Cost Federation

ADR-097 Phase 3 specifies a federation_spend event bus that publishes one event per federation_send completion: {peerId, taskId, tokensUsed, usdSpent, ts}. Cost-tracker is the declared consumer — it aggregates per-peer rolling windows (1h / 24h / 7d) and the federation breaker queries that aggregate to suspend peers exceeding the configured threshold.

Phase 3 isn't landed upstream yet. This skill is the consumer-side wiring; it activates the moment upstream publishes events to the federation-spend namespace. Until then it reports cleanly with a "no events found" notice.

When to use

Before opening federation traffic to a new peer — establish baseline.
Periodically (e.g. /loop 5m) to monitor per-peer spend across windows.
After ADR-097 Phase 2/3 lands — to verify breaker suspension reasoning.

Steps

Run the script:
bash
```
node plugins/ruflo-cost-tracker/scripts/federation.mjs
```
Optional env:
- FED_FORMAT=json — JSON instead of markdown
- FED_NAMESPACE=federation-spend — override target namespace
- FED_SUSPEND_THRESHOLD_USD=5.0 — breaker threshold (ADR-097 default)
Inspect — per-peer 1h/24h/7d windows of count + USD spent, plus a "Suspension threshold check" block flagging peers over the breaker line.

Storage contract (consumer side)

When Phase 3 lands, events should be persisted to namespace federation-spend with key prefix fed-spend- and JSON value matching:

json

{
  "peerId": "<peer-uuid>",
  "taskId": "<task-uuid>",
  "tokensUsed": 12345,
  "usdSpent": 0.0287,
  "ts": "2026-05-05T..."
}

The script reads any record matching that prefix, regardless of how upstream produces them. Multiple events per peer accumulate cleanly into the rolling-window sums.

Cross-references

ADR-097: Federation budget circuit breaker — the complete spec
cost-report — same data, different lens (cost-report focuses on local agent spend; this skill on per-peer federated spend)
ruflo-federation plugin — the producer side (when Phase 3 lands)