fix(vfx): classify hardwareless particle emitters once

docs/architecture/worldbuilder-inventory.md

@@ -207,6 +207,15 @@ anchors: `CPhysicsPart::GetMaxDegradeDistance` `0x0050D510`,
 `CPhysicsObj::ShouldDrawParticles` `0x0050FE60`, and
 `ParticleEmitter::UpdateParticles` `0x0051D180`.
 
+Hardwareless ParticleEmitterInfo records are also retained exactly. Retail
+`ParticleEmitter::SetInfo @ 0x0051CE90` returns false when
+`hw_gfxobj_id == INVALID_DID`; it does not substitute the software GfxObj.
+`EmitterDescRegistry` negative-caches that authored outcome and the hook sink
+reports it once per DAT ID rather than once per owner. This is classification
+and bounded diagnostics around the existing `DatCollection`, not a fallback
+reader or invented VFX. Evidence:
+`docs/research/2026-07-26-retail-hardwareless-particle-emitter-diagnostics.md`.
+
 **Retail shared world-alpha seam (2026-07-18).** WorldBuilder's editor
 renderers classify translucent mesh batches correctly, but they have no live
 retail `CPartCell`/`CShadowPart` list and render particles in a separate

docs/research/2026-07-26-retail-hardwareless-particle-emitter-diagnostics.md

@@ -0,0 +1,82 @@
+# Retail hardwareless particle-emitter resolution
+
+Date: 2026-07-26
+Oracle: matching Sept-2013 `acclient.exe` + `acclient.pdb`
+
+## Symptom
+
+Dense scenes repeatedly logged that ParticleEmitterInfo records such as
+`0x320002D6` and `0x320003B6`–`0x320003B9` were “not found” for many different
+owners. The records were present in the installed DAT, so the message was
+misleading and each owner repeated the same failed resolution work.
+
+## Named-retail behavior
+
+`ParticleEmitter::SetInfo @ 0x0051CE90` begins with:
+
+```text
+Destroy()
+info = suppliedInfo
+
+if info.hw_gfxobj_id == INVALID_DID:
+    Destroy()
+    return false
+
+particleObject = makeParticleObject(info.max_particles, info.sorting_sphere)
+...
+```
+
+`ParticleEmitter::SetInfo(DataID) @ 0x0051D3C0` first loads the
+ParticleEmitterInfo and delegates to the overload above.
+`ParticleManager::CreateParticleEmitter @ 0x0051B6C0` destroys the attempted
+emitter when either `SetInfo` or parenting fails. Retail does not substitute
+the software `gfxobj_id` for an absent hardware GfxObj.
+
+## Installed-DAT audit
+
+The production `DatCollection` and `EmitterDescRegistry` were exercised
+through `ProjectileVfxAudit --emitters`:
+
+| Emitter | Record | Software GfxObj | Hardware GfxObj | Retail outcome |
+|---|---|---:|---:|---|
+| `0x320002D6` | present/parsed | present | `0` | skip |
+| `0x320003B6` | present/parsed | present | `0` | skip |
+| `0x320003B7` | present/parsed | present | `0` | skip |
+| `0x320003B8` | present/parsed | present | `0` | skip |
+| `0x320003B9` | present/parsed | present | `0` | skip |
+
+These are authored hardwareless records, not missing DAT files.
+
+## Cross-reference
+
+- ACViewer `ParticleEmitter.SetInfo` returns false when `HWGfxObjID == 0`.
+  Its render initialization explicitly comments that this case is expected and
+  skips the absent emitter.
+- WorldBuilder contains no contradictory live-client hardware-emitter
+  fallback. Its particle code is an editor/rendering reference, while the
+  retail client remains the behavior oracle.
+
+## Runtime contract
+
+`EmitterDescRegistry` now stores either one resolved descriptor or one
+classified negative result per DAT ID:
+
+```text
+MissingEmitterInfo
+InvalidHardwareGfxObjId
+MissingHardwareGfxObj
+```
+
+The particle hook sink reports the first failure for each emitter DAT ID, not
+one line per owner. Hardwareless records say that retail skipped them rather
+than claiming the ParticleEmitterInfo was absent. No fallback asset or
+particle is fabricated.
+
+Registration of an explicit runtime descriptor clears a cached negative
+result, preserving test/tool injection and future hot-reload behavior.
+
+## Conformance coverage
+
+- `EmitterDescRegistry_NegativeCachesMissingDatAndRegisterClearsFailure`
+- `EmitterDescRegistry_ClassifiesAndCachesAuthoredHardwarelessEmitter`
+- `MissingEmitterAsset_ReportsOnlyOnceAcrossManyOwners`

src/AcDream.Core/Vfx/EmitterDescLoader.cs

@@ -13,6 +13,21 @@ using DatGfxObjFlags = DatReaderWriter.Enums.GfxObjFlags;
 
 namespace AcDream.Core.Vfx;
 
+public enum EmitterDescResolutionFailureKind
+{
+    None,
+    MissingEmitterInfo,
+    InvalidHardwareGfxObjId,
+    MissingHardwareGfxObj,
+}
+
+public readonly record struct EmitterDescResolutionFailure(
+    EmitterDescResolutionFailureKind Kind,
+    uint RelatedDatId = 0u)
+{
+    public static EmitterDescResolutionFailure None => default;
+}
+
 /// <summary>
 /// Resolves retail <c>ParticleEmitterInfo</c> dat records
 /// (<c>0x32xxxxxx</c>) into acdream runtime descriptors.
@@ -20,8 +35,11 @@ namespace AcDream.Core.Vfx;
 public sealed class EmitterDescRegistry
 {
     private readonly Func<uint, DatParticleEmitter?>? _resolver;
-    private readonly Func<DatParticleEmitter, float?>? _degradeDistanceResolver;
+    private readonly Func<DatParticleEmitter, EmitterDatResolution>?
+        _degradeDistanceResolver;
     private readonly ConcurrentDictionary<uint, EmitterDesc> _byId = new();
+    private readonly ConcurrentDictionary<uint, EmitterDescResolutionFailure>
+        _failures = new();
 
     public EmitterDescRegistry()
         : this((Func<uint, DatParticleEmitter?>?)null)
@@ -44,6 +62,7 @@ public sealed class EmitterDescRegistry
     {
         ArgumentNullException.ThrowIfNull(desc);
         _byId[desc.DatId] = desc;
+        _failures.TryRemove(desc.DatId, out _);
     }
 
     public EmitterDesc Get(uint emitterId)
@@ -55,35 +74,59 @@ public sealed class EmitterDescRegistry
     }
 
     public bool TryGet(uint emitterId, out EmitterDesc desc)
+        => TryGet(emitterId, out desc, out _);
+
+    public bool TryGet(
+        uint emitterId,
+        out EmitterDesc desc,
+        out EmitterDescResolutionFailure failure)
     {
         if (_byId.TryGetValue(emitterId, out desc!))
+        {
+            failure = EmitterDescResolutionFailure.None;
             return true;
+        }
+        if (_failures.TryGetValue(emitterId, out failure))
+        {
+            desc = null!;
+            return false;
+        }
+
         if (_resolver is not null)
         {
             var dat = _resolver(emitterId);
             if (dat is not null)
             {
-                float? resolvedDistance = _degradeDistanceResolver?.Invoke(dat);
-                if (_degradeDistanceResolver is not null && !resolvedDistance.HasValue)
+                EmitterDatResolution resolved = _degradeDistanceResolver?.Invoke(dat)
+                    ?? EmitterDatResolution.Success(
+                        RetailParticleDegradeDistance.DefaultDistance);
+                if (!resolved.Succeeded)
                 {
                     // ParticleEmitter::SetInfo (0x0051CE90) fails when the
                     // authored hardware GfxObj cannot be loaded. It never
                     // substitutes the software GfxObj.
+                    failure = resolved.Failure;
+                    _failures.TryAdd(emitterId, failure);
                     desc = null!;
                     return false;
                 }
-                float maxDegradeDistance = resolvedDistance
-                    ?? RetailParticleDegradeDistance.DefaultDistance;
-                desc = FromDat(emitterId, dat, maxDegradeDistance);
+                desc = FromDat(emitterId, dat, resolved.MaxDegradeDistance);
                 _byId[emitterId] = desc;
+                failure = EmitterDescResolutionFailure.None;
                 return true;
             }
         }
+
+        failure = new EmitterDescResolutionFailure(
+            EmitterDescResolutionFailureKind.MissingEmitterInfo,
+            emitterId);
+        _failures.TryAdd(emitterId, failure);
         desc = null!;
         return false;
     }
 
     public int Count => _byId.Count;
+    public int FailureCount => _failures.Count;
 
     public static EmitterDesc FromDat(
         uint emitterId,
@@ -155,25 +198,34 @@ public sealed class EmitterDescRegistry
         };
     }
 
-    private static float? ResolveMaxDegradeDistance(
+    private static EmitterDatResolution ResolveMaxDegradeDistance(
         IDatObjectSource dats,
         DatParticleEmitter emitter)
     {
         uint gfxObjId = GetRetailHardwareGfxObjId(emitter);
         if (gfxObjId == 0)
-            return null;
+        {
+            return EmitterDatResolution.Fail(
+                EmitterDescResolutionFailureKind.InvalidHardwareGfxObjId);
+        }
 
         DatGfxObj? gfx = SafeGet<DatGfxObj>(dats, gfxObjId);
         if (gfx is null)
-            return null;
+        {
+            return EmitterDatResolution.Fail(
+                EmitterDescResolutionFailureKind.MissingHardwareGfxObj,
+                gfxObjId);
+        }
         if (!gfx.Flags.HasFlag(DatGfxObjFlags.HasDIDDegrade)
             || gfx.DIDDegrade == 0)
         {
-            return RetailParticleDegradeDistance.DefaultDistance;
+            return EmitterDatResolution.Success(
+                RetailParticleDegradeDistance.DefaultDistance);
         }
 
         DatGfxObjDegradeInfo? degrade = SafeGet<DatGfxObjDegradeInfo>(dats, gfx.DIDDegrade);
-        return RetailParticleDegradeDistance.FromEntries(degrade?.Degrades);
+        return EmitterDatResolution.Success(
+            RetailParticleDegradeDistance.FromEntries(degrade?.Degrades));
     }
 
     internal static uint GetRetailHardwareGfxObjId(DatParticleEmitter emitter)
@@ -216,6 +268,26 @@ public sealed class EmitterDescRegistry
         DatParticleType.GlobalVelocity => ParticleType.GlobalVelocity,
         _ => ParticleType.Unknown,
     };
+
+    private readonly record struct EmitterDatResolution(
+        bool Succeeded,
+        float MaxDegradeDistance,
+        EmitterDescResolutionFailure Failure)
+    {
+        public static EmitterDatResolution Success(float maxDegradeDistance) =>
+            new(
+                true,
+                maxDegradeDistance,
+                EmitterDescResolutionFailure.None);
+
+        public static EmitterDatResolution Fail(
+            EmitterDescResolutionFailureKind kind,
+            uint relatedDatId = 0u) =>
+            new(
+                false,
+                0f,
+                new EmitterDescResolutionFailure(kind, relatedDatId));
+    }
 }
 
 /// <summary>

src/AcDream.Core/Vfx/ParticleHookSink.cs

@@ -40,6 +40,7 @@ public sealed class ParticleHookSink : IAnimationHookSink
     private readonly HashSet<uint> _examinationOwners = [];
     private readonly HashSet<uint> _hiddenPresentationOwners = [];
     private readonly HashSet<uint> _stoppingOwners = [];
+    private readonly HashSet<uint> _reportedEmitterResolutionFailures = [];
 
     // Production pose registries publish actual root/part/cell changes. Only
     // those owners are recomposed; static world emitters do no refresh work.
@@ -417,11 +418,16 @@ public sealed class ParticleHookSink : IAnimationHookSink
                 partIndex,
                 renderPass,
                 visibilityPolicy,
-                out int handle))
+                out int handle,
+                out EmitterDescResolutionFailure failure))
         {
-            DiagnosticSink?.Invoke(
-                $"ParticleEmitterInfo 0x{emitterInfoId:X8} for owner " +
-                $"0x{ownerLocalId:X8} was not found; no fallback was created.");
+            if (_reportedEmitterResolutionFailures.Add(emitterInfoId))
+            {
+                DiagnosticSink?.Invoke(FormatEmitterResolutionDiagnostic(
+                    emitterInfoId,
+                    ownerLocalId,
+                    failure));
+            }
             return;
         }
         _system.UpdateEmitterOwnerPosition(handle, ownerPosition);
@@ -534,6 +540,26 @@ public sealed class ParticleHookSink : IAnimationHookSink
         return true;
     }
 
+    private static string FormatEmitterResolutionDiagnostic(
+        uint emitterInfoId,
+        uint ownerLocalId,
+        EmitterDescResolutionFailure failure) =>
+        failure.Kind switch
+        {
+            EmitterDescResolutionFailureKind.InvalidHardwareGfxObjId =>
+                $"ParticleEmitterInfo 0x{emitterInfoId:X8} has no retail " +
+                $"hardware GfxObj; ParticleEmitter::SetInfo skipped it " +
+                $"(first owner 0x{ownerLocalId:X8}).",
+            EmitterDescResolutionFailureKind.MissingHardwareGfxObj =>
+                $"ParticleEmitterInfo 0x{emitterInfoId:X8} references missing " +
+                $"retail hardware GfxObj 0x{failure.RelatedDatId:X8}; " +
+                $"ParticleEmitter::SetInfo skipped it " +
+                $"(first owner 0x{ownerLocalId:X8}).",
+            _ =>
+                $"ParticleEmitterInfo 0x{emitterInfoId:X8} for owner " +
+                $"0x{ownerLocalId:X8} was not found; no fallback was created.",
+        };
+
     private readonly record struct EmitterBinding(
         uint OwnerLocalId,
         int PartIndex,

src/AcDream.Core/Vfx/ParticleSystem.cs

@@ -176,8 +176,29 @@ public sealed class ParticleSystem : IParticleSystem
         ParticleRenderPass renderPass,
         ParticleVisibilityPolicy visibilityPolicy,
         out int handle)
+        => TrySpawnEmitterById(
+            emitterId,
+            anchor,
+            rot,
+            attachedObjectId,
+            attachedPartIndex,
+            renderPass,
+            visibilityPolicy,
+            out handle,
+            out _);
+
+    public bool TrySpawnEmitterById(
+        uint emitterId,
+        Vector3 anchor,
+        Quaternion? rot,
+        uint attachedObjectId,
+        int attachedPartIndex,
+        ParticleRenderPass renderPass,
+        ParticleVisibilityPolicy visibilityPolicy,
+        out int handle,
+        out EmitterDescResolutionFailure failure)
     {
-        if (!_registry.TryGet(emitterId, out EmitterDesc? desc))
+        if (!_registry.TryGet(emitterId, out EmitterDesc? desc, out failure))
         {
             handle = 0;
             return false;
@@ -191,6 +212,7 @@ public sealed class ParticleSystem : IParticleSystem
             attachedPartIndex,
             renderPass,
             visibilityPolicy);
+        failure = EmitterDescResolutionFailure.None;
         return true;
     }
 

tests/AcDream.Core.Tests/Vfx/ParticleHookSinkTests.cs

@@ -264,6 +264,29 @@ public sealed class ParticleHookSinkTests
         Assert.Contains($"0x{Owner:X8}", diagnostic, StringComparison.Ordinal);
     }
 
+    [Fact]
+    public void MissingEmitterAsset_ReportsOnlyOnceAcrossManyOwners()
+    {
+        const uint missingId = 0x32DEAD00u;
+        const uint secondOwner = Owner + 1u;
+        var registry = new EmitterDescRegistry();
+        var system = new ParticleSystem(registry, new Random(42));
+        var poses = new MutablePoseSource();
+        poses.Publish(Owner, Matrix4x4.Identity, Matrix4x4.Identity);
+        poses.Publish(secondOwner, Matrix4x4.Identity, Matrix4x4.Identity);
+        var sink = new ParticleHookSink(system, poses);
+        var diagnostics = new List<string>();
+        sink.DiagnosticSink = diagnostics.Add;
+
+        sink.OnHook(Owner, Vector3.Zero, Create(missingId, logicalId: 0u));
+        sink.OnHook(secondOwner, Vector3.Zero, Create(missingId, logicalId: 0u));
+        sink.OnHook(Owner, Vector3.Zero, Create(missingId, logicalId: 0u));
+
+        Assert.Empty(system.EnumerateEmitters());
+        Assert.Single(diagnostics);
+        Assert.Contains($"0x{missingId:X8}", diagnostics[0], StringComparison.Ordinal);
+    }
+
     [Fact]
     public void MissingLivePose_HidesPresentationWithoutEndingEmitterLifetime()
     {

tests/AcDream.Core.Tests/Vfx/ParticleSystemTests.cs

@@ -1,6 +1,8 @@
 using System.Linq;
 using System.Numerics;
+using AcDream.Core.Content;
 using AcDream.Core.Vfx;
+using DatReaderWriter.Lib.IO;
 using DatReaderWriter.Types;
 using Xunit;
 
@@ -267,6 +269,35 @@ public sealed class ParticleSystemTests
         Assert.Same(desc, reg.Get(0x32001234u));
     }
 
+    [Fact]
+    public void EmitterDescRegistry_NegativeCachesMissingDatAndRegisterClearsFailure()
+    {
+        int calls = 0;
+        var reg = new EmitterDescRegistry(_ =>
+        {
+            calls++;
+            return null;
+        });
+        const uint emitterId = 0x3200DEADu;
+
+        Assert.False(reg.TryGet(emitterId, out _, out var first));
+        Assert.False(reg.TryGet(emitterId, out _, out var second));
+
+        Assert.Equal(1, calls);
+        Assert.Equal(
+            EmitterDescResolutionFailureKind.MissingEmitterInfo,
+            first.Kind);
+        Assert.Equal(first, second);
+        Assert.Equal(1, reg.FailureCount);
+
+        var desc = new EmitterDesc { DatId = emitterId };
+        reg.Register(desc);
+        Assert.True(reg.TryGet(emitterId, out var resolved, out var failure));
+        Assert.Same(desc, resolved);
+        Assert.Equal(EmitterDescResolutionFailureKind.None, failure.Kind);
+        Assert.Equal(0, reg.FailureCount);
+    }
+
     [Fact]
     public void LocalVelocity_TransformsABySpawnRotation()
     {
@@ -398,6 +429,31 @@ public sealed class ParticleSystemTests
         Assert.Equal(0u, EmitterDescRegistry.GetRetailHardwareGfxObjId(dat));
     }
 
+    [Fact]
+    public void EmitterDescRegistry_ClassifiesAndCachesAuthoredHardwarelessEmitter()
+    {
+        const uint emitterId = 0x320002D6u;
+        var dats = new FakeDatObjectSource();
+        dats.Add(
+            emitterId,
+            new DatReaderWriter.DBObjs.ParticleEmitter
+            {
+                GfxObjId = 0x010016C9u,
+                HwGfxObjId = 0u,
+            });
+        var reg = new EmitterDescRegistry(dats);
+
+        Assert.False(reg.TryGet(emitterId, out _, out var first));
+        Assert.False(reg.TryGet(emitterId, out _, out var second));
+
+        Assert.Equal(
+            EmitterDescResolutionFailureKind.InvalidHardwareGfxObjId,
+            first.Kind);
+        Assert.Equal(first, second);
+        Assert.Equal(1, dats.GetCallCount(emitterId));
+        Assert.Equal(1, reg.FailureCount);
+    }
+
     [Fact]
     public void RetailParticleDegradeDistance_MatchesRetailEntrySelection()
     {
@@ -1100,4 +1156,31 @@ public sealed class ParticleSystemTests
         sys.Tick(0.01f);
         Assert.Equal(2, sys.ActiveParticleCount);
     }
+
+    private sealed class FakeDatObjectSource : IDatObjectSource
+    {
+        private readonly Dictionary<uint, IDBObj> _objects = new();
+        private readonly Dictionary<uint, int> _calls = new();
+
+        public void Add(uint id, IDBObj value) => _objects[id] = value;
+
+        public int GetCallCount(uint id) =>
+            _calls.TryGetValue(id, out int count) ? count : 0;
+
+        public T Get<T>(uint fileId) where T : IDBObj
+        {
+            _calls.TryGetValue(fileId, out int count);
+            _calls[fileId] = count + 1;
+            return _objects.TryGetValue(fileId, out IDBObj? value)
+                && value is T typed
+                    ? typed
+                    : default!;
+        }
+
+        public bool TryGet<T>(uint fileId, out T value) where T : IDBObj
+        {
+            value = Get<T>(fileId);
+            return value is not null;
+        }
+    }
 }

tools/ProjectileVfxAudit/Program.cs

@@ -11,18 +11,57 @@ using DatReaderWriter.Lib.IO;
 using DatReaderWriter.Options;
 using DatReaderWriter.Types;
 using DatAnimation = DatReaderWriter.DBObjs.Animation;
+using DatParticleEmitter = DatReaderWriter.DBObjs.ParticleEmitter;
 using DatPhysicsScript = DatReaderWriter.DBObjs.PhysicsScript;
 
 string datDir = System.Environment.GetEnvironmentVariable("ACDREAM_DAT_DIR")
     ?? @"C:\Turbine\Asheron's Call";
 
 using var dats = new DatCollection(datDir, DatAccessType.Read);
-var physicsScripts = new RetailPhysicsScriptLoader(dats);
-var animations = new RetailAnimationLoader(dats);
+using var boundedDats = new AcDream.Content.DatCollectionAdapter(dats);
+var physicsScripts = new RetailPhysicsScriptLoader(boundedDats);
+var animations = new RetailAnimationLoader(boundedDats);
 Console.WriteLine($"DAT metadata audit: {datDir}");
 var failures = new List<string>();
 var representativePes = new HashSet<uint>();
 
+if (args.Contains("--emitters", StringComparer.OrdinalIgnoreCase))
+{
+    uint[] emitterIds =
+    [
+        0x320002D6u,
+        0x320003B6u,
+        0x320003B7u,
+        0x320003B8u,
+        0x320003B9u,
+    ];
+    var registry = new EmitterDescRegistry(boundedDats);
+    foreach (uint emitterId in emitterIds)
+    {
+        bool hasRaw = dats.Portal.Tree.TryGetFile(emitterId, out _);
+        DatParticleEmitter? emitter = SafeGet<DatParticleEmitter>(emitterId);
+        uint softwareGfxObjId = emitter?.GfxObjId.DataId ?? 0u;
+        uint hardwareGfxObjId = emitter?.HwGfxObjId.DataId ?? 0u;
+        bool hasSoftwareGfx = softwareGfxObjId != 0u
+            && SafeGet<GfxObj>(softwareGfxObjId) is not null;
+        bool hasHardwareGfx = hardwareGfxObjId != 0u
+            && SafeGet<GfxObj>(hardwareGfxObjId) is not null;
+        bool resolved = registry.TryGet(
+            emitterId,
+            out EmitterDesc? descriptor,
+            out EmitterDescResolutionFailure failure);
+        Console.WriteLine(
+            $"0x{emitterId:X8}: raw={hasRaw}, parsed={emitter is not null}, " +
+            $"gfx=0x{softwareGfxObjId:X8}, gfxParsed={hasSoftwareGfx}, " +
+            $"hwGfx=0x{hardwareGfxObjId:X8}, hwParsed={hasHardwareGfx}, " +
+            $"registry={resolved}, maxDist={descriptor?.MaxDegradeDistance:R}, " +
+            $"failure={failure.Kind}, related=0x{failure.RelatedDatId:X8}, " +
+            $"type={emitter?.EmitterType}/{emitter?.ParticleType}, " +
+            $"initial={emitter?.InitialParticles}, max={emitter?.MaxParticles}");
+    }
+    return;
+}
+
 var expectedSetups = new Dictionary<uint, (Vector3 Origin, float Radius, int Length, string Sha256)>
 {
     [0x02000124u] = (Vector3.Zero, 0.1f, 812, "630D19A9C79137F7BA90D01448B03E8F44D655FF77A4725792CB5660930A079E"),