Topic
A property where repeating an operation yields the same result as doing it once, often enforced via idempotency keys to prevent duplicate charges or orders.
Microsoft researcher Jiapeng Li's Limbo benchmark found AI agents duplicated side-effecting writes in 56% and 74% of in-flight and double-delivery episodes. Offering idempotency keys cut duplicates from 28% to 4%, so tools that move money or send mail should require them.
Reality
Splitting an AI agent's 'done' into three status fields stops a green CI run from standing in for a reviewer's acceptance, a dev.to tutorial argues. That costs 16 state values to track and a permission check on each transition.
Reality
Strands and CrewAI agents exited 0 on all six runs where a broken verification tool checked nothing, a recorded-proxy test on dev.to found. Only tool-call traffic captured outside the framework showed the failures.
Reality
Retried Buy clicks get the original order back in a dev.to guide that commits each order with its attempt key in one SQLite transaction. A disabled button only cuts double-clicks, and the guide's available text ends before it covers charging the card.
Reality
A lost response looks exactly like a failed request from the client. That single ambiguity is why any API that moves money has to treat a duplicate submission as normal traffic.
Reality
In a five-step saga, running compensations out of LIFO order leaves a payment captured against a cancelled order, a dev.to walkthrough shows. Its fix is a durable, versioned coordinator with idempotency keys on every step and every compensation.
Reality
Agent loops can repeat a state-changing tool call in eight separate ways, a dev.to post argues, and each can duplicate a refund whose reply was lost. The post's fix is a stable operation ID tied to the payload, with UNKNOWN outcomes held until someone checks the provider.
Reality
Every booking in a flash-sale seat design on dev.to runs through one atomic Redis Lua script, yet the counter still needed four separate fixes. The last one holds each booking until a Redis replica confirms the write.
Reality
A dev.to post says the 2026-07-28 specification dropped the initialize flow and Mcp-Session-Id, so MCP requests can land on any instance. The refund agent it walks through still breaks on the second pod.
Reality
Across 34 runs on three agent frameworks, a recorder proxy shows that what the dedup key names decides whether a retried publish executes once or twice, and that surviving a SIGKILL is a separate question about where state is kept.
Reality
A job-application tool records its intent before the POST and marks a timed-out submit UNKNOWN forever, then blocks the next attempt at that role until a person checks the inbox. Its 210 verified submissions count only confirmed closes.
Reality
A reconciliation job verified the charge with Paystack and marked the payment row SUCCESS, then fulfilment failed on an unrelated tenant-context bug, and the sweeper only ever reads PENDING rows.
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A dev.to walkthrough stores the provider's DNS zone ID as replaceable cache and checks the returned domain before every mutation. The cutover only closes when an independent DNS read matches the approved MX set.
Reality
A dev.to walkthrough of per-tenant subdomains on a gaming platform gives the TTL drop, the target change and the TTL restore separate deadlines, preconditions and audit evidence, so a worker that restarts can prove what it already applied.
Reality
A dev.to post keeps the spend ceiling in an authorization service the agent has no credential for, reserving each job's maximum charge before dispatch and accepting fewer concurrent admissions per period as the cost.
Reality
A dev.to walkthrough makes the shippable unit a five-field decision contract with evidence IDs, scored by a harness of 50 to 100 finance cases in which three of the four groups exist to see whether the agent stops.
Reality
A dev.to post argues that the email API versus SMTP question follows from where suppression lookups, message IDs and delivery-event state live, and its Go sketch leaves the transport as the only interface the decision touches.
Reality
Offset start times kept a shared file queue from colliding for months. One day-long Codex outage made every launchd lane start at the same instant, and the pickup scripts had no mutual exclusion to fall back on.
Reality
SQS standard queues and Lambda event source mappings both deliver at least once, and that guarantee is about the envelope. A lab in us-east-1 sent the same 150-real order four times and logged four charges.
Reality
A dev.to post argues that processing.guarantee=exactly_once_v2 charges coordination overhead to every message and still leaves external side effects for you to deduplicate by hand. The five-line alternative it offers has a gap of its own.
Reality
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