Unexpected shell validation failure despite valid $SHELL setting

Bug Description
claude complains about not having a valid shell, but $SHELL is set to a working zsh

Environment Info

• Platform: linux
• Terminal: tmux
• Version: 0.2.30
• Feedback ID: 11050e7c-6baa-4cbb-98f2-3ef0532d26d8

❯ echo $SHELL
/nix/store/m7l6yzmflrf9hjs8707lk9nkhi6f73n1-zsh-5.9/bin/zsh

❯ claude
╭────────────────────────────────────────────╮
│ ✻ Welcome to Claude Code research preview! │
│                                            │
│   /help for help                           │
│                                            │
│   cwd: /home/pbozeman/src/svc-example      │
╰────────────────────────────────────────────╯

╭───────────────────────────────────────────────────────────────────────────────────────╮
│ >                                                                                     │
╰───────────────────────────────────────────────────────────────────────────────────────╯
  ! for bash mode · / for commands · esc to undo                         \⏎ for newline


This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). The promise rejected with the reason:
Error: No suitable shell found. Claude CLI requires a Posix shell environment. Please ensure you have a valid shell installed and the SHELL environment variable set.
    at i6.findSuitableShell (file:///nix/store/g2i9z5sij5gsgcly3fcsh9vw20q5ybk2-claude-code-0.2.30/lib/node_modules/@anthropic-ai/claude-code/cli.mjs:339:8036)
    at new i6 (file:///nix/store/g2i9z5sij5gsgcly3fcsh9vw20q5ybk2-claude-code-0.2.30/lib/node_modules/@anthropic-ai/claude-code/cli.mjs:339:5985)
    at i6.getInstance (file:///nix/store/g2i9z5sij5gsgcly3fcsh9vw20q5ybk2-claude-code-0.2.30/lib/node_modules/@anthropic-ai/claude-code/cli.mjs:339:8426)
    at mw (file:///nix/store/g2i9z5sij5gsgcly3fcsh9vw20q5ybk2-claude-code-0.2.30/lib/node_modules/@anthropic-ai/claude-code/cli.mjs:344:1172)
    at aH (file:///nix/store/g2i9z5sij5gsgcly3fcsh9vw20q5ybk2-claude-code-0.2.30/lib/node_modules/@anthropic-ai/claude-code/cli.mjs:1162:14518)
    at cz1.<anonymous> (file:///nix/store/g2i9z5sij5gsgcly3fcsh9vw20q5ybk2-claude-code-0.