Function toSessionStateResponse

web/src/server/free-session/session-view.ts:21–80

(params: {
  row: InternalSessionRow | null
  position: number
  /** Snapshot of every model's queue depth at response time. Only consumed
   *  by the `queued` variant — active/ended don't need the selector. */
  queueDepthByModel: Record<string, number>
  graceMs: number
  now: Date
})

 * `{ status: 'none' }` to the client.
 */
export function toSessionStateResponse(params: {
  row: InternalSessionRow | null
  position: number
  /** Snapshot of every model's queue depth at response time. Only consumed
   *  by the `queued` variant — active/ended don't need the selector. */
  queueDepthByModel: Record<string, number>
  graceMs: number
  now: Date
}): SessionStateResponse | null {
  const { row, position, queueDepthByModel, graceMs, now } = params
  if (!row) return null

  if (row.status === 'active' && row.expires_at) {
    const expiresAtMs = row.expires_at.getTime()
    const nowMs = now.getTime()
    if (expiresAtMs > nowMs) {
      return {
        status: 'active',
        accessTier: row.access_tier ?? 'full',
        instanceId: row.active_instance_id,
        model: row.model,
        admittedAt: (row.admitted_at ?? row.created_at).toISOString(),
        expiresAt: row.expires_at.toISOString(),
        remainingMs: expiresAtMs - nowMs,
        ...limitedModeReasonFromRow(row),
      }
    }
    const graceEndsMs = expiresAtMs + graceMs
    if (graceEndsMs > nowMs) {
      return {
        status: 'ended',
        accessTier: row.access_tier ?? 'full',
        instanceId: row.active_instance_id,
        admittedAt: (row.admitted_at ?? row.created_at).toISOString(),
        expiresAt: row.expires_at.toISOString(),
        gracePeriodEndsAt: new Date(graceEndsMs).toISOString(),
        gracePeriodRemainingMs: graceEndsMs - nowMs,
        ...limitedModeReasonFromRow(row),
      }
    }
  }

  if (row.status === 'queued') {
    return {
      status: 'queued',
      accessTier: row.access_tier ?? 'full',
      instanceId: row.active_instance_id,
      model: row.model,
      position,
      queueDepth: queueDepthByModel[row.model] ?? 0,
      queueDepthByModel,
      estimatedWaitMs: estimateWaitMs({ position }),
      queuedAt: row.queued_at.toISOString(),
      ...limitedModeReasonFromRow(row),
    }
  }

  // active row past the grace window — callers should treat as "no session" and re-queue