fix: resolve three macOS startup issues (posix_spawnp, nvm PATH, session restore overlay)

[buallen]

Summary

This PR fixes three issues discovered while running claude-code-web as a persistent macOS launchd service accessed via ngrok. All three prevent the interface from working on a fresh macOS install with nvm.

Bug 1 — spawn-helper missing execute permission → posix_spawnp failed

Root cause: npm does not guarantee that executable bits are preserved when installing from the registry. node-pty's spawn-helper binary lands as -rw-r--r-- instead of -rwxr-xr-x, causing every single pty.spawn() call to throw posix_spawnp failed.

Fix: Added scripts/postinstall.js (invoked via "postinstall" in package.json) that walks all node_modules/node-pty/prebuilds/*/spawn-helper files and restores the execute bit if missing.

Bug 2 — nvm-installed claude not found when running as a service

Root cause: When cc-web runs under launchd (macOS) or systemd (Linux), PATH does not include nvm's per-version bin/ directory. findClaudeCommand() fell back to the short name "claude", which which found at runtime but node-pty's native posix_spawnp could not resolve later.

Fix: findClaudeCommand() now dynamically reads ~/.nvm/versions/node/ and prepends all discovered bin/claude absolute paths to the search list, ensuring an absolute path is always returned.

Bug 3 — posix_spawnp cannot exec a bare JS script (nvm symlink)

Root cause: The claude binary installed via nvm is a symlink → cli.js. node-pty passes the path directly to posix_spawnp, which on some macOS configurations fails to exec a script file even when the shebang is valid.

Fix: startSession() resolves symlinks before spawning. When the resolved target ends in .js, it spawns process.execPath <cli.js> [args] instead of the script directly.

Bug 4 — "Start Claude" overlay hidden on page reload for inactive sessions

Root cause: init() called this.hideOverlay() unconditionally after await switchToTab(). Because switchToTab awaits joinSession (which resolves when session_joined is received), the overlay state set by the session_joined handler (showOverlay('startPrompt') for inactive sessions) was immediately overridden by the subsequent hideOverlay() microtask continuation — leaving users with a blank terminal and no way to start Claude.

Fix: Removed the unconditional hideOverlay() from init(). The session_joined handler is already authoritative over overlay state and handles both the active (hide) and inactive (show startPrompt) cases correctly.

Test plan

• Fresh npm install -g claude-code-web on macOS — cc-web starts without posix_spawnp failed
• Running as launchd service — claude is found and starts correctly
• nvm-managed node install — claude spawns via node cli.js
• Close browser tab / refresh page with an inactive session — "Start Claude" button is visible
• Refresh page with an active Claude session — terminal resumes correctly without overlay

🤖 Generated with Claude Code