param(
    [int] $Port = 7788,
    [string] $Log = "$PSScriptRoot\sc_robust.log"
)

# Robust stub sidecar: survives port-in-use from a just-killed instance, and never
# dies on a transient error. Test scaffolding only.

function Say($msg) {
    for ($i = 0; $i -lt 5; $i++) {
        try { "$msg" | Out-File -FilePath $Log -Append -Encoding utf8; return }
        catch { Start-Sleep -Milliseconds 100 }
    }
}

"" | Out-File -FilePath $Log -Encoding utf8
Say "[sidecar] starting on 127.0.0.1:$Port"

$listener = New-Object System.Net.Sockets.TcpListener([System.Net.IPAddress]::Loopback, $Port)
$listener.Server.SetSocketOption('Socket', 'ReuseAddress', $true)

# Wait for the port to become bindable if a prior instance is still lingering.
$bound = $false
for ($i = 0; $i -lt 30 -and -not $bound; $i++) {
    try { $listener.Start(); $bound = $true }
    catch { Say "[sidecar] bind retry: $($_.Exception.Message)"; Start-Sleep -Seconds 1 }
}
if (-not $bound) { Say "[sidecar] could not bind $Port; giving up"; exit 1 }

Say "[sidecar] listening"

while ($true) {
    try {
        $client = $listener.AcceptTcpClient()
        Say "[sidecar] === shard connected ==="
        $reader = New-Object System.IO.StreamReader($client.GetStream())
        while ($null -ne ($line = $reader.ReadLine())) { Say "[sidecar] <- $line" }
        Say "[sidecar] === shard disconnected ==="
        $client.Close()
    }
    catch {
        Say "[sidecar] loop error: $($_.Exception.Message)"
        Start-Sleep -Milliseconds 300
    }
}