Idempotency Key

A common technique for achieving idempotency is for the client to generate a unique idempotency key sent with the request, while the server records the result associated with that key and returns the cached result upon receiving a duplicate request.

Common methods for achieving idempotency include assigning a unique request ID (idempotency key) to each write operation, or using conditional writes (compare-and-swap) that only execute when the target data is in the expected state.

Idempotency means that the same operation should yield the same final result regardless of whether it is executed once or multiple times; a common implementation is to generate a globally unique request ID (such as a UUID) for each request for server-side deduplication.

When validation fails, the specific error should be fed back to the model for correction, but retries must have limits on the number of attempts, timeout duration, and cost control, as retries increase latency and resource consumption.

In concurrent scenarios, "query first, then write" as a fallback when an idempotency key is missing is unreliable, and adds an extra round trip; the most robust approach is still server-side deduplication.

POST is a non-idempotent write, and retrying after a timeout can cause duplicate creation (such as creating two orders), requiring an idempotency key or avoiding retries.

An idempotency key is a unique identifier generated by the client (usually a UUID), which the server uses for deduplication: on first receipt it executes and caches the result, and when the same key arrives again it directly returns the cached result.

Idempotency keys usually need a reasonable TTL (such as 24 hours) and must be used together with an operation record table so that completed actions can still be identified through reconciliation logic after the key expires.

An idempotency key is a globally unique key generated by the client for each operation (usually a UUID) and sent to the external service with the request; the server checks whether the key already exists before processing, and if it does, returns the previous result without executing the actual action again.

In AI Agent scenarios, idempotency keys often fail: on the one hand, retries may be initiated by schedulers at different levels, resulting in keys that are not the same; on the other hand, the external providers that Agents call do not necessarily support idempotency key semantics.

Idempotency keys are a common means in distributed systems of preventing the same operation from being executed multiple times: the caller carries a globally unique identifier when initiating a request, the server deduplicates on that identifier, and on encountering a duplicate request with the same key it directly returns the first result without re-executing the side effects.

The idempotency key must come from stable input features (such as meeting ID or item content hash) and must not depend on the order or random IDs of this run, otherwise the key will change on rerun and deduplication will fail.

Workers should derive the idempotency key from the workflow ID and step index, compute a SHA256 hash over run_id, step_index, and payload, check the in-memory key-value cache before executing side effects, and immediately return the cached result if the key already exists with a completed status.

To avoid retries causing side effects to be executed repeatedly, idempotency keys or request identifiers should be used to ensure that the same logical request takes effect only once.

An idempotent operation has the same effect on the external world no matter how many times it is executed (such as querying the weather, reading a file, or sending a notification with a unique ID), while non-idempotent operations (such as transfers or placing orders) require checking state first or using an idempotency key when retried.

For tools that change state, idempotency keys or equivalent protective mechanisms should be used, and tool inputs should be validated and authorization enforced at the application layer

幂等性指对同一操作发起多次调用产生的结果与调用一次完全相同，应为每个业务动作生成唯一幂等键并将结果持久化绑定到该键以防止重复执行

Using refund-${email_id} as the idempotencyKey when issuing a refund ensures that crash retries will not result in duplicate refunds.

Account entry writes should have five safety guardrails: idempotency keys to prevent duplicate writes, a staging area first, a deterministic debit-credit balance check, full logging, and a rollback mechanism.

A common practice for achieving idempotency is to assign a globally unique idempotency key to each message or task, with the receiver checking whether the key has already been processed before handling it.