Function fetchNewEmails

apps/sim/lib/webhooks/polling/gmail.ts:148–253

(
  accessToken: string,
  config: GmailWebhookConfig,
  requestId: string,
  logger: Logger
)

}

async function fetchNewEmails(
  accessToken: string,
  config: GmailWebhookConfig,
  requestId: string,
  logger: Logger
) {
  try {
    const useHistoryApi = !!config.historyId
    let emails: GmailEmail[] = []
    let latestHistoryId = config.historyId

    if (useHistoryApi) {
      const messageIds = new Set<string>()
      let pageToken: string | undefined

      do {
        let historyUrl = `https://gmail.googleapis.com/gmail/v1/users/me/history?startHistoryId=${config.historyId}&historyTypes=messageAdded`
        if (pageToken) {
          historyUrl += `&pageToken=${pageToken}`
        }

        const historyResponse = await fetch(historyUrl, {
          headers: { Authorization: `Bearer ${accessToken}` },
        })

        if (!historyResponse.ok) {
          const status = historyResponse.status
          const errorData = await historyResponse.json().catch(() => ({}))
          logger.error(`[${requestId}] Gmail history API error:`, {
            status,
            statusText: historyResponse.statusText,
            error: errorData,
          })

          if (status === 403 || status === 429) {
            throw new Error(
              `Gmail API error ${status} — skipping to retry next poll cycle: ${JSON.stringify(errorData)}`
            )
          }

          logger.info(`[${requestId}] Falling back to search API after history API error ${status}`)
          const searchResult = await searchEmails(accessToken, config, requestId, logger)
          if (searchResult.emails.length === 0) {
            const freshHistoryId = await getGmailProfileHistoryId(accessToken, requestId, logger)
            if (freshHistoryId) {
              logger.info(
                `[${requestId}] Fetched fresh historyId ${freshHistoryId} after invalid historyId (was: ${config.historyId})`
              )
              return { emails: [], latestHistoryId: freshHistoryId }
            }
          }
          return searchResult
        }

        const historyData = await historyResponse.json()

        if (historyData.historyId) {
          latestHistoryId = historyData.historyId