feat(auditlog): payload filter uses InboundMaxBytes for ApiInbound rows

src/ScadaLink.AuditLog/Payload/DefaultAuditPayloadFilter.cs

@@ -118,7 +118,14 @@ public sealed class DefaultAuditPayloadFilter : IAuditPayloadFilter
         try
         {
             var opts = _options.CurrentValue;
-            var cap = IsErrorStatus(rawEvent.Status) ? opts.ErrorCapBytes : opts.DefaultCapBytes;
+            // Inbound API gets a dedicated, larger ceiling — request/response bodies are
+            // captured verbatim up to InboundMaxBytes (default 1 MiB) so support can
+            // replay exactly what the caller sent and what we returned. Other channels
+            // keep the global 8 KiB / 64 KiB policy.
+            // See docs/plans/2026-05-23-inbound-api-full-response-audit-design.md.
+            var cap = rawEvent.Channel == AuditChannel.ApiInbound
+                ? opts.InboundMaxBytes
+                : (IsErrorStatus(rawEvent.Status) ? opts.ErrorCapBytes : opts.DefaultCapBytes);
 
             // --- Header-redaction stage (runs BEFORE truncation) ----------
             var request = RedactHeaders(rawEvent.RequestSummary, opts.HeaderRedactList);

tests/ScadaLink.AuditLog.Tests/Payload/InboundChannelCapTests.cs

@@ -0,0 +1,133 @@
+using System.Text;
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
+using ScadaLink.AuditLog.Configuration;
+using ScadaLink.AuditLog.Payload;
+using ScadaLink.Commons.Entities.Audit;
+using ScadaLink.Commons.Types.Enums;
+
+namespace ScadaLink.AuditLog.Tests.Payload;
+
+/// <summary>
+/// Pins the docs/plans/2026-05-23-inbound-api-full-response-audit-design.md
+/// inbound carve-out: ApiInbound rows use InboundMaxBytes (default 1 MiB) for
+/// RequestSummary / ResponseSummary truncation, NOT DefaultCapBytes /
+/// ErrorCapBytes. Other channels keep the existing caps.
+/// </summary>
+/// <remarks>
+/// Uses a file-local <see cref="StaticMonitor"/> helper mirroring the
+/// convention in the sibling Payload tests (TruncationTests,
+/// FilterIntegrationTests, BodyRegexRedactionTests, etc.) — the
+/// <c>TestOptionsMonitor&lt;T&gt;</c> helper referenced by the plan is a
+/// private nested class inside <c>AuditLogOptionsBindingTests</c> and thus
+/// not reachable from this file.
+/// </remarks>
+public class InboundChannelCapTests
+{
+    private static AuditEvent MakeInbound(
+        AuditStatus status,
+        string? request = null,
+        string? response = null) =>
+        new()
+        {
+            EventId = Guid.NewGuid(),
+            OccurredAtUtc = DateTime.UtcNow,
+            Channel = AuditChannel.ApiInbound,
+            Kind = AuditKind.InboundRequest,
+            Status = status,
+            RequestSummary = request,
+            ResponseSummary = response,
+        };
+
+    [Fact]
+    public void ApiInbound_Delivered_RequestBody_BelowInboundMaxBytes_NotTruncated()
+    {
+        // Body well above the legacy 8 KiB default cap but under the 1 MiB
+        // inbound ceiling — must NOT truncate.
+        var body = new string('a', 100_000);
+        var opts = new AuditLogOptions();          // defaults
+        var filter = new DefaultAuditPayloadFilter(
+            new StaticMonitor(opts),
+            NullLogger<DefaultAuditPayloadFilter>.Instance);
+
+        var result = filter.Apply(MakeInbound(AuditStatus.Delivered, request: body));
+
+        Assert.False(result.PayloadTruncated);
+        Assert.Equal(100_000, Encoding.UTF8.GetByteCount(result.RequestSummary!));
+    }
+
+    [Fact]
+    public void ApiInbound_Delivered_ResponseBody_BelowInboundMaxBytes_NotTruncated()
+    {
+        var body = new string('a', 100_000);
+        var opts = new AuditLogOptions();
+        var filter = new DefaultAuditPayloadFilter(
+            new StaticMonitor(opts),
+            NullLogger<DefaultAuditPayloadFilter>.Instance);
+
+        var result = filter.Apply(MakeInbound(AuditStatus.Delivered, response: body));
+
+        Assert.False(result.PayloadTruncated);
+        Assert.Equal(100_000, Encoding.UTF8.GetByteCount(result.ResponseSummary!));
+    }
+
+    [Fact]
+    public void ApiInbound_Failed_BodyAboveInboundMaxBytes_TruncatedToInboundMaxBytes()
+    {
+        // Even on error rows, the inbound cap is InboundMaxBytes (NOT ErrorCapBytes).
+        var opts = new AuditLogOptions { InboundMaxBytes = 16_384 };
+        var oversized = new string('z', 50_000);
+        var filter = new DefaultAuditPayloadFilter(
+            new StaticMonitor(opts),
+            NullLogger<DefaultAuditPayloadFilter>.Instance);
+
+        var result = filter.Apply(MakeInbound(AuditStatus.Failed, response: oversized));
+
+        Assert.True(result.PayloadTruncated);
+        Assert.True(Encoding.UTF8.GetByteCount(result.ResponseSummary!) <= 16_384);
+    }
+
+    [Fact]
+    public void ApiOutbound_StillUsesDefaultCap_NotInboundMaxBytes()
+    {
+        // Regression guard: lifting the inbound cap MUST NOT change other
+        // channels. An ApiOutbound 100 KB body still hits the 8 KiB cap.
+        var opts = new AuditLogOptions();
+        var body = new string('a', 100_000);
+        var filter = new DefaultAuditPayloadFilter(
+            new StaticMonitor(opts),
+            NullLogger<DefaultAuditPayloadFilter>.Instance);
+
+        var evt = new AuditEvent
+        {
+            EventId = Guid.NewGuid(),
+            OccurredAtUtc = DateTime.UtcNow,
+            Channel = AuditChannel.ApiOutbound,
+            Kind = AuditKind.ApiCall,
+            Status = AuditStatus.Delivered,
+            RequestSummary = body,
+        };
+        var result = filter.Apply(evt);
+
+        Assert.True(result.PayloadTruncated);
+        Assert.True(Encoding.UTF8.GetByteCount(result.RequestSummary!) <= opts.DefaultCapBytes);
+    }
+
+    /// <summary>
+    /// IOptionsMonitor test double — returns the same snapshot on every read,
+    /// no change-token plumbing required for these tests. Mirrors the helper
+    /// used in <c>TruncationTests</c>, <c>FilterIntegrationTests</c>, etc.
+    /// </summary>
+    private sealed class StaticMonitor : IOptionsMonitor<AuditLogOptions>
+    {
+        private readonly AuditLogOptions _value;
+
+        public StaticMonitor(AuditLogOptions value) => _value = value;
+
+        public AuditLogOptions CurrentValue => _value;
+
+        public AuditLogOptions Get(string? name) => _value;
+
+        public IDisposable? OnChange(Action<AuditLogOptions, string?> listener) => null;
+    }
+}