# Audit `SourceNode` Stamping — Implementation Plan

> **For Claude:** REQUIRED SUB-SKILL: Use superpowers-extended-cc:executing-plans to implement this plan task-by-task.

**Goal:** Capture the cluster node of origin (`node-a` / `node-b` for site rows, `central-a` / `central-b` for central direct-write rows) on every `AuditLog`, `Notifications`, and `SiteCalls` row, end-to-end from the writing node through telemetry / reconciliation to the Central UI.

**Architecture:** Introduce a single `INodeIdentityProvider` exposing the local node name from `NodeOptions.NodeName` (new config key, bound from `ScadaLink:Node:NodeName`). Stamp `SourceNode` at the *writing node* — site `SqliteAuditWriter` for site rows, `CentralAuditWriter` for central direct-writes — and carry it verbatim through the existing gRPC `AuditEventDto` / `SiteCallOperationalDto` envelopes (additive new field), the `NotificationSubmit` S&F payload, and the `CachedCallTelemetry` packet. EF Core migrations add the column to all three central tables; site-side SQLite schemas use the existing idempotent `PRAGMA table_info` + `ALTER TABLE ADD COLUMN` pattern. UI gets a new "Node" column + filter on the three grids.

**Tech Stack:** .NET 8 / C# 12 sealed records, EF Core 8 (MS SQL on central, SQLite at sites), Akka.NET, Grpc.AspNetCore, Blazor Server, xUnit + Akka.TestKit + NSubstitute + Playwright. Migration naming: `YYYYMMDDHHmmss_DescriptiveTitle`.

**Out of scope (deferred):**
- Cross-table `SourceNode`-aware KPIs (e.g., "per-node stuck count"). The data is captured; dashboards stay site-keyed until a real ask lands.
- Backfilling existing rows with a best-guess `SourceNode`. New rows get the column; legacy rows stay `NULL`.
- Renaming `NodeHostname` (the Docker container hostname) — it stays as the diagnostic hostname; `NodeName` is the new semantic role-within-cluster name.

---

## Conventions

- All file paths are relative to repo root (`/Users/dohertj2/Desktop/scadalink-design`).
- TDD: red → green → commit. Failing test first, then implementation, then verify, then commit.
- One coherent change per commit. Commit messages prefix with the affected slice: `feat(audit):`, `feat(notif-outbox):`, `feat(sitecall-audit):`, `chore(docker):`, etc.
- After each task, run the targeted test set (`dotnet test <project> --filter <name>`) and the full solution build (`dotnet build ScadaLink.slnx`) before the commit.
- For tasks whose migration name needs a timestamp, use `date -u +%Y%m%d%H%M%S` at the moment of execution. The exact name doesn't matter for correctness; just keep them monotonically ordered.

---

## Task 0: Branch + Snapshot

**Files:** none (git only)

**Step 1: Create feature branch**

```bash
git checkout -b feature/audit-source-node
git status
```

Expected: branch created, working tree shows only the prior design-doc edits + the modified `appsettings.*.json` files already in `git status`.

**Step 2: Stash unrelated dirty files**

`docker/central-node-{a,b}/appsettings.Central.json` and `src/ScadaLink.CentralUI/Components/Pages/Login.razor` are dirty from prior unrelated work — do **NOT** include them in this feature's commits. Verify with `git diff --stat` what's already modified, and either revert or stash:

```bash
git diff --stat
git stash push -- docker/central-node-a/appsettings.Central.json docker/central-node-b/appsettings.Central.json src/ScadaLink.CentralUI/Components/Pages/Login.razor
```

Expected: clean diff against the prior commit + the design-doc edits from this session.

**Step 3: Baseline build + tests**

```bash
dotnet build ScadaLink.slnx
dotnet test tests/ScadaLink.AuditLog.Tests/ScadaLink.AuditLog.Tests.csproj
dotnet test tests/ScadaLink.NotificationOutbox.Tests/ScadaLink.NotificationOutbox.Tests.csproj
dotnet test tests/ScadaLink.SiteCallAudit.Tests/ScadaLink.SiteCallAudit.Tests.csproj
```

Expected: green. If any are red on `main`, **STOP** and surface that to the user — the plan assumes a green starting point.

**Step 4: Commit the in-progress design-doc edits from this session**

```bash
git add CLAUDE.md docs/requirements/Component-AuditLog.md docs/requirements/Component-NotificationOutbox.md docs/requirements/Component-SiteCallAudit.md docs/plans/2026-05-23-audit-source-node.md
git commit -m "docs(audit): add SourceNode column to AuditLog/Notifications/SiteCalls design + plan"
```

---

## Task 1: NodeOptions + INodeIdentityProvider

**Files:**
- Modify: `src/ScadaLink.Host/NodeOptions.cs`
- Create: `src/ScadaLink.Commons/Interfaces/Services/INodeIdentityProvider.cs`
- Create: `src/ScadaLink.Host/NodeIdentityProvider.cs`
- Modify: `src/ScadaLink.Host/SiteServiceRegistration.cs` (and central registration if separate — check `CentralServiceRegistration.cs` if it exists)
- Create test: `tests/ScadaLink.Host.Tests/NodeIdentityProviderTests.cs` (if Host.Tests doesn't exist, place under `tests/ScadaLink.AuditLog.Tests/Configuration/NodeIdentityProviderTests.cs` instead)

**Step 1: Failing test — provider returns configured NodeName**

```csharp
[Fact]
public void NodeIdentityProvider_returns_configured_NodeName()
{
    var opts = Options.Create(new NodeOptions { NodeName = "central-a", Role = "Central" });
    var provider = new NodeIdentityProvider(opts);
    Assert.Equal("central-a", provider.NodeName);
}

[Fact]
public void NodeIdentityProvider_returns_null_when_NodeName_unset()
{
    var opts = Options.Create(new NodeOptions { NodeName = "", Role = "Central" });
    var provider = new NodeIdentityProvider(opts);
    Assert.Null(provider.NodeName);
}
```

Run: `dotnet test tests/<project> --filter NodeIdentityProvider` → expected FAIL (types don't exist yet).

**Step 2: Add `NodeName` to `NodeOptions`**

```csharp
public class NodeOptions
{
    public string Role { get; set; } = string.Empty;
    public string NodeHostname { get; set; } = string.Empty;
    public string NodeName { get; set; } = string.Empty;   // <— new
    public string? SiteId { get; set; }
    public int RemotingPort { get; set; } = 8081;
    public int GrpcPort { get; set; } = 8083;
}
```

**Step 3: Create `INodeIdentityProvider` + implementation**

```csharp
// src/ScadaLink.Commons/Interfaces/Services/INodeIdentityProvider.cs
namespace ScadaLink.Commons.Interfaces.Services;

public interface INodeIdentityProvider
{
    /// <summary>
    /// Semantic role-within-cluster name of the local node — `node-a` / `node-b`
    /// for site nodes, `central-a` / `central-b` for central nodes. NULL when
    /// unconfigured (development/legacy hosts).
    /// </summary>
    string? NodeName { get; }
}
```

```csharp
// src/ScadaLink.Host/NodeIdentityProvider.cs
internal sealed class NodeIdentityProvider : INodeIdentityProvider
{
    public NodeIdentityProvider(IOptions<NodeOptions> options)
    {
        var name = options.Value.NodeName;
        NodeName = string.IsNullOrWhiteSpace(name) ? null : name.Trim();
    }

    public string? NodeName { get; }
}
```

**Step 4: Register the singleton in DI**

In `SiteServiceRegistration.cs` and `CentralServiceRegistration.cs` (or wherever `NodeOptions` is bound):

```csharp
services.AddSingleton<INodeIdentityProvider, NodeIdentityProvider>();
```

**Step 5: Run tests + build**

```bash
dotnet test tests/<project> --filter NodeIdentityProvider -v n
dotnet build ScadaLink.slnx
```

Expected: PASS, solution builds.

**Step 6: Commit**

```bash
git add src/ScadaLink.Host/NodeOptions.cs \
        src/ScadaLink.Commons/Interfaces/Services/INodeIdentityProvider.cs \
        src/ScadaLink.Host/NodeIdentityProvider.cs \
        src/ScadaLink.Host/SiteServiceRegistration.cs \
        tests/<project>/NodeIdentityProviderTests.cs
git commit -m "feat(host): add NodeName to NodeOptions + INodeIdentityProvider"
```

---

## Task 2: Add `SourceNode` to `AuditEvent` record

**Files:**
- Modify: `src/ScadaLink.Commons/Entities/Audit/AuditEvent.cs`
- Modify: any direct constructors of `AuditEvent` (compile errors will surface them)
- Modify: `tests/ScadaLink.AuditLog.Tests/AddAuditLogTests.cs` (or the closest equivalent) — add a SourceNode round-trip assertion.

**Step 1: Failing test**

```csharp
[Fact]
public void AuditEvent_carries_SourceNode_through_with_init()
{
    var ev = new AuditEvent
    {
        EventId = Guid.NewGuid(),
        OccurredAtUtc = DateTime.UtcNow,
        Channel = AuditChannel.ApiOutbound,
        Kind = AuditKind.ApiCall,
        Status = AuditStatus.Delivered,
        SourceSiteId = "site-a",
        SourceNode = "node-a",
    };

    Assert.Equal("node-a", ev.SourceNode);
}
```

Run: expected FAIL (property doesn't exist).

**Step 2: Add `SourceNode` to the record**

In `AuditEvent.cs`, add between `SourceSiteId` and `SourceInstanceId` (mirroring the design doc):

```csharp
public string? SourceNode { get; init; }
```

**Step 3: Resolve compile errors**

The record is `sealed` and used widely. Most usages will be init-only and won't break; positional constructors (if any) will. Fix them by adding `SourceNode = …` initializers OR by leaving `SourceNode = null` where the caller doesn't know the node yet (writer-level stamping happens in Task 9 + 10).

**Step 4: Run + commit**

```bash
dotnet test tests/ScadaLink.AuditLog.Tests --filter SourceNode -v n
dotnet build ScadaLink.slnx
git add src/ScadaLink.Commons/Entities/Audit/AuditEvent.cs tests/ScadaLink.AuditLog.Tests/AddAuditLogTests.cs
git commit -m "feat(audit): add SourceNode property to AuditEvent record"
```

---

## Task 3: Add `SourceNode` to `SiteCallOperational` + `SiteCall` entity

**Files:**
- Modify: `src/ScadaLink.Commons/Types/SiteCallOperational.cs`
- Modify: `src/ScadaLink.Commons/Entities/Audit/SiteCall.cs`
- Modify: tests in `tests/ScadaLink.SiteCallAudit.Tests/` that build a `SiteCall` — extend at least one to assert SourceNode is carried.

**Step 1: Failing test — `SiteCallOperational` constructed with SourceNode**

```csharp
[Fact]
public void SiteCallOperational_carries_SourceNode()
{
    var op = new SiteCallOperational(
        TrackedOperationId: TrackedOperationId.New(),
        Channel: "ApiOutbound",
        Target: "ERP.GetOrder",
        SourceSite: "site-a",
        SourceNode: "node-a",     // new positional arg
        Status: "Submitted",
        RetryCount: 0,
        LastError: null,
        HttpStatus: null,
        CreatedAtUtc: DateTime.UtcNow,
        UpdatedAtUtc: DateTime.UtcNow,
        TerminalAtUtc: null);

    Assert.Equal("node-a", op.SourceNode);
}
```

Run: expected FAIL.

**Step 2: Add `SourceNode` to `SiteCallOperational`**

Insert `string? SourceNode` between `SourceSite` and `Status`. **Update all callers** — the C# compiler will list every site that constructs the record. Most are in:
- `src/ScadaLink.ExternalSystemGateway/ExternalSystemClient.cs`
- `src/ScadaLink.DataConnectionLayer/...` (cached DB write site)
- `src/ScadaLink.Communication/...` (mappers)
- `src/ScadaLink.SiteCallAudit/SiteCallAuditActor.cs`
- All `tests/ScadaLink.SiteCallAudit.Tests/*` and `tests/ScadaLink.ConfigurationDatabase.Tests/Repositories/SiteCallAuditRepositoryTests.cs`

For now, pass `SourceNode: null` at every existing call site — actual stamping comes in Task 11.

**Step 3: Add `SourceNode` to `SiteCall` entity**

Mirror in `src/ScadaLink.Commons/Entities/Audit/SiteCall.cs` as `public string? SourceNode { get; init; }`.

**Step 4: Run + commit**

```bash
dotnet build ScadaLink.slnx
dotnet test tests/ScadaLink.SiteCallAudit.Tests --filter SourceNode -v n
git add src/ScadaLink.Commons/Types/SiteCallOperational.cs \
        src/ScadaLink.Commons/Entities/Audit/SiteCall.cs \
        <updated callers>
git commit -m "feat(sitecall-audit): add SourceNode to SiteCallOperational + SiteCall entity"
```

---

## Task 4: Add `SourceNode` to `Notification` entity + `NotificationSubmit` message

**Files:**
- Modify: `src/ScadaLink.Commons/Entities/Notifications/Notification.cs`
- Modify: `src/ScadaLink.Commons/Messages/Notification/NotificationMessages.cs`
- Modify: tests in `tests/ScadaLink.NotificationOutbox.Tests/`

**Step 1: Failing test**

```csharp
[Fact]
public void NotificationSubmit_carries_SourceNode()
{
    var submit = new NotificationSubmit(
        NotificationId: Guid.NewGuid().ToString("D"),
        ListName: "ops-team",
        Subject: "x",
        Body: "y",
        SourceSiteId: "site-a",
        SourceInstanceId: "instance-1",
        SourceScript: "OnAlarm",
        SourceNode: "node-a",            // new
        SiteEnqueuedAt: DateTimeOffset.UtcNow);

    Assert.Equal("node-a", submit.SourceNode);
}
```

Run: expected FAIL.

**Step 2: Add `SourceNode` to both**

In `Notification.cs`: `public string? SourceNode { get; set; }`.

In `NotificationMessages.cs`, extend the record additively (defaulted optional positional arg so existing callers compile — keep behind the optional `OriginExecutionId`/`OriginParentExecutionId` to preserve the existing tail):

```csharp
public record NotificationSubmit(
    string NotificationId,
    string ListName,
    string Subject,
    string Body,
    string SourceSiteId,
    string? SourceInstanceId,
    string? SourceScript,
    DateTimeOffset SiteEnqueuedAt,
    Guid? OriginExecutionId = null,
    Guid? OriginParentExecutionId = null,
    string? SourceNode = null);            // new, tail
```

**Step 3: Run + commit**

```bash
dotnet build ScadaLink.slnx
dotnet test tests/ScadaLink.NotificationOutbox.Tests --filter SourceNode -v n
git add src/ScadaLink.Commons/Entities/Notifications/Notification.cs \
        src/ScadaLink.Commons/Messages/Notification/NotificationMessages.cs \
        tests/ScadaLink.NotificationOutbox.Tests/<modified>.cs
git commit -m "feat(notif-outbox): add SourceNode to Notification entity + NotificationSubmit"
```

---

## Task 5: Add `source_node` to proto + update DTO mappers

**Files:**
- Modify: `src/ScadaLink.Communication/Protos/sitestream.proto`
- Modify: `src/ScadaLink.Communication/AuditEventDtoMapper.cs` (or wherever `ToDto` / `FromDto` live)
- Modify: `src/ScadaLink.Communication/SiteCallOperationalDtoMapper.cs` (likewise)
- Modify: `tests/ScadaLink.Communication.Tests/Protos/AuditEventProtoTests.cs`
- Modify: equivalent SiteCallOperational proto round-trip tests

**Step 1: Failing test — proto round-trip preserves SourceNode**

```csharp
[Fact]
public void AuditEventDto_round_trip_preserves_SourceNode()
{
    var ev = new AuditEvent { /* … */ SourceNode = "node-a", SourceSiteId = "site-a" };
    var dto = AuditEventDtoMapper.ToDto(ev);
    var back = AuditEventDtoMapper.FromDto(dto);
    Assert.Equal("node-a", back.SourceNode);
}

[Fact]
public void AuditEventDto_round_trip_preserves_null_SourceNode()
{
    var ev = new AuditEvent { /* … */ SourceNode = null };
    var dto = AuditEventDtoMapper.ToDto(ev);
    var back = AuditEventDtoMapper.FromDto(dto);
    Assert.Null(back.SourceNode);
}
```

Run: expected FAIL (compile error on `SourceNode` until mapper handles it).

**Step 2: Extend proto additively**

In `sitestream.proto`, **field numbers must be new and not reused**:

```proto
message AuditEventDto {
  // … existing fields 1..21 unchanged …
  string source_node = 22;        // empty string represents null
}

message SiteCallOperationalDto {
  // … existing fields 1..11 unchanged …
  string source_node = 12;        // empty string represents null
}
```

**Step 3: Regenerate + update mappers**

`Grpc.Tools` regenerates on build. Update `AuditEventDtoMapper.ToDto`:

```csharp
SourceNode = ev.SourceNode ?? string.Empty,
```

And `FromDto`:

```csharp
SourceNode = string.IsNullOrEmpty(dto.SourceNode) ? null : dto.SourceNode,
```

Same pattern for `SiteCallOperationalDtoMapper`.

**Step 4: Run + commit**

```bash
dotnet build ScadaLink.slnx
dotnet test tests/ScadaLink.Communication.Tests --filter SourceNode -v n
git add src/ScadaLink.Communication/Protos/sitestream.proto \
        src/ScadaLink.Communication/AuditEventDtoMapper.cs \
        src/ScadaLink.Communication/SiteCallOperationalDtoMapper.cs \
        tests/ScadaLink.Communication.Tests/Protos/AuditEventProtoTests.cs \
        tests/ScadaLink.Communication.Tests/<sitecall mapper tests>.cs
git commit -m "feat(comm): add source_node field to AuditEventDto + SiteCallOperationalDto proto"
```

---

## Task 6: EF migration — add `SourceNode` to `AuditLog` + index

**Files:**
- Create: `src/ScadaLink.ConfigurationDatabase/Migrations/<ts>_AddAuditLogSourceNode.cs` + `.Designer.cs`
- Modify: `src/ScadaLink.ConfigurationDatabase/Migrations/ScadaLinkDbContextModelSnapshot.cs`
- Modify: `src/ScadaLink.ConfigurationDatabase/Configurations/AuditLogEntityTypeConfiguration.cs`
- Create test: `tests/ScadaLink.ConfigurationDatabase.Tests/Migrations/AddAuditLogSourceNodeMigrationTests.cs`

**Step 1: Failing test (migration apply produces `SourceNode` column + index)**

Pattern from existing `AddAuditLogTableMigrationTests.cs`. Apply migration against a fresh MS SQL test fixture; assert `INFORMATION_SCHEMA.COLUMNS` contains `SourceNode varchar(64) NULL` and `sys.indexes` contains `IX_AuditLog_Node_Occurred` with columns `(SourceNode, OccurredAtUtc)`.

Run: expected FAIL.

**Step 2: Add migration via EF CLI**

From repo root:

```bash
dotnet ef migrations add AddAuditLogSourceNode \
    --project src/ScadaLink.ConfigurationDatabase \
    --startup-project src/ScadaLink.Host \
    --context ScadaLinkDbContext
```

Hand-edit the generated `Up()` / `Down()` to verify shape:

```csharp
migrationBuilder.AddColumn<string>(
    name: "SourceNode",
    table: "AuditLog",
    type: "varchar(64)",
    unicode: false,
    maxLength: 64,
    nullable: true);

migrationBuilder.CreateIndex(
    name: "IX_AuditLog_Node_Occurred",
    table: "AuditLog",
    columns: new[] { "SourceNode", "OccurredAtUtc" });
```

`Down()` drops the index then the column.

**Step 3: Update EF configuration**

In `AuditLogEntityTypeConfiguration.cs`, mirror the design doc:

```csharp
builder.Property(e => e.SourceNode).HasColumnType("varchar(64)").HasMaxLength(64);
builder.HasIndex(e => new { e.SourceNode, e.OccurredAtUtc })
       .HasDatabaseName("IX_AuditLog_Node_Occurred");
```

**Step 4: Run + commit**

```bash
dotnet build ScadaLink.slnx
dotnet test tests/ScadaLink.ConfigurationDatabase.Tests --filter AuditLogSourceNode -v n
git add src/ScadaLink.ConfigurationDatabase/Migrations/<ts>_AddAuditLogSourceNode.cs \
        src/ScadaLink.ConfigurationDatabase/Migrations/<ts>_AddAuditLogSourceNode.Designer.cs \
        src/ScadaLink.ConfigurationDatabase/Migrations/ScadaLinkDbContextModelSnapshot.cs \
        src/ScadaLink.ConfigurationDatabase/Configurations/AuditLogEntityTypeConfiguration.cs \
        tests/ScadaLink.ConfigurationDatabase.Tests/Migrations/AddAuditLogSourceNodeMigrationTests.cs
git commit -m "feat(db): add SourceNode column + IX_AuditLog_Node_Occurred index to AuditLog"
```

---

## Task 7: EF migration — add `SourceNode` to `Notifications`

**Files:**
- Create: `src/ScadaLink.ConfigurationDatabase/Migrations/<ts>_AddNotificationSourceNode.cs` + `.Designer.cs`
- Modify: `src/ScadaLink.ConfigurationDatabase/Migrations/ScadaLinkDbContextModelSnapshot.cs`
- Modify: `src/ScadaLink.ConfigurationDatabase/Configurations/NotificationOutboxConfiguration.cs`
- Create test: `tests/ScadaLink.ConfigurationDatabase.Tests/Migrations/AddNotificationSourceNodeMigrationTests.cs`

**Step 1–4:** Mirror Task 6 for the `Notifications` table. No new index (the spec says index only on `AuditLog`).

```bash
git commit -m "feat(db): add SourceNode column to Notifications"
```

---

## Task 8: EF migration — add `SourceNode` to `SiteCalls`

**Files:** equivalents under `SiteCalls`. No new index.

**Step 1–4:** Mirror Task 6. Configuration file is `SiteCallEntityTypeConfiguration.cs`.

```bash
git commit -m "feat(db): add SourceNode column to SiteCalls"
```

---

## Task 9: Site SQLite `AuditLog` — add `SourceNode` column (idempotent upgrade)

**Files:**
- Modify: `src/ScadaLink.AuditLog/Site/SqliteAuditWriter.cs`
- Modify: `tests/ScadaLink.AuditLog.Tests/Site/SqliteAuditWriterSchemaTests.cs`
- Modify: `tests/ScadaLink.AuditLog.Tests/Site/SqliteAuditWriterWriteTests.cs`

**Step 1: Failing test — schema includes SourceNode AND old DBs are upgraded**

```csharp
[Fact]
public async Task Initialize_creates_AuditLog_with_SourceNode_column()
{
    using var writer = new SqliteAuditWriter(/*…in-memory…*/);
    var cols = await ReadColumnsAsync("AuditLog");
    Assert.Contains("SourceNode", cols);
}

[Fact]
public async Task Initialize_adds_SourceNode_to_pre_existing_schema()
{
    // 1. open a SQLite file and create the OLD schema (no SourceNode)
    // 2. open SqliteAuditWriter against the same file
    // 3. assert SourceNode column now exists via PRAGMA table_info
}
```

Run: expected FAIL.

**Step 2: Update `InitializeSchema`**

Add `SourceNode TEXT NULL` to the `CREATE TABLE IF NOT EXISTS AuditLog (...)` DDL. Add a second `PRAGMA table_info`-based upgrade block matching the existing `ExecutionId` / `ParentExecutionId` pattern:

```csharp
if (!columns.Contains("SourceNode", StringComparer.OrdinalIgnoreCase))
{
    using var cmd = conn.CreateCommand();
    cmd.CommandText = "ALTER TABLE AuditLog ADD COLUMN SourceNode TEXT NULL;";
    cmd.ExecuteNonQuery();
}
```

**Step 3: Update INSERT statement to include SourceNode**

In the parameterized batch insert SQL (lines ~270-284), add the column + parameter.

**Step 4: Run + commit**

```bash
dotnet test tests/ScadaLink.AuditLog.Tests/Site/SqliteAuditWriterSchemaTests.cs --filter SourceNode -v n
dotnet build ScadaLink.slnx
git add src/ScadaLink.AuditLog/Site/SqliteAuditWriter.cs \
        tests/ScadaLink.AuditLog.Tests/Site/SqliteAuditWriterSchemaTests.cs \
        tests/ScadaLink.AuditLog.Tests/Site/SqliteAuditWriterWriteTests.cs
git commit -m "feat(audit): add SourceNode column to site SQLite AuditLog (idempotent upgrade)"
```

---

## Task 10: Site SQLite `OperationTracking` — add `SourceNode` column

**Files:**
- Modify: `src/ScadaLink.SiteRuntime/Tracking/OperationTrackingStore.cs`
- Modify: tests under `tests/ScadaLink.SiteRuntime.Tests/Tracking/` (or closest)

**Step 1: Failing test** — same pattern as Task 9, asserting the `OperationTracking` table grows a `SourceNode TEXT NULL` column on both fresh and pre-existing DBs.

**Step 2: Add column to CREATE TABLE + idempotent PRAGMA-based ALTER**

```sql
CREATE TABLE IF NOT EXISTS OperationTracking (
    -- ...existing columns...
    SourceNode TEXT NULL
);
```

Plus the same PRAGMA upgrade block.

**Step 3: Update `RecordEnqueueAsync` signature**

Accept `string? sourceNode` and pass through to INSERT.

**Step 4: Run + commit**

```bash
git commit -m "feat(site-runtime): add SourceNode column to OperationTracking + thread through RecordEnqueueAsync"
```

---

## Task 11: Stamp `SourceNode` at the site `SqliteAuditWriter`

**Files:**
- Modify: `src/ScadaLink.AuditLog/Site/SqliteAuditWriter.cs`
- Modify: DI registration that wires `SqliteAuditWriter` (likely `src/ScadaLink.AuditLog/AuditLogServiceCollectionExtensions.cs` or equivalent)
- Modify: `tests/ScadaLink.AuditLog.Tests/Site/SqliteAuditWriterWriteTests.cs`

**Step 1: Failing test**

```csharp
[Fact]
public async Task WriteAsync_stamps_SourceNode_from_INodeIdentityProvider_when_event_has_none()
{
    var nodeId = Substitute.For<INodeIdentityProvider>();
    nodeId.NodeName.Returns("node-a");
    using var writer = new SqliteAuditWriter(/*…*/, nodeId);
    await writer.WriteAsync(new AuditEvent { /*…*/ SourceNode = null });
    var rows = await ReadAllAsync();
    Assert.Equal("node-a", rows.Single().SourceNode);
}

[Fact]
public async Task WriteAsync_preserves_caller_provided_SourceNode()
{
    var nodeId = Substitute.For<INodeIdentityProvider>();
    nodeId.NodeName.Returns("node-a");
    using var writer = new SqliteAuditWriter(/*…*/, nodeId);
    await writer.WriteAsync(new AuditEvent { /*…*/ SourceNode = "node-z" });
    var rows = await ReadAllAsync();
    Assert.Equal("node-z", rows.Single().SourceNode);   // caller wins (e.g. reconciliation)
}
```

Run: expected FAIL.

**Step 2: Implementation**

Inject `INodeIdentityProvider` into `SqliteAuditWriter`. In `WriteAsync` / batch flush, **before** binding parameters:

```csharp
var stamped = ev.SourceNode is null ? ev with { SourceNode = _nodeIdentity.NodeName } : ev;
```

**Step 3: Run + commit**

```bash
git commit -m "feat(audit): stamp SourceNode at site SqliteAuditWriter from INodeIdentityProvider"
```

---

## Task 12: Stamp `SourceNode` at central `CentralAuditWriter`

**Files:**
- Modify: `src/ScadaLink.AuditLog/Central/CentralAuditWriter.cs`
- Modify: `tests/ScadaLink.AuditLog.Tests/Central/CentralAuditWriterTests.cs`

**Step 1: Failing test** — mirror Task 11 but for the central writer (Inbound API / Notification Outbox dispatcher path).

**Step 2: Implementation** — inject `INodeIdentityProvider`, stamp before `repo.InsertIfNotExistsAsync`. Same "caller wins" semantics.

**Step 3: Update `AuditLogRepository.InsertIfNotExistsAsync` to persist `SourceNode`**

This is in `src/ScadaLink.ConfigurationDatabase/Repositories/AuditLogRepository.cs` — extend the parameterized INSERT.

**Step 4: Run + commit**

```bash
git commit -m "feat(audit): stamp SourceNode at CentralAuditWriter + persist via AuditLogRepository"
```

---

## Task 13: Site → central — carry `SourceNode` on `NotificationSubmit`

**Files:**
- Modify: site code that constructs `NotificationSubmit` (likely under `src/ScadaLink.SiteRuntime/Scripts/` or `src/ScadaLink.NotificationService/Site/...`)
- Modify: S&F buffer schema if NotificationSubmit is serialized to SQLite (check `src/ScadaLink.StoreAndForward/StoreAndForwardStorage.cs` for a notification-specific column — likely the whole DTO is serialized as a blob, no schema change needed)
- Modify: `src/ScadaLink.NotificationOutbox/NotificationOutboxActor.cs` `HandleSubmit` to copy `SourceNode` into the `Notification` row
- Modify: `src/ScadaLink.ConfigurationDatabase/Repositories/NotificationOutboxRepository.cs` (or wherever) `InsertIfNotExistsAsync` SQL
- Modify: tests in `tests/ScadaLink.NotificationOutbox.Tests/NotificationOutboxActorIngestTests.cs`

**Step 1: Failing test — central persists SourceNode from NotificationSubmit**

```csharp
[Fact]
public async Task HandleSubmit_persists_SourceNode_from_payload()
{
    var submit = new NotificationSubmit(/*…*/, SourceNode: "node-b");
    actor.Tell(submit);
    await ExpectMsgAsync<NotificationSubmitAck>(m => m.Accepted);
    var row = await repo.GetByIdAsync(submit.NotificationId);
    Assert.Equal("node-b", row.SourceNode);
}
```

**Step 2: Implementation**

- Site: inject `INodeIdentityProvider` into the call site that builds `NotificationSubmit`, pass `SourceNode = nodeIdentity.NodeName`.
- Central: extend `HandleSubmit` to copy `submit.SourceNode` onto the `Notification` row; extend the repo INSERT to persist.

**Step 3: Run + commit**

```bash
git commit -m "feat(notif-outbox): carry + persist SourceNode end-to-end via NotificationSubmit"
```

---

## Task 14: Site → central — carry `SourceNode` on `SiteCallOperational` + cached telemetry

**Files:**
- Modify: site emitters of `SiteCallOperational` — `src/ScadaLink.ExternalSystemGateway/ExternalSystemClient.cs`, `src/ScadaLink.DataConnectionLayer/...` (cached DB write), and the S&F retry path that emits `Attempted` packets
- Modify: `src/ScadaLink.SiteCallAudit/SiteCallAuditActor.cs` (and any `SiteCallAuditIngestActor` that maps `SiteCallOperational` → `SiteCall`)
- Modify: `src/ScadaLink.ConfigurationDatabase/Repositories/SiteCallAuditRepository.cs` — extend monotonic upsert SQL to include `SourceNode`
- Modify: tests in `tests/ScadaLink.SiteCallAudit.Tests/SiteCallAuditActorTests.cs` and `tests/ScadaLink.ConfigurationDatabase.Tests/Repositories/SiteCallAuditRepositoryTests.cs`

**Step 1: Failing test — central persists `SourceNode` on upsert; subsequent upsert with same id keeps SourceNode set even if newer packet has it null**

```csharp
[Fact]
public async Task Upsert_persists_SourceNode_on_first_insert_and_preserves_on_status_advance()
{
    var id = TrackedOperationId.New();
    await repo.UpsertAsync(new SiteCall { TrackedOperationId = id, /*…*/ SourceNode = "node-a", Status = "Submitted" });
    await repo.UpsertAsync(new SiteCall { TrackedOperationId = id, /*…*/ SourceNode = null, Status = "Delivered" });
    var row = await repo.GetByIdAsync(id);
    Assert.Equal("node-a", row.SourceNode);
    Assert.Equal("Delivered", row.Status);
}
```

**Step 2: Implementation**

- Site emitters: inject `INodeIdentityProvider`, pass `SourceNode = nodeIdentity.NodeName` on construction.
- Repository: include `SourceNode` in the INSERT branch. In the conditional monotonic UPDATE branch, use `SourceNode = COALESCE(@SourceNode, SourceNode)` so later packets with a null don't blank out a previously-stamped value.

**Step 3: Run + commit**

```bash
git commit -m "feat(sitecall-audit): carry + persist SourceNode end-to-end via cached telemetry"
```

---

## Task 15: Central UI — add Node column + filter to AuditLog grid

**Files:**
- Modify: `src/ScadaLink.CentralUI/Components/Audit/AuditResultsGrid.razor` + `.razor.cs` (add column entry to `AllColumns`)
- Modify: `src/ScadaLink.CentralUI/Components/Audit/AuditFilterBar.razor` (add a text or multi-select Node filter)
- Modify: `src/ScadaLink.CentralUI/Services/AuditLogQueryService.cs` (extend the query/filter model)
- Modify: tests in `tests/ScadaLink.CentralUI.Tests/Services/AuditLogQueryServiceTests.cs`
- Modify: `tests/ScadaLink.CentralUI.PlaywrightTests/Audit/AuditGridColumnTests.cs` — assert the Node column renders

**Step 1: Failing test — query service supports `SourceNode` filter**

```csharp
[Fact]
public async Task Query_filters_by_SourceNode()
{
    // arrange 2 rows: one with SourceNode=node-a, one with node-b
    var rows = await service.QueryAsync(new AuditLogQuery { SourceNodes = new[] { "node-a" } });
    Assert.Single(rows);
}
```

**Step 2: Implementation**

- Extend `AuditLogQuery` with `IReadOnlyList<string>? SourceNodes` (multi-select like `Sites`).
- Extend the LINQ filter (`q.SourceNodes is { Count: > 0 } ? source.Where(r => q.SourceNodes.Contains(r.SourceNode)) : source`).
- Add a new column descriptor `("Node", row => row.SourceNode ?? "—")` between `Site` and `Channel` in `AllColumns`.
- Add a multi-select filter chip in `AuditFilterBar.razor`. Populate node options by `SELECT DISTINCT SourceNode FROM AuditLog WHERE SourceNode IS NOT NULL` (cached for 60s).

**Step 3: Run + commit**

```bash
git commit -m "feat(ui): add Node column + filter to AuditLog grid"
```

---

## Task 16: Central UI — add Node column + filter to Notifications grid

**Files:** mirror Task 15 for `src/ScadaLink.CentralUI/Components/Pages/Notifications/NotificationReport.razor` and its query service. No filter populate-from-DB required if scope is per-site already; a free-text Node filter is acceptable for v1.

```bash
git commit -m "feat(ui): add Node column + filter to NotificationOutbox grid"
```

---

## Task 17: Central UI — add Node column + filter to SiteCalls grid

**Files:** mirror Task 15 for `src/ScadaLink.CentralUI/Components/Pages/SiteCalls/SiteCallsReport.razor`.

```bash
git commit -m "feat(ui): add Node column + filter to SiteCalls grid"
```

---

## Task 18: Docker `appsettings` — set `NodeName` on all 8 nodes

**Files:**
- `docker/central-node-a/appsettings.Central.json` → `"NodeName": "central-a"`
- `docker/central-node-b/appsettings.Central.json` → `"NodeName": "central-b"`
- `docker/site-a-node-a/appsettings.Site.json` → `"NodeName": "node-a"`
- `docker/site-a-node-b/appsettings.Site.json` → `"NodeName": "node-b"`
- `docker/site-b-node-a/appsettings.Site.json` → `"NodeName": "node-a"`
- `docker/site-b-node-b/appsettings.Site.json` → `"NodeName": "node-b"`
- `docker/site-c-node-a/appsettings.Site.json` → `"NodeName": "node-a"`
- `docker/site-c-node-b/appsettings.Site.json` → `"NodeName": "node-b"`

Add `"NodeName": "<value>"` to the existing `"Node": { … }` object in each file. **Do not** disturb the two `central-*` files that show up dirty in pre-existing `git status` from before this branch — re-apply this change cleanly after stashing.

```bash
git add docker/central-node-a/appsettings.Central.json docker/central-node-b/appsettings.Central.json docker/site-a-node-a/appsettings.Site.json docker/site-a-node-b/appsettings.Site.json docker/site-b-node-a/appsettings.Site.json docker/site-b-node-b/appsettings.Site.json docker/site-c-node-a/appsettings.Site.json docker/site-c-node-b/appsettings.Site.json
git commit -m "chore(docker): set NodeName on all 8 cluster nodes"
```

---

## Task 19: Full-solution build + targeted test sweep

**Step 1: Build**

```bash
dotnet build ScadaLink.slnx
```

Expected: 0 errors, 0 warnings.

**Step 2: Run the touched test projects**

```bash
dotnet test tests/ScadaLink.AuditLog.Tests/ScadaLink.AuditLog.Tests.csproj
dotnet test tests/ScadaLink.NotificationOutbox.Tests/ScadaLink.NotificationOutbox.Tests.csproj
dotnet test tests/ScadaLink.SiteCallAudit.Tests/ScadaLink.SiteCallAudit.Tests.csproj
dotnet test tests/ScadaLink.Communication.Tests/ScadaLink.Communication.Tests.csproj
dotnet test tests/ScadaLink.ConfigurationDatabase.Tests/ScadaLink.ConfigurationDatabase.Tests.csproj
dotnet test tests/ScadaLink.CentralUI.Tests/ScadaLink.CentralUI.Tests.csproj
```

Expected: all green. If anything fails, fix it before proceeding.

**Step 3: Full solution test (sanity)**

```bash
dotnet test ScadaLink.slnx --no-build
```

---

## Task 20: Docker redeploy + smoke verify

**Step 1: Rebuild + redeploy the cluster**

```bash
bash docker/deploy.sh
```

Expected: image rebuilt, all 8 containers up. Watch for migration apply on central startup.

**Step 2: CLI smoke — generate one inbound, one notification, one cached call; verify SourceNode populated**

```bash
# Trigger something that emits each kind. The exact CLI commands depend on
# scripts deployed at the time; at minimum:
#   1. POST to inbound API → produces an InboundRequest row
#   2. Run a script that calls Notify.Send → produces NotifySend + NotifyDeliver
#   3. Run a script that calls ExternalSystem.CachedCall → produces CachedSubmit/Forwarded/Attempted/Delivered

# Then check SourceNode is populated:
docker exec scadalink-mssql /opt/mssql-tools/bin/sqlcmd -S localhost -U sa -P 'YourStrong!Passw0rd' -Q "SELECT TOP 20 Channel, Kind, SourceSiteId, SourceNode, Status FROM scadalink.dbo.AuditLog ORDER BY OccurredAtUtc DESC"
```

Expected:
- `InboundRequest` rows: `SourceSiteId IS NULL`, `SourceNode IN ('central-a','central-b')`.
- `NotifyDeliver` rows: `SourceSiteId IS NULL`, `SourceNode IN ('central-a','central-b')`.
- Site-originated rows: `SourceSiteId = 'site-a'`, `SourceNode IN ('node-a','node-b')`.

**Step 3: UI smoke**

Open `http://localhost:9000`, log in as `multi-role` / `password`, hit each of:
- Audit Log → confirm "Node" column shows values, confirm Node filter narrows results.
- Notifications → same.
- Site Calls → same.

**Step 4: Final commit (if anything had to be tweaked during smoke)**

```bash
git add -A
git status   # verify nothing surprising
git commit -m "chore(audit): smoke-verify SourceNode end-to-end across cluster"
```

---

## Acceptance Criteria (the whole-plan checklist)

- [ ] Every audit row written from this commit forward carries `SourceNode` populated (`central-a/b` for central direct-write, `node-a/b` for site rows).
- [ ] Every new `Notifications` and `SiteCalls` row carries `SourceNode` from the site.
- [ ] `IX_AuditLog_Node_Occurred` exists in central MS SQL.
- [ ] Site SQLite `AuditLog` and `OperationTracking` tables both have `SourceNode TEXT NULL`; existing site DBs are upgraded idempotently on startup.
- [ ] Proto `AuditEventDto.source_node = 22` and `SiteCallOperationalDto.source_node = 12` exist; no field numbers reused.
- [ ] Central UI Audit Log, Notifications, and Site Calls pages all display a "Node" column and support filtering by it.
- [ ] All test projects green.
- [ ] Cluster comes up clean via `bash docker/deploy.sh`; CLI smoke confirms expected node names land in the central tables.
- [ ] Design docs (already committed in Task 0) match the implementation.
