R debugger: Restart from debug controls disables breakpoints

System details:

Positron and OS details:

Positron Version: 2026.08.1 (user setup) build 2
Code - OSS Version: 1.124.0
Commit: 48dc4cee686939f35fe4a714d34375f67fd62082
Date: 2026-08-09T13:35:16-06:00
Electron: 42.2.0
Chromium: 148.0.7778.97
Node.js: 24.15.0
V8: 14.8.178.14-electron.0
OS: Windows_NT x64 10.0.26200

Session details:

R 4.6.1

Describe the issue:

Breakpoints do not work after the Restart button in the debug mode controls is clicked

Steps to reproduce the issue:

1. Add a breakpoint to any R script
2. Go into debugging mode
3. Click Restart in Debug controls
4. R Session restarts
5. Breakpoints are no longer activated -- both current and new breakpoints are ignored

Expected or desired behavior:

Breakpoints should work normally after restart.

The expected behavior does happen when I click the Restart button in the Console tab.

Were there any error messages in the UI, Output panel, or Developer Tools console?

This error appears when I click Restart in the Debug controls:

workbench.desktop.main.js:243747 Error: Cannot call write after a stream was destroyed
at _write (node:internal/streams/writable:489:11)
at Writable.write (node:internal/streams/writable:508:10)
at c:\Users\Charlie\AppData\Local\Programs\Positron\resources\app\extensions\positron-r\dist\extension.js:31:14061
at new Promise ()
at Gd.write (c:\Users\Charlie\AppData\Local\Programs\Positron\resources\app\extensions\positron-r\dist\extension.js:31:13982)
at ic.doWrite (c:\Users\Charlie\AppData\Local\Programs\Positron\resources\app\extensions\positron-r\dist\extension.js:3:1625)
at c:\Users\Charlie\AppData\Local\Programs\Positron\resources\app\extensions\positron-r\dist\extension.js:3:1524
$onExtensionRuntimeError @ workbench.desktop.main.js:243747
_doInvokeHandler @ workbench.desktop.main.js:935421
_invokeHandler @ workbench.desktop.main.js:935407
_receiveRequest @ workbench.desktop.main.js:935350
_receiveOneMessage @ workbench.desktop.main.js:935279
(anonymous) @ workbench.desktop.main.js:935151
_deliver @ workbench.desktop.main.js:4511
fire @ workbench.desktop.main.js:4536
fire @ workbench.desktop.main.js:253331
(anonymous) @ workbench.desktop.main.js:938874

Reproduce the failure with an R script breakpoint, using the Debug controls Restart button rather than the Console restart. Start by tracing the R debugger restart path around the reported stream error in the Positron R extension, then verify that existing and newly added breakpoints work after restart without the stream-destroyed error.