pnpm patch <name> requires node_modules/.modules.yaml to be present #8257

Verify latest release

• I verified that the issue exists in the latest pnpm release

pnpm version

9.4.0

Which area(s) of pnpm are affected? (leave empty if unsure)

CLI

Link to the code that reproduces this issue or a replay of the bug

No response

Reproduction steps

1. Ensure node_modules is not present
2. Attempt to patch a package (e.g. pnpm patch typescript)
3. Observe failure

 ERR_PNPM_PATCH_NO_LOCKFILE  No pnpm-lock.yaml found: Cannot patch without a lockfile

Describe the Bug

There are 2 issues I see here.

1. The error is misleading. pnpm-lock.yaml does exist, node_modules may or may not (the deciding factor is node_modules/.modules.yaml).
2. Patching relies on node_modules. This is an easy requirement to meet (just run pnpm i), it is inconvenient. Especially when pnpm has been relegated to the role of dependency resolver alone, like with build system integrations (in my case Bazel + Rules JS).

Expected Behavior

The patch workflow can run without needing node_modules.

Which Node.js version are you using?

20.14.0

Which operating systems have you used?

• macOS
• Windows
• Linux

If your OS is a Linux based, which one it is? (Include the version if relevant)

Linux (Dev Container running on Docker)