agent-browser — what the vendor skill leaves out

The vendor skill (agent-browser skills get core) is the reference: refs, commands, troubleshooting for stale refs, overlay-covered clicks, key-event interception. Read it first.

These are the failures it does not name. Every one below cost a real debugging session, and two of them produced false bug reports against the application before being understood.

0. RULE ZERO — a dead session lies to you

Before concluding anything about the app, prove input still reaches the page.

A session can reach a state where every command returns ✓ Done, snapshot and eval keep working, and no real input lands. Clicks do nothing. Hover fires nothing. Radix exit animations never run, so closed dialog overlays never unmount and then block everything else.

agent-browser doctor does not catch this — it checks the daemon and pid, and happily prints pass Session <name> (pid …) while the page is dead.