diff --git a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Heidenhain.Contracts/HeidenhainDriverOptions.cs b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Heidenhain.Contracts/HeidenhainDriverOptions.cs
index 157b171dd..880505ad2 100644
--- a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Heidenhain.Contracts/HeidenhainDriverOptions.cs
+++ b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Heidenhain.Contracts/HeidenhainDriverOptions.cs
@@ -65,7 +65,7 @@ public sealed class HeidenhainDeviceOptions
 
 /// <summary>
 ///     Access settings. Password fields are <b>references</b>, never literals: blank (no password),
-///     <c>secret:&lt;name&gt;</c> (the node's encrypted secret store) or <c>env:&lt;VARIABLE&gt;</c>. A literal is
+///     <c>secret:heidenhain/&lt;name&gt;</c> (the node's encrypted secret store) or <c>env:OTOPCUA_HEIDENHAIN_&lt;NAME&gt;</c>. A literal is
 ///     refused at parse and at the deploy gate, so a controller password never lands in the config database.
 /// </summary>
 public sealed class HeidenhainAccessOptions
diff --git a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Heidenhain/HeidenhainDriverProbe.cs b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Heidenhain/HeidenhainDriverProbe.cs
index 44f9c3785..fabd31043 100644
--- a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Heidenhain/HeidenhainDriverProbe.cs
+++ b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Heidenhain/HeidenhainDriverProbe.cs
@@ -13,9 +13,25 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.Heidenhain;
 /// <remarks>
 ///     Registered on admin nodes as well as driver nodes (the Test-Connect singleton is admin-pinned). The
 ///     resolver is optional: without one a <c>secret:</c> INSPECT password fails closed with a clear message.
+///     <para>
+///         The host registers the probe with a resolver <em>accessor</em>, never a resolved instance: the probe set is
+///         resolved inside the AdminOperations Akka starter, and resolving <see cref="ISecretResolver" /> there walks
+///         <c>AddZbSecrets</c> → <c>IAuditWriter</c> → <c>ActorAuditWriter</c>, whose constructor needs the
+///         <c>AuditWriterActorKey</c> registered later in the same builder — every central node failed to boot (#803
+///         live gate). The accessor runs per probe call, after the host is built.
+///     </para>
 /// </remarks>
-public sealed class HeidenhainDriverProbe(ISecretResolver? secretResolver = null) : IDriverProbe
+public sealed class HeidenhainDriverProbe : IDriverProbe
 {
+    private readonly Func<ISecretResolver?> _secretResolver;
+
+    /// <summary>Creates a probe with a fixed (optional) resolver — for tests and graphs without the Akka audit writer.</summary>
+    public HeidenhainDriverProbe(ISecretResolver? secretResolver = null) => _secretResolver = () => secretResolver;
+
+    /// <summary>Creates a probe that resolves the secret resolver lazily, once per probe call.</summary>
+    public HeidenhainDriverProbe(Func<ISecretResolver?> secretResolverAccessor) =>
+        _secretResolver = secretResolverAccessor ?? throw new ArgumentNullException(nameof(secretResolverAccessor));
+
     /// <inheritdoc />
     public string DriverType => DriverTypeNames.Heidenhain;
 
@@ -42,7 +58,7 @@ public sealed class HeidenhainDriverProbe(ISecretResolver? secretResolver = null
             string password;
             // Resolved only through the namespaced resolver (fail-closed at resolve time): Test Connect can never be
             // used to send another subsystem's secret or environment variable to an arbitrary Host.
-            try { password = await new HeidenhainCredentials(secretResolver).ResolveAsync(options, device, "INSPECT", cts.Token).ConfigureAwait(false); }
+            try { password = await new HeidenhainCredentials(_secretResolver()).ResolveAsync(options, device, "INSPECT", cts.Token).ConfigureAwait(false); }
             catch (HeidenhainCredentialException ex) { return new(false, ex.Message, null); }
 
             try { _ = Lsv2ReadOnlyPolicy.LoginPayload("INSPECT", password); }
diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/DeviceForms/HeidenhainDeviceForm.razor b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/DeviceForms/HeidenhainDeviceForm.razor
index ec8829186..aa0643451 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/DeviceForms/HeidenhainDeviceForm.razor
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/DeviceForms/HeidenhainDeviceForm.razor
@@ -38,7 +38,7 @@
                 <InputText id="hhData" @bind-Value="_model.DataPassword" @bind-Value:after="EmitAsync" class="form-control form-control-sm mono" placeholder="env:OTOPCUA_HEIDENHAIN_DATA_PASSWORD" />
             </div>
         </div>
-        <div class="form-text">Blank = use the driver-level reference. <span class="mono">secret:&lt;name&gt;</span> resolves from the node's secret store, <span class="mono">env:&lt;VAR&gt;</span> from the environment, at each login. A literal password is never stored.</div>
+        <div class="form-text">Blank = use the driver-level reference. <span class="mono">secret:heidenhain/&lt;name&gt;</span> resolves from the node's secret store, <span class="mono">env:OTOPCUA_HEIDENHAIN_&lt;NAME&gt;</span> from the environment, at each login. A literal password is never stored.</div>
         @if (_model.Validate() is { } error)
         {
             <div class="text-danger small mt-2">@error</div>
diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/DeviceForms/HeidenhainDeviceModel.cs b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/DeviceForms/HeidenhainDeviceModel.cs
index fe6ae03d6..4d9b43db2 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/DeviceForms/HeidenhainDeviceModel.cs
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/DeviceForms/HeidenhainDeviceModel.cs
@@ -47,7 +47,7 @@ public sealed class HeidenhainDeviceModel
         var errors = HeidenhainOptionsParser.ValidateDevice(new HeidenhainDeviceOptions { Host = Host.Trim(), Port = Port }).ToList();
         foreach (var (name, v) in new[] { ("INSPECT", InspectPassword), ("DNC", DncPassword), ("DATA", DataPassword) })
             if (!HeidenhainOptionsParser.IsCredentialReference(Blank(v)))
-                errors.Add($"{name} password must be blank, secret:<name> or env:<VARIABLE> — never a literal.");
+                errors.Add($"{name} password must be blank, secret:heidenhain/<name> or env:OTOPCUA_HEIDENHAIN_<NAME> — never a literal.");
         return errors.Count == 0 ? null : string.Join(" ", errors);
     }
 
diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/Forms/HeidenhainDriverForm.razor b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/Forms/HeidenhainDriverForm.razor
index ee0e6b005..96faaa293 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/Forms/HeidenhainDriverForm.razor
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/Forms/HeidenhainDriverForm.razor
@@ -70,7 +70,7 @@
                 <InputText id="hhDataPw" @bind-Value="_m.DataPassword" @bind-Value:after="EmitAsync" class="form-control form-control-sm mono" placeholder="env:OTOPCUA_HEIDENHAIN_DATA_PASSWORD" />
             </div>
         </div>
-        <div class="form-text">References only: blank, <span class="mono">secret:&lt;name&gt;</span> (node secret store) or <span class="mono">env:&lt;VAR&gt;</span>. Resolved at each login; a literal password is refused.</div>
+        <div class="form-text">References only: blank, <span class="mono">secret:heidenhain/&lt;name&gt;</span> (node secret store) or <span class="mono">env:OTOPCUA_HEIDENHAIN_&lt;NAME&gt;</span>. Resolved at each login; a literal password is refused.</div>
     </div>
 </section>
 
diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Uns/RawTreeService.cs b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Uns/RawTreeService.cs
index 74172dfd7..148a37a39 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Uns/RawTreeService.cs
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Uns/RawTreeService.cs
@@ -1271,6 +1271,16 @@ public sealed class RawTreeService(IDbContextFactory<OtOpcUaConfigDbContext> dbF
                 (dev, drv) => drv.DriverType)
             .FirstOrDefaultAsync(ct);
 
+    /// <summary>
+    ///     Driver-specific Tag-ROW rules beyond the TagConfig (lmxopcua#803): a Heidenhain tag must be Read-only
+    ///     and carry the data type the driver publishes — the same rule the deploy gate applies.
+    /// </summary>
+    private static string? TagRowProblem(string? driverType, RawTagInput input, string tagConfig) =>
+        string.Equals(driverType, DriverTypeNames.Heidenhain, StringComparison.OrdinalIgnoreCase)
+            ? Driver.Heidenhain.HeidenhainTagRules.DescribeRowProblem(
+                input.AccessLevel == Configuration.Enums.TagAccessLevel.ReadWrite, input.DataType, tagConfig)
+            : null;
+
     /// <summary>
     ///     The driver-typed <c>TagConfig</c> gate, applied on the SERVER for every tag-writing path —
     ///     create, update and bulk import alike.
@@ -1293,16 +1303,6 @@ public sealed class RawTreeService(IDbContextFactory<OtOpcUaConfigDbContext> dbF
     /// <param name="tagConfig">The normalised TagConfig JSON about to be persisted.</param>
     /// <param name="ct">Cancellation token.</param>
     /// <returns>An operator-facing error, or <see langword="null"/> when the config is acceptable.</returns>
-    /// <summary>
-    ///     Driver-specific Tag-ROW rules beyond the TagConfig (lmxopcua#803): a Heidenhain tag must be Read-only
-    ///     and carry the data type the driver publishes — the same rule the deploy gate applies.
-    /// </summary>
-    private static string? TagRowProblem(string? driverType, RawTagInput input, string tagConfig) =>
-        string.Equals(driverType, DriverTypeNames.Heidenhain, StringComparison.OrdinalIgnoreCase)
-            ? Driver.Heidenhain.HeidenhainTagRules.DescribeRowProblem(
-                input.AccessLevel == Configuration.Enums.TagAccessLevel.ReadWrite, input.DataType, tagConfig)
-            : null;
-
     private static async Task<string?> ValidateTagConfigAsync(
         OtOpcUaConfigDbContext db, string deviceId, string tagConfig, CancellationToken ct)
     {
diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.Host/Drivers/DriverFactoryBootstrap.cs b/src/Server/ZB.MOM.WW.OtOpcUa.Host/Drivers/DriverFactoryBootstrap.cs
index a3f0fa480..9bb0686d7 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.Host/Drivers/DriverFactoryBootstrap.cs
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.Host/Drivers/DriverFactoryBootstrap.cs
@@ -199,8 +199,12 @@ public static class DriverFactoryBootstrap
         // Factory-built so the probe resolves secret: INSPECT password references through the node's resolver
         // (registered on every node by AddZbSecrets; optional so a test graph without one still builds — a
         // secret: ref then fails closed with a clear probe message rather than sending the literal).
+        // ⚠️ Captured as an accessor, NOT resolved here: the probe set is resolved inside the AdminOperations
+        // Akka starter, and ISecretResolver → AddZbSecrets → IAuditWriter → ActorAuditWriter needs the
+        // AuditWriterActorKey that is registered later in that builder — resolving it eagerly crash-looped every
+        // central node at boot (#803 live gate). See ControlPlane ServiceCollectionExtensions' WithActors note.
         services.TryAddEnumerable(ServiceDescriptor.Singleton<IDriverProbe, HeidenhainProbe>(
-            sp => new HeidenhainProbe(sp.GetService<ISecretResolver>())));
+            sp => new HeidenhainProbe(() => sp.GetService<ISecretResolver>())));
 
         return services;
     }
diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/DriverProbeRegistrationTests.cs b/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/DriverProbeRegistrationTests.cs
index 085f6d312..f7fec3c7b 100644
--- a/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/DriverProbeRegistrationTests.cs
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/DriverProbeRegistrationTests.cs
@@ -102,4 +102,27 @@ public sealed class DriverProbeRegistrationTests
         probes.Count.ShouldBe(distinctTypes, "Duplicate IDriverProbe registrations — TryAddEnumerable should de-dup.");
         distinctTypes.ShouldBe(DriverTypeNames.All.Count);
     }
+
+    [Fact]
+    public void Resolving_the_probe_set_never_resolves_the_secret_resolver()
+    {
+        // #803 live gate: the probe set is resolved inside the AdminOperations Akka starter, where
+        // ISecretResolver -> AddZbSecrets -> IAuditWriter -> ActorAuditWriter throws (its actor key is
+        // registered later in the same builder). A probe that resolved the secret resolver eagerly crash-looped
+        // every central node at boot. Model that starter-time graph with a resolver factory that throws.
+        var resolved = 0;
+        var services = new ServiceCollection();
+        services.AddSingleton<ZB.MOM.WW.Secrets.Abstractions.ISecretResolver>(_ =>
+        {
+            resolved++;
+            throw new InvalidOperationException("ISecretResolver must not be resolved while building the probe set");
+        });
+        services.AddOtOpcUaDriverProbes();
+
+        using var sp = services.BuildServiceProvider();
+        var probes = sp.GetServices<IDriverProbe>().ToList();
+
+        probes.ShouldNotBeEmpty();
+        resolved.ShouldBe(0);
+    }
 }