github.io/shinychat/r/

• https://github.com/posit-dev/shinychat

• Report bugs at https://github.com/posit-dev/shinychat/issues

Open a live chat application in the browser

Description

Create a simple Shiny app for live chatting using an ellmer::Chat object. Note that these functions will mutate the input client object as you chat because your turns will be appended to the history.

The app created by chat_app() is suitable for interactive use by a single user. For multi-user Shiny apps, use the Shiny module chat functions – chat_mod_ui() and chat_mod_server() – and be sure to create a new chat client for each user session.

Usage

chat_app(client, ..., bookmark_store = "url")

chat_mod_ui(id, ..., client = deprecated(), messages = NULL)

chat_mod_server(
  id,
  client,
  bookmark_on_input = TRUE,
  bookmark_on_response = TRUE
)

Arguments

Value

• chat_app() returns a shiny::shinyApp() object.

• chat_mod_ui() returns the UI for a shinychat module.

• chat_mod_server() includes the shinychat module server logic, and returns a list containing:

  • last_input: A reactive value containing the last user input.

  • last_turn: A reactive value containing the last assistant turn.

  • update_user_input(): A function to update the chat input or submit a new user input. Takes the same arguments as update_chat_user_input(), except for id and session, which are supplied automatically.

  • append(): A function to append a new message to the chat UI. Takes the same arguments as chat_append(), except for id and session, which are supplied automatically.

  • clear(): A function to clear the chat history and the chat UI. clear() takes an optional list of messages used to initialize the chat after clearing. messages should be a list of messages, where each message is a list with role and content fields. The client_history argument controls how the chat client's history is updated after clearing. It can be one of: "clear" the chat history; "set" the chat history to messages; "append" messages to the existing chat history; or "keep" the existing chat history.

  • client: The chat client object, which is mutated as you chat.

Functions

• chat_app(): A simple Shiny app for live chatting. Note that this app is suitable for interactive use by a single user; do not use chat_app() in a multi-user Shiny app context.

• chat_mod_ui(): A simple chat app module UI.

• chat_mod_server(): A simple chat app module server.

Examples

## Not run: 
# Interactive in the console ----
client <- ellmer::chat_anthropic()
chat_app(client)

# Inside a Shiny app ----
library(shiny)
library(bslib)
library(shinychat)

ui <- page_fillable(
  titlePanel("shinychat example"),

  layout_columns(
    card(
      card_header("Chat with Claude"),
      chat_mod_ui(
        "claude",
        messages = list(
          "Hi! Use this chat interface to chat with Anthropic's `claude-3-5-sonnet`."
        )
      )
    ),
    card(
      card_header("Chat with ChatGPT"),
      chat_mod_ui(
        "openai",
        messages = list(
          "Hi! Use this chat interface to chat with OpenAI's `gpt-4o`."
        )
      )
    )
  )
)

server <- function(input, output, session) {
  claude <- ellmer::chat_anthropic(model = "claude-3-5-sonnet-latest") # Requires ANTHROPIC_API_KEY
  openai <- ellmer::chat_openai(model = "gpt-4o") # Requires OPENAI_API_KEY

  chat_mod_server("claude", claude)
  chat_mod_server("openai", openai)
}

shinyApp(ui, server)

## End(Not run)

Append an assistant response (or user message) to a chat control

Description

The chat_append function appends a message to an existing chat_ui(). The response can be a string, string generator, string promise, or string promise generator (as returned by the 'ellmer' package's chat, stream, chat_async, and stream_async methods, respectively).

This function should be called from a Shiny app's server. It is generally used to append the client's response to the chat, while user messages are added to the chat UI automatically by the front-end. You'd only need to use chat_append(role="user") if you are programmatically generating queries from the server and sending them on behalf of the user, and want them to be reflected in the UI.

Usage

chat_append(
  id,
  response,
  role = c("assistant", "user"),
  icon = NULL,
  session = getDefaultReactiveDomain()
)

Arguments

Value

Returns a promise that resolves to the contents of the stream, or an error. This promise resolves when the message has been successfully sent to the client; note that it does not guarantee that the message was actually received or rendered by the client. The promise rejects if an error occurs while processing the response (see the "Error handling" section).

Error handling

If the response argument is a generator, promise, or promise generator, and an error occurs while producing the message (e.g., an iteration in stream_async fails), the promise returned by chat_append will reject with the error. If the chat_append call is the last expression in a Shiny observer, shinychat will log the error message and show a message that the error occurred in the chat UI.

Examples

library(shiny)
library(coro)
library(bslib)
library(shinychat)

# Dumbest chatbot in the world: ignores user input and chooses
# a random, vague response.
fake_chatbot <- async_generator(function(input) {
  responses <- c(
    "What does that suggest to you?",
    "I see.",
    "I'm not sure I understand you fully.",
    "What do you think?",
    "Can you elaborate on that?",
    "Interesting question! Let's examine thi... **See more**"
  )

  await(async_sleep(1))
  for (chunk in strsplit(sample(responses, 1), "")[[1]]) {
    yield(chunk)
    await(async_sleep(0.02))
  }
})

ui <- page_fillable(
  chat_ui("chat", fill = TRUE)
)

server <- function(input, output, session) {
  observeEvent(input$chat_user_input, {
    response <- fake_chatbot(input$chat_user_input)
    chat_append("chat", response)
  })
}

shinyApp(ui, server)

Low-level function to append a message to a chat control

Description

For advanced users who want to control the message chunking behavior. Most users should use chat_append() instead.

Usage

chat_append_message(
  id,
  msg,
  chunk = TRUE,
  operation = c("append", "replace"),
  icon = NULL,
  session = getDefaultReactiveDomain()
)

Arguments

Value

Returns nothing (invisible(NULL)).

Examples

library(shiny)
library(coro)
library(bslib)
library(shinychat)

# Dumbest chatbot in the world: ignores user input and chooses
# a random, vague response.
fake_chatbot <- async_generator(function(id, input) {
  responses <- c(
    "What does that suggest to you?",
    "I see.",
    "I'm not sure I understand you fully.",
    "What do you think?",
    "Can you elaborate on that?",
    "Interesting question! Let's examine thi... **See more**"
  )

  # Use low-level chat_append_message() to temporarily set a progress message
  chat_append_message(id, list(role = "assistant", content = "_Thinking..._ "))
  await(async_sleep(1))
  # Clear the progress message
  chat_append_message(id, list(role = "assistant", content = ""), operation = "replace")

  for (chunk in strsplit(sample(responses, 1), "")[[1]]) {
    yield(chunk)
    await(async_sleep(0.02))
  }
})

ui <- page_fillable(
  chat_ui("chat", fill = TRUE)
)

server <- function(input, output, session) {
  observeEvent(input$chat_user_input, {
    response <- fake_chatbot("chat", input$chat_user_input)
    chat_append("chat", response)
  })
}

shinyApp(ui, server)

Clear all messages from a chat control

Description

Clear all messages from a chat control

Usage

chat_clear(id, session = getDefaultReactiveDomain())

Arguments

Examples

library(shiny)
library(bslib)

ui <- page_fillable(
  chat_ui("chat", fill = TRUE),
  actionButton("clear", "Clear chat")
)

server <- function(input, output, session) {
  observeEvent(input$clear, {
    chat_clear("chat")
  })

  observeEvent(input$chat_user_input, {
    response <- paste0("You said: ", input$chat_user_input)
    chat_append("chat", response)
  })
}

shinyApp(ui, server)

Add Shiny bookmarking for shinychat

Description

Adds Shiny bookmarking hooks to save and restore the ellmer chat client. Also restores chat messages from the history in the client.

If either bookmark_on_input or bookmark_on_response is TRUE, the Shiny App's bookmark will be automatically updated without showing a modal to the user.

Note: Only the client's chat state is saved/restored in the bookmark. If the client's state doesn't properly capture the chat's UI (i.e., a transformation is applied in-between receiving and displaying the message), then you may need to implement your own session$onRestore() (and possibly session$onBookmark) handler to restore any additional state.

To avoid restoring chat history from the client, you can ensure that the history is empty by calling client$set_turns(list()) before passing the client to chat_restore().

Usage

chat_restore(
  id,
  client,
  ...,
  bookmark_on_input = TRUE,
  bookmark_on_response = TRUE,
  session = getDefaultReactiveDomain()
)

Arguments

Value

Returns nothing (invisible(NULL)).

Examples

library(shiny)
library(bslib)
library(shinychat)

ui <- function(request) {
  page_fillable(
    chat_ui("chat", fill = TRUE)
  )
}

server <- function(input, output, session) {
  chat_client <- ellmer::chat_ollama(
    system_prompt = "Important: Always respond in a limerick",
    model = "qwen2.5-coder:1.5b",
    echo = TRUE
  )
  # Update bookmark to chat on user submission and completed response
  chat_restore("chat", chat_client)

  observeEvent(input$chat_user_input, {
    stream <- chat_client$stream_async(input$chat_user_input)
    chat_append("chat", stream)
  })
}

# Enable bookmarking!
shinyApp(ui, server, enableBookmarking = "server")

Create a chat UI element

Description

Inserts a chat UI element into a Shiny UI, which includes a scrollable section for displaying chat messages, and an input field for the user to enter new messages.

To respond to user input, listen for input$ID_user_input (for example, if id="my_chat", user input will be at input$my_chat_user_input), and use chat_append() to append messages to the chat.

Usage

chat_ui(
  id,
  ...,
  messages = NULL,
  placeholder = "Enter a message...",
  width = "min(680px, 100%)",
  height = "auto",
  fill = TRUE,
  icon_assistant = NULL
)

Arguments

Value

A Shiny tag object, suitable for inclusion in a Shiny UI

Examples

library(shiny)
library(bslib)
library(shinychat)

ui <- page_fillable(
  chat_ui("chat", fill = TRUE)
)

server <- function(input, output, session) {
  observeEvent(input$chat_user_input, {
    # In a real app, this would call out to a chat client or API,
    # perhaps using the 'ellmer' package.
    response <- paste0(
      "You said:\n\n",
      "<blockquote>",
      htmltools::htmlEscape(input$chat_user_input),
      "</blockquote>"
    )
    chat_append("chat", response)
    chat_append("chat", stream)
  })
}

shinyApp(ui, server)

Format ellmer content for shinychat

Description

Format ellmer content for shinychat

Usage

contents_shinychat(content)

Arguments

Value

Returns text, HTML, or web component tags formatted for use in chat_ui().

Extending contents_shinychat()

You can extend contents_shinychat() to handle custom content types in your application. contents_shinychat() is an S7 generic. If you haven't worked with S7 before, you can learn more about S7 classes, generics and methods in the S7 documentation.

We'll work through a short example creating a custom display for the results of a tool that gets local weather forecasts. We first need to create a custom class that extends ellmer::ContentToolResult.

library(ellmer)

WeatherToolResult <- S7::new_class(
  "WeatherToolResult",
  parent = ContentToolResult,
  properties = list(
    location_name = S7::class_character
  )
)

Next, we'll create a simple ellmer::tool() that gets the weather forecast for a location and returns our custom WeatherToolResult class. The custom class works just like a regular ContentToolResult, but it has an additional location_name property.

get_weather_forecast <- tool(
  function(lat, lon, location_name) {
    WeatherToolResult(
      weathR::point_tomorrow(lat, lon, short = FALSE),
      location_name = location_name
    )
  },
  name = "get_weather_forecast",
  description = "Get the weather forecast for a location.",
  arguments = list(
    lat = type_number("Latitude"),
    lon = type_number("Longitude"),
    location_name = type_string("Name of the location for display to the user")
  )
)

Finally, we can extend contents_shinychat() to render our custom content class for display in the chat interface. The basic process is to define a contents_shinychat() external generic and then implement a method for your custom class.

contents_shinychat <- S7::new_external_generic(
  package = "shinychat",
  name = "contents_shinychat",
  dispatch_args = "contents"
)

S7::method(contents_shinychat, WeatherToolResult) <- function(content) {
  # Your custom rendering logic here
}

You can use this pattern to completely customize how the content is displayed inside shinychat by returning HTML objects directly from this method.

You can also use this pattern to build upon the default shinychat display for tool requests and results. By using S7::super(), you can create the object shinychat uses for tool results (or tool requests), and then modify it to suit your needs.

S7::method(contents_shinychat, WeatherToolResult) <- function(content) {
  # Call the super method for ContentToolResult to get shinychat's defaults
  res <- contents_shinychat(S7::super(content, ContentToolResult))

  # Then update the result object with more specific content
  # In this case, we render the tool result dataframe as a {gt} table...
  res$value <- gt::as_raw_html(gt::gt(content@value))
  res$value_type <- "html"
  # ...and update the tool result title to include the location name
  res$title <- paste("Weather Forecast for", content@location_name)

  res
}

Note that you do not need to create a new class or extend contents_shinychat() to customize the tool display. Rather, you can use the strategies discussed in the Tool Calling UI article to customize the tool request and result display by providing a display list in the extra argument of the tool result.

Stream markdown content

Description

Streams markdown content into a output_markdown_stream() UI element. A markdown stream can be useful for displaying generative AI responses (outside of a chat interface), streaming logs, or other use cases where chunks of content are generated over time.

Usage

markdown_stream(
  id,
  content_stream,
  operation = c("replace", "append"),
  session = getDefaultReactiveDomain()
)

Arguments

Examples

library(shiny)
library(coro)
library(bslib)
library(shinychat)

# Define a generator that yields a random response
# (imagine this is a more sophisticated AI generator)
random_response_generator <- async_generator(function() {
  responses <- c(
    "What does that suggest to you?",
    "I see.",
    "I'm not sure I understand you fully.",
    "What do you think?",
    "Can you elaborate on that?",
    "Interesting question! Let's examine thi... **See more**"
  )

  await(async_sleep(1))
  for (chunk in strsplit(sample(responses, 1), "")[[1]]) {
    yield(chunk)
    await(async_sleep(0.02))
  }
})

ui <- page_fillable(
  actionButton("generate", "Generate response"),
  output_markdown_stream("stream")
)

server <- function(input, output, session) {
  observeEvent(input$generate, {
    markdown_stream("stream", random_response_generator())
  })
}

shinyApp(ui, server)

Create a UI element for a markdown stream.

Description

Creates a UI element for a markdown_stream(). A markdown stream can be useful for displaying generative AI responses (outside of a chat interface), streaming logs, or other use cases where chunks of content are generated over time.

Usage

output_markdown_stream(
  id,
  ...,
  content = "",
  content_type = "markdown",
  auto_scroll = TRUE,
  width = "min(680px, 100%)",
  height = "auto"
)

Arguments

Value

A shiny tag object.

See Also

markdown_stream()

Update the user input of a chat control

Description

Update the user input of a chat control

Usage

update_chat_user_input(
  id,
  ...,
  value = NULL,
  placeholder = NULL,
  submit = FALSE,
  focus = FALSE,
  session = getDefaultReactiveDomain()
)

Arguments

Examples

library(shiny)
library(bslib)
library(shinychat)

ui <- page_fillable(
  chat_ui("chat"),
  layout_columns(
    fill = FALSE,
    actionButton("update_placeholder", "Update placeholder"),
    actionButton("update_value", "Update user input")
  )
)

server <- function(input, output, session) {
  observeEvent(input$update_placeholder, {
    update_chat_user_input("chat", placeholder = "New placeholder text")
  })

  observeEvent(input$update_value, {
    update_chat_user_input("chat", value = "New user input", focus = TRUE)
  })

  observeEvent(input$chat_user_input, {
    response <- paste0("You said: ", input$chat_user_input)
    chat_append("chat", response)
  })
}

shinyApp(ui, server)