InboundEventDeduplicator

Deduplicates inbound platform events across redeliveries.

Channel adapters consult this before processing an inbound event: delivery platforms (WeCom, DingTalk, GitHub, GitLab, ...) redeliver the same event when no timely acknowledgment is received, and each redelivery must execute at most once.

Keys are opaque and caller-composed — typically channelId + "|" + platformEventId. Implementations backed by shared storage should namespace keys per deployment (for example with an environment or application prefix): platform event ids are only unique within one channel deployment, and a key shared by two deployments silently drops live traffic.

The default IdempotencyStore keeps state in the JVM heap, which only deduplicates within a single process: a redelivery that lands on another instance, or after a restart, is not recognized. Deployments running multiple channel instances should provide an implementation backed by shared storage (for example a Redis SET ... NX EX keyed by channel and platform event id). Injection today is programmatic: channels expose a fromProperties(channelId, routing, rawProperties, InboundEventDeduplicator) factory overload for hand-wired setups, while the config-driven path (agentscope.json resolved through the harness ChannelFactory) constructs channels with the default process-local store.

Implementations must be thread-safe: channels invoke #firstSeen(String) from concurrent callback threads.