Detects effective default browser using Windows API

Get-ProtocolAssoc.ps1

<# 
 Get-ProtocolAssoc.ps1
 Queries Windows for the effective handler of http/https using AssocQueryString.
 Compatible with Windows PowerShell 5.1 and PowerShell 7+.

 OUTPUT
  - Prints each field for http and https
  - Returns a PSCustomObject you can pipe to ConvertTo-Json

 USAGE
   powershell -NoProfile -ExecutionPolicy Bypass -File .\Get-ProtocolAssoc.ps1
#>

[CmdletBinding()]
param(
    [string[]]$Protocols = @('http','https'),
    [string]$Verb = 'open'
)

Set-StrictMode -Version Latest
$ErrorActionPreference = 'Stop'

function Write-Section {
    param([string]$Title)
    Write-Host "`n####################### $Title #######################" -ForegroundColor Yellow
}
function Write-Field {
    param([string]$Name, [string]$Value)
    if ([string]::IsNullOrEmpty($Value)) { $Value = '<null or empty>' }
    Write-Host ("{0}: {1}" -f $Name, $Value)
}

# ---- P/Invoke wrapper for AssocQueryStringW ----
if (-not ([System.Management.Automation.PSTypeName]'AssocNative').Type) {
Add-Type -Language CSharp -TypeDefinition @'
using System;
using System.Runtime.InteropServices;
using System.Text;

public static class AssocNative
{
    [Flags]
    public enum AssocF : uint
    {
        None = 0x00000000,
        Init_NoRemapCLSID = 0x00000001,
        Verify = 0x00000040,
        NoUserSettings = 0x00000010,
        IgnoreBaseClass = 0x00000020
    }

    public enum AssocStr : uint
    {
        Command          = 1,
        Executable       = 2,
        FriendlyDocName  = 3,
        FriendlyAppName  = 4,
        NoOpen           = 5,
        ShellNewValue    = 6,
        DDECommand       = 7,
        DDEApplication   = 8,
        DDEIfExec        = 9,
        DDETopic         = 10,
        InfoTip          = 11,
        QuickTip         = 12,
        TileInfo         = 13,
        ContentType      = 14,
        DefaultIcon      = 15,
        ShellExtension   = 16,
        DropTarget       = 17,
        DelegateExecute  = 18,
        SupportedURISchemes = 19,
        ProgID           = 20,
        AppID            = 21, // Some SDKs list AppID around here; value can vary by SDK. We handle failure gracefully.
        // Note: Different Windows SDKs have additional values; querying unknown ones may fail, which we catch.
    }

    [DllImport("Shlwapi.dll", CharSet = CharSet.Unicode, SetLastError = true, ExactSpelling = true, EntryPoint = "AssocQueryStringW")]
    public static extern int AssocQueryString(
        AssocF flags,
        AssocStr str,
        string pszAssoc,
        string pszExtra,
        StringBuilder pszOut,
        ref uint pcchOut
    );
}
'@
}

function Invoke-AssocQuery {
    param(
        [AssocNative+AssocF]$Flags,
        [AssocNative+AssocStr]$What,
        [Parameter(Mandatory)][string]$Assoc,   # e.g., "http"
        [string]$Verb = 'open'
    )
    # First call to get length
    [uint32]$len = 0
    [void][AssocNative]::AssocQueryString($Flags, $What, $Assoc, $Verb, $null, [ref]$len)
    if ($len -eq 0) { return $null }  # Not available

    $sb = New-Object System.Text.StringBuilder ([int]$len)
    $hr = [AssocNative]::AssocQueryString($Flags, $What, $Assoc, $Verb, $sb, [ref]$len)
    if ($hr -ne 0) { return $null }   # Failure => treat as not available
    # Some APIs include an extra null; trim it.
    $val = $sb.ToString().TrimEnd([char]0)
    if ([string]::IsNullOrWhiteSpace($val)) { return $null }
    $val
}

# Combine a couple of useful flags:
#  - Verify: ensure returned data maps to something real when possible
#  - Init_NoRemapCLSID: avoid remapping through class IDs
$AssocFlags = [AssocNative+AssocF]::Verify -bor [AssocNative+AssocF]::Init_NoRemapCLSID

function Get-ProtocolAssoc {
    param([Parameter(Mandatory)][string]$Protocol, [string]$Verb = 'open')

    $obj = [ordered]@{
        Protocol          = $Protocol
        Verb              = $Verb
        Command           = $null
        Executable        = $null
        FriendlyAppName   = $null
        AppID             = $null
        DefaultIcon       = $null
    }

    $obj.Command         = Invoke-AssocQuery -Flags $AssocFlags -What ([AssocNative+AssocStr]::Command)        -Assoc $Protocol -Verb $Verb
    $obj.Executable      = Invoke-AssocQuery -Flags $AssocFlags -What ([AssocNative+AssocStr]::Executable)     -Assoc $Protocol -Verb $Verb
    $obj.FriendlyAppName = Invoke-AssocQuery -Flags $AssocFlags -What ([AssocNative+AssocStr]::FriendlyAppName)-Assoc $Protocol -Verb $Verb
    # APPID is not guaranteed on all systems/SDKs; if query fails, we'll just leave it null.
    try { $obj.AppID     = Invoke-AssocQuery -Flags $AssocFlags -What ([AssocNative+AssocStr]::AppID)          -Assoc $Protocol -Verb $Verb } catch {}
    $obj.DefaultIcon     = Invoke-AssocQuery -Flags $AssocFlags -What ([AssocNative+AssocStr]::DefaultIcon)    -Assoc $Protocol -Verb $Verb

    [pscustomobject]$obj
}

$results = @()
foreach ($p in $Protocols) {
    Write-Section $p
    $info = Get-ProtocolAssoc -Protocol $p -Verb $Verb

    Write-Field 'Command'         $info.Command
    Write-Field 'Executable'      $info.Executable
    Write-Field 'FriendlyAppName' $info.FriendlyAppName
    Write-Field 'AppID'           $info.AppID
    Write-Field 'DefaultIcon'     $info.DefaultIcon

    $results += $info
}

# Emit structured results (pipe to ConvertTo-Json if desired)
$results