Function createTokenRefreshScheduler

src/bridge/jwtUtils.ts:73–257

({
  getAccessToken,
  onRefresh,
  label,
  refreshBufferMs = TOKEN_REFRESH_BUFFER_MS,
}: {
  getAccessToken: () => string | undefined | Promise<string | undefined>
  onRefresh: (sessionId: string) => void | Promise<void>
  label: string
  /** How long before expiry to fire refresh. Defaults to 5 min. */
  refreshBufferMs?: number
})

 * standalone bridge, WebSocket reconnect for the REPL bridge).
 */
export function createTokenRefreshScheduler({
  getAccessToken,
  onRefresh,
  label,
  refreshBufferMs = TOKEN_REFRESH_BUFFER_MS,
}: {
  getAccessToken: () => string | undefined | Promise<string | undefined>
  onRefresh: (sessionId: string) => void | Promise<void>
  label: string
  /** How long before expiry to fire refresh. Defaults to 5 min. */
  refreshBufferMs?: number
}): {
  schedule: (sessionId: string, token: string) => void
  scheduleFromExpiresIn: (sessionId: string, expiresInSeconds: number) => void
  cancel: (sessionId: string) => void
  cancelAll: () => void
} {
  const timers = new Map<string, ReturnType<typeof setTimeout>>()
  const failureCounts = new Map<string, number>()
  // Generation counter per session — incremented by schedule() and cancel()
  // so that in-flight async doRefresh() calls can detect when they've been
  // superseded and should skip setting follow-up timers.
  const generations = new Map<string, number>()

  function nextGeneration(sessionId: string): number {
    const gen = (generations.get(sessionId) ?? 0) + 1
    generations.set(sessionId, gen)
    return gen
  }

  function schedule(sessionId: string, token: string): void {
    const expiry = decodeJwtExpiry(token)
    if (!expiry) {
      // Token is not a decodable JWT (e.g. an OAuth token passed from the
      // REPL bridge WebSocket open handler).  Preserve any existing timer
      // (such as the follow-up refresh set by doRefresh) so the refresh
      // chain is not broken.
      logForDebugging(
        `[${label}:token] Could not decode JWT expiry for sessionId=${sessionId}, token prefix=${token.slice(0, 15)}…, keeping existing timer`,
      )
      return
    }

    // Clear any existing refresh timer — we have a concrete expiry to replace it.
    const existing = timers.get(sessionId)
    if (existing) {
      clearTimeout(existing)
    }

    // Bump generation to invalidate any in-flight async doRefresh.
    const gen = nextGeneration(sessionId)

    const expiryDate = new Date(expiry * 1000).toISOString()
    const delayMs = expiry * 1000 - Date.now() - refreshBufferMs
    if (delayMs <= 0) {
      logForDebugging(
        `[${label}:token] Token for sessionId=${sessionId} expires=${expiryDate} (past or within buffer), refreshing immediately`,
      )