Events

const off = app.on('pageView', ({ ctx, page, params, mode }) => track(ctx.from?.id, page)); // returns an unsubscribe function

event	payload	when
update	{ ctx, durationMs, outcome }	an update went through bot.use(app). outcome: easytg (handled by a page, dialogue, menu…), next (passed to your handlers; the time includes them), limited / busy (dropped), error
pageView	{ ctx, page, params, mode: 'send' | 'edit', chatId?, userId?, durationMs }	a page was shown (after redirects); durationMs covers render and delivery
sent	{ ctx, chatId, messageIds, page? }	new messages were sent: all ids of a split page or an album, e.g. to delete them later
dialogueStart	{ ctx, dialogue, params }	a dialogue started
dialogueFinish	{ ctx, dialogue, params, answers }	a dialogue was completed
dialogueCancel	{ ctx, dialogue, params, answers, reason }	reason: user, command, replaced, app or timeout (see Dialogues)
spam	SpamEvent	see Anti-spam
error	{ error, ctx, source: 'update' | 'sendTo' | 'edit' }	an error while handling buttons, dialogue input, menu buttons, deep links, page text input or the payments handlers (source: 'update'), or in sendTo / edit with emitProactiveErrors; without a listener it is logged
queueWait	{ ctx?, queue, position? }	a job has to wait for a queue slot
taskError	{ error, task: { id, name, payload, attempts }, willRetry }	a scheduled task failed; without a listener it is logged
payment	{ ctx, payment, payload }	a payment succeeded (with the payments option)
webAppData	{ ctx, data, raw, button }	a Mini App opened from replyMenu.webApp sent data; see Mini Apps
broadcastBatch	{ broadcast, batch, batches, result }	a batch of broadcastLater was sent
relayMessage	{ ctx, from, to, messageId }	a message was copied to the other user of a relay
relayEnd	{ botId, users, reason: 'app' | 'unreachable', ctx? }	a relay ended; with unreachable, ctx is the sender's update

// Slow updates, e.g. for metrics:
app.on('update', ({ ctx, durationMs, outcome }) => durationMs > 1000 && log.warn(`slow ${outcome} update`, ctx.update.update_id));

Listeners run one after another and are awaited; an error thrown by a listener is logged and doesn't stop the others.