R package build task fails when R binary is in user home directory (tilde not expanded in single quotes)

System details:

Positron and OS details:

Positron Version: 2026.01.0 build 147
Code - OSS Version: 1.106.0
Commit: 3290136f699527bf01b703b390457b05ef2b858a
Date: 2026-01-06T01:40:35.071Z
Electron: 37.7.0
Chromium: 138.0.7204.251
Node.js: 22.20.0
V8: 13.8.258.32-electron.0
OS: Darwin arm64 24.6.0

Session details:

R version 4.5.2 (2025-10-31)
Platform: x86_64-conda-linux-gnu

Describe the issue:

I'm a non-root user on a shared system, so I use pixi to manage my R installations and environments. This issue occurs when R is installed "globally" (into ~/.pixi/envs using pixi global install) or as a proper, non-global virtual environment into (into ~/path/to/project/.pixi). For simplicity, everything that follows assumes the global installation. My settings in this case are:

{
    "positron.r.customBinaries": ["/Users/gfindlay@ad.wisc.edu/.pixi/envs/my-r-env/bin/R"],
    "positron.r.interpreters.exclude": [
        "/usr/bin/R"
    ]
}

[!NOTE]
It's important that "positron.r.customBinaries" points to the R binary in the ~/.pixi/envs directory, and NOT to the trampoline binary (a static ELF executable) in ~/.pixi/bin, because Positron can't parse the latter to find R_HOME, so it marks the installation as invalid.

Building a package using devtools::build() from an R session started in the package directory works fine. Building a package using Cmd + Shift + B, which runs a build task that shells out, does not:

   *  Executing task: '~/.pixi/envs/my-r-env/bin/R' --quiet --no-restore
  --no-save -e 'pak::local_install(upgrade = FALSE)'

  /usr/bin/bash: line 1: ~/.pixi/envs/my-r-env/bin/R: No such file or
  directory

   *  The terminal process "/usr/bin/bash '-c',
  ''~/.pixi/envs/my-r-env/bin/R' --quiet --no-restore --no-save -e
  'pak::local_install(upgrade = FALSE)''" failed to launch (exit code:
  127).

Pretty sure the problem is that the ~ isn't being expanded because the path is in single quotes.
Why is a relative path being used in the first place? I provided an absolute path in "positron.r.customBinaries", and R itself reports absolute paths, so I figured the tilde must be coming from Positron's task configuration. I tested this by creating my own build task in .vscode/tasks.json:

{
    "version": "2.0.0",
    "tasks": [
        {
            "label": "R: My Build Package",
            "type": "shell",
            "command": "/Users/gfindlay@ad.wisc.edu/.pixi/envs/my-r-env/bin/R",
            "args": [
                "--quiet",
                "--no-restore",
                "--no-save",
                "-e",
                "pak::local_install(upgrade = FALSE)"
            ],
            "group": {
                "kind": "build",
                "isDefault": true
            },
            "problemMatcher": []
        }
    ]
}

Then Cmd + Shift + P -> Tasks: Run Task -> R: My Build Package. Works like a charm. So I went looking in the Positron source for the bug. I think it arises inside the R extension:

1. extensions/positron-r/src/provider.ts — makeMetadata() converts absolute
   paths to tilde form:
   https://github.com/posit-dev/positron/blob/4b8cc97a7a7a9468c02cd5ac0ee685192030825d/extensions/positron-r/src/provider.ts#L260-L262
2. extensions/positron-r/src/session-manager.ts — stores that tilde-form path
   as the R binary path used for tasks.
3. extensions/positron-r/src/tasks.ts — wraps the path in ShellQuoting.Strong
   (single quotes):
   https://github.com/posit-dev/positron/blob/4b8cc97a7a7a9468c02cd5ac0ee685192030825d/extensions/positron-r/src/tasks.ts#L118-L122

Maybe the solution is as simple as calling normalizeUserPath() from extensions/positron-r/src/path-utils.ts on the binpath in tasks.ts before passing it to ShellExecution?
https://github.com/posit-dev/positron/blob/4b8cc97a7a7a9468c02cd5ac0ee685192030825d/extensions/positron-r/src/path-utils.ts#L49-L58

Steps to reproduce the issue:

1. pixi global install --environment my-r-env r-base r-devtools r-pak.
2. "positron.r.customBinaries": ["/Users/gfindlay@ad.wisc.edu/.pixi/envs/my-r-env/bin/R"].
3. Open a workspace on your package under development.
4. Cmd + Shift + D; Cmd + Shift + B.

Thank you for Positron!

Start in extensions/positron-r/src/tasks.ts, then compare the path handling in extensions/positron-r/src/path-utils.ts and the tilde conversion in extensions/positron-r/src/provider.ts. Reproduce the package build with the custom R binary, and verify that the generated shell task launches the configured binary instead of passing an unexpanded tilde path.