[BUG] `claude upgrade` reports success but leaves `bin/claude.exe` as the fallback stub — native binary not linked

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Environment

• OS: macOS 26 → 27 (Darwin 27.0.0), arm64
• Node: v24.15.0 via nvm
• Install type: global npm install (~/.nvm/versions/node/v24.15.0/lib/node_modules/@anthropic-ai/claude-code)
• Affected versions: reproduced across three consecutive upgrades (2.1.272 → 2.1.273, and again up to 2.1.276)

Description

After running claude upgrade, the command prints a success message and package.json is updated to the new version, but bin/claude.exe is left as the placeholder shell-script stub instead of being replaced with the real native binary. Every subsequent claude invocation (from any directory, including ~) fails with:

Error: claude native binary not installed.

Either postinstall did not run (--ignore-scripts, some pnpm configs)
or the platform-native optional dependency was not downloaded
(--omit=optional).

Run the postinstall manually (adjust path for local vs global install):
node node_modules/@anthropic-ai/claude-code/install.cjs

Or reinstall without --ignore-scripts / --omit=optional.

This is misleading: the platform-native optional dependency (e.g. @anthropic-ai/claude-code-darwin-arm64) is correctly downloaded and present in node_modules at the new version. The problem is specifically that install.cjs's placeBinary() step — which copies/hardlinks the real binary over bin/claude.exe — never runs (or fails silently) as part of claude upgrade's own update flow.

Actual behavior

claude upgrade exits successfully while leaving bin/claude.exe as the ~200-byte stub script instead of the ~200MB native binary.

Workaround

Manually re-run the postinstall script, which correctly finds and links the already-downloaded native binary:

node "$(npm root -g)/@anthropic-ai/claude-code/install.cjs"

This fixes it every time without a full reinstall, confirming the native binary was already present — claude upgrade just isn't invoking (or is failing at) this linking step.

### What Should Happen?

### Expected behavior
`claude upgrade` should leave a working `claude` binary — either by running the postinstall step itself after updating, or by not reporting success until the binary is actually linked.


### Error Messages/Logs

```shell
Error: claude native binary not installed.

Either postinstall did not run (--ignore-scripts, some pnpm configs)
or the platform-native optional dependency was not downloaded
(--omit=optional).

Run the postinstall manually (adjust path for local vs global install):
node node_modules/@anthropic-ai/claude-code/install.cjs

Or reinstall without --ignore-scripts / --omit=optional.

Steps to Reproduce

Steps to reproduce

1. Install @anthropic-ai/claude-code globally via npm under nvm.
2. Run claude upgrade when a new version is available.
3. Observe the "Successfully updated" message.
4. Run claude --version (or any other command) → fails with "claude native binary not installed".

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.276

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_