feat(deploy): additive degraded flag on ApplyAck + publish-actor apply outcome reply (#601)

ApplyAck gains trailing Degraded/DegradedReason (defaulted, so an old node's
DPS JSON or gRPC ack decodes exactly as before). mesh_transport.proto adds
ApplyAckMessage.degraded = 6 / optional degraded_reason = 7. OpcUaPublishActor
replies RebuildCompleted(Degraded, Reason) on every handler path when the
RebuildAddressSpace carries ReportOutcome.

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

src/Core/ZB.MOM.WW.OtOpcUa.Commons/Messages/Deploy/ApplyAck.cs

@@ -7,9 +7,24 @@ public enum ApplyAckOutcome { Applied, Failed }
 /// <summary>
 /// Per-node acknowledgment returned by <c>DriverHostActor</c> to the dispatching coordinator.
 /// </summary>
+/// <param name="DeploymentId">The deployment being acknowledged.</param>
+/// <param name="NodeId">The acknowledging node.</param>
+/// <param name="Outcome">Whether the node applied the deployment.</param>
+/// <param name="FailureReason">Why the apply failed; null on <see cref="ApplyAckOutcome.Applied"/>.</param>
+/// <param name="CorrelationId">The dispatch's correlation id.</param>
+/// <param name="Degraded">
+///     Gitea #601: <see langword="true"/> when the node applied the deployment (the revision advanced) but
+///     its OPC UA address-space apply was DEGRADED — swallowed per-node sink faults, a failed rebuild, or no
+///     outcome reported in time — so the served address space may be partial. Only meaningful with
+///     <see cref="ApplyAckOutcome.Applied"/>. Trailing and defaulted so an ack from a node built before
+///     this field existed (DPS JSON or gRPC without field 6) decodes exactly as it always did: clean.
+/// </param>
+/// <param name="DegradedReason">A short, operator-readable description of the degradation, or null.</param>
 public sealed record ApplyAck(
     DeploymentId DeploymentId,
     NodeId NodeId,
     ApplyAckOutcome Outcome,
     string? FailureReason,
-    CorrelationId CorrelationId);
+    CorrelationId CorrelationId,
+    bool Degraded = false,
+    string? DegradedReason = null);

src/Core/ZB.MOM.WW.OtOpcUa.Commons/Messages/Mesh/MeshTransportDtoMapper.cs

@@ -216,6 +216,11 @@ public static class MeshTransportDtoMapper
         if (message.FailureReason is not null)
             proto.FailureReason = message.FailureReason;
 
+        // #601 — additive fields; a clean ack leaves both unset, byte-identical to a pre-#601 encode.
+        proto.Degraded = message.Degraded;
+        if (message.DegradedReason is not null)
+            proto.DegradedReason = message.DegradedReason;
+
         return proto;
     }
 
@@ -249,7 +254,10 @@ public static class MeshTransportDtoMapper
             NodeId.Parse(proto.NodeId),
             outcome,
             proto.HasFailureReason ? proto.FailureReason : null,
-            CorrelationId.Parse(proto.CorrelationId));
+            CorrelationId.Parse(proto.CorrelationId),
+            // #601 — absent on an old node's ack, which decodes as false/null: today's clean ack.
+            Degraded: proto.Degraded,
+            DegradedReason: proto.HasDegradedReason ? proto.DegradedReason : null);
     }
 
     // ---------------------------------------------------------------- Envelope

src/Core/ZB.MOM.WW.OtOpcUa.Commons/Protos/mesh_transport.proto

@@ -105,6 +105,11 @@ message ApplyAckMessage {
   ApplyOutcome outcome = 3;
   optional string failure_reason = 4;                     // nullable in the record — presence distinguishes null from ""
   string correlation_id = 5;                              // CorrelationId (Guid) in its "N" hex form
+  // Gitea #601 — ADDITIVE. True when the node applied the deployment but its address-space apply was
+  // degraded (sink faults, failed rebuild, or no outcome in time). An old node never sets it, so it decodes
+  // as false: exactly today's clean ack. Only meaningful with APPLY_OUTCOME_APPLIED.
+  bool degraded = 6;
+  optional string degraded_reason = 7;                    // short operator-readable reason; presence = set
 }
 
 // Mirrors ZB.MOM.WW.OtOpcUa.Commons.Messages.Deploy.ApplyAckOutcome, shifted by one so 0 stays