browse: GSTACK_CHROMIUM_PATH ignored in headless mode

[sun617]

Problem

GSTACK_CHROMIUM_PATH is only respected in launchHeaded() but not in launch() (headless mode). Skills like /qa use headless mode by default, so setting GSTACK_CHROMIUM_PATH has no effect.

This breaks browse on NixOS (and likely other non-FHS distros like Guix) where the bundled chromium_headless_shell binary fails because system libraries aren't in standard paths:

chrome-headless-shell: error while loading shared libraries: libglib-2.0.so.0: cannot open shared object file

Root Cause

In browse/dist/server-node.mjs:

• Line ~2491 (launchHeaded): reads process.env.GSTACK_CHROMIUM_PATH and passes it as executablePath to Playwright
• Line ~2440 (launch): calls chromium.launch() without executablePath, always using the bundled binary

Workaround

Export LD_LIBRARY_PATH from the system Chrome's Nix wrapper before running browse:

CHROME_LIBS=$(grep "LD_LIBRARY_PATH='" $(readlink -f $(which google-chrome-stable)) | grep "^LD_LIBRARY_PATH='" | sed "s/LD_LIBRARY_PATH='//;s/'.*//" | tr '\n' ':')
export LD_LIBRARY_PATH="$CHROME_LIBS"

This is fragile and has to be done every session.

Suggested Fix

Read GSTACK_CHROMIUM_PATH in launch() too:

  async launch() {
+   const executablePath = process.env.GSTACK_CHROMIUM_PATH || undefined;
    const launchArgs = [];
    // ...
    this.browser = await chromium.launch({
      headless: useHeadless,
      chromiumSandbox: process.platform !== "win32",
+     ...executablePath ? { executablePath } : {},
      ...launchArgs.length > 0 ? { args: launchArgs } : {}
    });

Environment

• OS: NixOS (Linux 6.19.11)
• gstack: v0.15.16.0
• System browser: Google Chrome 146.0.7680.177 (installed via Nix)
• GSTACK_CHROMIUM_PATH set to /run/current-system/sw/bin/google-chrome-stable