feat(pkg-r): Update module return value

[gadenbuie]

Updates chat_mod_server() to return a list of values including:

• 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.
• clear(): A function to clear the chat history and the chat UI. Takes a single argument, clear_history, which indicates whether to also clear the chat history in the client object. Defaults to TRUE.
• client: The chat client object, which is mutated as you chat.

Example app

library(shiny)
library(bslib)
pkgload::load_all(here::here("pkg-r"))
library(shinychat)

ui <- page_fillable(
  layout_columns(
    fill = FALSE,
    actionButton("update", "Tell me a joke!"),
    actionButton("clear", "Clear chat")
  ),
  layout_columns(
    card(
      card_header("Chat"),
      chat_mod_ui("chat")
    ),
    card(
      card_header("Debug info"),
      verbatimTextOutput("debug")
    )
  )
)

server <- function(input, output, session) {
  chat <- chat_mod_server("chat", ellmer::chat("openai/gpt-4.1-nano"))

  observeEvent(input$update, {
    chat$update_user_input("Tell me a joke!", submit = TRUE)
  })

  observeEvent(input$clear, {
    chat$clear()
  })

  output$debug <- renderPrint({
    list(
      last_turn = chat$last_turn(),
      last_input = chat$last_input()
    )
  })
}

shinyApp(ui, server)