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`