Ack bridged Matrix events

May provide reassurance that the bridge is currently working.
Half-Shot's bridge has always done this.

src/m2d/event-dispatcher.js

@@ -104,6 +104,7 @@ async event => {
 		// @ts-ignore
 		await matrixCommandHandler.execute(event)
 	}
+	await api.ackEvent(event)
 }))
 
 sync.addTemporaryListener(as, "type:m.sticker", guard("m.sticker",
@@ -113,6 +114,7 @@ sync.addTemporaryListener(as, "type:m.sticker", guard("m.sticker",
 async event => {
 	if (utils.eventSenderIsFromDiscord(event.sender)) return
 	const messageResponses = await sendEvent.sendEvent(event)
+	await api.ackEvent(event)
 }))
 
 sync.addTemporaryListener(as, "type:m.reaction", guard("m.reaction",
@@ -137,6 +139,7 @@ sync.addTemporaryListener(as, "type:m.room.redaction", guard("m.room.redaction",
 async event => {
 	if (utils.eventSenderIsFromDiscord(event.sender)) return
 	await redact.handle(event)
+	await api.ackEvent(event)
 }))
 
 sync.addTemporaryListener(as, "type:m.room.avatar", guard("m.room.avatar",

src/matrix/api.js

@@ -347,6 +347,26 @@ function getMedia(mxc, init = {}) {
 	})
 }
 
+/**
+ * Updates the m.read receipt in roomID to point to eventID.
+ * This doesn't modify m.fully_read, which matches [the behaviour of matrix-bot-sdk.](https://github.com/element-hq/matrix-bot-sdk/blob/e72a4c498e00c6c339a791630c45d00a351f56a8/src/MatrixClient.ts#L1227)
+ * @param {string} roomID
+ * @param {string} eventID
+ * @param {string?} [mxid]
+ */
+async function sendReadReceipt(roomID, eventID, mxid) {
+	await mreq.mreq("POST", path(`/client/v3/rooms/${roomID}/receipt/m.read/${eventID}`, mxid), {})
+}
+
+/**
+ * Acknowledge an event as read by calling api.sendReadReceipt on it.
+ * @param {Ty.Event.Outer<any>} event
+ * @param {string?} [mxid]
+ */
+async function ackEvent(event, mxid) {
+	await sendReadReceipt(event.room_id, event.event_id, mxid)
+}
+
 module.exports.path = path
 module.exports.register = register
 module.exports.createRoom = createRoom
@@ -373,3 +393,5 @@ module.exports.setUserPower = setUserPower
 module.exports.setUserPowerCascade = setUserPowerCascade
 module.exports.ping = ping
 module.exports.getMedia = getMedia
+module.exports.sendReadReceipt = sendReadReceipt
+module.exports.ackEvent = ackEvent