fix(browser): kill orphaned Chrome processes on Windows cleanup

[Younest-git]

Summary

On Windows, browser_navigate() starts a headless Chromium via agent-browser. When the browser session is cleaned up (via inactivity timeout, explicit cleanup_browser(), or Hermes shutdown), the agent-browser daemon is killed — but its child Chrome processes remain running because Windows does not automatically terminate child processes when the parent is killed.

Over multiple calls (and across sessions), these orphaned chrome.exe processes accumulate: users report 60–150+ chrome.exe zombies consuming GBs of RAM until they manually run taskkill /f /im chrome.exe.

Changes

1. _cleanup_single_browser_session() — Windows-specific Chrome kill

After killing the agent-browser daemon and cleaning up the socket directory, run taskkill /f /im chrome.exe on Windows to terminate any leftover Chrome child processes. The call is wrapped in a try/except so it never blocks cleanup:

if sys.platform == "win32":
    try:
        subprocess.run(["taskkill", "/F", "/IM", "chrome.exe"],
                       capture_output=True, timeout=5)
    except Exception:
        pass

2. Lower DEFAULT_SESSION_INACTIVITY_TIMEOUT from 120s → 30s

The inactivity-based cleanup thread runs every 30s. With a 120s timeout, orphaned sessions can survive for up to 2 minutes. Reducing to 30s tightens the window significantly without risking premature reaping during normal use.

Testing

• On Windows: verified that browser_navigate() + inactivity timeout triggers cleanup, and that taskkill removes all chrome.exe processes
• On non-Windows: the sys.platform == "win32" guard ensures no behavioral change
• The subprocess.run() call has a 5-second timeout and is wrapped in try/except — a hung taskkill cannot block cleanup

Related

Fixes the long-standing issue documented in the cleanup-chromium-leftovers community skill, where users had to rely on external scripts or manual taskkill to reclaim RAM.

[alt-glitch]

This was generated by AI during triage.

Related: competes with #43577 for the same Windows orphaned-Chrome cleanup goal. This PR runs a blanket taskkill /F /IM chrome.exe (kills every chrome.exe, including the user's own browser) plus lowers the default inactivity timeout 120s->30s; #43577 takes a more surgical approach (_reap_orphaned_chrome_processes via wmic, only reaping Chrome reparented to Explorer.exe, skipped while sessions are active). Both target the #32047 orphan leak. Flagging the cluster so a maintainer can pick the safer approach.