New runtime API: onNamespaceChange

System details:

Windows 11

Positron and OS details:

Positron Version: 2025.05.0 (system setup) build 26
Code - OSS Version: 1.98.0
Commit: f034cf42c2707c46479841ef5fbe3a68ae255053
Date: 2025-04-08T03:45:02.257Z
Electron: 34.2.0
Chromium: 132.0.6834.196
Node.js: 20.18.2
V8: 13.2.152.36-electron.0
OS: Windows_NT x64 10.0.26100

Interpreter details:

R 4.4.3

Describe the issue:

I created the Positron R Package Manager extension to replicate the RStudio package management experience for Positron users.

Nevertheless, one major limitation of the extension is that it cannot automatically refresh the package pane when the users load/unload packages or install/uninstall them from the console. Only activities through the package pane would trigger refreshes - and even I rarely do this as it is bad for replicability of the R project.

I wonder if Positron can expose a new API for external extensions such as mine so that the extension can be notified when a namespace change in the R session occurs.

Steps to reproduce the issue:

1. Install the Positron R Package Manager extension
2. Manually load a package, e.g. library(ggplot2)
3. The change is not reflected in the extension sidebar
4. Press the refresh button on the sidebar
5. The change is updated.

Expected or desired behavior:

The extension can automatically refresh itself when a namespace change in the R session occurs, notified by the API.

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

No.