agent-usage-guard is a Claude Code mod: it runs inside Claude Code and holds runaway spend before it happens. It reads your plan's live usage, and it holds subagent fan-out, heavy-context churn and retry loops.
Recorded from Claude Code's interactive UI with the guard loaded. A scripted local API stands in for Claude, so the sessions and token counts are staged and no usage is spent. Every question on screen is the guard's own. Rebuild it from the Northstar fixture.
It acts before the spend, not after it: before an agent starts, a prompt is sent, or a tool call runs. Agent limits hold across every Claude Code session on your machine, and fan-out and heavy context are capped at any usage level, not only near the limit. When you are at the keyboard it asks you, in Claude Code's own question dialog. When nobody can answer, it refuses and tells Claude why, so the model can wait, batch the work, or stop. /agent-guard report shows what it did.
