fix(db): register legacy task migrations

backend-tests/MigrationSnapshotTests.cs

@@ -1,3 +1,7 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Nexus.Api.Data;
 using Nexus.Api.Migrations;
 using Xunit;
 
@@ -5,6 +9,21 @@ namespace Nexus.Api.Tests;
 
 public sealed class MigrationSnapshotTests
 {
+    [Fact]
+    public void Historical_task_migrations_are_discoverable()
+    {
+        var options = new DbContextOptionsBuilder<NexusDbContext>()
+            .UseNpgsql(
+                "Host=127.0.0.1;Database=nexus_migration_contract;Username=nexus;Password=unused")
+            .Options;
+        using var db = new NexusDbContext(options);
+        var migrations = db.GetService<IMigrationsAssembly>().Migrations.Keys;
+
+        Assert.Contains("20260618233000_AddTaskParentChild", migrations);
+        Assert.Contains("20260618233001_AddTaskDueDate", migrations);
+        Assert.Contains("20260618233002_AddActivityTaskReference", migrations);
+    }
+
     [Fact]
     public void Snapshot_builds_agent_provisioning_relationships()
     {

backend-tests/ToxiproxyAgentProvisioningIntegrationTests.cs

@@ -140,7 +140,14 @@ public sealed class ToxiproxyAgentProvisioningIntegrationTests
 
         var reconciled = await service.GetByIdAsync(created.Proposal.Id);
         Assert.NotNull(reconciled);
-        Assert.Equal(AgentProposalStates.Ready, reconciled!.Status);
+        Assert.True(
+            string.Equals(
+                AgentProposalStates.Ready,
+                reconciled!.Status,
+                StringComparison.Ordinal),
+            $"Expected ready after read-only reconciliation, got "
+            + $"'{reconciled.Status}' ({reconciled.Error?.Code}: "
+            + $"{reconciled.Error?.Message}).");
         Assert.Equal("release-analyst", reconciled.OpenClawAgentId);
         Assert.Equal(1, gateway.CreateCalls);
     }

backend/Data/Migrations/20260618233000_AddTaskParentChild.cs

@@ -1,49 +1,59 @@
+using Microsoft.EntityFrameworkCore.Infrastructure;
 using Microsoft.EntityFrameworkCore.Migrations;
+using Nexus.Api.Data;
 
 #nullable disable
 
 namespace Nexus.Api.Migrations
 {
     /// <inheritdoc />
+    [DbContext(typeof(NexusDbContext))]
+    [Migration("20260618233000_AddTaskParentChild")]
     public partial class AddTaskParentChild : Migration
     {
         /// <inheritdoc />
         protected override void Up(MigrationBuilder migrationBuilder)
         {
-            migrationBuilder.AddColumn<Guid>(
-                name: "ParentTaskId",
-                table: "Tasks",
-                type: "uuid",
-                nullable: true);
+            // This historical migration originally lacked EF discovery
+            // metadata. Keep the catch-up operations idempotent so existing
+            // installations and fresh PostgreSQL databases converge safely.
+            migrationBuilder.Sql(
+                """
+                ALTER TABLE "Tasks"
+                    ADD COLUMN IF NOT EXISTS "ParentTaskId" uuid;
 
-            migrationBuilder.CreateIndex(
-                name: "IX_Tasks_ParentTaskId",
-                table: "Tasks",
-                column: "ParentTaskId");
+                CREATE INDEX IF NOT EXISTS "IX_Tasks_ParentTaskId"
+                    ON "Tasks" ("ParentTaskId");
 
-            migrationBuilder.AddForeignKey(
-                name: "FK_Tasks_Tasks_ParentTaskId",
-                table: "Tasks",
-                column: "ParentTaskId",
-                principalTable: "Tasks",
-                principalColumn: "Id",
-                onDelete: ReferentialAction.SetNull);
+                DO $$
+                BEGIN
+                    IF NOT EXISTS (
+                        SELECT 1
+                        FROM pg_constraint
+                        WHERE conname = 'FK_Tasks_Tasks_ParentTaskId'
+                          AND conrelid = '"Tasks"'::regclass
+                    ) THEN
+                        ALTER TABLE "Tasks"
+                            ADD CONSTRAINT "FK_Tasks_Tasks_ParentTaskId"
+                            FOREIGN KEY ("ParentTaskId")
+                            REFERENCES "Tasks" ("Id")
+                            ON DELETE SET NULL;
+                    END IF;
+                END $$;
+                """);
         }
 
         /// <inheritdoc />
         protected override void Down(MigrationBuilder migrationBuilder)
         {
-            migrationBuilder.DropForeignKey(
-                name: "FK_Tasks_Tasks_ParentTaskId",
-                table: "Tasks");
-
-            migrationBuilder.DropIndex(
-                name: "IX_Tasks_ParentTaskId",
-                table: "Tasks");
-
-            migrationBuilder.DropColumn(
-                name: "ParentTaskId",
-                table: "Tasks");
+            migrationBuilder.Sql(
+                """
+                ALTER TABLE "Tasks"
+                    DROP CONSTRAINT IF EXISTS "FK_Tasks_Tasks_ParentTaskId";
+                DROP INDEX IF EXISTS "IX_Tasks_ParentTaskId";
+                ALTER TABLE "Tasks"
+                    DROP COLUMN IF EXISTS "ParentTaskId";
+                """);
         }
     }
 }

backend/Data/Migrations/20260618233001_AddTaskDueDate.cs

@@ -1,28 +1,34 @@
+using Microsoft.EntityFrameworkCore.Infrastructure;
 using Microsoft.EntityFrameworkCore.Migrations;
+using Nexus.Api.Data;
 
 #nullable disable
 
 namespace Nexus.Api.Migrations
 {
     /// <inheritdoc />
+    [DbContext(typeof(NexusDbContext))]
+    [Migration("20260618233001_AddTaskDueDate")]
     public partial class AddTaskDueDate : Migration
     {
         /// <inheritdoc />
         protected override void Up(MigrationBuilder migrationBuilder)
         {
-            migrationBuilder.AddColumn<DateTimeOffset>(
-                name: "DueDate",
-                table: "Tasks",
-                type: "timestamp with time zone",
-                nullable: true);
+            migrationBuilder.Sql(
+                """
+                ALTER TABLE "Tasks"
+                    ADD COLUMN IF NOT EXISTS "DueDate" timestamp with time zone;
+                """);
         }
 
         /// <inheritdoc />
         protected override void Down(MigrationBuilder migrationBuilder)
         {
-            migrationBuilder.DropColumn(
-                name: "DueDate",
-                table: "Tasks");
+            migrationBuilder.Sql(
+                """
+                ALTER TABLE "Tasks"
+                    DROP COLUMN IF EXISTS "DueDate";
+                """);
         }
     }
 }

backend/Data/Migrations/20260618233002_AddActivityTaskReference.cs

@@ -1,37 +1,38 @@
+using Microsoft.EntityFrameworkCore.Infrastructure;
 using Microsoft.EntityFrameworkCore.Migrations;
+using Nexus.Api.Data;
 
 #nullable disable
 
 namespace Nexus.Api.Migrations
 {
     /// <inheritdoc />
+    [DbContext(typeof(NexusDbContext))]
+    [Migration("20260618233002_AddActivityTaskReference")]
     public partial class AddActivityTaskReference : Migration
     {
         /// <inheritdoc />
         protected override void Up(MigrationBuilder migrationBuilder)
         {
-            migrationBuilder.AddColumn<Guid>(
-                name: "TaskId",
-                table: "Activity",
-                type: "uuid",
-                nullable: true);
+            migrationBuilder.Sql(
+                """
+                ALTER TABLE "Activity"
+                    ADD COLUMN IF NOT EXISTS "TaskId" uuid;
 
-            migrationBuilder.CreateIndex(
-                name: "IX_Activity_TaskId",
-                table: "Activity",
-                column: "TaskId");
+                CREATE INDEX IF NOT EXISTS "IX_Activity_TaskId"
+                    ON "Activity" ("TaskId");
+                """);
         }
 
         /// <inheritdoc />
         protected override void Down(MigrationBuilder migrationBuilder)
         {
-            migrationBuilder.DropIndex(
-                name: "IX_Activity_TaskId",
-                table: "Activity");
-
-            migrationBuilder.DropColumn(
-                name: "TaskId",
-                table: "Activity");
+            migrationBuilder.Sql(
+                """
+                DROP INDEX IF EXISTS "IX_Activity_TaskId";
+                ALTER TABLE "Activity"
+                    DROP COLUMN IF EXISTS "TaskId";
+                """);
         }
     }
 }