Retries and deduplication

// A unique constraint does the de-duplication atomically, across every
// instance of your app. Example table:
//   CREATE TABLE processed_webhook_events (
//     event_id text PRIMARY KEY,
//     message_key text UNIQUE  -- data.message_id + ':' + type, when present
//   );
import type { Pool } from "pg";

export async function isFirstDelivery(db: Pool, event: { id: string; type: string; data: { message_id?: string } }) {
  const messageKey = event.data.message_id ? `${event.data.message_id}:${event.type}` : null;
  const result = await db.query(
    "INSERT INTO processed_webhook_events (event_id, message_key) VALUES ($1, $2) ON CONFLICT DO NOTHING",
    [event.id, messageKey],
  );
  return result.rowCount === 1; // false: already seen, return 2xx and stop
}

# A unique constraint does the de-duplication atomically, across every
# instance of your app. Example table:
#   CREATE TABLE processed_webhook_events (
#     event_id text PRIMARY KEY,
#     message_key text UNIQUE  -- data.message_id + ':' + type, when present
#   );
def is_first_delivery(conn, event: dict) -> bool:
    message_id = event["data"].get("message_id")
    message_key = f"{message_id}:{event['type']}" if message_id else None
    with conn.cursor() as cur:
        cur.execute(
            "INSERT INTO processed_webhook_events (event_id, message_key) "
            "VALUES (%s, %s) ON CONFLICT DO NOTHING",
            (event["id"], message_key),
        )
        first = cur.rowcount == 1  # False: already seen, return 2xx and stop
    conn.commit()
    return first

import { listMessages } from "./list-messages"; // the loop from the Pagination page
import { isFirstDelivery } from "./webhook-dedup"; // from the section above
import { handleInbound } from "./handlers"; // what your message.inbound handler does
// Your own storage; replace these with your database calls.
import { db, getCheckpoint, saveCheckpoint, findMessage, saveMessage } from "./store";

const OVERLAP_MS = 5 * 60 * 1000;

export async function reconcile(): Promise<void> {
  // e.g. "2026-11-10T15:04:10.112730Z"; on the first run, look back 24 hours
  const checkpoint = await getCheckpoint();
  const from = checkpoint ? Date.parse(checkpoint) : Date.now() - 24 * 60 * 60 * 1000;
  const since = new Date(from - OVERLAP_MS).toISOString();

  let newest = checkpoint;
  for await (const message of listMessages({ created_after: since })) {
    const known = await findMessage(message.id);
    if (!known || known.status !== message.status) {
      await saveMessage(message); // new, or its status changed while you were away
    }
    if (message.direction === "inbound") {
      const first = await isFirstDelivery(db, {
        id: `reconcile:${message.id}`,
        type: "message.inbound",
        data: { message_id: message.id },
      });
      if (first) await handleInbound(message);
    }
    if (!newest || message.created_at > newest) newest = message.created_at;
  }
  if (newest) await saveCheckpoint(newest);
}

from datetime import datetime, timedelta, timezone

from handlers import handle_inbound  # what your message.inbound handler does
from list_messages import list_messages  # the loop from the Pagination page
from webhook_dedup import is_first_delivery  # from the section above

# Your own storage; replace these with your database calls.
from store import conn, find_message, get_checkpoint, save_checkpoint, save_message

OVERLAP = timedelta(minutes=5)


def reconcile():
    # e.g. "2026-11-10T15:04:10.112730Z"; on the first run, look back 24 hours
    checkpoint = get_checkpoint()
    if checkpoint:
        start = datetime.fromisoformat(checkpoint.replace("Z", "+00:00"))
    else:
        start = datetime.now(timezone.utc) - timedelta(hours=24)
    since = (start - OVERLAP).strftime("%Y-%m-%dT%H:%M:%S.%fZ")

    newest = checkpoint
    for message in list_messages(created_after=since):
        known = find_message(message["id"])
        if known is None or known["status"] != message["status"]:
            save_message(message)  # new, or its status changed while you were away
        if message["direction"] == "inbound":
            first = is_first_delivery(conn, {
                "id": f"reconcile:{message['id']}",
                "type": "message.inbound",
                "data": {"message_id": message["id"]},
            })
            if first:
                handle_inbound(message)
        if newest is None or message["created_at"] > newest:
            newest = message["created_at"]
    if newest:
        save_checkpoint(newest)