fix: allow pnpm runtime set in workspace root (#11584)

* fix: allow `pnpm runtime set` in workspace root

`pnpm runtime set <name> <version>` previously failed in the root of a
multi-package workspace with the `ADDING_TO_ROOT` error. Since installing
a runtime is workspace-wide configuration, pass `--workspace-root` to the
underlying `pnpm add` call when not running globally.

* fix: use --ignore-workspace-root-check instead of --workspace-root

The previous fix forced every non-global runtime install to land in
the workspace root, which broke running the command from a workspace
subproject. Switch to --ignore-workspace-root-check, which only
suppresses the safety warning and leaves the install target as the
current directory.

.changeset/runtime-set-workspace-root.md

@@ -0,0 +1,6 @@
+---
+"@pnpm/engine.runtime.commands": patch
+"pnpm": patch
+---
+
+`pnpm runtime set <name> <version>` no longer fails in the root of a multi-package workspace with the `ADDING_TO_ROOT` error. Installing the workspace root is a valid target for a runtime, so the command now bypasses that safety check.

engine/runtime/commands/src/runtime/runtime.ts

@@ -94,6 +94,8 @@ function runtimeSet (opts: RuntimeCommandOptions, params: string[]): void {
   if (opts.global) {
     args.push('--global')
     if (opts.bin) args.push('--global-bin-dir', opts.bin)
+  } else {
+    args.push('--ignore-workspace-root-check')
   }
   if (opts.storeDir) args.push('--store-dir', opts.storeDir)
   if (opts.cacheDir) args.push('--cache-dir', opts.cacheDir)

engine/runtime/commands/test/runtime.test.ts

@@ -37,7 +37,7 @@ test('runtime set uses project dir when not global', async () => {
   }, ['set', 'node', '22'])
 
   expect(mockRunPnpmCli).toHaveBeenCalledWith(
-    ['add', 'node@runtime:22'],
+    ['add', 'node@runtime:22', '--ignore-workspace-root-check'],
     { cwd: '/tmp/project' }
   )
 })