hermes - 💡(How to fix) Fix Browser tool should prefer packaged agent-browser native binary when npm shim needs unavailable node

Bug description

On systemd gateway environments, PATH can expose an agent-browser npm shim while node itself is unavailable or not inherited by the service. In that case, resolving the shim leads to failures like /usr/bin/env: node: No such file or directory, even though the agent-browser package includes a platform-native binary that would work.

There is a related config/env issue: sandbox flags need to be passed via AGENT_BROWSER_ARGS, which the installed agent-browser binary reads. Older notes/logic around AGENT_BROWSER_CHROME_FLAGS can make the tool think sandbox args are configured when the binary will ignore them.

Steps to reproduce

1. Install/use Hermes in a service environment where node_modules/.bin/agent-browser is visible.
2. Start the gateway under systemd with a PATH that does not contain node.
3. Attempt to use browser automation.

Actual behavior

The tool can resolve the npm shim and fail with a missing node executable, even if node_modules/agent-browser/bin/agent-browser-linux-x64 exists and is executable. Sandbox flags may also be missed if only the legacy env var is considered.

Expected behavior

• If the PATH agent-browser is an npm shim requiring Node and node is unavailable, keep searching.
• Prefer the packaged native binary for the current platform when available.
• Use/inject AGENT_BROWSER_ARGS for Chrome launch flags; do not treat AGENT_BROWSER_CHROME_FLAGS as equivalent for installed agent-browser versions that ignore it.

Local workaround tested

A local patch added native-binary fallback resolution in tools/browser_tool.py and only treats AGENT_BROWSER_ARGS as the effective browser args env var. Browser automation worked in the affected systemd gateway environment after this change.

Environment

• Hermes checkout commit: 9f182bd7b
• OS: Ubuntu 24.04 / Linux
• Gateway: systemd user service
• Browser backend: local agent-browser / Chromium