param(
    [string]$ApiBaseUrl = "http://192.168.200.61:18121/api/v1",
    [string]$ClusterID = "cfc0743d-d960-49fb-9de8-96e063d5e4aa",
    [string]$ActorUserID = "f67d943f-5397-4b3a-a229-695fe67ad700",
    [string]$EntryNodeName = "test-1",
    [string]$ExitNodeName = "test-2",
    [string]$EntryBaseUrl = "http://192.168.200.61:19131",
    [string]$DockerSSH = "test-docker",
    [int]$InteractiveSessionCount = 2,
    [int]$InteractiveRounds = 24,
    [int]$InteractivePacketsPerBatch = 8,
    [int]$AbusivePacketCount = 1300,
    [int]$ExpectedAbusiveDelivered = 1024,
    [int]$BatchDelayMilliseconds = 25,
    [string]$RequiredNodeVersion = "0.2.183",
    [string]$ResultPath = "artifacts\c18z8-live-service-channel-backpressure-isolation-smoke-result.json"
)

Set-StrictMode -Version Latest
$ErrorActionPreference = "Stop"
Add-Type -AssemblyName System.Net.Http

$repoRoot = (Resolve-Path (Join-Path $PSScriptRoot "..\..")).ProviderPath
$runId = "c18z8-" + (Get-Date -Format "yyyyMMdd-HHmmss")
$resourceId = "vpn-$runId"

function Invoke-Api {
    param(
        [string]$Method,
        [string]$Path,
        [object]$Body = $null
    )
    $uri = "$ApiBaseUrl$Path"
    try {
        if ($null -eq $Body) {
            return Invoke-RestMethod -Method $Method -Uri $uri -TimeoutSec 30
        }
        return Invoke-RestMethod -Method $Method -Uri $uri -ContentType "application/json" -Body ($Body | ConvertTo-Json -Depth 80) -TimeoutSec 30
    }
    catch {
        $statusCode = $null
        if ($_.Exception.Response) {
            $statusCode = [int]$_.Exception.Response.StatusCode
        }
        $details = $_.ErrorDetails.Message
        if (-not $details) {
            $details = $_.Exception.Message
        }
        throw "$Method $Path failed with HTTP $statusCode`: $details"
    }
}

function Get-NodeByName {
    param([string]$Name)
    $nodes = (Invoke-Api -Method GET -Path "/clusters/$ClusterID/nodes?actor_user_id=$ActorUserID").nodes
    $node = @($nodes | Where-Object { $_.name -eq $Name }) | Select-Object -First 1
    if ($null -eq $node) {
        throw "Node '$Name' was not found in cluster $ClusterID"
    }
    return $node
}

function Get-MeshPort {
    param([string]$Name)
    switch ($Name) {
        "test-1" { return 19131 }
        "test-2" { return 19132 }
        "test-3" { return 19133 }
        default { return 19131 }
    }
}

function Enable-TestMeshListener {
    param([object]$Node)
    $port = Get-MeshPort -Name $Node.name
    Invoke-Api -Method PUT -Path "/clusters/$ClusterID/nodes/$($Node.id)/workloads/mesh-listener/desired" -Body @{
        actor_user_id = $ActorUserID
        desired_state = "enabled"
        runtime_mode = "container"
        version = "c18z8-live-fsc-backpressure-isolation"
        config = @{
            listen_addr = "0.0.0.0:$port"
            listen_port_mode = "manual"
            advertise_endpoint = "http://192.168.200.61:$port"
            advertise_transport = "direct_http"
            connectivity_mode = "private_lan"
            nat_type = "none"
            region = "docker-test"
            production_forwarding = $true
        }
        environment = @{}
    } | Out-Null
}

function Clear-OldSmokeRouteIntents {
    param(
        [string]$SourceNodeID,
        [string]$DestinationNodeID
    )
    $items = (Invoke-Api -Method GET -Path "/clusters/$ClusterID/mesh/route-intents?actor_user_id=$ActorUserID").route_intents
    foreach ($item in @($items)) {
        if ([string]$item.lifecycle_status -ne "active") {
            continue
        }
        if ([string]$item.service_class -ne "vpn_packets") {
            continue
        }
        if ([string]$item.source_selector.node_id -ne $SourceNodeID -or [string]$item.destination_selector.node_id -ne $DestinationNodeID) {
            continue
        }
        $smoke = ""
        if ($null -ne $item.policy -and $null -ne $item.policy.metadata) {
            $prop = $item.policy.metadata.PSObject.Properties["smoke"]
            if ($null -ne $prop) {
                $smoke = [string]$prop.Value
            }
        }
        if ($smoke -ne "c18z1_live_service_channel_ingress" -and $smoke -ne "c18z2_live_service_channel_soak" -and $smoke -ne "c18z3_live_service_channel_entry_ws_fallback" -and $smoke -ne "c18z4_live_service_channel_session_pressure" -and $smoke -ne "c18z5_live_service_channel_exit_restart" -and $smoke -ne "c18z6_live_service_channel_active_rebuild" -and $smoke -ne "c18z7_live_service_channel_concurrent_isolation" -and $smoke -ne "c18z8_live_service_channel_backpressure_isolation") {
            continue
        }
        Invoke-Api -Method POST -Path "/clusters/$ClusterID/mesh/route-intents/$($item.id)/expire" -Body @{ actor_user_id = $ActorUserID } | Out-Null
    }
}

function New-RouteIntent {
    param(
        [string]$SourceNodeID,
        [string]$DestinationNodeID,
        [int]$Priority,
        [string]$Label
    )
    $expiresAt = (Get-Date).ToUniversalTime().AddMinutes(10).ToString("o")
    return Invoke-Api -Method POST -Path "/clusters/$ClusterID/mesh/route-intents" -Body @{
        actor_user_id = $ActorUserID
        source_selector = @{ node_id = $SourceNodeID }
        destination_selector = @{ node_id = $DestinationNodeID }
        service_class = "vpn_packets"
        priority = $Priority
        policy = @{
            synthetic_enabled = $true
            route_version = "$runId-$Label"
            policy_version = "$runId-$Label"
            peer_directory_version = "$runId-$Label"
            hops = @($SourceNodeID, $DestinationNodeID)
            allowed_channels = @("vpn_packet", "fabric_control")
            max_ttl = 8
            max_hops = 8
            expires_at = $expiresAt
            metadata = @{
                smoke = "c18z8_live_service_channel_backpressure_isolation"
                run_id = $runId
                label = $Label
            }
        }
    }
}

function Get-SyntheticConfig {
    param([string]$NodeID)
    return Invoke-Api -Method GET -Path "/clusters/$ClusterID/nodes/$NodeID/mesh/synthetic-config?actor_user_id=$ActorUserID"
}

function Get-LatestHeartbeat {
    param([string]$NodeID)
    return (Invoke-Api -Method GET -Path "/clusters/$ClusterID/nodes/$NodeID/heartbeats?actor_user_id=$ActorUserID&limit=1").heartbeats[0]
}

function Get-LatestRuntimeReport {
    param([string]$NodeID)
    $hb = Get-LatestHeartbeat -NodeID $NodeID
    return @{
        heartbeat = $hb
        report = $hb.metadata.fabric_service_channel_runtime_report
    }
}

function Wait-ForRuntimeReady {
    param(
        [string]$NodeID,
        [int]$MinRoutes,
        [int]$TimeoutSeconds = 90
    )
    $deadline = (Get-Date).AddSeconds($TimeoutSeconds)
    do {
        $latest = Get-LatestRuntimeReport -NodeID $NodeID
        $report = $latest.report
        if ($null -ne $report -and
            $report.enabled -eq $true -and
            $report.production_payload_forwarding -eq $true -and
            [int]$report.route_candidate_total -ge $MinRoutes) {
            return $latest
        }
        Start-Sleep -Seconds 2
    } while ((Get-Date) -lt $deadline)
    throw "Timed out waiting for production service-channel runtime ready on node $NodeID"
}

function Wait-ForRuntimeConfigVersion {
    param(
        [string]$NodeID,
        [string]$ConfigVersion,
        [int]$TimeoutSeconds = 90
    )
    $deadline = (Get-Date).AddSeconds($TimeoutSeconds)
    do {
        $latest = Get-LatestRuntimeReport -NodeID $NodeID
        if ($null -ne $latest.report) {
            $loadedVersion = [string]$latest.report.config_version
            if ($loadedVersion -ge $ConfigVersion) {
                return $latest
            }
        }
        Start-Sleep -Seconds 2
    } while ((Get-Date) -lt $deadline)
    throw "Timed out waiting for node $NodeID to load synthetic config $ConfigVersion"
}

function Wait-ForRouteIntentVisible {
    param(
        [string]$NodeID,
        [string[]]$RouteIDs,
        [int]$TimeoutSeconds = 60
    )
    $deadline = (Get-Date).AddSeconds($TimeoutSeconds)
    do {
        $config = Get-SyntheticConfig -NodeID $NodeID
        $routes = @($config.synthetic_mesh_config.routes)
        $present = @($routes | Where-Object { $RouteIDs -contains $_.route_id })
        if ($present.Count -ge $RouteIDs.Count) {
            return $config
        }
        Start-Sleep -Seconds 2
    } while ((Get-Date) -lt $deadline)
    throw "Timed out waiting for routes '$($RouteIDs -join ",")' in synthetic config for node $NodeID"
}

function Wait-ForRouteIntentNotVisible {
    param(
        [string]$NodeID,
        [string]$RouteID,
        [int]$TimeoutSeconds = 90
    )
    $deadline = (Get-Date).AddSeconds($TimeoutSeconds)
    do {
        $config = Get-SyntheticConfig -NodeID $NodeID
        $routes = @($config.synthetic_mesh_config.routes)
        $present = @($routes | Where-Object { $_.route_id -eq $RouteID })
        if ($present.Count -eq 0) {
            return $config
        }
        Start-Sleep -Seconds 2
    } while ((Get-Date) -lt $deadline)
    throw "Timed out waiting for route '$RouteID' to disappear from synthetic config for node $NodeID"
}

function New-ServiceChannelLease {
    param(
        [string]$EntryNodeID,
        [string]$ExitNodeID,
        [string]$VPNResourceID = $resourceId
    )
    return (Invoke-Api -Method POST -Path "/clusters/$ClusterID/fabric/service-channels/leases" -Body @{
        actor_user_id = $ActorUserID
        organization_id = "org-c18z8-smoke"
        user_id = $ActorUserID
        resource_id = $VPNResourceID
        service_class = "vpn_packets"
        entry_node_ids = @($EntryNodeID)
        exit_node_ids = @($ExitNodeID)
        preferred_entry_node_id = $EntryNodeID
        preferred_exit_node_id = $ExitNodeID
        allowed_channels = @("vpn_packet", "bulk", "control")
        ttl_seconds = 300
        metadata = @{
            smoke = "c18z8_live_service_channel_backpressure_isolation"
            run_id = $runId
        }
    }).fabric_service_channel_lease
}

function ConvertTo-Base64UrlJson {
    param([object]$Value)
    $json = $Value | ConvertTo-Json -Depth 80 -Compress
    $bytes = [System.Text.Encoding]::UTF8.GetBytes($json)
    return [Convert]::ToBase64String($bytes).TrimEnd("=").Replace("+", "-").Replace("/", "_")
}

function Get-ObjectPropertyValue {
    param(
        [object]$Object,
        [string]$Name
    )
    if ($null -eq $Object) {
        return $null
    }
    $prop = $Object.PSObject.Properties[$Name]
    if ($null -eq $prop) {
        return $null
    }
    return $prop.Value
}

function New-TestIPv4UDPPacket {
    param([int]$SourcePort)
    $payload = [System.Text.Encoding]::ASCII.GetBytes("c18z1-$SourcePort")
    $totalLength = 20 + 8 + $payload.Length
    $packet = New-Object byte[] $totalLength
    $packet[0] = 0x45
    $packet[1] = 0
    $packet[2] = [byte](($totalLength -shr 8) -band 0xff)
    $packet[3] = [byte]($totalLength -band 0xff)
    $packet[8] = 64
    $packet[9] = 17
    $packet[12] = 10; $packet[13] = 18; $packet[14] = 1; $packet[15] = 10
    $packet[16] = 10; $packet[17] = 18; $packet[18] = 2; $packet[19] = 20
    $udpOffset = 20
    $destPort = 3389
    $udpLength = 8 + $payload.Length
    $packet[$udpOffset] = [byte](($SourcePort -shr 8) -band 0xff)
    $packet[$udpOffset + 1] = [byte]($SourcePort -band 0xff)
    $packet[$udpOffset + 2] = [byte](($destPort -shr 8) -band 0xff)
    $packet[$udpOffset + 3] = [byte]($destPort -band 0xff)
    $packet[$udpOffset + 4] = [byte](($udpLength -shr 8) -band 0xff)
    $packet[$udpOffset + 5] = [byte]($udpLength -band 0xff)
    [Array]::Copy($payload, 0, $packet, 28, $payload.Length)
    return $packet
}

function New-TestIPv4UDPPacketBatch {
    param(
        [int]$SourcePort,
        [int]$Count
    )
    $packets = @()
    for ($i = 0; $i -lt $Count; $i++) {
        $packets += ,(New-TestIPv4UDPPacket -SourcePort $SourcePort)
    }
    return $packets
}

function New-PacketBatchBody {
    param([byte[][]]$Packets)
    $stream = [System.IO.MemoryStream]::new()
    foreach ($packet in $Packets) {
        $length = $packet.Length
        $stream.WriteByte([byte](($length -shr 24) -band 0xff))
        $stream.WriteByte([byte](($length -shr 16) -band 0xff))
        $stream.WriteByte([byte](($length -shr 8) -band 0xff))
        $stream.WriteByte([byte]($length -band 0xff))
        $stream.Write($packet, 0, $packet.Length)
    }
    return $stream.ToArray()
}

function Read-PacketBatchBody {
    param([byte[]]$Body)
    $packets = @()
    $offset = 0
    while (($offset + 4) -le $Body.Length) {
        $length = ([int]$Body[$offset] -shl 24) -bor ([int]$Body[$offset + 1] -shl 16) -bor ([int]$Body[$offset + 2] -shl 8) -bor [int]$Body[$offset + 3]
        $offset += 4
        if ($length -lt 0 -or ($offset + $length) -gt $Body.Length) {
            throw "Malformed packet batch body: length=$length offset=$offset body_length=$($Body.Length)"
        }
        $packet = New-Object byte[] $length
        [Array]::Copy($Body, $offset, $packet, 0, $length)
        $packets += ,$packet
        $offset += $length
    }
    if ($offset -ne $Body.Length) {
        throw "Malformed packet batch body: trailing_bytes=$($Body.Length - $offset)"
    }
    return $packets
}

function Receive-ExitServiceChannelPacketBatch {
    param(
        [string]$VPNResourceID,
        [int]$TimeoutMilliseconds = 5000
    )
    $exitBaseUrl = "http://192.168.200.61:$(Get-MeshPort -Name $ExitNodeName)"
    $url = "$exitBaseUrl/api/v1/clusters/$ClusterID/vpn-connections/$VPNResourceID/tunnel/client/packets?batch=true&timeout_ms=$TimeoutMilliseconds"
    $client = [System.Net.Http.HttpClient]::new()
    try {
        $client.Timeout = [TimeSpan]::FromSeconds([Math]::Max(10, [Math]::Ceiling($TimeoutMilliseconds / 1000) + 5))
        $response = $client.GetAsync($url).GetAwaiter().GetResult()
        if ([int]$response.StatusCode -eq 204) {
            return @()
        }
        $body = $response.Content.ReadAsByteArrayAsync().GetAwaiter().GetResult()
        if (-not $response.IsSuccessStatusCode) {
            $message = [System.Text.Encoding]::UTF8.GetString($body)
            throw "Exit service-channel GET $url failed with HTTP $([int]$response.StatusCode): $message"
        }
        return @(Read-PacketBatchBody -Body $body)
    }
    finally {
        $client.Dispose()
    }
}

function Invoke-ServiceChannelPost {
    param(
        [object]$Lease,
        [int]$PortStart,
        [string]$VPNResourceID = $resourceId
    )
    $packets = @()
    for ($i = 0; $i -lt 8; $i++) {
        $packets += ,(New-TestIPv4UDPPacket -SourcePort ($PortStart + $i))
    }
    $path = $Lease.entry_http.path_template.
        Replace("{cluster_id}", $ClusterID).
        Replace("{channel_id}", $Lease.channel_id).
        Replace("{resource_id}", $VPNResourceID)
    $url = "$EntryBaseUrl$path`?batch=true"
    $headers = @{
        "X-RAP-Service-Channel-Token" = $Lease.token.token
        "X-RAP-Fabric-Channel-ID" = $Lease.channel_id
        "X-RAP-Service-Class" = "vpn_packets"
        "X-RAP-Channel-Class" = "vpn_packet"
        "X-RAP-Service-Channel-Authority-Payload" = ConvertTo-Base64UrlJson -Value $Lease.authority_payload
        "X-RAP-Service-Channel-Authority-Signature" = ConvertTo-Base64UrlJson -Value $Lease.authority_signature
    }
    $body = New-PacketBatchBody -Packets $packets
    $client = [System.Net.Http.HttpClient]::new()
    try {
        $client.Timeout = [TimeSpan]::FromSeconds(30)
        $request = [System.Net.Http.HttpRequestMessage]::new([System.Net.Http.HttpMethod]::Post, $url)
        foreach ($header in $headers.GetEnumerator()) {
            [void]$request.Headers.TryAddWithoutValidation($header.Key, [string]$header.Value)
        }
        $content = [System.Net.Http.ByteArrayContent]::new($body)
        $content.Headers.ContentType = [System.Net.Http.Headers.MediaTypeHeaderValue]::Parse("application/vnd.rap.vpn-packet-batch.v1")
        $request.Content = $content
        $response = $client.SendAsync($request).GetAwaiter().GetResult()
        $responseBody = $response.Content.ReadAsStringAsync().GetAwaiter().GetResult()
        if (-not $response.IsSuccessStatusCode) {
            throw "Service-channel POST $url failed with HTTP $([int]$response.StatusCode): $responseBody"
        }
        return [pscustomobject]@{
            StatusCode = [int]$response.StatusCode
            Body = $responseBody
        }
    }
    finally {
        $client.Dispose()
    }
}

function Get-IngressSendPackets {
    param([string]$NodeID)
    $latest = Get-LatestRuntimeReport -NodeID $NodeID
    $ingress = $latest.report.ingress
    $sendPackets = Get-ObjectPropertyValue -Object $ingress -Name "send_packets"
    if ($null -eq $sendPackets) {
        return 0
    }
    return [int]$sendPackets
}

function Get-IngressRouteFailures {
    param([string]$NodeID)
    $latest = Get-LatestRuntimeReport -NodeID $NodeID
    $ingress = $latest.report.ingress
    $failures = Get-ObjectPropertyValue -Object $ingress -Name "send_route_failures"
    if ($null -eq $failures) {
        return 0
    }
    return [int]$failures
}

function Get-IngressFlowDropped {
    param([string]$NodeID)
    $latest = Get-LatestRuntimeReport -NodeID $NodeID
    $ingress = $latest.report.ingress
    if ($null -eq $ingress) {
        return 0
    }
    $flowScheduler = Get-ObjectPropertyValue -Object $ingress -Name "flow_scheduler"
    if ($null -eq $flowScheduler) {
        return 0
    }
    $dropped = Get-ObjectPropertyValue -Object $flowScheduler -Name "dropped"
    if ($null -eq $dropped) {
        return 0
    }
    return [int]$dropped
}

function Get-ExitQueueDepth {
    param(
        [string]$NodeID,
        [string]$VPNConnectionID
    )
    $latest = Get-LatestRuntimeReport -NodeID $NodeID
    $queueKey = "$VPNConnectionID`:client_to_gateway"
    $depths = $latest.report.inbox.queue_depths
    if ($null -eq $depths) {
        return 0
    }
    $prop = $depths.PSObject.Properties[$queueKey]
    if ($null -eq $prop) {
        return 0
    }
    return [int]$prop.Value
}

function Wait-ForExitQueueDepth {
    param(
        [string]$NodeID,
        [string]$VPNConnectionID,
        [int]$MinDepth,
        [int]$TimeoutSeconds = 90
    )
    $deadline = (Get-Date).AddSeconds($TimeoutSeconds)
    do {
        $depth = Get-ExitQueueDepth -NodeID $NodeID -VPNConnectionID $VPNConnectionID
        if ($depth -ge $MinDepth) {
            return $depth
        }
        Start-Sleep -Seconds 2
    } while ((Get-Date) -lt $deadline)
    throw "Timed out waiting for exit queue depth >= $MinDepth on node $NodeID"
}

function Invoke-ServiceChannelPostSafe {
    param(
        [object]$Lease,
        [int]$PortStart,
        [string]$VPNResourceID = $resourceId
    )
    try {
        $response = Invoke-ServiceChannelPost -Lease $Lease -PortStart $PortStart -VPNResourceID $VPNResourceID
        return [pscustomobject]@{
            ok = $true
            status_code = [int]$response.StatusCode
            error = ""
        }
    }
    catch {
        return [pscustomobject]@{
            ok = $false
            status_code = 0
            error = $_.Exception.Message
        }
    }
}

function ConvertTo-WebSocketURL {
    param([string]$URL)
    if ($URL.StartsWith("https://")) {
        return "wss://" + $URL.Substring("https://".Length)
    }
    if ($URL.StartsWith("http://")) {
        return "ws://" + $URL.Substring("http://".Length)
    }
    return $URL
}

function Invoke-ServiceChannelWebSocketSend {
    param(
        [object]$Lease,
        [int]$PortStart,
        [string]$VPNResourceID = $resourceId
    )
    $packets = @()
    for ($i = 0; $i -lt 8; $i++) {
        $packets += ,(New-TestIPv4UDPPacket -SourcePort ($PortStart + $i))
    }
    $path = $Lease.entry_http.websocket_path_template.
        Replace("{cluster_id}", $ClusterID).
        Replace("{channel_id}", $Lease.channel_id).
        Replace("{resource_id}", $VPNResourceID)
    $url = ConvertTo-WebSocketURL -URL "$EntryBaseUrl$path"
    $socket = [System.Net.WebSockets.ClientWebSocket]::new()
    $cts = [System.Threading.CancellationTokenSource]::new([TimeSpan]::FromSeconds(20))
    try {
        $null = $socket.Options.SetRequestHeader("X-RAP-Service-Channel-Token", [string]$Lease.token.token)
        $null = $socket.Options.SetRequestHeader("X-RAP-Fabric-Channel-ID", [string]$Lease.channel_id)
        $null = $socket.Options.SetRequestHeader("X-RAP-Service-Class", "vpn_packets")
        $null = $socket.Options.SetRequestHeader("X-RAP-Channel-Class", "vpn_packet")
        $null = $socket.Options.SetRequestHeader("X-RAP-Service-Channel-Authority-Payload", (ConvertTo-Base64UrlJson -Value $Lease.authority_payload))
        $null = $socket.Options.SetRequestHeader("X-RAP-Service-Channel-Authority-Signature", (ConvertTo-Base64UrlJson -Value $Lease.authority_signature))
        $null = $socket.ConnectAsync([Uri]$url, $cts.Token).GetAwaiter().GetResult()
        $body = New-PacketBatchBody -Packets $packets
        $segment = [ArraySegment[byte]]::new($body)
        $null = $socket.SendAsync($segment, [System.Net.WebSockets.WebSocketMessageType]::Binary, $true, $cts.Token).GetAwaiter().GetResult()
        Start-Sleep -Milliseconds 300
        if ($socket.State -eq [System.Net.WebSockets.WebSocketState]::Open) {
            $null = $socket.CloseOutputAsync([System.Net.WebSockets.WebSocketCloseStatus]::NormalClosure, "c18z8 sent", $cts.Token).GetAwaiter().GetResult()
        }
        return [pscustomobject]@{
            ok = $true
            url = $url
            sent_packets = $packets.Count
            state = [string]$socket.State
            error = ""
        }
    }
    catch {
        return [pscustomobject]@{
            ok = $false
            url = $url
            sent_packets = 0
            state = [string]$socket.State
            error = $_.Exception.Message
        }
    }
    finally {
        $socket.Dispose()
        $cts.Dispose()
    }
}

function Invoke-ServiceChannelWebSocketPressure {
    param(
        [object]$Lease,
        [int]$PortStart,
        [int]$PreSwitchBatches,
        [int]$PostSwitchBatches,
        [int]$PacketsInBatch,
        [int]$DelayMilliseconds,
        [scriptblock]$AfterPreSwitchAction,
        [string]$VPNResourceID = $resourceId
    )
    $path = $Lease.entry_http.websocket_path_template.
        Replace("{cluster_id}", $ClusterID).
        Replace("{channel_id}", $Lease.channel_id).
        Replace("{resource_id}", $VPNResourceID)
    $url = ConvertTo-WebSocketURL -URL "$EntryBaseUrl$path"
    $socket = [System.Net.WebSockets.ClientWebSocket]::new()
    $cts = [System.Threading.CancellationTokenSource]::new([TimeSpan]::FromSeconds(120))
    $sentBatches = 0
    $sentPackets = 0
    $switchActionRan = $false
    try {
        $null = $socket.Options.SetRequestHeader("X-RAP-Service-Channel-Token", [string]$Lease.token.token)
        $null = $socket.Options.SetRequestHeader("X-RAP-Fabric-Channel-ID", [string]$Lease.channel_id)
        $null = $socket.Options.SetRequestHeader("X-RAP-Service-Class", "vpn_packets")
        $null = $socket.Options.SetRequestHeader("X-RAP-Channel-Class", "vpn_packet")
        $null = $socket.Options.SetRequestHeader("X-RAP-Service-Channel-Authority-Payload", (ConvertTo-Base64UrlJson -Value $Lease.authority_payload))
        $null = $socket.Options.SetRequestHeader("X-RAP-Service-Channel-Authority-Signature", (ConvertTo-Base64UrlJson -Value $Lease.authority_signature))
        $null = $socket.ConnectAsync([Uri]$url, $cts.Token).GetAwaiter().GetResult()

        $totalBatches = $PreSwitchBatches + $PostSwitchBatches
        for ($batch = 0; $batch -lt $totalBatches; $batch++) {
            if ($batch -eq $PreSwitchBatches -and $null -ne $AfterPreSwitchAction) {
                & $AfterPreSwitchAction
                $switchActionRan = $true
            }
            $packets = @()
            for ($i = 0; $i -lt $PacketsInBatch; $i++) {
                $packets += ,(New-TestIPv4UDPPacket -SourcePort ($PortStart + ($batch * 100) + $i))
            }
            $body = New-PacketBatchBody -Packets $packets
            $segment = [ArraySegment[byte]]::new($body)
            $null = $socket.SendAsync($segment, [System.Net.WebSockets.WebSocketMessageType]::Binary, $true, $cts.Token).GetAwaiter().GetResult()
            $sentBatches++
            $sentPackets += $packets.Count
            if ($DelayMilliseconds -gt 0) {
                Start-Sleep -Milliseconds $DelayMilliseconds
            }
        }
        Start-Sleep -Milliseconds 500
        if ($socket.State -eq [System.Net.WebSockets.WebSocketState]::Open) {
            $null = $socket.CloseOutputAsync([System.Net.WebSockets.WebSocketCloseStatus]::NormalClosure, "c18z8 sent", $cts.Token).GetAwaiter().GetResult()
        }
        return [pscustomobject]@{
            ok = $true
            url = $url
            sent_batches = $sentBatches
            sent_packets = $sentPackets
            switch_action_ran = $switchActionRan
            state = [string]$socket.State
            error = ""
        }
    }
    catch {
        return [pscustomobject]@{
            ok = $false
            url = $url
            sent_batches = $sentBatches
            sent_packets = $sentPackets
            switch_action_ran = $switchActionRan
            state = [string]$socket.State
            error = $_.Exception.Message
        }
    }
    finally {
        $socket.Dispose()
        $cts.Dispose()
    }
}

function Open-ServiceChannelWebSocket {
    param(
        [object]$Lease,
        [string]$VPNResourceID
    )
    $path = $Lease.entry_http.websocket_path_template.
        Replace("{cluster_id}", $ClusterID).
        Replace("{channel_id}", $Lease.channel_id).
        Replace("{resource_id}", $VPNResourceID)
    $url = ConvertTo-WebSocketURL -URL "$EntryBaseUrl$path"
    $socket = [System.Net.WebSockets.ClientWebSocket]::new()
    $cts = [System.Threading.CancellationTokenSource]::new([TimeSpan]::FromSeconds(180))
    $null = $socket.Options.SetRequestHeader("X-RAP-Service-Channel-Token", [string]$Lease.token.token)
    $null = $socket.Options.SetRequestHeader("X-RAP-Fabric-Channel-ID", [string]$Lease.channel_id)
    $null = $socket.Options.SetRequestHeader("X-RAP-Service-Class", "vpn_packets")
    $null = $socket.Options.SetRequestHeader("X-RAP-Channel-Class", "vpn_packet")
    $null = $socket.Options.SetRequestHeader("X-RAP-Service-Channel-Authority-Payload", (ConvertTo-Base64UrlJson -Value $Lease.authority_payload))
    $null = $socket.Options.SetRequestHeader("X-RAP-Service-Channel-Authority-Signature", (ConvertTo-Base64UrlJson -Value $Lease.authority_signature))
    $null = $socket.ConnectAsync([Uri]$url, $cts.Token).GetAwaiter().GetResult()
    return [pscustomobject]@{
        lease = $Lease
        resource_id = $VPNResourceID
        socket = $socket
        cts = $cts
        url = $url
        sent_batches = 0
        sent_packets = 0
        error = ""
    }
}

function Send-ServiceChannelWebSocketBatch {
    param(
        [object]$Session,
        [int]$PortStart,
        [int]$PacketsInBatch
    )
    $packets = @()
    for ($i = 0; $i -lt $PacketsInBatch; $i++) {
        $packets += ,(New-TestIPv4UDPPacket -SourcePort ($PortStart + $i))
    }
    $body = New-PacketBatchBody -Packets $packets
    $segment = [ArraySegment[byte]]::new($body)
    $null = $Session.socket.SendAsync($segment, [System.Net.WebSockets.WebSocketMessageType]::Binary, $true, $Session.cts.Token).GetAwaiter().GetResult()
    $Session.sent_batches = [int]$Session.sent_batches + 1
    $Session.sent_packets = [int]$Session.sent_packets + $packets.Count
}

function Send-ServiceChannelWebSocketPacketBatch {
    param(
        [object]$Session,
        [byte[][]]$Packets
    )
    $body = New-PacketBatchBody -Packets $Packets
    $segment = [ArraySegment[byte]]::new($body)
    $null = $Session.socket.SendAsync($segment, [System.Net.WebSockets.WebSocketMessageType]::Binary, $true, $Session.cts.Token).GetAwaiter().GetResult()
    $Session.sent_batches = [int]$Session.sent_batches + 1
    $Session.sent_packets = [int]$Session.sent_packets + $Packets.Count
}

function Close-ServiceChannelWebSocket {
    param([object]$Session)
    if ($null -eq $Session) {
        return
    }
    try {
        if ($null -ne $Session.socket -and $Session.socket.State -eq [System.Net.WebSockets.WebSocketState]::Open) {
            $null = $Session.socket.CloseOutputAsync([System.Net.WebSockets.WebSocketCloseStatus]::NormalClosure, "c18z8 sent", $Session.cts.Token).GetAwaiter().GetResult()
        }
    }
    catch {}
    try {
        if ($null -ne $Session.socket) {
            $Session.socket.Dispose()
        }
    }
    catch {}
    try {
        if ($null -ne $Session.cts) {
            $Session.cts.Dispose()
        }
    }
    catch {}
}

function Send-BatchSeries {
    param(
        [object]$Lease,
        [int]$Count,
        [int]$PortBase,
        [int]$DelayMilliseconds = 100,
        [string]$VPNResourceID = $resourceId
    )
    $results = @()
    for ($i = 0; $i -lt $Count; $i++) {
        $results += Invoke-ServiceChannelPostSafe -Lease $Lease -PortStart ($PortBase + ($i * 100)) -VPNResourceID $VPNResourceID
        if ($DelayMilliseconds -gt 0) {
            Start-Sleep -Milliseconds $DelayMilliseconds
        }
    }
    return $results
}

function Invoke-RemoteDocker {
    param([string]$Command)
    & ssh $DockerSSH $Command
    if ($LASTEXITCODE -ne 0) {
        throw "ssh $DockerSSH command failed: $Command"
    }
}

function Stop-TestUpdaters {
    Invoke-RemoteDocker -Command "docker stop rap_host_agent_updater_test-1 rap_host_agent_updater_test-2 rap_host_agent_updater_test-3 >/dev/null 2>&1 || true"
}

function Start-TestUpdaters {
    Invoke-RemoteDocker -Command "docker start rap_host_agent_updater_test-1 rap_host_agent_updater_test-2 rap_host_agent_updater_test-3 >/dev/null 2>&1 || true"
}

function Restart-ExitContainer {
    param([string]$Name)
    $containerName = "rap_test_node_" + $Name.Replace("-", "_")
    Invoke-RemoteDocker -Command "docker restart $containerName >/dev/null"
}

function Restart-NodeContainer {
    param([string]$Name)
    $containerName = "rap_test_node_" + $Name.Replace("-", "_")
    Invoke-RemoteDocker -Command "docker restart $containerName >/dev/null"
}

function Get-BackendClientGatewayDepth {
    param([string]$VPNConnectionID)
    $stats = (Invoke-Api -Method GET -Path "/clusters/$ClusterID/vpn-connections/$VPNConnectionID/tunnel/stats").vpn_packet_stats
    $queue = $stats.client_to_gateway
    if ($null -eq $queue) {
        return 0
    }
    $depthProp = $queue.PSObject.Properties["queue_depth"]
    if ($null -eq $depthProp) {
        return 0
    }
    return [int]$depthProp.Value
}

function Wait-ForIngressRoute {
    param(
        [string]$NodeID,
        [string]$RouteID,
        [int]$MinSendPackets,
        [int]$TimeoutSeconds = 45
    )
    $deadline = (Get-Date).AddSeconds($TimeoutSeconds)
    do {
        $latest = Get-LatestRuntimeReport -NodeID $NodeID
        $ingress = $latest.report.ingress
        $sendPackets = Get-ObjectPropertyValue -Object $ingress -Name "send_packets"
        $selectedRoute = Get-ObjectPropertyValue -Object $ingress -Name "last_selected_route_id"
        if ($null -ne $ingress -and
            [int]$sendPackets -ge $MinSendPackets -and
            [string]$selectedRoute -eq $RouteID) {
            return $latest
        }
        Start-Sleep -Seconds 2
    } while ((Get-Date) -lt $deadline)
    throw "Timed out waiting for ingress telemetry route=$RouteID packets>=$MinSendPackets on node $NodeID"
}

function Wait-ForIngressAnyRoute {
    param(
        [string]$NodeID,
        [string[]]$RouteIDs,
        [int]$MinSendPackets,
        [int]$TimeoutSeconds = 45
    )
    $deadline = (Get-Date).AddSeconds($TimeoutSeconds)
    do {
        $latest = Get-LatestRuntimeReport -NodeID $NodeID
        $ingress = $latest.report.ingress
        $sendPackets = Get-ObjectPropertyValue -Object $ingress -Name "send_packets"
        $selectedRoute = Get-ObjectPropertyValue -Object $ingress -Name "last_selected_route_id"
        if ($null -ne $ingress -and
            [int]$sendPackets -ge $MinSendPackets -and
            $RouteIDs -contains [string]$selectedRoute) {
            return $latest
        }
        Start-Sleep -Seconds 2
    } while ((Get-Date) -lt $deadline)
    throw "Timed out waiting for ingress telemetry routes='$($RouteIDs -join ",")' packets>=$MinSendPackets on node $NodeID"
}

function Wait-ForExitInbox {
    param(
        [string]$NodeID,
        [string]$VPNConnectionID,
        [int]$TimeoutSeconds = 45
    )
    $queueKey = "$VPNConnectionID`:client_to_gateway"
    $deadline = (Get-Date).AddSeconds($TimeoutSeconds)
    do {
        $latest = Get-LatestRuntimeReport -NodeID $NodeID
        $depths = $latest.report.inbox.queue_depths
        if ($null -ne $depths) {
            $prop = $depths.PSObject.Properties[$queueKey]
            if ($null -ne $prop -and [int]$prop.Value -gt 0) {
                return $latest
            }
        }
        Start-Sleep -Seconds 2
    } while ((Get-Date) -lt $deadline)
    throw "Timed out waiting for exit inbox queue '$queueKey' on node $NodeID"
}

function Send-FeedbackHeartbeat {
    param(
        [string]$EntryNodeID,
        [string]$BadRouteID,
        [string]$GoodRouteID
    )
    return Invoke-Api -Method POST -Path "/clusters/$ClusterID/nodes/$EntryNodeID/heartbeats" -Body @{
        health_status = "healthy"
        reported_version = $RequiredNodeVersion
        capabilities = @{
            native_node_agent = $true
            fabric_service_channel_runtime = $true
            fabric_service_channel_route_manager = $true
            smoke_feedback_injection = "c18z8"
        }
        service_states = @{ smoke = "c18z8_backpressure_isolation_feedback" }
        metadata = @{
            fabric_service_channel_runtime_report = @{
                schema_version = "c18l.fabric_service_channel_runtime_report.v1"
                ingress = @{
                    flow_scheduler = @{
                        channel_stats = @{
                            "c18z8-backpressure-isolation-flow" = @{
                                last_route_id = $GoodRouteID
                                last_failed_route_id = $BadRouteID
                                last_error = "c18z8 forced stale route during backpressure isolation smoke"
                                consecutive_failures = 3
                                stall_count = 1
                                last_send_duration_ms = 250
                                route_rebuild_recommended = $true
                                degraded_fallback_recommended = $false
                            }
                        }
                    }
                }
            }
            smoke = @{
                name = "c18z8_live_service_channel_backpressure_isolation"
                run_id = $runId
            }
        }
    }
}

function Wait-ForConfigDecision {
    param(
        [string]$NodeID,
        [string]$BadRouteID,
        [string]$ExpectedReplacementID,
        [int]$TimeoutSeconds = 60
    )
    $deadline = (Get-Date).AddSeconds($TimeoutSeconds)
    do {
        $config = Get-SyntheticConfig -NodeID $NodeID
        $decisions = @($config.synthetic_mesh_config.route_path_decisions.decisions)
        $decision = @($decisions | Where-Object {
            $_.route_id -eq $BadRouteID -and
            $_.rebuild_status -eq "applied" -and
            $_.replacement_route_id -eq $ExpectedReplacementID
        }) | Select-Object -First 1
        if ($null -ne $decision) {
            return @{
                config = $config
                decision = $decision
            }
        }
        Start-Sleep -Seconds 2
    } while ((Get-Date) -lt $deadline)
    throw "Timed out waiting for applied rebuild decision $BadRouteID -> $ExpectedReplacementID"
}

function Wait-ForAppliedRebuildTransition {
    param(
        [string]$NodeID,
        [string]$BadRouteID = "",
        [string]$ReplacementRouteID = "",
        [int]$TimeoutSeconds = 90
    )
    $deadline = (Get-Date).AddSeconds($TimeoutSeconds)
    do {
        $latest = Get-LatestRuntimeReport -NodeID $NodeID
        $transition = $null
        if ($null -ne $latest.report -and $null -ne $latest.report.ingress) {
            $prop = $latest.report.ingress.PSObject.Properties["route_manager_transition"]
            if ($null -ne $prop) {
                $transition = $prop.Value
            }
        }
        if ($null -ne $transition -and [string]$transition.status -eq "applied_rebuild") {
            return $latest
        }
        if ($BadRouteID -ne "" -and $ReplacementRouteID -ne "") {
            Send-FeedbackHeartbeat -EntryNodeID $NodeID -BadRouteID $BadRouteID -GoodRouteID $ReplacementRouteID | Out-Null
        }
        Start-Sleep -Seconds 2
    } while ((Get-Date) -lt $deadline)
    throw "Timed out waiting for node route-manager transition applied_rebuild on node $NodeID"
}

$entryNode = Get-NodeByName -Name $EntryNodeName
$exitNode = Get-NodeByName -Name $ExitNodeName
$primaryRouteID = ""
$alternateRouteID = ""
$updatersStopped = $false
$sessions = @()
$result = $null

try {
    Stop-TestUpdaters
    $updatersStopped = $true

    Enable-TestMeshListener -Node $entryNode
    Enable-TestMeshListener -Node $exitNode
    Clear-OldSmokeRouteIntents -SourceNodeID $entryNode.id -DestinationNodeID $exitNode.id

    $primaryIntent = New-RouteIntent -SourceNodeID $entryNode.id -DestinationNodeID $exitNode.id -Priority 2000000000 -Label "primary"
    $alternateIntent = New-RouteIntent -SourceNodeID $entryNode.id -DestinationNodeID $exitNode.id -Priority 1999999999 -Label "alternate"
    $primaryRouteID = $primaryIntent.route_intent.id
    $alternateRouteID = $alternateIntent.route_intent.id
    $routeIDs = @($primaryRouteID, $alternateRouteID)

    $visibleConfig = Wait-ForRouteIntentVisible -NodeID $entryNode.id -RouteIDs $routeIDs
    $exitVisibleConfig = Wait-ForRouteIntentVisible -NodeID $exitNode.id -RouteIDs $routeIDs
    $readyBefore = Wait-ForRuntimeReady -NodeID $entryNode.id -MinRoutes 2
    $exitReadyBefore = Wait-ForRuntimeReady -NodeID $exitNode.id -MinRoutes 0
    $loadedConfig = Wait-ForRuntimeConfigVersion -NodeID $entryNode.id -ConfigVersion $visibleConfig.synthetic_mesh_config.config_version
    $exitLoadedConfig = Wait-ForRuntimeConfigVersion -NodeID $exitNode.id -ConfigVersion $exitVisibleConfig.synthetic_mesh_config.config_version

    $baselineSendPackets = Get-IngressSendPackets -NodeID $entryNode.id
    $baselineRouteFailures = Get-IngressRouteFailures -NodeID $entryNode.id
    $baselineDropped = Get-IngressFlowDropped -NodeID $entryNode.id
    $baselineFlowScheduler = $readyBefore.report.ingress.flow_scheduler

    $sessionSpecs = @()
    $abusiveResourceID = "$resourceId-abusive"
    $abusiveLease = New-ServiceChannelLease -EntryNodeID $entryNode.id -ExitNodeID $exitNode.id -VPNResourceID $abusiveResourceID
    if ($abusiveLease.status -ne "ready") {
        throw "Lease status for abusive session was '$($abusiveLease.status)', want ready"
    }
    $sessionSpecs += [pscustomobject]@{
        kind = "abusive"
        index = 0
        resource_id = $abusiveResourceID
        lease = $abusiveLease
        baseline_exit_depth = Get-ExitQueueDepth -NodeID $exitNode.id -VPNConnectionID $abusiveResourceID
        baseline_backend_depth = Get-BackendClientGatewayDepth -VPNConnectionID $abusiveResourceID
        expected_packets = $ExpectedAbusiveDelivered
    }

    for ($index = 0; $index -lt $InteractiveSessionCount; $index++) {
        $sessionResourceID = "$resourceId-i$($index + 1)"
        $lease = New-ServiceChannelLease -EntryNodeID $entryNode.id -ExitNodeID $exitNode.id -VPNResourceID $sessionResourceID
        if ($lease.status -ne "ready") {
            throw "Lease status for interactive session $($index + 1) was '$($lease.status)', want ready"
        }
        $sessionSpecs += [pscustomobject]@{
            kind = "interactive"
            index = $index + 1
            resource_id = $sessionResourceID
            lease = $lease
            baseline_exit_depth = Get-ExitQueueDepth -NodeID $exitNode.id -VPNConnectionID $sessionResourceID
            baseline_backend_depth = Get-BackendClientGatewayDepth -VPNConnectionID $sessionResourceID
            expected_packets = ($InteractiveRounds * $InteractivePacketsPerBatch)
        }
    }

    foreach ($spec in $sessionSpecs) {
        $session = Open-ServiceChannelWebSocket -Lease $spec.lease -VPNResourceID $spec.resource_id
        $session | Add-Member -NotePropertyName kind -NotePropertyValue $spec.kind
        $session | Add-Member -NotePropertyName index -NotePropertyValue $spec.index
        $sessions += $session
    }

    $abusiveSession = @($sessions | Where-Object { $_.kind -eq "abusive" }) | Select-Object -First 1
    $interactiveSessions = @($sessions | Where-Object { $_.kind -eq "interactive" })
    $abusiveSent = $false
    for ($round = 0; $round -lt $InteractiveRounds; $round++) {
        foreach ($session in $interactiveSessions) {
            Send-ServiceChannelWebSocketBatch -Session $session -PortStart (24000 + ($round * 100) + ([int]$session.index * 10)) -PacketsInBatch $InteractivePacketsPerBatch
        }

        if (-not $abusiveSent -and $round -ge [Math]::Floor($InteractiveRounds / 3)) {
            [byte[][]]$abusivePackets = New-TestIPv4UDPPacketBatch -SourcePort 39000 -Count $AbusivePacketCount
            Send-ServiceChannelWebSocketPacketBatch -Session $abusiveSession -Packets $abusivePackets
            $abusiveSent = $true
        }

        if ($BatchDelayMilliseconds -gt 0) {
            Start-Sleep -Milliseconds $BatchDelayMilliseconds
        }
    }
    if (-not $abusiveSent) {
        [byte[][]]$abusivePackets = New-TestIPv4UDPPacketBatch -SourcePort 39000 -Count $AbusivePacketCount
        Send-ServiceChannelWebSocketPacketBatch -Session $abusiveSession -Packets $abusivePackets
    }

    Start-Sleep -Milliseconds 500
    foreach ($session in $sessions) {
        Close-ServiceChannelWebSocket -Session $session
    }

    $expectedInteractivePacketsPerSession = $InteractiveRounds * $InteractivePacketsPerBatch
    $expectedInteractiveTotalPackets = $expectedInteractivePacketsPerSession * $InteractiveSessionCount
    $expectedAbusiveDropDelta = [Math]::Max(1, ($AbusivePacketCount - $ExpectedAbusiveDelivered))
    $minimumAbusiveDelivered = [Math]::Min($ExpectedAbusiveDelivered, 960)
    $expectedTotalDeliveredMinimum = $expectedInteractiveTotalPackets + $minimumAbusiveDelivered
    $postPressureIngress = Wait-ForIngressAnyRoute -NodeID $entryNode.id -RouteIDs $routeIDs -MinSendPackets ($baselineSendPackets + $expectedTotalDeliveredMinimum) -TimeoutSeconds 120

    $sessionResults = @()
    foreach ($i in 0..($sessionSpecs.Count - 1)) {
        $spec = $sessionSpecs[$i]
        $session = $sessions[$i]
        $minDepth = [int]$spec.baseline_exit_depth + [int]$spec.expected_packets
        if ($spec.kind -eq "abusive") {
            $minDepth = [int]$spec.baseline_exit_depth + 1
        }
        $exitDepth = Wait-ForExitQueueDepth -NodeID $exitNode.id -VPNConnectionID $spec.resource_id -MinDepth $minDepth -TimeoutSeconds 120
        $deliveredPackets = [int]$exitDepth - [int]$spec.baseline_exit_depth
        $backendDepth = Get-BackendClientGatewayDepth -VPNConnectionID $spec.resource_id
        $sessionResults += [pscustomobject]@{
            kind = $spec.kind
            index = $spec.index
            resource_id = $spec.resource_id
            channel_id = $spec.lease.channel_id
            sent_batches = $session.sent_batches
            sent_packets = $session.sent_packets
            expected_packets = $spec.expected_packets
            minimum_expected_depth = $minDepth
            baseline_exit_depth = $spec.baseline_exit_depth
            exit_depth = $exitDepth
            exit_delta = ([int]$exitDepth - [int]$spec.baseline_exit_depth)
            delivered_packets = $deliveredPackets
            baseline_backend_depth = $spec.baseline_backend_depth
            backend_depth = $backendDepth
            backend_delta = ([int]$backendDepth - [int]$spec.baseline_backend_depth)
            final_state = [string]$session.socket.State
        }
    }

    $finalEntryRuntime = Get-LatestRuntimeReport -NodeID $entryNode.id
    $finalExitRuntime = Get-LatestRuntimeReport -NodeID $exitNode.id
    $finalRouteFailures = Get-IngressRouteFailures -NodeID $entryNode.id
    $finalDropped = Get-IngressFlowDropped -NodeID $entryNode.id
    $expiredAlternate = Invoke-Api -Method POST -Path "/clusters/$ClusterID/mesh/route-intents/$alternateRouteID/expire" -Body @{ actor_user_id = $ActorUserID }
    $expiredPrimary = Invoke-Api -Method POST -Path "/clusters/$ClusterID/mesh/route-intents/$primaryRouteID/expire" -Body @{ actor_user_id = $ActorUserID }

    $routeFailureDelta = $finalRouteFailures - $baselineRouteFailures
    $droppedDelta = $finalDropped - $baselineDropped
    $finalFlowScheduler = $finalEntryRuntime.report.ingress.flow_scheduler
    $maxChannelDropDelta = 0
    $maxChannelEnqueuedDelta = 0
    $maxChannelHighWatermark = 0
    $dropChannelID = ""
    $enqueuedChannelID = ""
    $finalChannelStats = Get-ObjectPropertyValue -Object $finalFlowScheduler -Name "channel_stats"
    if ($null -ne $finalChannelStats) {
        foreach ($prop in @($finalChannelStats.PSObject.Properties)) {
            $finalDroppedForChannel = [int](Get-ObjectPropertyValue -Object $prop.Value -Name "dropped")
            $finalEnqueuedForChannel = [int](Get-ObjectPropertyValue -Object $prop.Value -Name "enqueued")
            $baselineDroppedForChannel = 0
            $baselineEnqueuedForChannel = 0
            $baselineStats = Get-ObjectPropertyValue -Object $baselineFlowScheduler -Name "channel_stats"
            if ($null -ne $baselineStats) {
                $baselineProp = $baselineStats.PSObject.Properties[$prop.Name]
                if ($null -ne $baselineProp) {
                    $baselineDroppedForChannel = [int](Get-ObjectPropertyValue -Object $baselineProp.Value -Name "dropped")
                    $baselineEnqueuedForChannel = [int](Get-ObjectPropertyValue -Object $baselineProp.Value -Name "enqueued")
                }
            }
            $deltaForChannel = $finalDroppedForChannel - $baselineDroppedForChannel
            if ($deltaForChannel -gt $maxChannelDropDelta) {
                $maxChannelDropDelta = $deltaForChannel
                $dropChannelID = $prop.Name
            }
            $enqueuedDeltaForChannel = $finalEnqueuedForChannel - $baselineEnqueuedForChannel
            if ($enqueuedDeltaForChannel -gt $maxChannelEnqueuedDelta) {
                $maxChannelEnqueuedDelta = $enqueuedDeltaForChannel
                $enqueuedChannelID = $prop.Name
            }
            $highWatermark = [int](Get-ObjectPropertyValue -Object $prop.Value -Name "high_watermark")
            if ($highWatermark -gt $maxChannelHighWatermark) {
                $maxChannelHighWatermark = $highWatermark
            }
        }
    }

    $result = [ordered]@{
        schema_version = "c18z8.live_service_channel_backpressure_isolation_smoke.v1"
        run_id = $runId
        base_url = $ApiBaseUrl
        entry_base_url = $EntryBaseUrl
        cluster_id = $ClusterID
        entry_node = @{ name = $entryNode.name; id = $entryNode.id }
        exit_node = @{ name = $exitNode.name; id = $exitNode.id }
        resource_id_prefix = $resourceId
        route_intents = @{
            primary_route_intent_id = $primaryRouteID
            alternate_route_intent_id = $alternateRouteID
            expired_primary_status = $expiredPrimary.route_intent.lifecycle_status
            expired_alternate_status = $expiredAlternate.route_intent.lifecycle_status
        }
        pressure = @{
            interactive_session_count = $InteractiveSessionCount
            interactive_rounds = $InteractiveRounds
            interactive_packets_per_batch = $InteractivePacketsPerBatch
            expected_interactive_packets_per_session = $expectedInteractivePacketsPerSession
            expected_interactive_total_packets = $expectedInteractiveTotalPackets
            abusive_packet_count = $AbusivePacketCount
            expected_abusive_delivered = $ExpectedAbusiveDelivered
            minimum_abusive_delivered = $minimumAbusiveDelivered
            expected_abusive_drop_delta = $expectedAbusiveDropDelta
            expected_total_delivered_minimum = $expectedTotalDeliveredMinimum
            sent_total_batches = (@($sessionResults | Measure-Object -Property sent_batches -Sum).Sum)
            sent_total_packets = (@($sessionResults | Measure-Object -Property sent_packets -Sum).Sum)
        }
        route_failures = @{
            baseline = $baselineRouteFailures
            final = $finalRouteFailures
            delta = $routeFailureDelta
        }
        flow_drops = @{
            baseline = $baselineDropped
            final = $finalDropped
            delta = $droppedDelta
            expected_min_delta = $expectedAbusiveDropDelta
            max_channel_drop_delta = $maxChannelDropDelta
            max_channel_drop_id = $dropChannelID
            max_channel_enqueued_delta = $maxChannelEnqueuedDelta
            max_channel_enqueued_id = $enqueuedChannelID
        }
        exit_queue = @{
            total_depth = (@($sessionResults | Measure-Object -Property exit_depth -Sum).Sum)
        }
        backend_fallback_queue = @{
            total_delta = (@($sessionResults | Measure-Object -Property backend_delta -Sum).Sum)
        }
        sessions = $sessionResults
        passed = $true
        checks = [ordered]@{
            production_forwarding_ready = ($readyBefore.report.production_payload_forwarding -eq $true)
            exit_production_forwarding_ready = ($exitReadyBefore.report.production_payload_forwarding -eq $true)
            route_intents_visible_before_pressure = (@($visibleConfig.synthetic_mesh_config.routes | Where-Object { $routeIDs -contains $_.route_id }).Count -ge 2)
            exit_route_intents_visible_before_pressure = (@($exitVisibleConfig.synthetic_mesh_config.routes | Where-Object { $routeIDs -contains $_.route_id }).Count -ge 2)
            entry_runtime_loaded_visible_config = ([string]$loadedConfig.report.config_version -ge [string]$visibleConfig.synthetic_mesh_config.config_version)
            exit_runtime_loaded_visible_config = ([string]$exitLoadedConfig.report.config_version -ge [string]$exitVisibleConfig.synthetic_mesh_config.config_version)
            signed_leases_ready = (@($sessionSpecs | Where-Object { $_.lease.status -eq "ready" }).Count -eq ($InteractiveSessionCount + 1))
            interactive_sessions_sent_all_packets = (@($sessionResults | Where-Object { $_.kind -eq "interactive" -and $_.sent_packets -eq $_.expected_packets }).Count -eq $InteractiveSessionCount)
            interactive_sessions_exit_inbox_received_all_packets = (@($sessionResults | Where-Object { $_.kind -eq "interactive" -and $_.exit_depth -ge ($_.baseline_exit_depth + $_.expected_packets) }).Count -eq $InteractiveSessionCount)
            abusive_session_sent_all_packets = (@($sessionResults | Where-Object { $_.kind -eq "abusive" -and $_.sent_packets -eq $AbusivePacketCount }).Count -eq 1)
            abusive_session_exit_batch_reached_exit = (@($sessionResults | Where-Object { $_.kind -eq "abusive" -and $_.exit_delta -ge 1 }).Count -eq 1)
            abusive_session_bounded_delivery_scheduled = ($maxChannelEnqueuedDelta -ge $ExpectedAbusiveDelivered -and $maxChannelEnqueuedDelta -le $AbusivePacketCount)
            no_backend_fallback_used = ((@($sessionResults | Measure-Object -Property backend_delta -Sum).Sum) -eq 0)
            backpressure_drops_observed = ($droppedDelta -ge $expectedAbusiveDropDelta)
            abusive_channel_drop_observed = ($maxChannelDropDelta -ge $expectedAbusiveDropDelta)
            backpressure_active_visible = ($finalFlowScheduler.backpressure_active -eq $true)
            scheduler_high_watermark_reached = ($maxChannelHighWatermark -ge 900)
            no_route_failures = ($routeFailureDelta -eq 0)
            route_intents_expired = ($expiredPrimary.route_intent.lifecycle_status -eq "expired" -and $expiredAlternate.route_intent.lifecycle_status -eq "expired")
        }
        telemetry = @{
            final_entry_ingress = $finalEntryRuntime.report.ingress
            final_exit_inbox = $finalExitRuntime.report.inbox
            post_pressure_ingress = $postPressureIngress.report.ingress
            baseline_flow_scheduler = $baselineFlowScheduler
            final_flow_scheduler = $finalFlowScheduler
            sessions = $sessionResults
        }
    }

    $failedChecks = @($result.checks.GetEnumerator() | Where-Object { $_.Value -ne $true })
    if ($failedChecks.Count -gt 0) {
        throw "C18Z8 failed checks: $($failedChecks.Name -join ', ')"
    }
}
finally {
    foreach ($session in @($sessions)) {
        try { Close-ServiceChannelWebSocket -Session $session } catch {}
    }
    if ($primaryRouteID) {
        try { Invoke-Api -Method POST -Path "/clusters/$ClusterID/mesh/route-intents/$primaryRouteID/expire" -Body @{ actor_user_id = $ActorUserID } | Out-Null } catch {}
    }
    if ($alternateRouteID) {
        try { Invoke-Api -Method POST -Path "/clusters/$ClusterID/mesh/route-intents/$alternateRouteID/expire" -Body @{ actor_user_id = $ActorUserID } | Out-Null } catch {}
    }
    if ($updatersStopped) {
        try { Start-TestUpdaters } catch { Write-Warning "Could not restart test updaters: $($_.Exception.Message)" }
    }
}

$resultFullPath = Join-Path $repoRoot $ResultPath
$resultDir = Split-Path -Parent $resultFullPath
if (-not (Test-Path $resultDir)) {
    New-Item -ItemType Directory -Path $resultDir | Out-Null
}
$result | ConvertTo-Json -Depth 100 | Set-Content -Path $resultFullPath -Encoding UTF8
Write-Host "C18Z8 live service-channel backpressure isolation smoke passed. Result: $resultFullPath"
$result