Add custom domain support to tunnel management SDKs

[DavidObando]

Design

When a tunnel service deployment uses a custom domain (e.g. "app.github.dev"), the control-plane URL is derived by prepending "cp." to that domain, producing "https://cp.app.github.dev/". Because custom-domain deployments handle cluster routing at the infrastructure level, the SDK must not rewrite the hostname with a cluster ID the way it does for the standard multi-cluster "global.rel.tunnels.api.visualstudio.com" deployment.

Implementation (all five SDKs)

1. Added an isCustomDomain flag to each management client, set automatically in the constructor when the service URI hostname starts with "cp.".

2. The BuildUri / buildUri / build_uri method now skips the cluster-ID-to-hostname rewriting logic when isCustomDomain is true, leaving the hostname unchanged.

3. Added a static factory method on each client to construct from a custom domain string:

   • C#: TunnelManagementClient.ForCustomDomain(domain, ...)
   • TypeScript: TunnelManagementHttpClient.forCustomDomain(domain, ...)
   • Go: NewManagerForCustomDomain(domain, ...)
   • Java: TunnelManagementClient.forCustomDomain(domain, ...)
   • Rust: new_tunnel_management_for_custom_domain(ua, domain)

   Each factory validates the domain, builds the "https://cp.{domain}/" service URI, and delegates to the existing constructor/builder.

Files changed

cs/src/Management/TunnelManagementClient.cs

• Added isCustomDomain field, set in constructor.
• BuildUri() skips ReplaceTunnelServiceHostnameClusterId when custom domain is detected.
• Added ForCustomDomain() static factory.

ts/src/management/tunnelManagementHttpClient.ts

• Added isCustomDomain field, set in constructor.
• buildUri() skips cluster-ID hostname manipulation.
• Added forCustomDomain() static factory.

go/tunnels/manager.go

• Added isCustomDomain field on Manager struct.
• buildUri() skips cluster-ID prepend when true.
• Added NewManagerForCustomDomain() function.

java/src/.../management/TunnelManagementClient.java

• Added isCustomDomain field, set in constructor.
• buildUri() skips cluster-ID manipulation.
• Added forCustomDomain() static factory.

rs/src/management/http_client.rs

• Added is_custom_domain to struct, builder, and From impl.
• build_uri() skips cluster-ID rewriting.
• Added new_tunnel_management_for_custom_domain() builder fn.
• environment() setter auto-detects "cp." prefix.

Tests added

Each SDK has two new tests:

• Custom domain URI keeps "cp.{domain}" hostname unchanged.
• Standard service URI still rewrites hostname with cluster ID.

C#: CustomDomainDoesNotModifyHostname,
StandardServiceUriReplacesClusterIdInHostname
TS: customDomainDoesNotModifyHostname,
standardServiceUriReplacesClusterIdInHostname
Go: TestCustomDomainDoesNotModifyHostname,
TestStandardServiceUriReplacesClusterId
Java: forCustomDomainCreatesClient,
forCustomDomainRejectsBlank
Rust: custom_domain_does_not_modify_hostname,
standard_service_uri_replaces_cluster_id

Other Tasks:

• If you updated the Go SDK did you update the PackageVersion in tunnels.go
• If you updated the TS SDK did you update the dependencies in package.json for connections and management to require a dependency that is > the current published version(Found using npm view @microsoft/dev-tunnels-contracts). This will fix issues where yarn will pull the old version of packages and will cause mismatched dependencies. See example PR