fix(drivers): mid-connect ApplyDelta adopts config in Calculation, refuses it in Galaxy (#664)

AdoptConfigDuringInit re-runs InitializeAsync(newConfig) and acks success, but
Calculation and Galaxy ignored the JSON there: Calculation kept its old tag
set, and Galaxy connected on its old endpoint. Calculation now rebuilds its tag
table from a config with a body (sharing AdoptConfig with ReinitializeAsync and
stopping any running timer scheduler first). Galaxy, which cannot hot-swap its
options, refuses a non-equivalent one the way ReinitializeAsync does. The actor
now sends DeltaApplied once the adopted init succeeds, so a dependency
consumer's mux interest is re-registered. Unreachable from deploys since #516.

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe

CLAUDE.md

@@ -1168,6 +1168,9 @@ host logger factory (wired in `DriverFactoryBootstrap`; the FOCAS and TwinCAT fa
   re-attaches/re-subscribes alarms as well as data, so a failed alarm subscribe is retried every tick.
   A Connected in-place `ApplyDelta` (unreachable from deploys since #516) releases both subscriptions at the
   driver, reinitialises, then re-subscribes both (#663) — it used to keep handles the reinit had invalidated.
+  A mid-connect `ApplyDelta` re-runs `InitializeAsync(newConfig)`, so **every driver's `InitializeAsync` must adopt a
+  config with a body** — Calculation now does, Galaxy (no hot-swap) now refuses a non-equivalent one, and the actor
+  sends `DeltaApplied` once the adopted init succeeds (#664).
   `docs/DriverLifecycle.md`.
 - **S7 (#632/#638):** STRING/WSTRING/CHAR/WCHAR and DTL/DATE/TOD/TIME/S5TIME codecs (`S7ValueCodecs`; TOD/TIME/S5TIME
   surface as Int32 ms); an undecodable buffer or unrepresentable write is `BadOutOfRange` with no health impact.

docs/DriverLifecycle.md

@@ -264,6 +264,16 @@ Things to know before touching any of this:
   Calculation and Galaxy take their config at construction and ignore the JSON passed to `InitializeAsync`.
   Not reachable from a deploy since #516 (a DriverConfig change respawns). Pin:
   `An_in_place_ApplyDelta_leaves_one_live_data_and_one_live_alarm_subscription` (one case per wrong fix).
+- **A mid-connect `ApplyDelta` re-runs `InitializeAsync(newConfig)` — so every driver's `InitializeAsync` must
+  honour the JSON (#664).** `AdoptConfigDuringInit` adopts a delta that lands while Connecting/Reconnecting by
+  re-initialising, and acks on adoption. Every driver re-parses a config with a body (#516/#630) except two that
+  used to ignore it: **Calculation** now rebuilds its tag table from it (sharing `AdoptConfig` with
+  `ReinitializeAsync`, and disposing any running timer scheduler first), and **Galaxy**, which cannot hot-swap
+  its options, now **refuses** a non-equivalent config with the same `NotSupportedException` its
+  `ReinitializeAsync` throws — it used to connect on the old endpoint while the deploy reported success. A
+  `"{}"`/empty document still keeps the constructor options. Once the adopted init succeeds the actor sends
+  `DeltaApplied`, so the host re-registers a dependency consumer's mux interest — the mid-connect path used to
+  send nothing. A new driver must follow the same rule. Unreachable from a deploy since #516.
 - **Restart tests must assert a FUNCTION, never existence.** `RestartDriver_respawns_the_child_without_an_actor_name_collision`
   asserts only that a child exists after a restart, and it passed green against the dead driver 03/S16
   describes. It is kept — its own subject, the `InvalidActorNameException`, is real — but the load-bearing

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Calculation/CalculationDriver.cs

@@ -239,6 +239,35 @@ public sealed class CalculationDriver : IDriver, IDependencyConsumer, ISubscriba
         return new CalculationDriverOptions { RawTags = _options.RawTags, RunTimeout = _options.RunTimeout };
     }
 
+    /// <summary>Re-bind the tag table from <paramref name="driverConfigJson"/> — shared by
+    /// <see cref="ReinitializeAsync"/> and (for a config with a body) <see cref="InitializeAsync"/> so the two
+    /// adoption paths cannot drift. Timers must already be stopped.</summary>
+    private void AdoptConfig(string driverConfigJson)
+    {
+        var newOptions = ParseOptions(driverConfigJson);
+        lock (_lock)
+        {
+            // Queued evaluations were prepared against the OUTGOING tag table (old script source, old
+            // dependency set), so they are stale the moment the rebuild lands — drop them rather than
+            // publish one last pre-edit value after the delta was applied.
+            _pending.Clear();
+            RebuildTagTable(newOptions);
+        }
+        // Drop compiled scripts (IScriptCacheOwner contract — stops collectible ALCs accreting AND forces a
+        // recompile from each tag's NEW ScriptSource).
+        _evaluator.ClearCompiledScripts();
+    }
+
+    /// <summary>True when the supplied DriverConfig JSON carries a real body. The bootstrapper always passes a
+    /// populated document; unit tests pass <c>"{}"</c> to exercise lifecycle shape — those keep the
+    /// constructor-supplied tags (an empty document would otherwise bind to an EMPTY tag table).</summary>
+    private static bool HasConfigBody(string? driverConfigJson)
+    {
+        if (string.IsNullOrWhiteSpace(driverConfigJson)) return false;
+        var trimmed = driverConfigJson.Trim();
+        return trimmed is not "{}" and not "[]";
+    }
+
     /// <summary>Minimal reinit-bind DTO — the calc driver has no backend config, only the injected raw tags
     /// (+ an optional eval-timeout, ignored on reinit since the evaluator is ctor-fixed). Mirrors the factory's
     /// <c>CalculationDriverConfigDto</c>.</summary>
@@ -257,8 +286,17 @@ public sealed class CalculationDriver : IDriver, IDependencyConsumer, ISubscriba
     public string DriverType => DriverTypeNames.Calculation;
 
     /// <inheritdoc />
+    /// <remarks>
+    ///     #664: <c>InitializeAsync</c> is reachable on a LIVE driver — <c>DriverInstanceActor.AdoptConfigDuringInit</c>
+    ///     re-runs it with a NEW config when an ApplyDelta lands mid-connect — so it adopts a config carrying a
+    ///     real body (the #516 convention every other driver follows), and disposes any running timer scheduler
+    ///     before arming a fresh one (#630: re-initialise without teardown must not leak). A <c>"{}"</c> / empty
+    ///     document keeps the constructor-supplied tags, as unit tests rely on.
+    /// </remarks>
     public Task InitializeAsync(string driverConfigJson, CancellationToken cancellationToken)
     {
+        StopTimers();
+        if (HasConfigBody(driverConfigJson)) AdoptConfig(driverConfigJson);
         _running = true;
         StartTimers();
         _logger.LogInformation(
@@ -279,18 +317,8 @@ public sealed class CalculationDriver : IDriver, IDependencyConsumer, ISubscriba
         // reflects the new authored tags, and the host re-registers the mux interest post-reinit (the
         // DriverInstanceActor.DeltaApplied → DriverHostActor path, sequenced AFTER this completes).
         StopTimers();
-        var newOptions = ParseOptions(driverConfigJson);
+        AdoptConfig(driverConfigJson);
-        lock (_lock)
+        // Re-arm timers off the rebuilt tag set.
-        {
-            // Queued evaluations were prepared against the OUTGOING tag table (old script source, old
-            // dependency set), so they are stale the moment the rebuild lands — drop them rather than
-            // publish one last pre-edit value after the delta was applied.
-            _pending.Clear();
-            RebuildTagTable(newOptions);
-        }
-        // Drop compiled scripts (IScriptCacheOwner contract — stops collectible ALCs accreting AND forces a
-        // recompile from each tag's NEW ScriptSource) + re-arm timers off the rebuilt tag set.
-        _evaluator.ClearCompiledScripts();
         _running = true;
         StartTimers();
         return Task.CompletedTask;

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Galaxy/GalaxyDriver.cs

@@ -348,9 +348,18 @@ public sealed class GalaxyDriver
         ReplayAsync(cancellationToken);
 
     /// <inheritdoc />
+    /// <remarks>
+    ///     #664: <c>InitializeAsync</c> is reachable on a live driver with a NEW config —
+    ///     <c>DriverInstanceActor.AdoptConfigDuringInit</c> re-runs it when an ApplyDelta lands mid-connect. The
+    ///     driver cannot hot-swap its options (they shape the gw session; see <see cref="ReinitializeAsync"/>), so a
+    ///     non-equivalent config with a real body is REFUSED here too rather than silently ignored — the driver
+    ///     would otherwise connect on its old endpoint while the deploy reported the change applied. A
+    ///     <c>"{}"</c> / empty document is the unit-test lifecycle shape and keeps the constructor options.
+    /// </remarks>
     public async Task InitializeAsync(string driverConfigJson, CancellationToken cancellationToken)
     {
         ObjectDisposedException.ThrowIf(_disposed, this);
+        if (HasConfigBody(driverConfigJson)) RefuseNonEquivalentConfig(driverConfigJson);
 
         // Tests inject seams via the internal ctor; production InitializeAsync builds
         // the gateway client + session + per-capability runtime components from
@@ -650,48 +659,65 @@ public sealed class GalaxyDriver
     public Task ReinitializeAsync(string driverConfigJson, CancellationToken cancellationToken)
     {
         ObjectDisposedException.ThrowIf(_disposed, this);
-        if (!string.IsNullOrWhiteSpace(driverConfigJson))
+        if (!string.IsNullOrWhiteSpace(driverConfigJson)) RefuseNonEquivalentConfig(driverConfigJson);
-        {
-            // In-place config reapply. The driver does not currently support hot-swapping
-            // GalaxyDriverOptions at runtime — changing the gateway endpoint, MxAccess
-            // client name, or reconnect policy requires tearing down the gw session,
-            // supervisor, event pump, and address space. The host stack handles that via
-            // DriverInstance restart, so this method only accepts an equivalent config (no
-            // meaningful change) and refreshes health; a non-equivalent reapply throws
-            // NotSupportedException so the caller knows the change wasn't applied.
-            //
-            // Materialise the incoming config and compare against the live options. We
-            // refuse any change that would require a session teardown rather than
-            // pretending to apply it.
-            GalaxyDriverOptions incoming;
-            try
-            {
-                // Reuse the factory's parse pipeline so any missing-required-field
-                // error surfaces with the same diagnostic text as InitializeAsync.
-                var transient = GalaxyDriverFactoryExtensions.CreateInstance(_driverInstanceId, driverConfigJson);
-                incoming = transient.Options;
-                // The transient instance never started a runtime — disposing is cheap.
-                transient.Dispose();
-            }
-            catch (Exception ex) when (ex is not NotSupportedException and not ObjectDisposedException)
-            {
-                throw new NotSupportedException(
-                    $"GalaxyDriver.ReinitializeAsync could not parse the incoming DriverConfig JSON for '{_driverInstanceId}': {ex.Message}",
-                    ex);
-            }
-
-            if (!OptionsAreEquivalent(_options, incoming))
-            {
-                throw new NotSupportedException(
-                    "GalaxyDriver.ReinitializeAsync does not support hot-swapping driver options at runtime " +
-                    "(gateway endpoint, MxAccess client name, reconnect policy, etc.). Restart the DriverInstance " +
-                    "through the host stack to apply a config change.");
-            }
-        }
         _health = new DriverHealth(DriverState.Healthy, DateTime.UtcNow, null);
         return Task.CompletedTask;
     }
 
+
+    /// <summary>True when the supplied DriverConfig JSON carries a real body (not empty / <c>"{}"</c> / <c>"[]"</c>).</summary>
+    private static bool HasConfigBody(string? driverConfigJson)
+    {
+        if (string.IsNullOrWhiteSpace(driverConfigJson)) return false;
+        var trimmed = driverConfigJson.Trim();
+        return trimmed is not "{}" and not "[]";
+    }
+
+    /// <summary>
+    ///     Throw <see cref="NotSupportedException"/> unless <paramref name="driverConfigJson"/> describes options
+    ///     runtime-equivalent to the live ones (see <see cref="OptionsAreEquivalent"/>). Shared by
+    ///     <see cref="ReinitializeAsync"/> and <see cref="InitializeAsync"/> (#664) so neither path can silently
+    ///     ignore a config change it cannot apply.
+    /// </summary>
+    private void RefuseNonEquivalentConfig(string driverConfigJson)
+    {
+        // In-place config reapply. The driver does not currently support hot-swapping
+        // GalaxyDriverOptions at runtime — changing the gateway endpoint, MxAccess
+        // client name, or reconnect policy requires tearing down the gw session,
+        // supervisor, event pump, and address space. The host stack handles that via
+        // DriverInstance restart, so this method only accepts an equivalent config (no
+        // meaningful change) and refreshes health; a non-equivalent reapply throws
+        // NotSupportedException so the caller knows the change wasn't applied.
+        //
+        // Materialise the incoming config and compare against the live options. We
+        // refuse any change that would require a session teardown rather than
+        // pretending to apply it.
+        GalaxyDriverOptions incoming;
+        try
+        {
+            // Reuse the factory's parse pipeline so any missing-required-field
+            // error surfaces with the same diagnostic text as InitializeAsync.
+            var transient = GalaxyDriverFactoryExtensions.CreateInstance(_driverInstanceId, driverConfigJson);
+            incoming = transient.Options;
+            // The transient instance never started a runtime — disposing is cheap.
+            transient.Dispose();
+        }
+        catch (Exception ex) when (ex is not NotSupportedException and not ObjectDisposedException)
+        {
+            throw new NotSupportedException(
+                $"GalaxyDriver could not parse the incoming DriverConfig JSON for '{_driverInstanceId}': {ex.Message}",
+                ex);
+        }
+
+        if (!OptionsAreEquivalent(_options, incoming))
+        {
+            throw new NotSupportedException(
+                "GalaxyDriver does not support hot-swapping driver options at runtime " +
+                "(gateway endpoint, MxAccess client name, reconnect policy, etc.). Restart the DriverInstance " +
+                "through the host stack to apply a config change.");
+        }
+    }
+
     /// <summary>
     ///     Compare two <see cref="GalaxyDriverOptions"/> for runtime equivalence — every
     ///     field that drives gw session shape or reconnect behaviour must match. Compared

src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Drivers/DriverInstanceActor.cs

@@ -221,6 +221,12 @@ public sealed class DriverInstanceActor : ReceiveActor, IWithTimers
     private readonly ILoggingAdapter _log = Context.GetLogger();
     private string? _currentConfigJson;
 
+    /// <summary>#664: set when <see cref="AdoptConfigDuringInit"/> adopts a new config mid-connect; the next
+    /// (generation-matched) <see cref="InitializeSucceeded"/> sends <see cref="DeltaApplied"/> to the parent and
+    /// clears it, so a dependency consumer's mux interest is re-registered against the ADOPTED config — the
+    /// same post-reinit notification the Connected <see cref="HandleApplyDeltaAsync"/> path sends.</summary>
+    private bool _adoptedConfigPendingNotify;
+
     /// <summary>Monotonic token tagging each <see cref="InitializeAsync"/> attempt. An init result is
     /// honoured only when its generation matches the latest; an older result is from a superseded attempt
     /// (e.g. an <see cref="ApplyDelta"/> adopted a new config mid-(re)connect) and is dropped. Touched only
@@ -468,6 +474,7 @@ public sealed class DriverInstanceActor : ReceiveActor, IWithTimers
             if (msg.Generation != _initGeneration) return;
             _log.Info("DriverInstance {Id}: connected", _driverInstanceId);
             Become(Connected);
+            NotifyAdoptedConfig();
             PublishHealthSnapshot();
             ResubscribeDesired();
             AttachAlarmSource();
@@ -771,6 +778,7 @@ public sealed class DriverInstanceActor : ReceiveActor, IWithTimers
             Timers.Cancel("retry-connect");
             _log.Info("DriverInstance {Id}: reconnected", _driverInstanceId);
             Become(Connected);
+            NotifyAdoptedConfig();
             PublishHealthSnapshot();
             ResubscribeDesired();
             AttachAlarmSource();
@@ -878,9 +886,19 @@ public sealed class DriverInstanceActor : ReceiveActor, IWithTimers
         _log.Info("DriverInstance {Id}: ApplyDelta during (re)connect — adopting new config, re-initialising now",
             _driverInstanceId);
         InitializeAsync(msg.DriverConfigJson);
+        _adoptedConfigPendingNotify = true;
         Sender.Tell(new ApplyResult(true, "config adopted; reinitializing", msg.Correlation));
     }
 
+    /// <summary>Send the deferred <see cref="DeltaApplied"/> for a mid-connect adoption (#664) once the driver
+    /// has actually initialised on the adopted config. A no-op otherwise.</summary>
+    private void NotifyAdoptedConfig()
+    {
+        if (!_adoptedConfigPendingNotify) return;
+        _adoptedConfigPendingNotify = false;
+        Context.Parent.Tell(new DeltaApplied(_driverInstanceId));
+    }
+
     /// <summary>Adopt a new config while Connected, in place, via <see cref="IDriver.ReinitializeAsync"/>.
     /// <para>#663: every driver's reinit releases its device/session state (#630), so the driver-side data and
     /// native-alarm subscriptions do not survive it — but this handler used to keep both handles, and the

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Calculation.Tests/CalculationDriverTests.cs

@@ -413,6 +413,34 @@ public sealed class CalculationDriverTests
         report.SkippedCount.ShouldBe(1, "the reinit payload's tag has no scriptId, so it is no longer a calc tag");
     }
 
+    /// <summary>
+    ///     Gitea #664 — <c>InitializeAsync</c> re-runs on a LIVE driver with a new config when an ApplyDelta lands
+    ///     mid-connect (<c>DriverInstanceActor.AdoptConfigDuringInit</c>). It used to ignore the JSON, so the
+    ///     driver kept its constructor tag set while the deploy reported the change applied. A config with a body
+    ///     now rebuilds the tag table (and the dependency-ref set the host re-registers from).
+    /// </summary>
+    [Fact]
+    public async Task InitializeAsync_on_a_live_driver_adopts_a_config_with_a_body()
+    {
+        var (driver, published, _) = Build(CalcTag("calc/e/a", "return (double)ctx.GetTag(\"src/a\").Value * 2.0;"));
+        await driver.InitializeAsync("{}", TestContext.Current.CancellationToken);
+        driver.DependencyRefs.ShouldBe(new[] { "src/a" });
+
+        var adopted = System.Text.Json.JsonSerializer.Serialize(new
+        {
+            rawTags = new[] { CalcTag("calc/e/b", "return (double)ctx.GetTag(\"src/b\").Value + 1.0;") },
+        });
+        await driver.InitializeAsync(adopted, TestContext.Current.CancellationToken);
+
+        driver.DependencyRefs.ShouldBe(new[] { "src/b" });
+        driver.OnDependencyValue("src/b", 4.0, StatusGood, DateTime.UtcNow);
+        await Settle(driver);
+        published.ShouldContain(e => e.FullReference == "calc/e/b" && Equals(e.Snapshot.Value, 5.0));
+        published.ShouldNotContain(e => e.FullReference == "calc/e/a");
+
+        await driver.ShutdownAsync(TestContext.Current.CancellationToken);
+    }
+
     /// <summary>Minimal capturing <see cref="ILogger{T}"/> so a test can assert on what the driver's own
     /// logger received (mirrors the equivalent helper in CalculationEvaluatorTests).</summary>
     private sealed class CapturingLogger : ILogger<CalculationDriver>

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Tests/GalaxyDriverFactoryTests.cs

@@ -168,7 +168,9 @@ public sealed class GalaxyDriverFactoryTests
             dataWriter: null, subscriber: new NoopSubscriber());
         driver.GetHealth().State.ShouldBe(DriverState.Unknown);
 
-        await driver.InitializeAsync(MinimalConfig, CancellationToken.None);
+        // #664: InitializeAsync now refuses a config that differs from the live options, so this uses the
+        // "{}" lifecycle shape (MinimalConfig's ApiKeySecretRef differs from BuildOptions()).
+        await driver.InitializeAsync("{}", CancellationToken.None);
         driver.GetHealth().State.ShouldBe(DriverState.Healthy);
         driver.GetHealth().LastSuccessfulRead.ShouldNotBeNull();
 
@@ -206,6 +208,38 @@ public sealed class GalaxyDriverFactoryTests
         driver.GetHealth().LastSuccessfulRead!.Value.ShouldBeGreaterThan(firstStamp);
     }
 
+    /// <summary>
+    ///     Gitea #664 — <c>InitializeAsync</c> re-runs on a live driver with a NEW config when an ApplyDelta lands
+    ///     mid-connect. Galaxy cannot hot-swap its options, and it used to ignore the JSON — connecting on the OLD
+    ///     endpoint while the deploy reported the change applied. A non-equivalent config is now refused, exactly
+    ///     as <c>ReinitializeAsync</c> refuses it; an equivalent one still initialises.
+    /// </summary>
+    [Fact]
+    public async Task InitializeAsync_refuses_a_non_equivalent_config_and_accepts_an_equivalent_one()
+    {
+        const string moved = """
+            {
+              "Gateway": { "Endpoint": "https://elsewhere.test:5001", "ApiKeySecretRef": "key" },
+              "MxAccess": { "ClientName": "OtOpcUa-A" }
+            }
+            """;
+        const string same = """
+            {
+              "Gateway": { "Endpoint": "https://mxgw.test:5001", "ApiKeySecretRef": "key" },
+              "MxAccess": { "ClientName": "OtOpcUa-A" }
+            }
+            """;
+        using var driver = new GalaxyDriver(
+            "galaxy-x", BuildOptions(), hierarchySource: null, dataReader: null,
+            dataWriter: null, subscriber: new NoopSubscriber());
+
+        await Should.ThrowAsync<NotSupportedException>(() => driver.InitializeAsync(moved, CancellationToken.None));
+        driver.GetHealth().State.ShouldBe(DriverState.Unknown, "a refused init must not report Healthy");
+
+        await driver.InitializeAsync(same, CancellationToken.None);
+        driver.GetHealth().State.ShouldBe(DriverState.Healthy);
+    }
+
     private static GalaxyDriverOptions BuildOptions() => new(
         new GalaxyGatewayOptions("https://mxgw.test:5001", "key"),
         new GalaxyMxAccessOptions("OtOpcUa-A"),
@@ -283,7 +317,8 @@ public sealed class GalaxyDriverFactoryTests
         using var driver = new GalaxyDriver(
             "g", BuildOptions(), hierarchySource: null, dataReader: null,
             dataWriter: null, subscriber: new NoopSubscriber());
-        await driver.InitializeAsync(MinimalConfig, CancellationToken.None);
+        // #664: "{}" — MinimalConfig is not equivalent to BuildOptions(), and InitializeAsync now refuses that.
+        await driver.InitializeAsync("{}", CancellationToken.None);
         driver.GetHostStatuses().ShouldBeEmpty();
     }
 

tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/DriverInstanceActorTests.cs

@@ -338,6 +338,40 @@ public sealed class DriverInstanceActorTests : RuntimeActorTestBase
         driver.InitConfigs.ShouldContain(good);
     }
 
+    /// <summary>
+    ///     Gitea #664 — a mid-connect adoption sends <see cref="DriverInstanceActor.DeltaApplied"/> once the
+    ///     driver has initialised on the ADOPTED config, so the host re-registers a dependency consumer's mux
+    ///     interest (the Calculation driver's refs change with its tag set). It used to send nothing, leaving the
+    ///     old interest registered. The notification is one-shot: a later reconnect on the same config sends none.
+    /// </summary>
+    [Fact]
+    public void A_mid_connect_adoption_notifies_DeltaApplied_once_after_the_adopted_init_succeeds()
+    {
+        const string bad = "{\"v\":\"bad\"}";
+        const string good = "{\"v\":\"good\"}";
+        var driver = new SubscribableStubDriver
+        {
+            InitBehavior = cfg => cfg == good ? Task.CompletedTask : throw new InvalidOperationException("bad-cfg"),
+        };
+        var parent = CreateTestProbe();
+        parent.IgnoreMessages(m => m is not DriverInstanceActor.DeltaApplied);
+        var actor = parent.ChildActorOf(DriverInstanceActor.Props(driver, reconnectInterval: TimeSpan.FromMilliseconds(50)));
+        actor.Tell(new DriverInstanceActor.SetDesiredSubscriptions(new[] { "tag-a" }, TimeSpan.FromMilliseconds(100)));
+
+        actor.Tell(new DriverInstanceActor.InitializeRequested(bad));
+        AwaitCondition(() => driver.InitializeCount >= 2, PresenceBudget);
+
+        actor.Tell(new DriverInstanceActor.ApplyDelta(good, CorrelationId.NewId()));
+        parent.ExpectMsg<DriverInstanceActor.DeltaApplied>(PresenceBudget);
+        driver.InitConfigs.ShouldContain(good, "the notification must follow an init on the adopted config");
+
+        // A reconnect on the same config re-runs InitializeSucceeded; the positive control is its re-subscribe.
+        var subscribes = driver.SubscribeCount;
+        actor.Tell(new DriverInstanceActor.ForceReconnect());
+        AwaitCondition(() => driver.SubscribeCount > subscribes, PresenceBudget);
+        parent.ExpectNoMsg(TimeSpan.FromMilliseconds(300));
+    }
+
     /// <summary>A stale InitializeSucceeded from an old (superseded) config cannot hijack the state:
     /// while a gated old-config init is pending in Connecting, an ApplyDelta adopts a new config; the
     /// old init completing afterwards is ignored, and only the new config drives Connected.</summary>