diff --git a/archreview/plans/R2-06-serverhistorian-failfast-plan.md.tasks.json b/archreview/plans/R2-06-serverhistorian-failfast-plan.md.tasks.json
index 2bf733da..54febf58 100644
--- a/archreview/plans/R2-06-serverhistorian-failfast-plan.md.tasks.json
+++ b/archreview/plans/R2-06-serverhistorian-failfast-plan.md.tasks.json
@@ -57,7 +57,7 @@
     {
       "id": "T8",
       "subject": "U-7 live leg: HISTGW_BOOL_SANDBOX_TAG in GatewayLiveFixture + EnsureTags_boolean_sandbox_provisions_as_Int1 + EnsureTags_type_change_outcome_is_observable retype probe (skip-clean offline; verify all-skip run)",
-      "status": "pending",
+      "status": "completed",
       "blockedBy": [
         "T7"
       ]
diff --git a/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway.Tests/Live/GatewayLiveFixture.cs b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway.Tests/Live/GatewayLiveFixture.cs
index eda48b62..25caa3e8 100644
--- a/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway.Tests/Live/GatewayLiveFixture.cs
+++ b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway.Tests/Live/GatewayLiveFixture.cs
@@ -22,6 +22,7 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway.Tests.Live;
 ///             <item><c>HISTGW_GATEWAY_APIKEY</c> — the <c>histgw_&lt;id&gt;_&lt;secret&gt;</c> key (must carry <c>historian:read</c> + <c>historian:write</c> scopes). Required; absent ⇒ all tests skip.</item>
 ///             <item><c>HISTGW_TEST_TAG</c> — an existing Galaxy / historian tag for the read round-trip.</item>
 ///             <item><c>HISTGW_WRITE_SANDBOX_TAG</c> — a Float sandbox tag the write round-trip may <c>EnsureTags</c> + write (e.g. <c>HistGW.LiveTest.Sandbox</c>).</item>
+///             <item><c>HISTGW_BOOL_SANDBOX_TAG</c> — a writable Boolean sandbox tag (e.g. <c>HistGW.LiveTest.BoolSandbox</c>) for the 0.2.0 Boolean <c>EnsureTags</c> leg + the retype probe (archreview 06/U-7). Dedicated — never the shared write sandbox.</item>
 ///             <item><c>HISTGW_ALARM_SOURCE</c> — a source name for the alarm <c>SendEvent</c> → <c>ReadEvents</c> round-trip.</item>
 ///             <item><c>HISTGW_GATEWAY_ALLOW_UNTRUSTED</c> — <c>true</c> to accept a self-signed dev cert (optional).</item>
 ///         </list>
@@ -44,6 +45,7 @@ public sealed class GatewayLiveFixture
     private const string EnvApiKey = "HISTGW_GATEWAY_APIKEY";
     private const string EnvTestTag = "HISTGW_TEST_TAG";
     private const string EnvWriteSandboxTag = "HISTGW_WRITE_SANDBOX_TAG";
+    private const string EnvBoolSandboxTag = "HISTGW_BOOL_SANDBOX_TAG";
     private const string EnvAlarmSource = "HISTGW_ALARM_SOURCE";
     private const string EnvAllowUntrusted = "HISTGW_GATEWAY_ALLOW_UNTRUSTED";
 
@@ -68,6 +70,7 @@ public sealed class GatewayLiveFixture
         _apiKey = Trimmed(EnvApiKey);
         TestTag = Trimmed(EnvTestTag);
         WriteSandboxTag = Trimmed(EnvWriteSandboxTag);
+        BoolSandboxTag = Trimmed(EnvBoolSandboxTag);
         AlarmSource = Trimmed(EnvAlarmSource);
         _allowUntrusted = string.Equals(
             Trimmed(EnvAllowUntrusted), "true", StringComparison.OrdinalIgnoreCase);
@@ -105,6 +108,10 @@ public sealed class GatewayLiveFixture
     /// <summary>The Float sandbox tag for the write round-trip (<c>HISTGW_WRITE_SANDBOX_TAG</c>); null when unset.</summary>
     public string? WriteSandboxTag { get; }
 
+    /// <summary>The dedicated Boolean sandbox tag for the 0.2.0 Boolean EnsureTags leg + retype probe
+    /// (<c>HISTGW_BOOL_SANDBOX_TAG</c>, archreview 06/U-7); null when unset.</summary>
+    public string? BoolSandboxTag { get; }
+
     /// <summary>The source name for the alarm round-trip (<c>HISTGW_ALARM_SOURCE</c>); null when unset.</summary>
     public string? AlarmSource { get; }
 
diff --git a/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway.Tests/Live/GatewayLiveIntegrationTests.cs b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway.Tests/Live/GatewayLiveIntegrationTests.cs
index 8479aaa1..96260f1d 100644
--- a/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway.Tests/Live/GatewayLiveIntegrationTests.cs
+++ b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway.Tests/Live/GatewayLiveIntegrationTests.cs
@@ -253,4 +253,124 @@ public sealed class GatewayLiveIntegrationTests(GatewayLiveFixture fixture) : IC
             HistorianWriteOutcome.Ack,
             "the alarm SendEvent must be acked (the AlarmEventMapper must NOT set the wire event Id — the gateway rejects a client-supplied id).");
     }
+
+    /// <summary>
+    ///     archreview 06/U-7 — Boolean provisioning leg on the 0.2.0 contract. Through the <b>real</b>
+    ///     <see cref="GatewayTagProvisioner"/>, <c>EnsureTags</c> a <see cref="DriverDataType.Boolean"/>
+    ///     request for the dedicated Boolean sandbox tag (mapped to <c>Int1</c> with explicit proto3
+    ///     presence), assert it is ensured (not failed), then <c>WriteLiveValues</c> a <c>1.0</c> and read
+    ///     it back over a wide window. This retires "the live EnsureTags leg has never run on 0.2.0" for
+    ///     the Boolean path. The ±12h read window + timezone caveat mirror <see cref="Write_then_read_on_sandbox_tag"/>.
+    /// </summary>
+    [Fact]
+    [Trait("Category", "LiveIntegration")]
+    public async Task EnsureTags_boolean_sandbox_provisions_as_Int1()
+    {
+        if (_fx.NotConfigured) Assert.Skip(_fx.SkipReason!);
+        if (_fx.BoolSandboxTag is null)
+            Assert.Skip("Skipped: set HISTGW_BOOL_SANDBOX_TAG to a writable Boolean sandbox tag (e.g. HistGW.LiveTest.BoolSandbox) to run the 0.2.0 Boolean EnsureTags leg.");
+
+        var ct = TestContext.Current.CancellationToken;
+        var tag = _fx.BoolSandboxTag;
+
+        // EnsureTags (Boolean → Int1) through the REAL provisioner seam (the same code path deploys use).
+        await using var writeClient = _fx.CreateClient();
+        var provisioner = new GatewayTagProvisioner(writeClient, NullLogger<GatewayTagProvisioner>.Instance);
+        var provision = await provisioner.EnsureTagsAsync(
+            new[] { new HistorianTagProvisionRequest(tag, DriverDataType.Boolean, null, "OtOpcUa live validation Boolean sandbox") },
+            ct);
+
+        provision.Ensured.ShouldBe(1,
+            "the Boolean sandbox tag must be ensured (needs the gateway on 0.2.0 contracts + an API key carrying historian:tags:write).");
+        provision.Failed.ShouldBe(0);
+
+        // WriteLiveValues a Boolean-as-1.0 and read it back (SQL live path can lag a flush cadence → poll).
+        const ushort goodQuality = 192; // OPC-DA "Good" floor.
+        var writeUtc = DateTime.UtcNow;
+        const double written = 1.0;
+        var valueWriter = new GatewayHistorianValueWriter(writeClient, NullLogger<GatewayHistorianValueWriter>.Instance);
+        var acked = await valueWriter.WriteLiveValuesAsync(
+            tag, new[] { new HistorizationValue(writeUtc, written, goodQuality) }, ct);
+        acked.ShouldBeTrue("the Boolean live write must be acked (gateway RuntimeDb:Enabled=true + EnsureTags-provisioned tag).");
+
+        await using var dataSource = _fx.CreateDataSource();
+        DataValueSnapshot? hit = null;
+        var deadline = DateTime.UtcNow + TimeSpan.FromSeconds(15);
+        do
+        {
+            var read = await dataSource.ReadRawAsync(
+                tag, writeUtc - TimeSpan.FromHours(12), writeUtc + TimeSpan.FromHours(12), maxValuesPerNode: 50_000, ct);
+            hit = read.Samples.FirstOrDefault(s => s.Value is double d && Math.Abs(d - written) < 0.5);
+            if (hit is not null) break;
+            await Task.Delay(TimeSpan.FromSeconds(1), ct);
+        }
+        while (DateTime.UtcNow < deadline);
+
+        hit.ShouldNotBeNull($"the written Boolean sample ({written}) should read back from '{tag}'.");
+        TestContext.Current.SendDiagnosticMessage(
+            $"Boolean round-trip: EnsureTags(Int1) + WriteLiveValues '{tag}'={written} → read back at {hit!.SourceTimestampUtc:O}.");
+    }
+
+    /// <summary>
+    ///     archreview 06/U-7 retype probe — answers the assessment note's open question: what does the
+    ///     deployed AVEVA Historian do when <c>EnsureTags</c> (an <b>upsert</b>) is asked to change an
+    ///     existing tag's type? Against the <b>dedicated Boolean sandbox tag only</b> (never the shared
+    ///     Float write sandbox), EnsureTags first as <c>Float</c> then as <c>Int1</c> and assert the second
+    ///     call's per-tag outcome is <em>deterministic and observable</em> — either <c>Success=true</c>
+    ///     (retype / tag-versioning accepted) or <c>Success=false</c> with a non-empty <c>Error</c> (mapped
+    ///     to the provisioner's <c>failed</c> tally). The assertion accepts both because the contract
+    ///     guarantees only the observability, not the policy; the observed behavior is emitted as a
+    ///     diagnostic so the run documents which of accepted-versioned / accepted-retyped / rejected the
+    ///     historian exhibits (fed back into docs/Historian.md after the first live run).
+    /// </summary>
+    [Fact]
+    [Trait("Category", "LiveIntegration")]
+    public async Task EnsureTags_type_change_outcome_is_observable()
+    {
+        if (_fx.NotConfigured) Assert.Skip(_fx.SkipReason!);
+        if (_fx.BoolSandboxTag is null)
+            Assert.Skip("Skipped: set HISTGW_BOOL_SANDBOX_TAG to a dedicated Boolean sandbox tag to run the retype probe.");
+
+        var ct = TestContext.Current.CancellationToken;
+        var tag = _fx.BoolSandboxTag;
+
+        await using var client = _fx.CreateClient();
+
+        // First establish the tag as Float, then ask EnsureTags to retype it to Int1 (Boolean).
+        await client.EnsureTagsAsync(
+            new[]
+            {
+                new HistorianTagDefinition
+                {
+                    TagName = tag,
+                    DataType = HistorianDataType.Float,
+                    EngineeringUnit = string.Empty,
+                    Description = "OtOpcUa live validation retype probe (stage 1: Float)",
+                },
+            },
+            ct);
+
+        var retype = await client.EnsureTagsAsync(
+            new[]
+            {
+                new HistorianTagDefinition
+                {
+                    TagName = tag,
+                    DataType = HistorianDataType.Int1,
+                    EngineeringUnit = string.Empty,
+                    Description = "OtOpcUa live validation retype probe (stage 2: Int1)",
+                },
+            },
+            ct);
+
+        var outcome = retype.Results.ShouldHaveSingleItem();
+        var observable = outcome.Success || !string.IsNullOrEmpty(outcome.Error);
+        observable.ShouldBeTrue(
+            "the retype outcome must be deterministic + observable: either Success=true (retype/version accepted) " +
+            "or Success=false with a non-empty Error (mapped to the provisioner's failed tally).");
+
+        TestContext.Current.SendDiagnosticMessage(
+            $"retype probe '{tag}' Float→Int1: Success={outcome.Success}, Error='{outcome.Error}'. " +
+            "(records the deployed historian's in-place analog-retype policy — feed this back into docs/Historian.md).");
+    }
 }