PATH check false-positive on macOS/fish: "~/.local/bin is not in your PATH" despite being present

Summary

The native installation PATH check (OF1 in the bundle) fires a persistent warning even when ~/.local/bin is unambiguously present in $PATH. The warning appears on every claude upgrade and recurs during normal sessions. The suggested fix is also wrong syntax for fish shell.

Environment

• Claude Code version: 2.1.114
• OS: macOS Darwin 24.6.0 (Apple Silicon)
• Shell: fish

Reproduction

1. Install Claude Code natively on macOS with fish as the login shell
2. Run claude upgrade (or start a session)
3. Warning appears despite correct PATH

Evidence that PATH is correct

$ echo $PATH | tr ' ' '\n'
/opt/homebrew/bin
/opt/homebrew/sbin
/Users/ian/go/bin
/usr/local/go/bin
/Users/ian/.local/bin        ← present and clean
/Users/ian/bin
...

Simulating the exact check from OF1 inside a fish subprocess passes:

$ node -e "console.log(process.env.PATH.split(':').includes('/Users/ian/.local/bin'))"
true

Root cause analysis

The installer creates ~/.local/bin/env.fish and injects a source line into ~/.config/fish/conf.d/uv.env.fish (a file it shouldn't touch). That env file adds the path using the unresolved form $HOME/.local/share/../bin rather than $HOME/.local/bin.

OF1's PATH check does a plain string comparison (no path.resolve):

D === w  // w = path.join(os.homedir(), ".local", "bin") = "/Users/ian/.local/bin"

So "/Users/ian/.local/share/../bin" !== "/Users/ian/.local/bin" — the check misses the installer's own path entry. The PDH function uses path.resolve() and handles this correctly; OF1 does not.

After cleaning up the installer's residue, the clean path /Users/ian/.local/bin remains in PATH and the simulation confirms the check should pass — yet the live warning persists. The check appears to run in a context where process.env.PATH differs from what fish exports to normal subprocesses. This was not fully resolved during diagnosis.

Secondary bugs

1. DISABLE_INSTALLATION_CHECKS does not suppress this warning. The env var guard in OF1 only wraps checks after the native PATH check, not the PATH check itself.

1. Wrong fix suggested for fish. The fix message emits:

``
echo 'export PATH="$HOME/.local/bin:$PATH"' >> ~/.config/fish/config.fish
`
export is bash syntax. The correct fish idiom is fish_add_path ~/.local/bin`.

1. Installer writes into uv.env.fish, which is semantically owned by the uv Python package manager. This silently corrupts uv's own env setup for any user with both tools installed.

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Diagnosed by Claude Sonnet 4.6 running at max effort via claude CLI on behalf of the affected user.