User → Cloud App (SP)
   │
   └── Redirect to Azure AD
          │
          ├── Azure AD checks federated domain
          │
          └── Redirect to on-premises AD FS
                 │
                 ├── AD FS authenticates against Active Directory
                 │
                 ├── AD FS issues SAML token
                 │
                 └── Token posted back to Azure AD
                        │
                        ├── Azure AD validates federation trust
                        │
                        ├── Azure AD issues its own token
                        │
                        └── User receives access token for cloud app

# Install AD FS role
Install-WindowsFeature ADFS-Federation -IncludeManagementTools

# Configure AD FS farm
Install-AdfsFarm `
    -CertificateThumbprint $certThumbprint `
    -FederationServiceDisplayName "Corp Federation Service" `
    -FederationServiceName "fs.corp.example.com" `
    -ServiceAccountCredential $gmsaCredential

# Verify AD FS is operational
Get-AdfsProperties | Select-Object HostName, Identifier, FederationPassiveAddress

# Install Microsoft Graph PowerShell module
Install-Module Microsoft.Graph -Scope CurrentUser

# Connect to Microsoft Graph
Connect-MgGraph -Scopes "Domain.ReadWrite.All"

# Convert managed domain to federated
# Using AD FS federation metadata URL
$domainId = "corp.example.com"
$federationConfig = @{
    issuerUri = "http://fs.corp.example.com/adfs/services/trust"
    metadataExchangeUri = "https://fs.corp.example.com/adfs/services/trust/mex"
    passiveSignInUri = "https://fs.corp.example.com/adfs/ls/"
    signOutUri = "https://fs.corp.example.com/adfs/ls/?wa=wsignout1.0"
    signingCertificate = $base64Cert
    preferredAuthenticationProtocol = "saml"
}

# Apply federation settings to domain
New-MgDomainFederationConfiguration -DomainId $domainId -BodyParameter $federationConfig

# Add Relying Party Trust for Azure AD
Add-AdfsRelyingPartyTrust `
    -Name "Microsoft Office 365 Identity Platform" `
    -MetadataUrl "https://nexus.microsoftonline-p.com/federationmetadata/2007-06/federationmetadata.xml"

# Configure claim rules
$rules = @"
@RuleTemplate = "LdapClaims"
@RuleName = "Extract AD Attributes"
c:[Type == "http://schemas.microsoft.com/ws/2008/06/identity/claims/windowsaccountname",
   Issuer == "AD AUTHORITY"]
=> issue(store = "Active Directory",
   types = ("http://schemas.xmlsoap.org/claims/UPN",
            "http://schemas.xmlsoap.org/ws/2005/05/identity/claims/emailaddress",
            "http://schemas.xmlsoap.org/ws/2005/05/identity/claims/givenname",
            "http://schemas.xmlsoap.org/ws/2005/05/identity/claims/surname"),
   query = ";userPrincipalName,mail,givenName,sn;{0}",
   param = c.Value);

@RuleTemplate = "PassThroughClaims"
@RuleName = "Pass Through UPN as NameID"
c:[Type == "http://schemas.xmlsoap.org/claims/UPN"]
=> issue(Type = "http://schemas.xmlsoap.org/ws/2005/05/identity/claims/nameidentifier",
   Issuer = c.Issuer, OriginalIssuer = c.OriginalIssuer,
   Value = c.Value,
   ValueType = c.ValueType,
   Properties["http://schemas.xmlsoap.org/ws/2005/05/identity/claimproperties/format"]
       = "urn:oasis:names:tc:SAML:2.0:nameid-format:persistent");
"@

Set-AdfsRelyingPartyTrust `
    -TargetName "Microsoft Office 365 Identity Platform" `
    -IssuanceTransformRules $rules

# Check current certificate expiration
Get-AdfsCertificate -CertificateType Token-Signing | Select-Object Thumbprint, NotAfter

# AD FS supports auto-rollover (enabled by default)
Get-AdfsProperties | Select-Object AutoCertificateRollover

# If manual rotation is needed:
# 1. Add new certificate as secondary
Set-AdfsCertificate -CertificateType Token-Signing -Thumbprint $newThumbprint -IsPrimary $false
# 2. Update Azure AD with new certificate
# 3. Promote to primary
Set-AdfsCertificate -CertificateType Token-Signing -Thumbprint $newThumbprint -IsPrimary $true
# 4. Remove old certificate
Remove-AdfsCertificate -CertificateType Token-Signing -Thumbprint $oldThumbprint