diff --git a/apps/penpal/DEPENDENCIES.md b/apps/penpal/DEPENDENCIES.md
index 7b990643d..44cd380ef 100644
--- a/apps/penpal/DEPENDENCIES.md
+++ b/apps/penpal/DEPENDENCIES.md
@@ -58,6 +58,7 @@ see-also:
 - **Used by:** Building the React frontend (Vite), running frontend tests (Vitest), running e2e tests (Playwright)
 - **Where it runs:** Dev and CI only (compiled JS/HTML assets bundled into .app)
 - **Why external:** Vite and TypeScript compiler require a Node.js runtime
+- **Note:** This project uses **pnpm** (not npm). The root `package.json` enforces this via the `packageManager` field, and `pnpm-workspace.yaml` defines the workspace. Do not use `npm install` or commit `package-lock.json` files.
 
 ## Optional Runtime Dependencies
 
diff --git a/apps/penpal/justfile b/apps/penpal/justfile
index 3d7efdf4d..a3f9aa61e 100644
--- a/apps/penpal/justfile
+++ b/apps/penpal/justfile
@@ -173,7 +173,7 @@ prepare version:
     # Update version in Cargo.toml (source of truth)
     sed -i '' 's/^version = ".*"/version = "{{version}}"/' frontend/src-tauri/Cargo.toml
     # Update version in package.json
-    cd frontend && npm version "{{version}}" --no-git-tag-version && cd ..
+    cd frontend && pnpm version "{{version}}" --no-git-tag-version && cd ..
 
     # Generate and review changelog
     just changelog {{version}}