Ever watched an email agent reply to the same message twice? The recipient gets two near-identical responses seconds apart, screenshots them, and your carefully engineered assistant suddenly looks like a script with a stutter. Worse: under real load, this isn't a freak event. It's the default outcome if you haven't designed against it. The double-reply problem has three distinct causes, and each one needs its own fix. Let's walk through them. Why duplicates happen at all First cause: webhook redelivery . Nylas — like most webhook providers — guarantees at-least-once delivery. If your endpoint doesn't return a 200 fast enough, or a transient network blip eats the response, the same message.created notification shows up again. Process both, send two replies. Second: concurrent workers . Your handler probably runs on multiple instances — Lambda invocations, ECS tasks, worker processes. Two of them can pick up the same notification at nearly the same instant and both start generating a reply. Third: shared inboxes . Two agents (or an agent and a human) watching the same mailbox can both decide a message is theirs to answer. This one isn't a duplicate event at all — it's a coordination problem, and it's the hardest to patch at the application layer. Fix one: deduplicate deliveries Track which message IDs you've processed, and check before doing anything else: app . post ( " /webhooks/nylas " , async ( req , res ) => { res . status ( 200 ). end (); const event = req . body ; if ( event . type !== " message.created " ) return ; const messageId = event . data . object . id ; // Atomic check-and-set. If the key exists, bail. const alreadyProcessed = await db . processedMessages . setIfAbsent ( messageId , { receivedAt : Date . now (), }); if ( alreadyProcessed ) return ; await handleMessage ( event . data . object ); }); The check-and-set must be atomic. In Redis that's SET messageId 1 NX EX 86400 ; in Postgres it's INSERT ... ON CONFLICT DO NOTHING with a row-count check. G

Day 0, 10:00 — your agent sends a demo follow-up. Day 2, 14:37 — the prospect replies with a question. Day 2, 14:39 — they send a second thought. Day 5 — silence, then a reply to something the agent said a week ago. Somewhere between day 0 and day 5, your process restarted twice and deployed once. A single send-and-forget email is easy. The timeline above is the actual job: a conversation spanning five exchanges over days, where the agent has to remember what it said, what it's waiting for, and where in the workflow it stands — across restarts, deploys, and hours of dead air. The multi-turn conversation recipe builds this loop on a Nylas Agent Account (the feature's in beta), running entirely on webhooks and the Threads API — no polling, no missed messages. State lives outside the model The core design decision: every active conversation gets a durable record keyed by the thread ID. const conversationRecord = { threadId : " nylas-thread-id " , grantId : AGENT_GRANT_ID , contactEmail : " prospect@example.com " , purpose : " demo_followup " , // What started this conversation step : " awaiting_reply " , // Where in the workflow we are turnCount : 1 , maxTurns : 10 , // Safety cap before escalation lastActivityAt : " 2026-04-14T10:00:00Z " , metadata : {}, }; The step field is the heart of it — a tiny state machine tracking what the agent is waiting for, which determines how the next inbound message gets handled. The store has to be durable (Postgres, Redis with AOF, DynamoDB); the gap between messages can be days, so in-memory state is a non-starter. Starting a conversation means sending the first message and persisting the record under the threadId the send returns: async function startConversation ({ to , subject , body , purpose , metadata }) { const sent = await nylas . messages . send ({ identifier : AGENT_GRANT_ID , requestBody : { to : [{ email : to . email , name : to . name }], subject , body , }, }); await db . conversations . create ({ threadId : sent . dat

Gaming handhelds are amazing. They make it so much easier to fit all kinds of games into my day. Sadly, they’re less affordable than they’ve ever been — due to an unprecedented, AI-fueled shortage of memory chips, an unforced oil crisis, rampant inflation, fallout from tariffs, and more. But that’s not going to stop you. […]

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It's intended for camping, but BougeRV's T1 light is so versatile that it also makes for a great summer travel companion that'll continue to light the dark corners of your life long after you return. I used it for a few months during a recent road trip in my camper van, and it's the light […]

Light up and secure your driveway, backyard, or porch with a floodlight security camera.