Remove the Stage-1 bootstrap-logger line (Log.Logger = new LoggerConfiguration()
.WriteTo.Console().CreateBootstrapLogger()) from AddZbSerilog. A shared library must
not mutate process-global state: when multiple hosts are built in one process (integration
tests, Aspire multi-host, parallel test runs) the second call throws "The logger is
already frozen".
AddSerilog is now called with preserveStaticLogger: true so Serilog.Extensions.Hosting
leaves the static Log.Logger entirely untouched. The DI-registered application logger is
the only artifact AddZbSerilog produces.
Apps that want a pre-Build() bootstrap logger should set Log.Logger themselves in
Program.cs before calling AddZbSerilog — that decision belongs to the application.
Three new regression tests in MultiHostTests verify: two hosts build in the same process
without throwing; Log.Logger is not mutated; each host gets its own independent DI ILogger.
Docs (SPEC.md §5 and shared-contract ZB.MOM.WW.Telemetry.md) updated: the "two-stage
bootstrap" framing is replaced with the correct description — library registers only the
DI application logger; optional Stage-1 bootstrap is the app's responsibility.
Joseph Doherty
f569d537d1