R 4.6.0: Session watcher not working

Describe the bug

'R: Creating R Terminal' results in 'R: (not attached)'.

To Reproduce

On a host with docker installed:

docker run --rm -p 8888:8888 -ti glcr.b-data.ch/jupyterlab/r/base:4.6.0

Follow the instructions in the terminal, i.e. open URL http://127.0.0.1:8888/lab?token=${TOKEN} in a browser.

Inside the container

1. JupyterLab: Click on 'code-server'
2. code-server: Open View > Command Palette... > R: Create R Terminal

Can you fix this issue by yourself? (We appreciate the help)

No

(If applicable) Please attach setting.json

"r.plot.useHttpgd": true,
"r.rterm.linux": "/usr/local/bin/R",
"r.rterm.option": [
  "--no-save",
  "--no-restore"
],
"r.workspaceViewer.showObjectSize": true,

Expected behavior

Session watcher also works with R 4.6.0 and later.

Screenshots

-

Environment (please complete the following information):

• OS: Linux (Debian 13)
• code-server Version: 4.117.0
  • aka Code Version 1.117.0
• R Version: 4.6.0
• vscode-R version: 2.8.8

Additional context

R version 4.6.0 (2026-04-24) -- "Because it was There"
Copyright (C) 2026 The R Foundation for Statistical Computing
Platform: aarch64-unknown-linux-gnu

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.

  Natural language support but running in an English locale

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

> .vsc.attach()
Error in .vsc.attach() : could not find function ".vsc.attach"

First reproduce the failure with the provided Docker command, code-server flow, and R 4.6.0 environment. Trace the session watcher from “R: Create R Terminal” through the reported .vsc.attach() error; done means the watcher attaches successfully and the R terminal is no longer marked “(not attached)” on R 4.6.0 and later.