Buy a standing watch from DataSieve (https://api.datasieve.xyz). standard = $0.10/7d, 1 condition, 50 triggers; composite = $0.25/7d, up to 5 any-match conditions (e.g. 5 heartbeat dead-man switches), 200 triggers; standard30 = $0.35/30d and composite30 = $0.85/30d — one payment covers the month, for agents that will not be awake to renew weekly. Payment is a gasless USDC transfer signed locally. Events go to your webhookUrl (HMAC-signed) if set, and always to a server-side mailbox drained with drain_events; every event carries a signed Ed25519 observation receipt you can replay to third parties. Failed calls are never billed. The watch id + secret are remembered locally so later calls need only the id.

State, heartbeat lastCheckedAt, triggersUsed/cap, expiry, delivery stats, and for dead-man switches: up/down, lastPingAt, nextDeadline, pingUrl. Secret is looked up from local state if omitted.

Collect everything the watch caught — works with zero infrastructure (the mailbox pattern). Pass since = last seen event id for incremental drains.

Extends the watch one more period (7 days, or 30 on the *30 tiers) at its tier price and resets the trigger budget. Renewing a paused watch also reactivates it.

Stop a watch firing (chain, web, heartbeat, schedule) without deleting it. The expiry clock keeps running. Use before a planned agent shutdown so your dead-man switch does not cry wolf.

Backlog-free resume: heartbeat deadlines restart from now and schedules jump to their next FUTURE slot — nothing that elapsed during the pause replays.

Next N run times for a cron expression in any IANA timezone, plus seconds-until-next. If the goal is for something to HAPPEN at those times, create_watch with a schedule condition instead — DataSieve fires the cron as signed webhooks for the life of the watch.

The cheapest possible real x402 purchase: proves this wallet + client can pay a production seller before you point it at anything expensive. Returns payer + network; failed calls are never billed.

Every DataSieve event carries receipt {alg, keyId, statement, sig} — an Ed25519 attestation that DataSieve observed the event. This checks it against the service key, so an agent can validate evidence handed to it by ANOTHER agent without trusting that agent.

Keep a dead-man switch alive. Pass the pingUrl from create_watch (or a watchId whose ping URLs are in local state). Call this at least once per intervalSeconds.

Scanner cursor lag vs chain head — verify the watcher is alive before you buy.

Check whether a buying key is configured and whether it can afford a watch. Reports the wallet address, its USDC balance on the configured network, and what each tier costs. Call this before create_watch; it never spends anything.

Buy a coordination workspace ($0.25 / 7 days, 1000 ops) — the only x402 seller of multi-agent primitives. After this ONE payment, every barrier and lock operation is FREE and FAST (no per-op settlement). Use it to fan-in sub-agents (coord_barrier) and to stop two agents doing the same irreversible thing (coord_lock).

BARRIER: "wake me when all N of my sub-agents finish." Returns an arriveUrl — hand it to each sub-agent (it is a capability: they can arrive but cannot read or delete your workspace). When the N-th part arrives we fire ONE webhook carrying every part's collected context. If the TTL passes first you get a "partial" event naming exactly who never showed. Timeout is a feature, not an error.

Report that this part is done. Pass the arriveUrl from coord_barrier plus a part name and optional ctx (whatever you want handed to whoever consumes the released barrier). Idempotent per part: a retrying agent cannot inflate the count.

LOCK: "only one agent does this irreversible thing." Returns a leaseId, or 409 with who holds it. The lease AUTO-EXPIRES after ttlSeconds, so a crashed agent can never deadlock your fleet. Call coord_release when done (or just let it expire).

Collect barrier releases/partials that happened while nothing of yours was running.