feat(alarms): HiLo trigger type with per-band level, hysteresis, messages, overrides

Adds a new HiLo alarm trigger type with four configurable setpoints
(LoLo / Lo / Hi / HiHi). Each setpoint carries an optional priority,
deadband (for hysteresis), and operator message. The site runtime emits
AlarmStateChanged with an AlarmLevel field so consumers can differentiate
warning vs critical bands.

Plumbing:
  - new AlarmLevel enum + AlarmStateChanged.Level/Message init properties
  - AlarmTriggerEditor (Blazor) gets a HiLo render with severity tinting
  - AlarmTriggerConfigCodec extracted from the editor for testability
  - sitestream.proto carries level + message over gRPC
  - SemanticValidator enforces numeric attribute, setpoint ordering,
    non-negative deadband
  - on-trigger scripts get an Alarm global (Name/Level/Priority/Message)
    so notification routing can branch by severity
  - per-instance InstanceAlarmOverride entity + EF migration + flattening
    step + CLI commands; HiLo overrides merge setpoint-by-setpoint, binary
    types whole-replace
  - DebugView shows a Level badge + per-band message tooltip
  - App.razor auto-reloads on permanent Blazor circuit failure
  - docker/regen-proto.sh automates the proto regen workflow (the linux/arm64
    protoc segfault means generated files are checked in for now)

src/ScadaLink.ConfigurationDatabase/Configurations/InstanceConfiguration.cs

@@ -41,6 +41,11 @@ public class InstanceConfiguration : IEntityTypeConfiguration<Instance>
             .HasForeignKey(o => o.InstanceId)
             .OnDelete(DeleteBehavior.Cascade);
 
+        builder.HasMany(i => i.AlarmOverrides)
+            .WithOne()
+            .HasForeignKey(o => o.InstanceId)
+            .OnDelete(DeleteBehavior.Cascade);
+
         builder.HasMany(i => i.ConnectionBindings)
             .WithOne()
             .HasForeignKey(b => b.InstanceId)
@@ -67,6 +72,23 @@ public class InstanceAttributeOverrideConfiguration : IEntityTypeConfiguration<I
     }
 }
 
+public class InstanceAlarmOverrideConfiguration : IEntityTypeConfiguration<InstanceAlarmOverride>
+{
+    public void Configure(EntityTypeBuilder<InstanceAlarmOverride> builder)
+    {
+        builder.HasKey(o => o.Id);
+
+        builder.Property(o => o.AlarmCanonicalName)
+            .IsRequired()
+            .HasMaxLength(400); // Larger than attribute names to fit composed paths.
+
+        builder.Property(o => o.TriggerConfigurationOverride)
+            .HasMaxLength(4000);
+
+        builder.HasIndex(o => new { o.InstanceId, o.AlarmCanonicalName }).IsUnique();
+    }
+}
+
 public class InstanceConnectionBindingConfiguration : IEntityTypeConfiguration<InstanceConnectionBinding>
 {
     public void Configure(EntityTypeBuilder<InstanceConnectionBinding> builder)

src/ScadaLink.ConfigurationDatabase/Migrations/20260513055537_AddInstanceAlarmOverrides.cs

@@ -0,0 +1,49 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace ScadaLink.ConfigurationDatabase.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddInstanceAlarmOverrides : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "InstanceAlarmOverrides",
+                columns: table => new
+                {
+                    Id = table.Column<int>(type: "int", nullable: false)
+                        .Annotation("SqlServer:Identity", "1, 1"),
+                    InstanceId = table.Column<int>(type: "int", nullable: false),
+                    AlarmCanonicalName = table.Column<string>(type: "nvarchar(400)", maxLength: 400, nullable: false),
+                    TriggerConfigurationOverride = table.Column<string>(type: "nvarchar(4000)", maxLength: 4000, nullable: true),
+                    PriorityLevelOverride = table.Column<int>(type: "int", nullable: true)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_InstanceAlarmOverrides", x => x.Id);
+                    table.ForeignKey(
+                        name: "FK_InstanceAlarmOverrides_Instances_InstanceId",
+                        column: x => x.InstanceId,
+                        principalTable: "Instances",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                });
+
+            migrationBuilder.CreateIndex(
+                name: "IX_InstanceAlarmOverrides_InstanceId_AlarmCanonicalName",
+                table: "InstanceAlarmOverrides",
+                columns: new[] { "InstanceId", "AlarmCanonicalName" },
+                unique: true);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "InstanceAlarmOverrides");
+        }
+    }
+}

src/ScadaLink.ConfigurationDatabase/Migrations/ScadaLinkDbContextModelSnapshot.cs

@@ -478,6 +478,37 @@ namespace ScadaLink.ConfigurationDatabase.Migrations
                     b.ToTable("Instances");
                 });
 
+            modelBuilder.Entity("ScadaLink.Commons.Entities.Instances.InstanceAlarmOverride", b =>
+                {
+                    b.Property<int>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("int");
+
+                    SqlServerPropertyBuilderExtensions.UseIdentityColumn(b.Property<int>("Id"));
+
+                    b.Property<string>("AlarmCanonicalName")
+                        .IsRequired()
+                        .HasMaxLength(400)
+                        .HasColumnType("nvarchar(400)");
+
+                    b.Property<int>("InstanceId")
+                        .HasColumnType("int");
+
+                    b.Property<int?>("PriorityLevelOverride")
+                        .HasColumnType("int");
+
+                    b.Property<string>("TriggerConfigurationOverride")
+                        .HasMaxLength(4000)
+                        .HasColumnType("nvarchar(4000)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("InstanceId", "AlarmCanonicalName")
+                        .IsUnique();
+
+                    b.ToTable("InstanceAlarmOverrides");
+                });
+
             modelBuilder.Entity("ScadaLink.Commons.Entities.Instances.InstanceAttributeOverride", b =>
                 {
                     b.Property<int>("Id")
@@ -1144,6 +1175,15 @@ namespace ScadaLink.ConfigurationDatabase.Migrations
                         .IsRequired();
                 });
 
+            modelBuilder.Entity("ScadaLink.Commons.Entities.Instances.InstanceAlarmOverride", b =>
+                {
+                    b.HasOne("ScadaLink.Commons.Entities.Instances.Instance", null)
+                        .WithMany("AlarmOverrides")
+                        .HasForeignKey("InstanceId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+                });
+
             modelBuilder.Entity("ScadaLink.Commons.Entities.Instances.InstanceAttributeOverride", b =>
                 {
                     b.HasOne("ScadaLink.Commons.Entities.Instances.Instance", null)
@@ -1271,6 +1311,8 @@ namespace ScadaLink.ConfigurationDatabase.Migrations
 
             modelBuilder.Entity("ScadaLink.Commons.Entities.Instances.Instance", b =>
                 {
+                    b.Navigation("AlarmOverrides");
+
                     b.Navigation("AttributeOverrides");
 
                     b.Navigation("ConnectionBindings");

src/ScadaLink.ConfigurationDatabase/Repositories/DeploymentManagerRepository.cs

@@ -169,6 +169,7 @@ public class DeploymentManagerRepository : IDeploymentManagerRepository
     {
         return await _dbContext.Set<Instance>()
             .Include(i => i.AttributeOverrides)
+            .Include(i => i.AlarmOverrides)
             .Include(i => i.ConnectionBindings)
             .FirstOrDefaultAsync(i => i.Id == instanceId, cancellationToken);
     }
@@ -177,6 +178,7 @@ public class DeploymentManagerRepository : IDeploymentManagerRepository
     {
         return await _dbContext.Set<Instance>()
             .Include(i => i.AttributeOverrides)
+            .Include(i => i.AlarmOverrides)
             .Include(i => i.ConnectionBindings)
             .FirstOrDefaultAsync(i => i.UniqueName == uniqueName, cancellationToken);
     }

src/ScadaLink.ConfigurationDatabase/Repositories/TemplateEngineRepository.cs

@@ -222,6 +222,7 @@ public class TemplateEngineRepository : ITemplateEngineRepository
     {
         return await _context.Instances
             .Include(i => i.AttributeOverrides)
+            .Include(i => i.AlarmOverrides)
             .Include(i => i.ConnectionBindings)
             .FirstOrDefaultAsync(i => i.Id == id, cancellationToken);
     }
@@ -230,6 +231,7 @@ public class TemplateEngineRepository : ITemplateEngineRepository
     {
         return await _context.Instances
             .Include(i => i.AttributeOverrides)
+            .Include(i => i.AlarmOverrides)
             .Include(i => i.ConnectionBindings)
             .ToListAsync(cancellationToken);
     }
@@ -246,6 +248,7 @@ public class TemplateEngineRepository : ITemplateEngineRepository
         return await _context.Instances
             .Where(i => i.SiteId == siteId)
             .Include(i => i.AttributeOverrides)
+            .Include(i => i.AlarmOverrides)
             .Include(i => i.ConnectionBindings)
             .ToListAsync(cancellationToken);
     }
@@ -254,6 +257,7 @@ public class TemplateEngineRepository : ITemplateEngineRepository
     {
         return await _context.Instances
             .Include(i => i.AttributeOverrides)
+            .Include(i => i.AlarmOverrides)
             .Include(i => i.ConnectionBindings)
             .FirstOrDefaultAsync(i => i.UniqueName == uniqueName, cancellationToken);
     }
@@ -307,6 +311,43 @@ public class TemplateEngineRepository : ITemplateEngineRepository
         }
     }
 
+    // InstanceAlarmOverride
+
+    public async Task<IReadOnlyList<InstanceAlarmOverride>> GetAlarmOverridesByInstanceIdAsync(int instanceId, CancellationToken cancellationToken = default)
+    {
+        return await _context.InstanceAlarmOverrides
+            .Where(o => o.InstanceId == instanceId)
+            .ToListAsync(cancellationToken);
+    }
+
+    public async Task<InstanceAlarmOverride?> GetAlarmOverrideAsync(int instanceId, string alarmCanonicalName, CancellationToken cancellationToken = default)
+    {
+        return await _context.InstanceAlarmOverrides
+            .FirstOrDefaultAsync(
+                o => o.InstanceId == instanceId && o.AlarmCanonicalName == alarmCanonicalName,
+                cancellationToken);
+    }
+
+    public async Task AddInstanceAlarmOverrideAsync(InstanceAlarmOverride alarmOverride, CancellationToken cancellationToken = default)
+    {
+        await _context.InstanceAlarmOverrides.AddAsync(alarmOverride, cancellationToken);
+    }
+
+    public Task UpdateInstanceAlarmOverrideAsync(InstanceAlarmOverride alarmOverride, CancellationToken cancellationToken = default)
+    {
+        _context.InstanceAlarmOverrides.Update(alarmOverride);
+        return Task.CompletedTask;
+    }
+
+    public async Task DeleteInstanceAlarmOverrideAsync(int id, CancellationToken cancellationToken = default)
+    {
+        var alarmOverride = await _context.InstanceAlarmOverrides.FindAsync(new object[] { id }, cancellationToken);
+        if (alarmOverride != null)
+        {
+            _context.InstanceAlarmOverrides.Remove(alarmOverride);
+        }
+    }
+
     // InstanceConnectionBinding
 
     public async Task<IReadOnlyList<InstanceConnectionBinding>> GetBindingsByInstanceIdAsync(int instanceId, CancellationToken cancellationToken = default)

src/ScadaLink.ConfigurationDatabase/ScadaLinkDbContext.cs

@@ -30,6 +30,7 @@ public class ScadaLinkDbContext : DbContext, IDataProtectionKeyContext
     // Instances
     public DbSet<Instance> Instances => Set<Instance>();
     public DbSet<InstanceAttributeOverride> InstanceAttributeOverrides => Set<InstanceAttributeOverride>();
+    public DbSet<InstanceAlarmOverride> InstanceAlarmOverrides => Set<InstanceAlarmOverride>();
     public DbSet<InstanceConnectionBinding> InstanceConnectionBindings => Set<InstanceConnectionBinding>();
     public DbSet<Area> Areas => Set<Area>();