diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6650eea..ba49389 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -20,8 +20,10 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
+        # Node 20 is not tested: pnpm 11 is pure ESM and requires Node >=22, so
+        # `pnpm install` cannot run on it. Node 20 reached end-of-life in April
+        # 2026, and engines.node is set to >=22 to match what is actually tested.
         node-version:
-          - 20.x
           - 22.x
           - 24.x
     steps:
diff --git a/package.json b/package.json
index 6d9c948..12ecfbd 100644
--- a/package.json
+++ b/package.json
@@ -5,9 +5,9 @@
   "type": "module",
   "license": "MIT",
   "author": "Logan Lindquist Land",
-  "packageManager": "pnpm@10.34.5",
+  "packageManager": "pnpm@11.18.0",
   "engines": {
-    "node": ">=20"
+    "node": ">=22"
   },
   "repository": {
     "type": "git",
diff --git a/pnpm-workspace.yaml b/pnpm-workspace.yaml
new file mode 100644
index 0000000..0b1f57e
--- /dev/null
+++ b/pnpm-workspace.yaml
@@ -0,0 +1,16 @@
+# pnpm 11 supply-chain hardening.
+# These are pnpm 11's defaults, stated explicitly so the security posture is
+# visible in review and survives future changes to pnpm's own defaults.
+
+minimumReleaseAge: 1440 # block packages younger than 24h
+blockExoticSubdeps: true # no git/tarball transitive deps
+strictDepBuilds: true # fail install on unapproved postinstalls
+verifyDepsBeforeRun: install # re-check lockfile before `pnpm run`
+
+# Postinstall allowlist. Empty map = block all build scripts.
+#
+# Deliberately empty: no dependency in this tree requests a build script. With
+# strictDepBuilds enabled, `pnpm install` would fail with ERR_PNPM_IGNORED_BUILDS
+# if one appeared, so this staying empty is an enforced property, not an
+# oversight. Add an entry only after auditing that package's postinstall.
+allowBuilds: {}