diff --git a/CLAUDE.md b/CLAUDE.md
index 935c55cf..57b72912 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -1350,7 +1350,7 @@ historian tagname, which is the tag's driver `FullName`.
 ### Pluggable backends, SQL Server and HistoryUpdate (2026-10)
 
 - **Selection:** `ServerHistorian:Backend` (`Gateway` default | `SqlServer` | `QuestDb`; unknown fails host start). `HistorianBackendRegistry` → `IHistorianBackendProvider` builds all five seams; the gateway keys are only required for `Gateway`. `SqlServer` uses `ServerHistorian:SqlServer:{ConnectionString (required), Schema=hist, CommandTimeout=30s, AutoCreateSchema=true}`.
-- **SQL Server** (`Driver.Historian.SqlServer`): `hist.Sample` PK `(TagId, SourceTimeUtc)` — writes are insert-if-absent, so outbox redelivery is idempotent. Stores every value kind with its **real status**; per-sample aggregates (12, simple definitions) are pushed down to T-SQL with bucket math in **100 ns ticks**; the Part 13 time-weighted five (TimeAverage/TimeAverage2/Total/Total2/Interpolative, #671 — ⚠️ `Total` is now the time-weighted integral, no longer `SUM`) stream window + 4 bound rows into the shared `TimeWeightedAggregator` (both SQL backends, identical results; client `AggregateConfiguration` ignored; status = the SDK `AggregateCalculator` time-based rule, Uncertain time counts as Good; reverse `Interpolative` anchored at the later time; window capped by `ServerHistorian:MaxTimeWeightedRawRows` ⇒ `BadTooManyOperations`). Docker-dev recipe, schema and aggregate semantics: `docs/Historian.md` §"SQL Server backend". Integration tests need `HISTORIAN_SQL_TEST_CONNECTION`. **Retention (#667):** opt-in `SqlServer:RetentionDays` (+ `PurgeInterval` 1h, `PurgeBatchSize` 4000) -> `HistorianRetentionService` purges old `hist.Sample` (per tag) / `hist.Event` in `DELETE TOP(n)` batches, Primary-gated on `IHistorizationRoleView`, one purger per DB via `sp_getapplock`; counter `otopcua.historian.retention.purged{table}`. Optional `IHistorianBackendProvider.CreateRetention` (default null). `docs/Historian.md` §Retention.
+- **SQL Server** (`Driver.Historian.SqlServer`): `hist.Sample` PK `(TagId, SourceTimeUtc)` — writes are insert-if-absent, so outbox redelivery is idempotent. Stores every value kind with its **real status**; per-sample aggregates (10, simple definitions) are pushed down to T-SQL with bucket math in **100 ns ticks**; the Part 13 time-weighted seven (TimeAverage/TimeAverage2/Total/Total2/Interpolative, #671 — ⚠️ `Total` is now the time-weighted integral, no longer `SUM` — plus the **duration-based** PercentGood/PercentBad, #680) stream window + 4 bound rows into the shared `TimeWeightedAggregator` (both SQL backends, identical results; reverse `Interpolative` anchored at the later time; window capped by `ServerHistorian:MaxTimeWeightedRawRows` ⇒ `BadTooManyOperations`, percentages included). ⚠️ **#680 status rules (client-visible):** TimeAverage/Total are Uncertain if any part of the interval uses an Uncertain value, is bridged across a Bad sample, is extrapolated past the last sample (⇒ a live tag's latest interval is Uncertain) or is not covered; TimeAverage2/Total2 keep the SDK time-based rule (Uncertain time counts as Good) but never extrapolate past the last sample — that interval is Partial, later ones `BadNoData` (a report-by-exception tag with nothing after its last sample reads `BadNoData` until its next sample arrives). `docs/Historian.md` §"Time-weighted aggregates". Docker-dev recipe, schema and aggregate semantics: `docs/Historian.md` §"SQL Server backend". Integration tests need `HISTORIAN_SQL_TEST_CONNECTION`. **Retention (#667):** opt-in `SqlServer:RetentionDays` (+ `PurgeInterval` 1h, `PurgeBatchSize` 4000) -> `HistorianRetentionService` purges old `hist.Sample` (per tag) / `hist.Event` in `DELETE TOP(n)` batches, Primary-gated on `IHistorizationRoleView`, one purger per DB via `sp_getapplock`; counter `otopcua.historian.retention.purged{table}`. Optional `IHistorianBackendProvider.CreateRetention` (default null). `docs/Historian.md` §Retention.
 - **QuestDB** (`Driver.Historian.QuestDb`, `ServerHistorian:QuestDb:*`, Npgsql over PG wire; docker-dev overlay `docker-compose.questdb.yml`): same kinds/status/aggregates/HistoryUpdate as SqlServer, soft delete by tombstone (INSERT only — never `UPDATE`/`DELETE`; every read filters `NOT deleted`). ⚠️ **Timestamps are µs** (`QuestDbConnection.Round`/`BindTimestamp`; `IHistorianDataSource.TimestampResolutionTicks` = 10 steps HistoryRead paging), **pre-1970 cannot be stored** (writer drops, HistoryUpdate `BadOutOfRange`), every write waits for WAL visibility, TTL is enforced on write commits only, set Npgsql `Maximum Pool Size` < QuestDB's 64. `docs/Historian.md` §"QuestDB backend".
 - ⚠️ **Reverse processed reads are Part 13/SDK-anchored (#677, client-visible):** every aggregate on SqlServer/QuestDB now anchors a reverse read at its later time — window `(end, start]`, partial interval earliest, each stamped with its later edge (was: earlier-anchored, stamped earlier edge); on forward reads Partial also marks the interval the data starts inside (not Average — the SDK's rule, forward-only); a non-default client `AggregateConfiguration` ⇒ `BadAggregateConfigurationRejected`; Gateway provisioning sends `IntegralDivisor = 1`. SDK-parity tests: `SdkAggregateParityTests`. `docs/Historian.md` §Aggregates.
 - **Real status fix:** the recorder used to stamp every sample Good (`192`); it now carries the driver's status. ⚠️ On the **Gateway** backend this changes nothing stored: the gateway discards quality (C-002), so AVEVA still stores Good.
@@ -1381,7 +1381,7 @@ authorization uses the standard `AccessLevels.HistoryRead` bit set at materializ
 | `MaxTieClusterOverfetch` | `65536` | Bounded over-fetch the HistoryRead-Raw paging uses to page within an oversized same-timestamp tie cluster (retained from the prior backend) |
 | `HistoryReadBatchParallelism` | `4` | Max nodes served concurrently within one HistoryRead batch (03/S3); `⌈N/P⌉ × CallTimeout` worst case instead of sequential |
 | `MaxConcurrentHistoryReadBatches` | `16` | Process-wide concurrent HistoryRead batch cap (03/S3); flood degrades to `BadTooManyOperations`. Total in-flight reads capped at 16 × 4 = 64 |
-| `MaxTimeWeightedRawRows` | `1000000` | `SqlServer`/`QuestDb` only (#671): raw in-window rows one time-weighted aggregate read (incl. `Total`) may stream into the C# evaluator; window query capped at this + 1, past it ⇒ `BadTooManyOperations` for that node. ≤ 0 = unbounded |
+| `MaxTimeWeightedRawRows` | `1000000` | `SqlServer`/`QuestDb` only (#671): raw in-window rows one time-weighted aggregate read (incl. `Total` and, since #680, PercentGood/PercentBad) may stream into the C# evaluator; window query capped at this + 1, past it ⇒ `BadTooManyOperations` for that node. ≤ 0 = unbounded |
 | `HistoryReadDeadline` | `00:01:00` | Per-request HistoryRead wall-clock deadline (03/S3); a node still in flight surfaces `BadTimeout`. Non-positive = unbounded |
 
 ### Alarm-history path (`AlarmHistorian` section)
diff --git a/docs/Historian.md b/docs/Historian.md
index 194833ed..9d2a5d2a 100644
--- a/docs/Historian.md
+++ b/docs/Historian.md
@@ -1002,6 +1002,16 @@ and the raw-row cap below). Bucketing (edges, truncated interval, reverse anchor
 >   two samples now has a value instead of `BadNoData`.
 > - **Partial:** set on the forward end-of-data interval (`TimeAverage2`/`Total2`/percentages) and, on a reverse read, on the interval
 >   holding the latest sample when nothing follows it (all of this family but `Interpolative`).
+> - ⚠️ **Report-by-exception tags (a slowly changing or deadband-filtered value) are the visible case.** A tag whose last stored
+>   sample lies *before* the window and that has nothing after it has, by Part 13, **ended its data**: every interval of
+>   `TimeAverage2` / `Total2` / `PercentGood` / `PercentBad` is **`BadNoData`**, and every interval of `TimeAverage` / `Total` is the
+>   held value, **Uncertain**. When the next sample arrives, a re-read of the same window returns values / `Good` for those intervals
+>   (the held value is then interpolated between real samples, not extrapolated). So a dashboard, a ScadaBridge consumer or any
+>   client that caches processed results for "closed" intervals can see an interval go `BadNoData` → value, or Uncertain → Good, on a
+>   later read — re-read recent intervals, or use `TimeAverage`/`Total` (which always carry a value) for a report-by-exception tag. The
+>   SDK's own calculators behave the same way. Likewise the interval holding a tag's latest sample is Partial and, until a later
+>   sample arrives, `TimeAverage2`/`Total2` there cover only up to it — the comms-loss recovery shape (a single Good sample after an
+>   outage marker, nothing after) answers that sample's value (`Total2` 0), Uncertain + Partial, never Bad/null.
 
 **Server defaults, fixed:** `TreatUncertainAsBad = false`, `PercentDataBad = PercentDataGood = 100`, `UseSlopedExtrapolation = false`
 (`ServerAggregateConfiguration` in the OPC UA server project — the SDK's own `AggregateManager` defaults, which a test pins). **A
@@ -1049,8 +1059,10 @@ are used", and the SDK's `AverageAggregateCalculator`):
 value held up to an outage). The duration is the interval's, cut at the end of the data:
 
 - After the end of the data ⇒ `BadNoData` (Part 13 "After End of Data"); the interval the data ends inside covers only up to the last
-  sample and is **Partial** (forward); when the data ends exactly on its start there is nothing to cover and the value is the last
-  sample's (`Total2` 0), with its status.
+  sample and is **Partial** (forward). When it has no non-Bad time before the last sample — the data ends exactly on its start, or the
+  last sample is the first usable one after an outage (comms-loss recovery), or the tag's only sample — there is nothing to cover and
+  the value is the last sample's (`Total2` 0): `Good` only when the data ends exactly on the interval start with a Good sample,
+  otherwise `UncertainDataSubNormal` (the SDK answers the same, modulo its 1 ms artifact).
 - Every instant of the (covered) interval non-Bad ⇒ `Good`.
 - Some non-Bad time but not all (an outage, or time before the first sample) ⇒ `UncertainDataSubNormal`.
 - No non-Bad time but some outage time (an interval wholly inside an outage) ⇒ generic **`Bad`** (`0x80000000`), value null — Part 13's
@@ -1118,7 +1130,15 @@ ours follow Part 13: `TimeAverage2`/`Total2` stop at the last sample, the percen
 read the SDK's backward slice files a sample exactly on an interval's later edge as its early bound — so a reverse `Interpolative` at
 such a point comes back Interpolated (Uncertain if a Bad sample follows) and a reverse `TimeAverage`/`Total` interval ending on it takes
 the status of the segment beyond it — where ours, like the SDK forward, returns the raw sample and keeps the interval's own segments
-(an SDK defect: its forward and reverse answers differ).
+(an SDK defect: its forward and reverse answers differ). Three more, kept deliberately (#680 review): an **outage marker as the last
+sample** (nothing after it) runs Bad to the window end here — `TimeAverage2`/`Total2` generic `Bad` and the percentages 100 % Bad
+after it, no end-of-data Partial on the interval holding it, and `TimeAverage`/`Total` Uncertain over the span the last usable value is
+held up to the marker (no Good value follows ⇒ extrapolated) — where the SDK treats the data as ended at the marker (`BadNoData` after
+it, Partial on that interval, the held span Good): the tag is in an outage, not out of data. **Booleans** are stepped here (a
+non-analog value is held; the simple bound next to an Uncertain sample takes the earlier sample's status), while the SDK interpolates
+them as numbers — e.g. an interval that is `false` for its first half and `true` for its second averages 0.5 here, 1 in the SDK, and a
+PercentGood region ahead of an Uncertain Boolean is Good here, Uncertain in the SDK. Each is pinned by `TimeWeightedAggregatorTests` and
+by a parity dataset (`OutageLast`, `BoolSwitch`) whose masks are documented in `SdkAggregateParityTests`.
 
 **Pushdown trade-off.** Unlike the per-sample aggregates, the time-weighted family is **not** pushed down to SQL: the backend streams
 the window's rows plus the four bounds (one batch of five result sets on SQL Server; a bounds `UNION ALL` + a window select on QuestDB)
diff --git a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common/TimeWeightedAggregator.cs b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common/TimeWeightedAggregator.cs
index 5f0d6446..f2b328ca 100644
--- a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common/TimeWeightedAggregator.cs
+++ b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common/TimeWeightedAggregator.cs
@@ -337,11 +337,16 @@ public sealed class TimeWeightedAggregator
                 {
                     // After the end of the data: nothing to aggregate (Part 13 "After End of Data: Bad_NoData").
                     if (lo > dataEnd) return AggregateEvaluator.NoData(stamp, now);
-                    if (lo == dataEnd && _prevAny is { } last)
+                    if (_usableTicks[i] == 0 && dataEnd < hi && _prevAny is { } last)
                     {
-                        // The data ends exactly on this interval's start: nothing covered; the value at that instant.
+                        // The data ends inside this interval and no non-Bad time precedes its last sample here (the data
+                        // ends on the interval's start; or the last sample is the first usable one after an outage — the
+                        // comms-loss recovery shape — or the tag's only sample): nothing covered, so the value at that
+                        // instant (Total2 0). Good only when the data ends exactly on the interval start with a Good
+                        // sample (nothing before it in the interval); otherwise the interval also holds Bad / no-data time
+                        // ⇒ Uncertain (the SDK answers the same, modulo its 1 ms artifact).
                         if (!IsNumeric(last)) return Calc(null, HistorianStatusCodes.BadAggregateInvalidInputs);
-                        var st = last.IsGood ? HistorianStatusCodes.Good : HistorianStatusCodes.UncertainDataSubNormal;
+                        var st = lo == dataEnd && last.IsGood ? HistorianStatusCodes.Good : HistorianStatusCodes.UncertainDataSubNormal;
                         return Calc(_aggregate == HistoryAggregateType.TimeAverage2 ? last.Value.Number : 0d, st, endOfData);
                     }
                     duration = Math.Min(hi, dataEnd) - lo;
diff --git a/tests/Drivers/Historian.Conformance/ProcessedConformance.cs b/tests/Drivers/Historian.Conformance/ProcessedConformance.cs
index 448ad111..8958b19f 100644
--- a/tests/Drivers/Historian.Conformance/ProcessedConformance.cs
+++ b/tests/Drivers/Historian.Conformance/ProcessedConformance.cs
@@ -352,16 +352,28 @@ public abstract class ProcessedConformance : ConformanceBase
                     }
             }
             var reverseInterpolative = agg == HistoryAggregateType.Interpolative && from > to;
-            // Documented SDK divergence (#680, see SdkAggregateParityTests): on a reverse read the SDK files a sample exactly
-            // on an interval's later edge as its early bound, so TimeAverage/Total there take the status of the segment
-            // beyond it (Dense: +20 next to the Bad +22.5).
-            var reverseEdgeStatus = from > to && agg is HistoryAggregateType.TimeAverage or HistoryAggregateType.Total;
-            SdkAggregateOracle.ShouldMatch(ours, SdkAggregateOracle.Run(agg, start, end, interval, rows),
+            var sdk = SdkAggregateOracle.Run(agg, start, end, interval, rows);
+            if (from > to && agg is HistoryAggregateType.TimeAverage or HistoryAggregateType.Total)
+            {
+                // Documented SDK divergence (#680, see SdkAggregateParityTests.MaskDocumented): on a reverse read the SDK files
+                // a sample exactly on an interval's later edge as its early bound, so a TimeAverage/Total interval ending on a
+                // sample takes the status of the segment beyond it (Dense: +20 next to the Bad +22.5). Only that interval,
+                // only Good (ours) vs Uncertain (SDK), is aligned.
+                var plan = BucketPlan.Create(start, end, interval);
+                for (long i = 0; i < plan.BucketCount; i++)
+                {
+                    var k = (int)(plan.BucketCount - 1 - i);
+                    if (k < sdk.Count && rows.Any(r => r.Item1.Ticks == plan.UpperTicks(i))
+                        && (ours[k].StatusCode & 0xFFFF0000u) == 0
+                        && (sdk[k].StatusCode & 0xFFFF0000u) == 0x40A40000u)
+                        ours[k] = ours[k] with { StatusCode = ours[k].StatusCode | 0x40A40000u };
+                }
+            }
+            SdkAggregateOracle.ShouldMatch(ours, sdk,
                 $"{agg} {from}→{to}/{intervalS}s",
                 compareCalculatedInterpolatedBits: tw && !reverseInterpolative,
                 // pre-existing, #680: Start/End raw-sample timestamp + status; Delta status (see SdkAggregateParityTests).
-                compareCodeBits: agg != HistoryAggregateType.Delta && !reverseInterpolative && !startOrEnd
-                                 && !reverseEdgeStatus,
+                compareCodeBits: agg != HistoryAggregateType.Delta && !reverseInterpolative && !startOrEnd,
                 compareTimestamps: !startOrEnd);
         }
     }
diff --git a/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common.Tests/SdkAggregateParityTests.cs b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common.Tests/SdkAggregateParityTests.cs
index a8efc390..f7d03091 100644
--- a/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common.Tests/SdkAggregateParityTests.cs
+++ b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common.Tests/SdkAggregateParityTests.cs
@@ -32,6 +32,16 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common.Tests;
 ///         <c>GetRegionsInValueSet</c>); Part 13 ends TimeAverage2/Total2 at the last sample and runs the PercentGood/Bad
 ///         region to the interval end, which ours does (#680; pinned by <c>TimeWeightedAggregatorTests</c>). That
 ///         interval's value is not compared; its status, Partial bit and timestamp are.</item>
+///       <item><b>an outage marker as the last sample</b> (<see cref="OutageLast"/>): ours runs the outage to the window
+///         end — TimeAverage2/Total2 <c>Bad</c>, the percentages 100 % Bad, no end-of-data Partial on the interval holding
+///         it; the SDK treats the data as ended (<c>BadNoData</c> after it, Partial on that interval); and TimeAverage/Total
+///         over the span the last usable value is held up to the marker are Uncertain here (no Good value follows ⇒
+///         extrapolated, Part 13), Good in the SDK — masked by
+///         <see cref="MaskDocumented"/>;</item>
+///       <item><b>Booleans</b> (<see cref="BoolSwitch"/>): ours steps them (Part 13: a non-analog value is held, and the
+///         bound next to an Uncertain sample takes the earlier sample's status); the SDK interpolates them as numbers — its
+///         values (e.g. 1 vs our 0.5 over an interval switching half-way) and the Good/Uncertain choice are not compared,
+///         Bad vs non-Bad, timestamps and Partial are;</item>
 ///       <item><b>TimeAverage / Total, reverse, a sample exactly on an interval's later edge:</b> the SDK's backward
 ///         <c>UpdateSlice</c> files it as the early bound (below), so the interval takes the status of the segment beyond
 ///         it (Uncertain when that segment skips a Bad sample); ours keeps the interval's own segments — masked by
@@ -91,6 +101,48 @@ public sealed class SdkAggregateParityTests
         S(100, HistorianValue.FromDouble(40), Good),
     ];
 
+    /// <summary>
+    ///     #680 review: the comms-loss recovery shape — a Good sample, an outage marker, then ONE recovery sample and nothing
+    ///     after (+27.5, inside an interval of every window, never on an edge): the interval holding the recovery sample has
+    ///     no non-Bad time before it, so TimeAverage2/Total2 answer the sample's value (Total2 0), Uncertain + Partial.
+    /// </summary>
+    private static readonly StoredSample[] RecoveryEnds =
+    [
+        S(-10, HistorianValue.FromDouble(10), Good),
+        S(5, HistorianValue.Empty, BadNoCommunication),
+        S(27.5, HistorianValue.FromDouble(20), Good),
+    ];
+
+    /// <summary>
+    ///     #680 review: an outage marker as the LAST sample (+31, nothing after) — ours: the outage runs to the window end
+    ///     (TimeAverage2/Total2 Bad, the percentages 100 % Bad); the SDK: the data ended (BadNoData, Partial on the interval
+    ///     holding the marker). Also TimeAverage/Total over the span the last usable value is held up to the marker: ours
+    ///     Uncertain (Part 13 — no Good value after it, so extrapolated), the SDK Good. Documented, deliberate differences.
+    /// </summary>
+    private static readonly StoredSample[] OutageLast =
+    [
+        S(-10, HistorianValue.FromDouble(10), Good),
+        S(25, HistorianValue.FromDouble(20), Good),
+        S(31, HistorianValue.Empty, BadNoCommunication),
+    ];
+
+    /// <summary>
+    ///     #680 review: Boolean (stepped) data with an Uncertain and a Bad sample. Ours steps Booleans (Part 13: a
+    ///     non-analog value is held); the SDK interpolates them as numbers and bounds them sloped — so only timestamps,
+    ///     status and Partial are compared for the values it computes that way (see <see cref="MaskDocumented"/>).
+    /// </summary>
+    private static readonly StoredSample[] BoolSwitch =
+    [
+        S(-10, HistorianValue.FromBoolean(true), Good),
+        S(10, HistorianValue.FromBoolean(false), Good),
+        S(27.5, HistorianValue.FromBoolean(true), Uncertain),
+        S(32, HistorianValue.FromBoolean(false), Good),
+        S(47.5, HistorianValue.FromBoolean(true), Good),
+        S(62, HistorianValue.FromBoolean(true), Bad),
+        S(71, HistorianValue.FromBoolean(false), Good),
+        S(100, HistorianValue.FromBoolean(true), Good),
+    ];
+
     /// <summary>Data that starts inside the window (no sample before +7) and runs past its end.</summary>
     private static readonly StoredSample[] LateStart = Enumerable.Range(0, 20)
         .Select(i => S(7 + i * 5, HistorianValue.FromDouble(i % 2 == 0 ? 20 : 40), Good))
@@ -148,7 +200,11 @@ public sealed class SdkAggregateParityTests
         var plan = BucketPlan.Create(At(from), At(to), TimeSpan.FromSeconds(intervalS));
         var list = ours.ToList();
         var last = data.Max(x => x.TimeUtc).Ticks;
-        var dataEnds = last < Math.Max(At(from).Ticks, At(to).Ticks) && data.Single(x => x.TimeUtc.Ticks == last).IsUsable;
+        var endsInWindow = last < Math.Max(At(from).Ticks, At(to).Ticks);
+        var dataEnds = endsInWindow && data.Single(x => x.TimeUtc.Ticks == last).IsUsable;
+        var outageEnds = endsInWindow && !dataEnds;
+        var boolean = data.Any(x => x.Value.Kind == HistorianValueKind.Boolean);
+        var percent = agg is HistoryAggregateType.PercentGood or HistoryAggregateType.PercentBad;
         for (long i = 0; i < plan.BucketCount; i++)
         {
             var k = (int)(plan.Reversed ? plan.BucketCount - 1 - i : i);
@@ -170,6 +226,36 @@ public sealed class SdkAggregateParityTests
             if (dataEnds && (twoVariant || agg is HistoryAggregateType.PercentGood or HistoryAggregateType.PercentBad)
                 && last >= plan.LowerTicks(i) && last < plan.UpperTicks(i) && sdk[k].Value is not null)
                 list[k] = list[k] with { Value = sdk[k].Value };
+            // An outage marker as the last sample: ours runs the outage to the window end (no end-of-data Partial on the
+            // interval holding it; Bad / 100 % Bad after it); the SDK treats the data as ended there.
+            if (outageEnds && (twoVariant || percent))
+            {
+                if (last >= plan.LowerTicks(i) && last < plan.UpperTicks(i))
+                    list[k] = list[k] with
+                    {
+                        StatusCode = (list[k].StatusCode & ~HistorianInfoBits.HistorianPartial)
+                                     | (sdk[k].StatusCode & HistorianInfoBits.HistorianPartial),
+                    };
+                else if (plan.LowerTicks(i) > last && (sdk[k].StatusCode & StatusBits.CodeBitsMask) == HistorianStatusCodes.BadNoData)
+                    list[k] = list[k] with { Value = null, StatusCode = HistorianStatusCodes.BadNoData };
+            }
+            // ...and TimeAverage/Total hold the last usable value up to that marker: Part 13 calls that extrapolation (no
+            // Good value after it) ⇒ Uncertain; the SDK, which sees a later (Bad) sample, reports the held span Good.
+            var lastUsable = data.Where(x => x.IsUsable).Max(x => x.TimeUtc).Ticks;
+            if (outageEnds && agg is HistoryAggregateType.TimeAverage or HistoryAggregateType.Total
+                && plan.LowerTicks(i) < last && plan.UpperTicks(i) > lastUsable
+                && (list[k].StatusCode & StatusBits.CodeBitsMask) == HistorianStatusCodes.UncertainDataSubNormal
+                && (sdk[k].StatusCode & StatusBits.CodeBitsMask) == HistorianStatusCodes.Good)
+                list[k] = list[k] with { StatusCode = list[k].StatusCode & ~StatusBits.CodeBitsMask };
+            // Booleans: the SDK slopes them (values, and the status of a bound next to an Uncertain sample); ours steps.
+            if (boolean && sdk[k].Value is not null && list[k].Value is not null)
+                list[k] = list[k] with { Value = sdk[k].Value };
+            if (boolean && (StatusBits.IsGood(list[k].StatusCode) || StatusBits.IsGood(sdk[k].StatusCode))
+                && !StatusBits.IsBad(list[k].StatusCode) && !StatusBits.IsBad(sdk[k].StatusCode))
+                list[k] = list[k] with
+                {
+                    StatusCode = (list[k].StatusCode & ~StatusBits.CodeBitsMask) | (sdk[k].StatusCode & StatusBits.CodeBitsMask),
+                };
         }
         return list;
     }
@@ -188,6 +274,7 @@ public sealed class SdkAggregateParityTests
         foreach (var (name, data) in new[]
                  {
                      ("Bounded", Bounded), ("Dense", Dense), ("EndsInside", EndsInside), ("OutageInside", OutageInside),
+                     ("RecoveryEnds", RecoveryEnds), ("OutageLast", OutageLast), ("BoolSwitch", BoolSwitch),
                  })
         {
             try
diff --git a/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common.Tests/TimeWeightedAggregatorTests.cs b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common.Tests/TimeWeightedAggregatorTests.cs
index b9351326..6965e13d 100644
--- a/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common.Tests/TimeWeightedAggregatorTests.cs
+++ b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common.Tests/TimeWeightedAggregatorTests.cs
@@ -180,6 +180,84 @@ public sealed class TimeWeightedAggregatorTests
         ((double)Run(HistoryAggregateType.TimeAverage, 0, 20, 0, late).Single().Value!).ShouldBe(10d);
     }
 
+    [Fact]
+    public void A_recovery_sample_after_an_outage_that_ends_the_data_is_its_own_value_Uncertain_and_Partial()
+    {
+        // #680 review (the comms-loss recovery shape): −10 = 10 G, +5 outage, +25 = 20 G (the recovery), nothing after.
+        // [0,20): 10 held into the outage over [0,5) ⇒ TimeAverage2 10 (Total2 50), Uncertain. [20,40) holds the end of the
+        // data but no non-Bad time before it ⇒ the sample's value 20 (Total2 0), Uncertain + Partial — never Bad/null (the
+        // SDK answers the same). [40,60) is after the end of the data ⇒ BadNoData.
+        StoredSample[] s =
+        [
+            S(-10, HistorianValue.FromDouble(10), Good), S(5, HistorianValue.Empty, BadNoCommunication),
+            S(25, HistorianValue.FromDouble(20), Good),
+        ];
+        var ta2 = Run(HistoryAggregateType.TimeAverage2, 0, 60, 20, s);
+        Values(ta2, 10, 20, null);
+        ta2.Select(x => x.StatusCode).ShouldBe([UncertainCalc, UncertainCalcPartial, NoDataCalc]);
+        var t2 = Run(HistoryAggregateType.Total2, 0, 60, 20, s);
+        Values(t2, 50, 0, null);
+        t2.Select(x => x.StatusCode).ShouldBe([UncertainCalc, UncertainCalcPartial, NoDataCalc]);
+    }
+
+    [Fact]
+    public void A_single_sample_is_its_own_value_Uncertain_and_Partial()
+    {
+        // #680 review: the tag's only sample, +25 = 20. One interval [0,60) ⇒ 20 (Total2 0), Uncertain + Partial (time
+        // before the data is Bad). At 20 s: [0,20) before the data ⇒ BadNoData; [20,40) the sample ⇒ 20, Uncertain +
+        // Partial; [40,60) after the end of the data ⇒ BadNoData.
+        StoredSample[] one = [S(25, HistorianValue.FromDouble(20), Good)];
+        var whole = Run(HistoryAggregateType.TimeAverage2, 0, 60, 0, one).Single();
+        ((double)whole.Value!).ShouldBe(20d);
+        whole.StatusCode.ShouldBe(UncertainCalcPartial);
+        var total = Run(HistoryAggregateType.Total2, 0, 60, 0, one).Single();
+        ((double)total.Value!).ShouldBe(0d);
+        total.StatusCode.ShouldBe(UncertainCalcPartial);
+        var split = Run(HistoryAggregateType.TimeAverage2, 0, 60, 20, one);
+        Values(split, null, 20, null);
+        split.Select(x => x.StatusCode).ShouldBe([NoDataCalc, UncertainCalcPartial, NoDataCalc]);
+    }
+
+    [Fact]
+    public void An_outage_marker_as_the_last_sample_runs_Bad_to_the_window_end()
+    {
+        // #680 review, a deliberate difference from the SDK (which treats the data as ended at the marker): −10 = 10 G,
+        // +25 = 20 G, +30 outage, nothing after. TimeAverage2 [20,40): [20,25) 18.5714…→20 (96.43) + [25,30) 20 held into
+        // the outage (100) over 10 s = 19.642857…, Uncertain, NOT Partial (the data did not end — the tag is in an
+        // outage); [40,60) inside the still-open outage ⇒ generic Bad. PercentBad [40,60) = 100, Good. TimeAverage holds
+        // 20 to the window end — extrapolated (no Good value follows) ⇒ Uncertain.
+        StoredSample[] s =
+        [
+            S(-10, HistorianValue.FromDouble(10), Good), S(25, HistorianValue.FromDouble(20), Good),
+            S(30, HistorianValue.Empty, BadNoCommunication),
+        ];
+        var ta2 = Run(HistoryAggregateType.TimeAverage2, 0, 60, 20, s);
+        ((double)ta2[1].Value!).ShouldBe(19.642857142857142, 1e-9);
+        ta2.Select(x => x.StatusCode).Skip(1).ShouldBe([UncertainCalc, BadCalc]);
+        var pb = Run(HistoryAggregateType.PercentBad, 0, 60, 20, s);
+        Values(pb, 0, 50, 100);
+        pb.ShouldAllBe(x => x.StatusCode == GoodCalc);
+        Run(HistoryAggregateType.TimeAverage, 0, 60, 20, s).Select(x => x.StatusCode).Skip(1)
+            .ShouldBe([UncertainCalc, UncertainCalc]);
+    }
+
+    [Fact]
+    public void Boolean_percent_regions_take_the_stepped_bound_status()
+    {
+        // #680 review: −10 = true G, +15 = true U, +30 = false G, +50 = false G. [0,20): the bound at +0 is stepped from the
+        // Good −10 (a Boolean is held, not sloped toward the Uncertain +15) ⇒ [0,15) Good, [15,20) Uncertain ⇒ PercentGood
+        // 75. (The SDK slopes Booleans, so it calls the bound Uncertain and answers 0.) [20,40): [20,30) Uncertain (bound
+        // stepped from the Uncertain +15), [30,40) Good ⇒ 50.
+        StoredSample[] s =
+        [
+            S(-10, HistorianValue.FromBoolean(true), Good), S(15, HistorianValue.FromBoolean(true), Uncertain),
+            S(30, HistorianValue.FromBoolean(false), Good), S(50, HistorianValue.FromBoolean(false), Good),
+        ];
+        Values(Run(HistoryAggregateType.PercentGood, 0, 40, 20, s), 75, 50);
+        // TimeAverage over the same Booleans is stepped: [20,40) = 1 over [20,30), 0 over [30,40) ⇒ 0.5 (the SDK: 1).
+        Values(Run(HistoryAggregateType.TimeAverage, 0, 40, 20, s), 1, 0.5);
+    }
+
     // ---------------------------------------------------------------- #680: PercentGood / PercentBad are duration-based
 
     [Fact]