meter — the kill-brake for agent spend. 429-as-a-service.

  POST /{topic}/spend    body: a number, or {"amount": n, "note": "..."}
                         200 = proceed · 429 = stop (body carries a raise URL)
                         ?dry=1 checks without committing
  PUT  /{topic}          set config: {"cap": 50, "period": "day|month|total", "unit": "usd"}
  GET  /{topic}          status (JSON for curl, live page for browsers) · ?wait=30 long-polls
  POST /{topic}/raise    {"by": 10} or {"to": 100}
  GET  /{topic}/log      recent spend entries, newest first (?limit=50)
  GET  /{topic}/sse      live spend events (SSE)

Topics are created by first use and match [a-zA-Z0-9_-]{1,64} — pick an unguessable name.
Full docs: GET /README.md (the whole contract, markdown) · GET /llms.txt (agent index)