fix: self-update accepts ranges; drop exact-semver gate

`pnpm self-update` resolves semver ranges to a specific version, so
`devEngines.packageManager.version: ">=10 <11"` can also go through
the self-update path. That makes readTargetVersion total — it always
returns a string or throws — so the runtime auto-switch fallback (and
the `pnpm_config_pm_on_fail=download` export from #252) is no longer
reachable and gets removed.

Adds a range case to the cache_store_path matrix.

.github/workflows/test.yaml

@@ -214,6 +214,8 @@ jobs:
             manifest: '{"packageManager":"pnpm@10.33.0","dependencies":{"is-odd":"3.0.1"}}'
           - label: 'devEngines exact pnpm@10.33.0'
             manifest: '{"devEngines":{"packageManager":{"name":"pnpm","version":"10.33.0"}},"dependencies":{"is-odd":"3.0.1"}}'
+          - label: 'devEngines range >=10 <11'
+            manifest: '{"devEngines":{"packageManager":{"name":"pnpm","version":">=10 <11"}},"dependencies":{"is-odd":"3.0.1"}}'
 
     steps:
       - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4.3.1

src/install-pnpm/run.ts

@@ -84,10 +84,9 @@ export async function runSelfInstaller(inputs: Inputs): Promise<SelfInstallerRes
     ? path.join(dest, 'node_modules', '@pnpm', 'exe', process.platform === 'win32' ? 'pnpm.exe' : 'pnpm')
     : path.join(dest, 'node_modules', 'pnpm', 'bin', 'pnpm.mjs')
 
-  // Determine the target version
+  // Self-update the bootstrap to the requested pnpm version. readTargetVersion
+  // either returns a value or throws, so this always runs.
   const targetVersion = readTargetVersion({ version, packageJsonFile })
-
-  if (targetVersion) {
   const cmd = standalone ? bootstrapPnpm : process.execPath
   const args = standalone ? ['self-update', targetVersion] : [bootstrapPnpm, 'self-update', targetVersion]
   const exitCode = await runCommand(cmd, args, { cwd: dest })
@@ -99,28 +98,17 @@ export async function runSelfInstaller(inputs: Inputs): Promise<SelfInstallerRes
   // PNPM_HOME/bin so consumers of the bin_dest output (e.g.
   // `${steps.pnpm.outputs.bin_dest}/pnpm`) invoke the requested version.
   //
-    // When the requested version equals the bootstrap version, self-update
+  // When the requested version resolves to the bootstrap version, self-update
   // is a no-op and PNPM_HOME/bin is not created — fall back to pnpmHome,
   // whose symlinks already point at the right version.
   const updatedBinDir = path.join(pnpmHome, 'bin')
   return { exitCode: 0, binDest: existsSync(updatedBinDir) ? updatedBinDir : pnpmHome }
-  }
-
-  // No exact target version we can self-update to (devEngines pins a
-  // semver range, or nothing is pinned at all). Rely on the bootstrap
-  // pnpm to switch versions at runtime. Force `pmOnFail=download` so a
-  // project that pins `devEngines.packageManager.onFail = "error"` doesn't
-  // trip BAD_PM_VERSION before the switch can happen (issue #252). Scoped
-  // to this branch so users who pass an explicit `version:` input keep
-  // strict onFail behavior.
-  exportVariable('pnpm_config_pm_on_fail', 'download')
-  return { exitCode: 0, binDest: pnpmHome }
 }
 
 function readTargetVersion(opts: {
   readonly version?: string | undefined
   readonly packageJsonFile: string
-}): string | undefined {
+}): string {
   const { version, packageJsonFile } = opts
   const { GITHUB_WORKSPACE } = process.env
 
@@ -167,15 +155,10 @@ Remove one of these versions to avoid version mismatch errors like ERR_PNPM_BAD_
   // `cache: pnpm` on cold caches (issue #233).
   //
   // devEngines.packageManager takes priority over packageManager, matching
-  // pnpm's getWantedPackageManager logic. devEngines.packageManager.version
+  // pnpm's getWantedPackageManager logic. `pnpm self-update` accepts both
-  // can be a semver range; `pnpm self-update` needs a specific version, so
+  // exact versions and semver ranges, so we pass either through directly.
-  // for ranges we fall through to the bootstrap auto-switch path.
+  if (devEngines?.packageManager?.name === 'pnpm' && devEngines.packageManager.version) {
-  if (devEngines?.packageManager?.name === 'pnpm') {
+    return devEngines.packageManager.version
-    const v = devEngines.packageManager.version
-    if (v != null && isExactSemver(v)) {
-      return v
-    }
-    return undefined
   }
 
   if (packageManagerVersion) {
@@ -196,10 +179,6 @@ Please specify it by one of the following ways:
   - in the package.json with the key "devEngines.packageManager"`)
 }
 
-function isExactSemver(v: string): boolean {
-  return /^\d+\.\d+\.\d+(?:-[0-9A-Za-z-]+(?:\.[0-9A-Za-z-]+)*)?(?:\+[0-9A-Za-z-]+(?:\.[0-9A-Za-z-]+)*)?$/.test(v)
-}
-
 function getSystemNodeVersion(): Promise<{ major: number; minor: number }> {
   return new Promise((resolve) => {
     const cp = spawn('node', ['--version'], { stdio: ['pipe', 'pipe', 'pipe'], shell: process.platform === 'win32' })