docs(health): align shared-contract to shipped API + per-lib CLAUDE.md + cleanup

- Contract: DatabaseHealthCheck<TContext> ctor now shows IServiceProvider (resolves
  IDbContextFactory<TContext> when registered, else a scoped TContext; pool-safe)
- Contract: RequireActiveNode gains retryAfterSeconds = 5 default parameter
- Packages: remove dangling AspNetCore.HealthChecks.UI.Client PackageVersion (no
  csproj referenced it)
- Tests: fix CS8625 in RoleLessCases — use object?[] so null role rows compile
  warning-free under Nullable=enable
- Add ZB.MOM.WW.Health/CLAUDE.md (packages, responsibilities, consumer matrix,
  build/test/pack commands, status + pointer to components/health/)

ZB.MOM.WW.Health/CLAUDE.md

@@ -0,0 +1,72 @@
+# ZB.MOM.WW.Health
+
+Health-check libraries for the **ZB.MOM.WW SCADA family** (OtOpcUa, MxAccessGateway, ScadaBridge). These are **libraries, not a service** — each package is linked directly into the consuming application at build time. There is no central health process or network hop; probes run in-process alongside the application.
+
+The library normalizes the three-tier health endpoint convention (`/health/ready`, `/health/active`, `/healthz`) and provides reusable probe implementations so the three sister projects share a common surface without duplicating probe logic.
+
+**Built at 0.1.0. NOT yet adopted by the three apps.** Adoption is tracked in `~/Desktop/scadaproj/components/health/GAPS.md`.
+
+---
+
+## Packages
+
+| Package | Responsibilities | Key Dependencies |
+|---|---|---|
+| `ZB.MOM.WW.Health` | Core tier convention, `MapZbHealth` extension, canonical JSON writer (`ZbHealthWriter`), `IActiveNodeGate` seam, `GrpcDependencyHealthCheck` reachability probe, tier-tag constants (`ZbHealthTags`). No Akka or EF dependency. | `Microsoft.AspNetCore.App` (framework ref), `Grpc.Net.Client` |
+| `ZB.MOM.WW.Health.Akka` | `AkkaClusterHealthCheck` with a configurable `AkkaClusterStatusPolicy` (presets: `Default` / `OtOpcUaCompat`), `ActiveNodeHealthCheck` with an optional role filter, and `AkkaActiveNodeGate` that backs `IActiveNodeGate` from cluster member state. | `ZB.MOM.WW.Health`, `Akka.Cluster` |
+| `ZB.MOM.WW.Health.EntityFrameworkCore` | `DatabaseHealthCheck<TContext>` — resolves `IDbContextFactory<TContext>` when registered, else a scoped `TContext`; pool-safe. Default probe: `CanConnectAsync`. Optional `ProbeQuery` delegate for query-based validation. | `ZB.MOM.WW.Health`, `Microsoft.EntityFrameworkCore` |
+
+---
+
+## Consumer matrix
+
+| Consumer | `ZB.MOM.WW.Health` (core) | `ZB.MOM.WW.Health.Akka` | `ZB.MOM.WW.Health.EntityFrameworkCore` |
+|---|:---:|:---:|:---:|
+| **OtOpcUa** | yes | yes | yes |
+| **MxAccessGateway** | yes | — | — |
+| **ScadaBridge** | yes | yes | yes |
+
+MxAccessGateway consumes the core package only — it has no Akka cluster and no EF DbContext. OtOpcUa and ScadaBridge consume all three packages.
+
+---
+
+## Build, test, and pack commands
+
+```bash
+# From ZB.MOM.WW.Health/
+
+# Build
+dotnet build ZB.MOM.WW.Health.slnx
+dotnet build ZB.MOM.WW.Health.slnx -c Release
+
+# Test (no external dependencies — no running Akka cluster, no database)
+dotnet test ZB.MOM.WW.Health.slnx
+
+# Pack (three .nupkg files land in artifacts/)
+dotnet pack ZB.MOM.WW.Health.slnx -c Release -o ./artifacts
+```
+
+All three test assemblies run offline:
+
+| Assembly | Tests |
+|---|---|
+| `ZB.MOM.WW.Health.Tests` | 20 |
+| `ZB.MOM.WW.Health.Akka.Tests` | 32 |
+| `ZB.MOM.WW.Health.EntityFrameworkCore.Tests` | 6 |
+| **Total** | **58** |
+
+`GeneratePackageOnBuild` is off — pack explicitly with the command above.
+
+---
+
+## Status
+
+Built at **0.1.0** and published to the Gitea NuGet feed. **Not yet adopted** by the three apps — adoption is tracked in the component backlog:
+
+- `~/Desktop/scadaproj/components/health/GAPS.md` — adoption order, effort, and risk
+
+Design documentation:
+
+- `~/Desktop/scadaproj/components/health/spec/SPEC.md` — normalized three-tier target
+- `~/Desktop/scadaproj/components/health/shared-contract/ZB.MOM.WW.Health.md` — proposed API (aligned to shipped code)
+- `~/Desktop/scadaproj/components/health/current-state/` — per-project current state (code-verified)

ZB.MOM.WW.Health/Directory.Packages.props

@@ -11,7 +11,6 @@
 
     <!-- Health Checks / ASP.NET Core -->
     <PackageVersion Include="Microsoft.Extensions.Diagnostics.HealthChecks.Abstractions" Version="10.0.7" />
-    <PackageVersion Include="AspNetCore.HealthChecks.UI.Client" Version="9.0.0" />
     <PackageVersion Include="Microsoft.AspNetCore.Mvc.Testing" Version="10.0.7" />
 
     <!-- gRPC -->

ZB.MOM.WW.Health/tests/ZB.MOM.WW.Health.Akka.Tests/ActiveNodeDecisionTests.cs

@@ -14,12 +14,12 @@ namespace ZB.MOM.WW.Health.Akka.Tests;
 public sealed class ActiveNodeDecisionTests
 {
     // Role-less: requiredRole == null. hasRole is irrelevant. Healthy iff (selfUp && isLeader), else Unhealthy.
-    public static IEnumerable<object[]> RoleLessCases() => new[]
+    public static IEnumerable<object?[]> RoleLessCases() => new[]
     {
-        new object[] { true, true, false, (string?)null, HealthStatus.Healthy },
+        new object?[] { true, true, false, (string?)null, HealthStatus.Healthy },
-        new object[] { true, false, false, (string?)null, HealthStatus.Unhealthy },
+        new object?[] { true, false, false, (string?)null, HealthStatus.Unhealthy },
-        new object[] { false, true, false, (string?)null, HealthStatus.Unhealthy },
+        new object?[] { false, true, false, (string?)null, HealthStatus.Unhealthy },
-        new object[] { false, false, false, (string?)null, HealthStatus.Unhealthy },
+        new object?[] { false, false, false, (string?)null, HealthStatus.Unhealthy },
     };
 
     [Theory]

components/health/shared-contract/ZB.MOM.WW.Health.md

@@ -91,7 +91,8 @@ public interface IActiveNodeGate
 public static class ActiveNodeGateExtensions
 {
     public static IEndpointConventionBuilder RequireActiveNode(
-        this IEndpointConventionBuilder builder);
+        this IEndpointConventionBuilder builder,
+        int retryAfterSeconds = 5);
 }
 
 /// Checks that a downstream gRPC channel is reachable.
@@ -221,8 +222,9 @@ namespace ZB.MOM.WW.Health.EntityFrameworkCore;
 public sealed class DatabaseHealthCheck<TContext> : IHealthCheck
     where TContext : DbContext
 {
+    // Resolves IDbContextFactory<TContext> when registered, else a scoped TContext; pool-safe.
     public DatabaseHealthCheck(
-        IDbContextFactory<TContext>      factory,
+        IServiceProvider                      serviceProvider,
         DatabaseHealthCheckOptions<TContext>? options = null);
 
     public Task<HealthCheckResult> CheckHealthAsync(