resolveEntityKey() and checkEntity() checked manifest.agents[input] directly,
bypassing the disabled filter in agentKeys(). This let users run `spawn cursor
<cloud>` even though cursor is disabled, wasting time provisioning a VM for an
agent that can't route through OpenRouter. Now both functions check the disabled
flag and show the disabled_reason to the user.
Also removes stale cursor references from spawn skill templates injected into
child VMs.
Agent: code-health
Co-authored-by: B <6723574+louisgv@users.noreply.github.com>
Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>