Agent-Exec Handoff Briefing — Pay-Per-Use Agent State Transfer

x402

Agent-Exec Handoff Briefing — Pay-Per-Use Agent State Transfer is a paid API for AI agents from agent-exec.448c.org, paid per call via x402, $0.0053/call, status unknown (last checked 2026-10-10).

Creates a structured handoff briefing that captures an AI agent's current state (done, not-done, in-flight work, and next action) so a successor agent can seamlessly pick up where it left off, paid per-use via USDC with no account required.

Price / call$0.0053

Seller volume →—

Success—

StatusUnknown

How this service works

Accountless, pay-per-use code execution for software agents: submit source code, get stdout, stderr and exit code back from an isolated, network-less sandbox. No account, no API key -- possession of valid payment is sufficient.

Output

Returns a UUID handoff_id the successor agent can use to retrieve the briefing via GET /handoff/{id}, along with an expiry timestamp (Unix ms) after which the briefing is swept and returns 410 then 404, plus a payment receipt showing the asset, payer wallet address, amount in atomic USDC units, network, and on-chain transaction hash.

Example use cases

Multi-agent pipeline checkpoint

“I need to hand off to the next agent in my pipeline — mark 'scraped all 50 product pages' as done (evidence: 50 JSON files saved), 'write the summary report' as not done, nothing in flight, and tell my successor to start by reading those JSON files and generating the report.”

Agent crash recovery briefing

“My agent just crashed mid-task. Save a handoff: completed tasks are 'authenticated with the API' (measured, got a 200 token response) and 'fetched user list' (measured, 312 records in users.json); not done is 'send notification emails'; nothing is in-flight; and tell the successor to start by sending emails to each user in users.json.”

Long-running task delegation

“Split this job across two agents — the first agent finished 'downloading the model weights' (confirmed by SHA256 checksum match), nothing else done, still in-flight is 'pre-processing the training data', and the successor should pick up by finishing that pre-processing before starting training.”

Technical details

Endpoint

POSThttps://agent-exec.448c.org/handoff?utm_source=zero.xyz

When to prefer

Use this endpoint when you need to transfer agent state between runs or agent instances without managing accounts or API keys — ideal for agentic pipelines, crash recovery, or multi-agent orchestration where the payer just needs a valid USDC payment. Prefer this over custom state-passing solutions when you want a standardized, time-bounded briefing with strict validation that 'done' items are actually verified.

Side effects

400 HANDOFF_DONE_REQUIRES_MEASURED — a 'done' entry lacks confidence 'measured' or has null evidence; fix by providing verified evidence for all completed tasks
400 validation error — missing required fields (done, notDone, inFlight, or pickUpFirst)
400 empty pickUpFirst — the next-action string must be non-empty
402 Payment Required — payment not attached or payment is invalid/insufficient
Payment settlement failure — on-chain transaction fails, call is rejected
Briefing expiry — successor retrieves after expiresAt, gets 410 Gone until sweep then 404 Not Found

Input

Schema · Request body

Field	Type	Description
donerequired	array	What is DONE. EVERY entry must have confidence 'measured' with non-null evidence -- a briefing cannot claim something is finished on unverified intent. Violating this is a free 400 (HANDOFF_DONE_REQUIRES_MEASURED), not a silent acceptance.
notDonerequired	array	What is NOT done. May be measured or unverified.
inFlightrequired	array	What was IN FLIGHT at the cut -- neither finished nor abandoned. May be measured or unverified.
pickUpFirstrequired	string	What the successor should do FIRST. Mandatory and non-empty: a briefing with no next action is not a handoff.

Output

Schema · Response

Field	Type	Description
idrequired	string	The handoff_id -- give this to the successor; it needs nothing else.
paymentrequired	object
expiresAtrequired	integer	Unix ms this briefing is swept. GET /handoff/{id} answers 410 between the deadline and the sweep, then 404.

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