acdream/docs/architecture/retail-divergence-register.md

# Retail Divergence Register — 2026-06-12

**What this is.** The single auditable register of every known place acdream's
runtime behavior can deviate from the retail client (Sept 2013 EoR build,
`docs/research/named-retail/`). It was triggered by a week of "small things"
surfacing one at a time through playtesting — a ±5 m culling-box promise
(#119), an epsilon eye-clip + rescue (knife-edge port), a half-ported cell
walk — each of which was a *known* deviation that lived only in a code
comment until it produced a visible symptom.

**The rule.** Every intentional deviation from retail behavior gets a row in
this register. A deviation discovered without a row here is a bug twice over:
once for the behavior, once for the missing row. When you add a deviation
(new adaptation, new stopgap, new approximation), add the row in the same
commit. When you retire one (port the retail mechanism), delete the row in
the same commit.

**The review trigger.** Any unexplained visual or physics symptom → scan this
register FIRST, before instrumenting. Filter by the subsystem you're staring
at; each row's "Risk if assumption breaks" column is written as the symptom
you would observe. Most of the historical multi-session sagas (#119 vanishing
staircase, #98 cellar ascent, the doorway FLAP) began as a deviation in
exactly this register's scope.

**Kinds.**
- **Intentional architecture** — deliberate design choices we stand behind; retiring them would be a redesign, not a fix.
- **Adaptation** — required by a real structural difference (async streaming vs synchronous load, ACE vs retail server semantics, GL vs D3D). Correct *given the difference*; each carries an equivalence argument.
- **Documented approximation** — we know retail's mechanism and chose a cheaper/safer stand-in with a recorded justification.
- **Temporary stopgap** — known-incomplete; explicitly awaiting a port/phase. These are scheduled debt.
- **Unclear** — the recorded justification is missing, contradictory, or never argued. These are the most dangerous rows and head the retire list.

Dedup convention: one divergence = one row at its primary site; secondary
sites listed in parentheses. Issue numbers in **bold** are the symptom
history. Sources: 5-area code sweep 2026-06-12 +
`docs/architecture/worldbuilder-inventory.md` + `docs/ISSUES.md`
accepted-divergence entries (#96, #49, #50).

---

## 1. Intentional architecture (IA) — 17 rows

| # | Divergence | Where (file:line) | Why it is safe / justified | Risk if assumption breaks | Retail oracle |
|---|---|---|---|---|---|
| IA-1 | Contact-plane pre-seed on grounded movers (**#96 ACCEPTED** per ISSUES.md) — retail's `CTransition::init` clears `contact_plane_valid`; we seed from the body's previous-frame plane | `src/AcDream.Core/Physics/PhysicsEngine.cs:919` | Removing it broke last-step stair `step_up` (`892019b`, reverted); seed propagates the body's *real current* plane, behavior matched retail in the A6.P3 gates | A stale pre-seeded plane lets `AdjustOffset` project sub-step 1 onto a plane retail wouldn't have yet — wrong slope motion / step-up acceptance right after leaving a surface | `CTransition::init`, pc:272547 family |
| IA-2 | Lateral self-heal beyond retail's keep-curr: when no candidate contains the sphere, try `FindVisibleChildCell` over the claim's stab-list before keeping the claim | `src/AcDream.Core/Physics/CellTransit.cs:912` | Reuses the recovery retail's own `AdjustPosition` performs (:280028 stab-list mode), applied at the `find_cell_list` site to heal near-miss claims without a doorway crossing | In containment-gap geometry, membership flips to a neighbouring room where retail keeps curr — wrong render root / collision cell at gap positions | `find_cell_list` keep-curr pc:308788-308825; `find_visible_child_cell` :311444 |
| IA-3 | `get_state_velocity` prefers dat cycle velocity (`MotionData.Velocity × speedMod`) over the decompiled constant; constant kept only as max-speed clamp | `src/AcDream.Core/Physics/MotionInterpreter.cs:315` | Retail's constant equals the Humanoid RunForward `MotionData.Velocity`, so both paths agree on retail dats; dat is ground truth for other MotionTables (r03 §1.3) | Where dat velocity ≠ constant, body speed differs from the retail binary — DR / observer drift on exotic creatures or modded dats | `FUN_00528960`; `_DAT_007c96e0` RunAnimSpeed |
| IA-4 | `MultiplyFramerate` omits retail's negative-factor StartFrame↔EndFrame swap (direction encoded in Framerate sign instead) | `src/AcDream.Core/Physics/AnimationSequencer.cs:129` | Our callers (ForwardSpeed updates) only pass positive factors; Advance loop handles negative framerates against StartFrame as lower bound | A future negative-factor caller (reverse playback) scales without swapping bounds — wrong frame range traversal instead of clean reversal | `FUN_005267E0`; ACE Sequence.cs L277-287 |
| IA-5 | Per-ENTITY vertex-derived AABB culling (+5 m animated-drift margin; animated entities bypass cull) vs retail per-PART dat drawing spheres | `src/AcDream.App/Rendering/Wb/WbDrawDispatcher.cs:693` (bounds at `src/AcDream.Core/World/WorldEntity.cs:153`, `src/AcDream.Core/Meshing/GfxObjBounds.cs:14`; dead `PerEntityCullRadius=5.0f` at dispatcher :210) | Batched MDI rendering can't cheaply cull per part; bounds derive from the SAME dat vertex data that gets drawn (containment by construction — the **#119** fix, `6a9b529`; memory: feedback_culling_bounds_from_drawn_data) | Geometry escaping bounds+margin (pose drift >5 m, a hydration path skipping `SetLocalBounds`) makes the whole entity vanish on-screen — the #119 vanishing-staircase class | `CGfxObj.drawing_sphere` / viewconeCheck 0x005a09a4 |
| IA-6 | Chat scrollback 500 lines vs retail ~200 (configurable) | `src/AcDream.Core/Chat/ChatLog.cs:19` | Strictly more useful for a dev client + plugins; deliberate default | Negligible — only if a plugin/UI behavior is ever specified against retail's exact retention cap | retail chat scrollback (~200) |
| IA-7 | PhysicsScript replay keyed by (scriptId, entityId) replaces the prior instance; retail's ScriptManager linked list could hold duplicates | `src/AcDream.Core/Vfx/PhysicsScriptRunner.cs:51` | Prevents duplicate-stacking on server retriggers; flat keyed list simpler than retail's linked schedule; hedged to retail's common path | A server intentionally layering the same script on the same object shows ONE effect where retail shows several (overlapping casts/impacts) | `ScriptManager::Start` FUN_0051be40 / tick FUN_0051bfb0 |
| IA-8 | Synthetic outdoor cell node as render root (outdoor-as-cell, Option A): one unified `DrawInside` path; retail roots at a real CLandCell with a separate outdoor pipeline | `src/AcDream.App/Rendering/OutdoorCellNode.cs:23` | Eliminating the inside/outside render branch kills the indoor FLAP by construction (2026-06-07 cutover); R-A2 restored retail's per-building flood topology | Any consumer assuming the root is a real cell mis-handles the synthetic node — historically the 2↔6 flood-depth oscillation and doorway-flap class | `SmartBox::RenderNormalMode` → DrawInside, decomp:92635; `LScape::draw` 0x00506330; ConstructView(CBldPortal) decomp:433827 |
| IA-9 | One unified camera matrix for terrain — retail's separate `LScape::update_viewpoint` landscape viewpoint does not exist | `src/AcDream.App/Rendering/TerrainModernRenderer.cs:266` | Phase W T4.2: with one matrix everywhere, viewpoint-desync bugs are unrepresentable — the unification IS the correctness argument | Anything retail derives from the landcell-relative viewpoint (float precision at extreme coords, viewpoint-keyed state) has no analogue; a future port expecting it silently reads the camera | `LScape::update_viewpoint`; `LScape::draw` 0x00506330 |
| IA-10 | Transparent groups sorted back-to-front per GROUP by first-instance position (no within-group sort) vs retail per-poly BSP-order draw | `src/AcDream.App/Rendering/Wb/WbDrawDispatcher.cs:1364` (comparer :1662) | One MDI call per pass requires group-granularity ordering; per-poly sorting is incompatible with instanced multi-draw; works when group instances are spatially coherent | Spatially spread or interleaved transparent groups composite in the wrong order — popping / wrong see-through layering as the camera moves | retail per-poly BSP-order transparent draw (D3DPolyRender / PView::DrawCells) |
| IA-11 | Tier-1 cross-frame batch-classification cache for static entities (retail re-walks part arrays every frame) | `src/AcDream.App/Rendering/Wb/EntityClassificationCache.cs:12` | Issue #53 perf tier; invariants documented (keys = EntityId + OWNING-landblock hint post-**#119** fix `2163308`; invalidation at despawn/LB-unload; mutation audit 2026-05-10) | Key collision or missed invalidation serves one entity another's batches — session-sticky wrong meshes (the #119 broken-stairs/water-barrel symptom) | retail per-frame part-array classification (no cache) |
| IA-12 | UI toolkit mirrors retail behavior from research docs, not a byte-port — keystone.dll is outside decomp coverage; observed constants embedded (drag 3 px, tooltip 1000 ms) | `src/AcDream.App/UI/README.md:3` | keystone.dll has no PDB/decomp; semantics reconstructed from the six `docs/research/retail-ui/` deep-dives, keeping retail's event-type constants so panel switch-cases transplant cleanly | Edge-case input semantics the research under-specified (drag threshold, tooltip timing, focus hand-off, capture corners) differ silently with no oracle to diff against | keystone.dll Device DAT_00837ff4; docs/research/retail-ui/04-input-events.md |
| IA-13 | GameEventType registry deliberately omits event types retail ignores; unknown events fall through unhandled | `src/AcDream.Core.Net/Messages/GameEventType.cs:11` | Retail also ignores them — dropping matches retail by construction | If the "retail ignores X" judgment is wrong for any opcode (or a server mod uses one), the event is silently dropped with no diagnostic pointing at the omission | retail GameEvent dispatch (ignored-event set) |
| IA-14 | Rendering + dat-handling base is WorldBuilder's tested port, not a fresh retail-decomp port (Phase N.4/O design stance) | `docs/architecture/worldbuilder-inventory.md` (code at `src/AcDream.{Core,App}/Rendering/Wb/`) | WB visually verified on the AC world, MIT, same stack; known WB↔retail deltas resolved case-by-case — terrain split kept retail `FSplitNESW` (**#51**, pinned by `SplitFormulaDivergenceTest`), scenery drift accepted (AP-31) | A WB-upstream divergence not yet caught ships silently as "our" behavior; guard = the inventory doc's 🟢/🔴 split + per-formula divergence tests | retail decomp per algorithm; `tests/.../SplitFormulaDivergenceTest.cs` |
| IA-15 | D.2b retail UI is our own UiHost/UiElement retained-mode tree drawing dat-sprite window frames, not a byte-port of keystone.dll's LayoutDesc binary tree. Both the vitals window (`LayoutDesc 0x2100006C`) and the chat window (`LayoutDesc 0x21000006`) are rendered by the LayoutDesc importer; `UiNineSlicePanel`/`RetailChromeSprites` now back only plugin panels | `src/AcDream.App/UI/Layout/LayoutImporter.cs` (vitals + chat) + `src/AcDream.App/UI/Layout/ChatWindowController.cs` | keystone.dll has no PDB/decomp so a byte-port is impossible by definition; we mirror retail's ElementDesc field model + controls.ini tokens, and the chrome sprites ARE the real dat RenderSurfaces (Step-0 prove-out 2026-06-14 confirmed 0x06004CC2 center + 0x060074BF..C6 bevel). The 8-piece edge/corner→position mapping is DATA-DRIVEN from the dat: the `LayoutImporter` reads `LayoutDesc 0x2100006C`/`0x21000006` and resolves chrome element positions + sprite ids directly from parsed dat fields; vitals locked by the conformance fixture `tests/AcDream.App.Tests/UI/Layout/fixtures/vitals_2100006C.json` | Remaining residual risk: anchor resolution at non-800×600 and the controls.ini cascade still lack an oracle — layout scaling at non-reference resolution and stylesheet token inheritance differ silently | `LayoutDesc 0x2100006C`/`0x21000006` (SHIPPED); `docs/research/2026-06-15-layoutdesc-format.md`; controls.ini tokens; keystone.dll layout eval (no PDB) |
| IA-17 | Toolbar window FRAME is toolkit-supplied (per-window UiNineSlicePanel 8-piece bevel, drawn over content via UiElement.OnDrawAfterChildren) rather than the window-manager-owned chrome retail paints uniformly around every window | `src/AcDream.App/Rendering/GameWindow.cs` (toolbar mount) + `src/AcDream.App/UI/UiNineSlicePanel.cs` | LayoutDesc 0x21000016 has NO baked frame; retail's toolbar frame is window-manager chrome (keystone.dll). We draw the same reusable 8-piece bevel chat/vitals use; border drawn over content so the toolbar's 2px-wide row-2 right cap (W=8) can't poke through. Same pattern as the chat window. | Until a central window manager owns chrome uniformly, per-window wraps can drift (size/offset/z-order) from each other and from retail; the border-over-content rule is the toolkit's, not the WM's | gmToolbarUI WM chrome (keystone.dll, no PDB); no bevel ids in LayoutDesc 0x21000016 (toolbar dump) |
| IA-18 | Effect overlay tile (enum 0x10000005) is a `ReplaceColor` SURFACE SOURCE — pure-white pixels in the composited drag icon are replaced PER-PIXEL with the same (x,y) pixel of the effect tile (the SURFACE overload `SurfaceWindow::ReplaceColor` 0x004415b0), preserving the tile's texture/gradient; the tile itself is NOT blitted as an additional layer. This IS faithful retail behavior. **Anti-regression: do NOT re-implement this as a blit layer NOR as a flat-color replace (it is a per-pixel surface copy).** | `src/AcDream.App/UI/IconComposer.cs` (`ReplaceWhiteFromSurface`) | Faithful port of `IconData::RenderIcons` @407614 → the SURFACE overload `ReplaceColor` 0x004415b0 (`dst[x,y]=src[x,y]` where `dst==white`); confirmed via clean Ghidra decompile + named decomp + visual (the Energy Crystal's blue is a gradient, 2026-06-17). | A blit-layer or flat-color re-implementation would show the wrong effect look (no gradient) — the visual-verification regression that retired the mean-color approximation | `IconData::RenderIcons` acclient_2013_pseudo_c.txt:407524; `ReplaceColor` SURFACE overload 0x004415b0:71656; `docs/research/2026-06-17-stateful-icon-RESOLVED.md` |

---

## 2. Adaptation (AD) — 28 rows

| # | Divergence | Where (file:line) | Why it is safe / justified | Risk if assumption breaks | Retail oracle |
|---|---|---|---|---|---|
| AD-1 | Lost-cell machinery replaced by recoverable outdoor demote (**#107** safety net) + outdoor-restore `max(terrainZ, z)` under-terrain lift; retail goes `GotoLostCell` | `src/AcDream.Core/Physics/PhysicsEngine.cs:553` (+ :808) | acdream has no lost-cell state machine; outdoor landcell is the recoverable equivalent; the #107 auto-entry hold should make the demote branch unreachable | Gap in the hold → player committed to outdoor terrain inside/under a building (fake-grounded spawn, fall-through); a legit below-heightmap server restore is silently lifted — upward warp vs server | `GotoLostCell` pc:283418; `SetPositionInternal` 0x00515bd0, pc:283892-283945 |
| AD-2 | Async spawn gates replacing retail's synchronous cell load. **#135 refinement:** an INDOOR spawn/teleport (cell ≥ 0x0100, hydratable) gates ONLY on the EnvCell floor (`IsSpawnCellReady`), NOT the terrain heightmap; an OUTDOOR spawn (or an unhydratable indoor claim that demotes outdoor) gates on the terrain-ready hold (**#106**). A dungeon's negative-offset cells can place the spawn's WORLD position in a neighbour terrain landblock the #135 dungeon collapse doesn't load, so a terrain requirement would hang indoor login/teleport forever (cellReady true, terrain null) — the player lands on the cell floor, terrain is irrelevant indoors. Claims beyond NumCells skip the gate (demoted) | `src/AcDream.App/Rendering/GameWindow.cs` (`isSpawnGroundReady` lambda ~1010 + `TeleportArrivalReadiness` ~5012) (+ `src/AcDream.App/Input/PlayerModeAutoEntry.cs:69`, `src/AcDream.Core/Physics/PhysicsEngine.cs:468`) | Entering earlier integrates gravity against an empty world (free-fall into void); the gate is the async-streaming equivalent of retail's blocking load; a looser "any struct present" version reproduced the transparent-interior wedge. Indoor-on-cellReady is the faithful equivalent of retail's synchronous cell load + place-on-floor (terrain under a dungeon is meaningless; the pre-#135 terrain hold only passed because the 25×25 window streamed the neighbour terrain) | Gate opens early → raw claim commit → outdoor demote mid-building; predicate never satisfied (streamer stall, dat edge case) → login wedges in pre-player mode; an indoor spawn whose cell never hydrates now holds on cellReady alone (no terrain backstop) — but that path is exactly the #107 hold | retail synchronous cell load before SetPosition (no gate exists) |
| AD-3 | Outdoor seeds always walk the transit array (retail skips the walk when the seed CLandCell is null/unloaded); per-cell lookups no-op on unhydrated data | `src/AcDream.Core/Physics/CellTransit.cs:503` | Equivalence argument: with nothing hydrated every lookup inside the walk no-ops, so the result matches retail's skipped walk | Near partially-streamed landblocks, building-transit promotion silently can't fire until structs hydrate — membership stays outdoor while the player is inside a building | `CObjCell::find_cell_list` 0052b535-0052b56c (null-CLandCell case) |
| AD-4 | `point_in_cell` against an unhydrated CellBSP returns false (skip) rather than the null-node "inside" default; retail never queries unloaded cells | `src/AcDream.Core/Physics/CellTransit.cs:588` | The null-node default would make an unhydrated cell spuriously claim every point; skipping is the conservative streaming-safe choice | During hydration, a point genuinely inside a not-yet-loaded cell resolves outdoor/stale — transient membership misclassification driving wrong collision set and render root | `CEnvCell::find_visible_child_cell` :311397; cell-BSP vtable[0x84] |
| AD-5 | Outdoor `point_in_cell` is an identity compare against the global XY-column cell from `LandDefs.AdjustToOutside` (no per-cell containment test) | `src/AcDream.Core/Physics/CellTransit.cs:865` | Landcells are disjoint 24 m columns — identity-compare against the column under the sphere centre is exactly equivalent to retail's per-candidate test | If block-origin/lcoord math is wrong at a landblock seam, the compare silently never matches — outdoor membership freezes at boundaries (the pre-#106 symptom) | `find_cell_list` pick pc:308788-308825; `CLandCell::point_in_cell` (get_block_offset pc:308804) |
| AD-6 | Per-LANDBLOCK shadow re-flood on hydration vs retail per-CELL `recalc_cross_cells` | `src/AcDream.Core/Physics/ShadowObjectRegistry.cs:339` | The streaming unit IS the landblock; one hook per hydration event covers both race directions (entity-before-cells, cells-after-spawn) | Any cell-hydration path that doesn't raise the landblock hook leaves an entity's shadow set stale — walk-through / missing collisions in just-streamed cells | `CObjCell::init_objects` → `recalc_cross_cells`, 0x0052b420 / 0x00515a30 |
| AD-7 | Full collision exemption on ETHEREAL alone; retail requires ETHEREAL_PS **and** IGNORE_COLLISIONS_PS (ETHEREAL-alone takes the unported `obstruction_ethereal` path) | `src/AcDream.Core/Physics/CollisionExemption.cs:78` | ACE's `Door.Open()` broadcasts ETHEREAL only (0x0001000C); without the shortcut, opened doors stay solid on ACE | ETHEREAL-only targets generate NO contact where retail records contact-but-allows-passage; against a retail-semantics server the bit means something different than we implement | pc:276782 (combined gate), :276795 (obstruction_ethereal) |
| AD-8 | MoveTo arrival gate `max(minDistance, distanceToObject)`; retail tests `dist <= min_distance` only | `src/AcDream.Core/Physics/RemoteMoveToDriver.cs:161` | ACE ships the threshold in `distance_to_object` with `min_distance == 0`; without the max, monsters never "arrive" and oscillate at melee range (user-reported 2026-04-28) | A server using both wire fields with retail semantics + large `distance_to_object` makes remotes stop short of the retail arrival point | `MoveToManager::HandleMoveToPosition` chase-arrival |
| AD-9 | 1.5 s stale-destination give-up timer on remote MoveTo (retail's MoveToManager runs until cancelled) | `src/AcDream.Core/Physics/RemoteMoveToDriver.cs:136` | Liveness guard sized to ACE's ~1 Hz re-emit cadence; prevents steering toward a stale destination after a missed cancel (the run-in-place symptom) | A server emitting MoveTo slower than ~1.5 s makes remotes freeze mid-chase and snap later instead of steering continuously | MoveToManager (no equivalent timeout) |
| AD-10 | Remote slope projection relocated to the queue-empty/head-reached combiner boundary; retail projects inside `CTransition::adjust_offset` during the sweep | `src/AcDream.Core/Physics/PositionManager.cs:47` | Remote bodies don't run a full local transition sweep; boundary projection removes the ~5 Hz Z staircase on slopes, no-op on flat ground | The single-point terrain-normal sample can differ from the sweep's contact plane (cell boundaries, props underfoot) — remote Z drift / stair-stepping | `CTransition::adjust_offset` pc:272296-272346 |
| AD-11 | Useability fallback: retail blocks Use entirely on null/zero useability; we allow it (behavioral fallback in the `IsUseableTarget` caller; justification recorded here) | `src/AcDream.Core/Physics/PhysicsDiagnostics.cs:163` | ACE's seed DB ships many weenies with `_useability` unset; without the fallback doors/lifestones/creatures are un-Useable on ACE | Objects a retail-faithful server intentionally marks non-useable become useable in acdream — wrong interaction gating when the ACE-ships-null assumption stops holding | `ItemHolder::UseObject` pc:402923 |
| AD-12 | SecondaryAttributeTable coefficients hardcoded (Health=End×0.5, Stam=End×1.0, Mana=Self×1.0) instead of dat-read; unknown attributes contribute 0 | `src/AcDream.Core/Player/LocalPlayerState.cs:279` | Coefficients never vary across retail dat versions; re-confirmed by ACE AttributeFormula.cs + holtburger; dat port can replace later | A customized portal.dat with modified vital formulas silently yields wrong max-vitals; a missing attribute snapshot underestimates max | SecondaryAttributeTable portal.dat 0x0E0..0x0E2; `CreatureVital::GetMaxValue` 0x0058F2DD |
| AD-13 | 1-second dedup window for identical system chat messages (retail has none) | `src/AcDream.Core/Chat/ChatLog.cs:29` | ACE dual-sends the same system text (0xF7E0 + 0x02EB) for back-compat; without dedup every line doubled (Phase J compromise) | Two genuinely distinct but textually identical system messages within 1 s collapse to one line where retail shows both | ACE dual-send 0xF7E0 + 0x02EB |
| AD-14 | Script anchor world position cached at `Play()` time; retail fires hooks via vtable dispatch on the live owning PhysicsObj | `src/AcDream.Core/Vfx/PhysicsScriptRunner.cs:55` | Core's runner is decoupled from the entity graph; documented contract pushes per-frame anchor refresh to the owning subsystem (done for AttachLocal) | Any caller that forgets the per-frame refresh strands long-running effects at the spawn position while the entity walks away | FUN_0051bfb0 per-frame hook dispatch on owner |
| AD-15 | `IsEnv` masks low-16 of the cell id (`(Id & 0xFFFF) >= 0x100`) where retail tests the full id | `src/AcDream.Core/World/Cells/ObjCell.cs:25` | Every real prefixed EnvCell id has low-16 ≥ 0x100 and every outdoor cell ≤ 0x40 — identical answers for all real dat ids, works for both bare and prefixed forms | None for real dat data; a hypothetical convention-violating id would route to the wrong (BSP vs terrain) point-in-cell logic | `CObjCell::GetVisible` pc:308215 |
| AD-16 | Building-flood gate is a CPU frustum test on each building's `PortalBounds` AABB; retail floods exactly when the shell draws and an aperture survives (no bounds constant anywhere) | `src/AcDream.App/Rendering/GameWindow.cs:7634` | Documented as the tight equivalent of the shell viewconeCheck for flood purposes (the FPS fix the Chebyshev≤1 hack approximated); per-portal admission still goes through BuildFromExterior's screen clip; missing-bounds buildings always flood (safe over-include) | A too-small/stale PortalBounds AABB means the interior never floods — doorway shows a hole/black aperture from outside (inverse of the vanishing-staircase class) | `DrawBuilding` 0x0059f2a0; `BSPPORTAL::portal_draw_portals_only` 0x53d870 |
| AD-17 | ≤8 GPU `gl_ClipDistance` half-planes per view region, degrading to a union-AABB scissor (over-include) on multi-polygon / >8-edge views; particles always scissor; scissor slices disable per-object viewcone culling. Retail CPU-clips against the exact portal polygon | `src/AcDream.App/Rendering/ClipPlaneSet.cs:23` | GL guarantees only 8 simultaneous clip planes; invariant documented: over-inclusion is safe, under-inclusion is the bug class | Fallback on complex multi-aperture views draws terrain/sky/particles/objects outside the true aperture but inside its AABB — background/interior bleed strips at doorways (the **#130** family) | `ACRender::polyClipFinish` decomp:702749; PView portal_view slices |
| AD-18 | Aperture far-Z punch is two-pass stencil-gated with an invented mark bias: 0.0005 NDC capped to a 0.5 m EYE-SPACE span (`MarkBiasNdc`); retail's single DEPTHTEST_ALWAYS punch is safe only under painter's far→near order we don't have | `src/AcDream.App/Rendering/PortalDepthMaskRenderer.cs:149` | **#117** (2026-06-11): the unconditional punch erased nearer occluders, painting interiors through them; the two-pass form is the z-buffered equivalent of retail's ordering safety. **#129** (2026-06-12): the constant-NDC bias spanned ~190 m of eye depth at a landblock (non-linear depth) → distant occluders punched; the eye-space cap bounds the reach (`Issue129PunchBiasTests`). DO-NOT-RETRY: punch must stay depth-gated (ISSUES #108) | Door-plane-hugging geometry beyond the 0.5 m cap re-occludes the aperture (a **#108**-class regression at >10 m viewing range); an occluder within the cap in front of a distant aperture still punches through | `D3DPolyRender::DrawPortalPolyInternal` 0x0059bc90 (maxZ1=7 / maxZ2=6) |
| AD-19 | Under outdoor roots, ALL dynamics draw in one z-buffered final pass; retail draws objects painter-ordered per landcell inside the landscape pass (interior roots route per **#118**) | `src/AcDream.App/Rendering/RetailPViewRenderer.cs:126` | The dynamics-drawn-LAST invariant is what makes the aperture depth punch safe (first BR-2 attempt punched after dynamics and erased the player, reverted `88be519`); z-buffer substitutes for painter's order on opaque geometry | Punch/seal correctness hinges on an ordering invariant — any pass added after DrawDynamicsLast, or alpha content needing painter order, gets erased inside apertures or composites wrong | `LScape::draw` → `DrawBlock` 0x005a17c0 → DrawSortCell pc:430124; `PView::DrawCells` 0x005a4840 |
| AD-20 | Camera sweep fallback seeds the eye's `AdjustPosition` from the PLAYER's cell; retail re-seats at the sought eye's own tracked cell (rest of function is a verbatim `update_viewer` port) | `src/AcDream.App/Rendering/PhysicsCameraCollisionProbe.cs:97` | acdream's camera doesn't track the sought-eye's cell separately; the eye is near the player so the player-cell stab list is assumed to cover it | An eye outside the player cell's stab-list coverage (boundary corners, cross-landblock pull-back) seats in the wrong cell — and the viewer cell roots the whole render: one-frame wrong root (flap-class flash) | `SmartBox::update_viewer` 0x00453ce0, pc:92878-92883 |
| AD-21 | Null-clipRoot legacy outdoor safety path (no portal visibility, no punches/seals, no-clip terrain) for pre-spawn / login / legacy cameras; in-world retail always has a viewer_cell root | `src/AcDream.App/Rendering/GameWindow.cs:7671` | Result is null ONLY when neither an interior root nor the synthetic outdoor node exists; kept so the login screen shows the live sky | If viewer-root resolution ever returns null in-world (membership bug, fly-camera edge), the frame silently degrades — interiors stop drawing through doorways; the old two-branch FLAP reappears for those frames | `SmartBox::RenderNormalMode` decomp:92635 |
| AD-22 | Async streamed mesh loading with point-of-use self-heal (`EnsureLoaded` re-request in the dispatcher's per-frame meshMissing path, **#128**); retail loads synchronously — geometry is never absent | `src/AcDream.App/Rendering/Wb/WbMeshAdapter.cs:211` | Documented convergence argument: the self-heal makes absence transient, converging the async pipeline to retail's never-absent guarantee | A missing mesh referenced OUTSIDE the dispatcher's walk (a future consumer not touching meshMissing) stays permanently invisible — the #119/#128 broken-stairs class; best case, late pop-in | retail synchronous content load (note at WbMeshAdapter.cs:211) |
| AD-23 | Live entities with `ServerGuid != 0` and null `ParentCellId` are culled (ClipSlotCull) while indoor clip routing is active; retail objects are always cell-resident (synchronous add-to-cell at creation) | `src/AcDream.App/Rendering/Wb/WbDrawDispatcher.cs:484` | Phase U.4 policy: parentless = unresolved indoors, equivalent to retail's not-in-any-visible-cell ⇒ not drawn, *given membership resolves promptly* | An entity whose membership lags (late CreateObject hydration, resolver hiccup) blinks invisible while the player is indoors, even in plain sight | retail per-cell object lists in PView traversal |
| AD-24 | EnvCell shell geometry hash-deduplicated ((environmentId, structure, surface overrides) → 31-multiplier hash) and instanced; retail draws each CEnvCell's own structure directly | `src/AcDream.App/Rendering/Wb/EnvCellRenderer.cs:276` | Verbatim WB EnvCellRenderManager port (Phase A8); dedup is what makes the single-VAO MDI cell pipeline cheap; intended visuals identical | A hash collision between distinct tuples renders the wrong interior shell in some room with NO diagnostic firing — wrong walls/floor in a dungeon room | retail `PView::DrawCells` → per-cell drawing_bsp (cited at :319) |
| AD-25 | Wall-bounce velocity reflection suppressed on landing (fires only airborne-before AND airborne-after); retail bounces unless grounded→grounded-and-not-sledding | `src/AcDream.App/Input/PlayerMovementController.cs:1212` | Our per-frame architecture amplifies the artifact (post-reflection +Z defeats the `Velocity.Z <= 0` landing-snap gate → micro-bounce death spiral); at elasticity 0.05 retail's landing bounce is imperceptible; sledding reverts to retail rule | Landing-reflection-dependent behavior (slope-landing momentum, high-elasticity surfaces) won't reproduce; the suppression masks the landing-snap gate fragility and could outlive its reason | `handle_all_collisions` pc:282699-282715; ACE PhysicsObj.cs:2656-2721 |
| AD-26 | Auto-walk arrival requires facing alignment (invented 5° arrive / 30° walk-while-turning bands); retail's check is `dist <= radius` exact | `src/AcDream.App/Input/PlayerMovementController.cs:575` | ACE does the final `Rotate(target)` server-side before the Use callback; without a local gate the body used items while facing away (user feedback 2026-05-15). Thresholds are NOT retail constants | Arrival delayed by the rotation phase; if heading convergence fights another yaw writer, `AutoWalkArrived` never fires and the queued Use/PickUp never completes | `MoveToManager::HandleMoveToPosition`; `apply_interpreted_movement` |
| AD-27 | Use/PickUp action re-sent on natural auto-walk arrival; retail sends the action once (server MoveToChain callback completes it) | `src/AcDream.App/Input/PlayerMovementController.cs:322` | ACE's server-side chain may have timed out by the time our body arrives; the close-range re-send hits ACE's WithinUseRadius fast-path | If the server's chain has NOT timed out, the action executes twice — door toggles open-then-closed, use-once interactions double-fire; protocol noise on non-ACE servers | ACE CreateMoveToChain / WithinUseRadius |
| AD-28 | Chat transcript (`UiText`) and input (`UiChatInput`) are two separate widget classes placed inside their dat-authored container panels; retail's `ChatInterface` uses a single mode-flagged `UIElement_Text` (Type-12) that switches between read and edit mode | `src/AcDream.App/UI/Layout/ChatWindowController.cs:135` (transcript) + `:150` (input) | `UIElement_Text` is inside keystone.dll with no PDB/decomp; a two-widget split is functionally equivalent (read-only scroll, editable input) and is the structural adaptation required by our UiElement architecture | A future consumer expecting a single widget for both read/write (e.g. a plugin calling the chat API and getting one widget back) must be written to the two-widget contract | `UIElement_Text` (Type-12) @ keystone.dll; `gmMainChatUI::PostInit` @0x4ce130 |
| AD-29 | `ClientObjectTable` fires global `ObjectAdded`/`ObjectUpdated`/`ObjectRemoved` events; consumers filter by guid on their end. Retail dispatches per-object via `NoticeRegistrar` observer dispatch — each UI cell observes only its specific object guid | `src/AcDream.Core/Items/ClientObjectTable.cs:48` (events); `src/AcDream.App/UI/Layout/ToolbarController.cs:115` (guid filter) | `NoticeRegistrar` is inside keystone.dll with no PDB/decomp; global broadcast + consumer-side filter is functionally equivalent for the current panel count and object volumes seen in practice | At high object counts (>1 000 objects), every `ObjectUpdated` wakes every subscribed consumer — O(n·m) notification cost instead of retail's O(1) per-observer dispatch; a consumer that forgets the guid filter processes all objects (a latent correctness bug) | `NoticeRegistrar` (keystone.dll, no PDB); retail per-object observer registration in `CObjectMaint` |

---

## 3. Documented approximation (AP) — 42 rows

| # | Divergence | Where (file:line) | Why it is safe / justified | Risk if assumption breaks | Retail oracle |
|---|---|---|---|---|---|
| AP-1 | Snap-path Z settle: validated claims ground on their own walkable polys, but floor-less claims (thresholds, stair lips) fall through to a legacy nearest-in-Z scan over every CellSurface in the landblock; retail settles via `CheckPositionInternal` → `find_valid_position` | `src/AcDream.Core/Physics/PhysicsEngine.cs:614` | `find_valid_position` unported; the **#111** fix narrowed the legacy pick's blast radius (validated claims bypass it) rather than replacing it | A threshold/stair-lip snap can still pick a neighbouring cell's same-height floor by iteration order — wrong cell or Z at login/teleport arrival (the #111 clobber class) | `SetPositionInternal` :283426 → find_valid_position |
| AP-2 | Visual-AABB fallback collision shape for Setups with no retail physics data; retail emits NO shapes (phantom). **#101** fixed the GfxObj-only class; the Setup-without-shapes fallback remains | `src/AcDream.Core/Physics/PhysicsDataCache.cs:96` | Lets the player collide with decorative meshes shipping no CylSphere/part-BSP instead of walking through furniture-like props | Retail-phantom entities block movement (the **#100/#101** family), and the synthetic box gives non-retail push-out normals when it collides | `CPartArray::InitParts` (cited at PhysicsDataCache.cs:386-389) |
| AP-3 | Step-down chain triggered only when contact is invalid OR steeper than walkable; retail's `transitional_insert` OK-path ALWAYS runs it | `src/AcDream.Core/Physics/TransitionTypes.cs:1197` | Conditional preserves the observed-to-matter cases (edge departure, steep cliff-slide) without running the chain every step (per pc:273191 agent reports) | Steps where retail runs step-down despite a valid walkable contact (bump maintenance, edge-slide arming) are skipped — float-off or missed edge slides in untested geometry | `transitional_insert` OK-path pc:273191 |
| AP-4 | CliffSlide check moved BEFORE retail's Branch-1 (`!OnWalkable` → restore+OK) gate, compensating our L.2.3i FloorZ OnWalkable bookkeeping | `src/AcDream.Core/Physics/TransitionTypes.cs:1316` | Retail's order with our incomplete OnWalkable stops the player dead every frame on steep slopes ("stay on the roof"); reorder restores downhill drift | CliffSlide fires in states where retail's Branch 1 would restore-and-OK — body slides where retail holds, e.g. contact-plane-bearing steep geometry near edges | retail EdgeSlide dispatch order (transitional_insert step-down failure) |
| AP-5 | Step-down skips Placement validation for the contact-maintenance call (`runPlacement=false`); ACE/retail run it unconditionally (kept for DoStepUp) | `src/AcDream.Core/Physics/TransitionTypes.cs:3393` | Residual wall-slide artifacts made Placement misfire, leaving players stuck near walls; the skip was the targeted L.2.3h fix | Step-down can settle into positions Placement would reject — slight wall embedding, or accepting a step-down through overlap geometry retail catches | `CTransition::step_down` pc:272952; ACE Transition.cs:731-741 |
| AP-6 | Analytic swept-sphere cylinder collision (XY overlap + step-over + wall-slide) instead of retail CylSphere functions via the 6-path dispatcher; A6.P6 step-over branch ports `step_sphere_up`'s clearance check | `src/AcDream.Core/Physics/TransitionTypes.cs:2601` | Claimed to match retail for the exercised cases (trunks, NPC bodies, door foot-colliders); step-over and step_up_slide fallback retro-fitted from retail when the door phantom surfaced | Unported branches (push direction, interpenetration resolution) differ from retail against cylinder entities — the phantom-collision / sticky-NPC family | `CCylSphere::step_sphere_up` pc:324516-324538 |
| AP-7 | `calc_friction` threshold 0.0 with retail's state gate missing; retail uses 0.25 gated by an undecoded state check | `src/AcDream.Core/Physics/PhysicsBody.cs:307` | Bumping the threshold without the gate hammered normal walking (3 → 0.16 m/s); as-read 0.0 kept; locomotion probably state-exempted in retail. Filed L.3c-followup | Friction engages under different conditions — post-landing slides, knockback decay, sledding speeds mismatch retail's deceleration | pc:276702-276705 (state gate + 0.25) |
| AP-8 | Remote MoveTo driver is a minimum viable subset: no target re-tracking, no sticky/StickTo, no fail-distance detector, no sphere-cylinder distance variant | `src/AcDream.Core/Physics/RemoteMoveToDriver.cs:44` | All server-side concerns the local body needn't model; ACE re-emits MoveTo ~1 Hz with refreshed origins, substituting for re-tracking | If the re-emit cadence assumption breaks (or sticky-follow packets appear), chase/flee motion visibly diverges — orbiting, overshoot, giving up where retail tracks | `MoveToManager::HandleMoveToPosition` 0x00529d80 |
| AP-9 | Fixed π/2 rad/s in-motion turn rate; per-creature TurnSpeed unwired | `src/AcDream.Core/Physics/RemoteMoveToDriver.cs:77` | Matches ACE's monster TurnSpeed default; field hook documented for the future port | Creatures with non-default turn speeds rotate at the wrong rate — facing-correction mismatch vs retail observers | run_turn_factor 0x007c8914; `apply_run_to_command` 0x00527be0 |
| AP-10 | Dry-corner water depth: retail's 0.1 m allowed sink-in collapsed to 0 | `src/AcDream.Core/Physics/TerrainSurface.cs:481` | The 0.1 offset destabilizes the feet-exactly-on-plane contact-touch check (dist > EPSILON → SetContactPlane never fires → float/fall); retail's ~10 cm sink-in is visually indistinguishable | Masks a contact-touch epsilon fragility — other water-depth values exercising the same instability could oscillate shoreline walkable validation; retail's wet/dry corner sink-in visual absent | `ObjCell.get_water_depth` / `calc_water_depth` (via ACE port) |
| AP-11 | Hand-authored 4-keyframe fallback sky set (sunrise/noon/sunset, fog ~80–350 m) when the Region dat isn't loaded yet | `src/AcDream.Core/World/SkyState.cs:167` | A renderable sky is needed during boot before the Region dat parses; safety net on region-load failure | Any window where the fallback is active shows sky/fog lighting only roughly resembling retail's dat-driven values | SkyTimeOfDay keyframes, Region dat 0x13000000 |
| AP-12 | Enchantment family-stacking tiebreak by largest SpellId; retail picks highest Generation, tie-broken by latest cast | `src/AcDream.Core/Spells/EnchantmentMath.cs:89` | `ActiveEnchantmentRecord` doesn't carry Generation; SpellId correlates with generation level in practice | Where spell ids don't track power within a family (or same-generation re-cast), the wrong buff wins — vital-max / stat values diverge from retail | `CEnchantmentRegistry::EnchantAttribute` 0x00594570 (pc:416110) |
| AP-13 | `ComputeDamage` is a simplified retail damage formula (no augmentations/ratings) — verified DEAD CODE as of 2026-06-04, M2 scaffolding | `src/AcDream.Core/Combat/CombatModel.cs:184` | Not on the critical path; stubbed from r02 §5 + ACE CombatManager for the future M2 predictive display | If wired into the M2 attack-bar estimate as-is, predicted numbers diverge whenever augs/ratings apply | r02 §5; ACE CombatManager |
| AP-14 | Encumbrance multiplier is a rough piecewise-linear stand-in (1.0→50%, ~0.7@100%, 0.1@300%) for retail's exact curve | `src/AcDream.Core/Items/ItemInstance.cs:187` | Hand-fit segments capture the curve's shape for scaffolding | Client-side burden-scaled effects (speed prediction) differ from retail at most burden ratios when loaded | r06 §6 (retail encumbered multiplier curve) |
| AP-15 | WeenieError translation table covers only ~30 common codes (from ACE enum docs, not retail string_table.bin); unknown codes render raw hex | `src/AcDream.Core/Chat/WeenieErrorMessages.cs:26` | Untranslated codes are rare, fall back losslessly, 30-second add when reported | Server messages outside the table show as raw hex instead of the retail sentence | retail string_table.bin; ACE WeenieError*.cs |
| AP-16 | Point/spot lights selected per-object / per-cell as the **8 nearest reaching lights** (sphere-overlap, nearest-first) via `LightManager.SelectForObject`, capped at `MaxLightsPerObject=8`; called from `WbDrawDispatcher.ComputeEntityLightSet` (objects) and `EnvCellRenderer.GetCellLightSet` (cell shells). Retail's bake (`SetStaticLightingVertexColors`) sums ALL reaching static lights per vertex with no count cap. Retail's *hardware* path (`minimize_object_lighting` 0x0054d480) DOES cap at 8 per object, so the cap is faithful to retail's hardware path — not to its bake path. The `LightManager.Tick` UBO path survives for DIRECTIONAL (sun) lights only; `mesh_modern.vert`'s UBO loop skips point/spot entries (`posAndKind.w != 0 → continue`) — point lights reach the shader exclusively via the per-object SSBO (binding 5) | `src/AcDream.Core/Lighting/LightManager.cs:234` (`SelectForObject`); `MaxLightsPerObject` ~line 174; call sites `WbDrawDispatcher.ComputeEntityLightSet` + `EnvCellRenderer.GetCellLightSet` | Matches retail's hardware constraint (8 lights per object/cell); selection is nearest-sphere-overlap which faithfully allocates lights to the surfaces that actually see them | Surfaces reached by >8 point lights are dimmer than retail's uncapped bake — rare (a dungeon room has a handful of torches), but real; see AP-35 for the bake-vs-GPU-evaluate architecture difference | `minimize_object_lighting` 0x0054d480 (retail's 8-light hardware cap); `SetStaticLightingVertexColors` 0x0059cfe0 (retail's bake, no count cap) |
| AP-17 | Spell metadata from third-party CSV (3,956 rows, bad rows silently skipped), not the portal.dat SpellTable; Family feeds stacking decisions | `src/AcDream.Core/Spells/SpellTable.cs:10` | The dat spell-table port (obfuscated/encrypted aspects) wasn't done; CSV closed #11 fast and unblocked #6 stacking | Any CSV↔dat drift (wrong Family, missing rows) silently produces wrong buff-stacking winners and wrong panel info | portal.dat SpellTable 0x0E00000E |
| AP-18 | Radar/indicator RGBA hand-tuned from screenshots; dispatch order ports `GetBlipColor` exactly but the real `RGBAColor_Radar*` static data is unrecovered | `src/AcDream.Core/Ui/RadarBlipColors.cs:33` | Color constants live in retail static data not yet extracted; comment invites tightening when recovered | Blip/indicator hues differ subtly from retail color cues | `gmRadarUI::GetBlipColor` 0x004d76f0; RGBAColor_Radar* (unrecovered) |
| AP-19 | `PortalSideEpsilon` 0.01 (≈1 cm) instead of retail F_EPSILON ≈ 0.0002 — a documented render-root-lag tolerance, NOT a retail constant. DO-NOT-RETRY: T2 (BR-4) tried the retail value; CornerFloodReplay refuted it | `src/AcDream.App/Rendering/PortalVisibilityBuilder.cs:49` | Retail's tight epsilon only works with eye-exact swept curr_cell tracking; our viewer cell lags the eye by up to ~1 cm at pressed corners. Tighten after the #108-membership family + cdstW near-clip pin land | A 1 cm misclassification band at portal planes can flood or cull a portal the eye hasn't crossed — one-frame leaks / grey flashes at knife-edge doorway/corner positions | F_EPSILON @0x007c8c70; `PView::InitCell` 0x005a4b70 |
| AP-20 | Sub-pixel view-polygon vertex merge fixed at 1080p-reference NDC units (2/1080); retail merges at ~1 actual screen pixel | `src/AcDream.App/Rendering/PortalProjection.cs:179` | Unit approximation whose coarseness only strengthens convergence — the merge is the flood's fixpoint floor (replaced MaxReprocessPerCell=16) | At 4K+ a legitimately visible 1–2 px sliver aperture collapses to degenerate and rejects — a thin/distant doorway stops admitting its flood slightly earlier than retail | `Render::copy_view` 0x0054dfc0 |
| AP-21 | Entity translucency: two-pass alpha-test (N.5 Decision 2, invented 0.95/0.05 thresholds); AlphaBlend + Additive + InvAlpha all composite under (SrcAlpha, 1−SrcAlpha) — retail applies per-surface D3D blend incl. true additive. EnvCellRenderer + ParticleBatcher DO switch to additive; divergence confined to GfxObj/Setup entities via WbDrawDispatcher | `src/AcDream.App/Rendering/Wb/WbDrawDispatcher.cs:1563` (+ `Shaders/mesh_modern.frag:10`; #52 amendment removed the α≥0.95 discard) | Matches original WB's model; keeps the bindless MDI pipeline at two indirect draws; spec §6 documents the falsifiable fallback — a third indirect call with `glBlendFunc(SrcAlpha, One)` (~30 min) on a magic-content regression | Additive glow/magic entity surfaces composite darker / occlude instead of brightening — the predicted regression once spell VFX density increases; α<0.05 discard drops faint fringes retail blends | SurfaceType.Additive → D3DBLEND_ONE per-surface routing |
| AP-22 | Invented `setup.Radius` cylinder (height = Height or Radius×2) for shapeless live entities; shape + height formula not from the retail shape walk | `src/AcDream.App/Rendering/GameWindow.cs:3250` | ShadowShapeBuilder (faithful walk) only emits CylSphere/Sphere/Part-BSP; the legacy cylinder preserves prior behavior so rare decorative props don't lose collision | Those props collide with an invented footprint (especially the Radius×2 height guess) — slides/blocks at non-retail distances | `find_obj_collisions` → `CPartArray::FindObjCollisions` pc:286236 |
| AP-23 | Invented per-type use-radius heuristic (3 m creatures / 2 m doors-lifestones-portals-corpses / 0.6 m rest) for close-range gating + speculative turn-to-target | `src/AcDream.App/Rendering/GameWindow.cs:11120` | ACE broadcasts nothing actionable on the close branch (WithinUseRadius shortcut); the true radius arrives only on the far MoveToObject branch — a local stand-in is required (B.6) | A target whose real UseRadius differs from the bucket misjudges the gate — Use/PickUp deferred for an auto-walk that never comes, or fires early into a server "too far" | ACE Player_Move.cs:66; wire MoveToObject (type 6) carries the true radius |
| AP-24 | Jump charge fill rate guessed at 2.0 extent/s (full in 0.5 s); retail's divisor illegible (clobbered x87 in `GetPowerBarLevel`). Height→velocity formula is byte-faithful | `src/AcDream.App/Input/PlayerMovementController.cs:170` | Only time-to-fill diverges; 2.0/s matched retail muscle memory better than 1.0/s; targeted Ghidra decompile of 0x0056ADE0 already flagged (M2 research) | Every held-spacebar jump reaches a different extent than the same hold in retail — fence/gap jumps succeed/fail differently until the constant is recovered | FUN_0056ade0 (GetPowerBarLevel) |
| AP-25 | Run/Jump skill pushed to movement = attributeBonus + Init + Ranks — no augmentations, multipliers, or vitae | `src/AcDream.Core.Net/GameEventWiring.cs:346` | Closest to ACE's CreatureSkill.Current short of porting the full Aug/Multiplier/Vitae chain (K-fix7/13) | A character with augs or post-death vitae predicts wrong local run speed / jump arc — dying would NOT slow the local player though the server moves them slower: drift + snap-back | ACE CreatureSkill.Current; ACE Skill.cs (Jump=22, Run=24) |
| AP-26 | DDD interrogation answered with an empty dat-version list (count=0); retail reports actual dat iteration state | `src/AcDream.Core.Net/Messages/DddInterrogationResponse.cs:18` | ACE is satisfied by the empty ack; pattern from holtburger | A dat-patching-enabled server could push a full patch or reject on version mismatch — the lie is harmless only while the server never acts on it | DDD flow 0xF7E5/0xF7E6 |
| AP-27 | PlayerDescription trailer: GameplayOptions skipped by a 4-byte-aligned heuristic scan for a valid inventory parse; options blob captured opaque, never decoded (retail decodes + applies UI options) | `src/AcDream.Core.Net/Messages/PlayerDescriptionParser.cs:69` | Variable-length opaque blobs; mirrors holtburger's heuristics; follow-up issue extends when panels consume those sections | An options blob that coincidentally parses as a valid inventory (or inventory not landing at EOF) yields wrong/empty inventory+equipped at login; retail-persisted UI options silently ignored | ACE GameEventPlayerDescription.WriteEventBody; holtburger events.rs:195-218 |
| AP-28 | 3D audio falloff via OpenAL InverseDistanceClamped with picked constants (ref 2 m, max 1000 m, rolloff 1); voice pool/eviction IS cited to retail | `src/AcDream.App/Audio/OpenAlAudioEngine.cs:146` | Stands in for retail's DirectSound-era attenuation; r05 §5.3 documents inverse-square behavior but the three AL params were picked, not ported | Sounds attenuate at a different rate — too loud/quiet at range side-by-side; gain-driven eviction comparisons inherit the skew | FUN_00550ad0 (voice pool only); r05 §5.3 |
| AP-29 | Target-indicator fallback for entities with no baked selection sphere: invented 1.5 m × scale box + 16/12 px screen floors (primary path is a faithful `GetObjectBoundingBox` port) | `src/AcDream.App/UI/TargetIndicatorPanel.cs:86` | Fallback only fires when the Setup didn't bake a selection sphere — rare in practice | Sphere-less entities get a non-retail indicator size/placement; the pixel floors prevent retail's far-distance collapse | `SmartBox::GetObjectBoundingBox` 0x00452e20; `GetSelectionSphere` |
| AP-30 | AutonomousPosition diff cadence compares with epsilons (1 mm pos, 1e-4 normal, 1 mm dist); retail's `Frame::is_equal` is an exact float compare | `src/AcDream.App/Input/PlayerMovementController.cs:1541` | Sub-millimeter epsilon is well below any movement worth suppressing; comparisons are against last-SENT state so drift accumulates past the epsilon | Sub-epsilon drift suppresses an AP send retail would have made — negligible today; a consumer expecting retail's exact send-on-any-change cadence sees fewer packets | `Frame::is_equal` pc:700263 |
| AP-31 | Scenery placement drift + the 0xA9B1 road-edge tree — WB-upstream divergences from retail, ACCEPTED (**#49/#50**, 2026-05-11) | `src/AcDream.Core/World/SceneryGenerator.cs` (via `WbSceneryAdapter`) | Piecemeal patching against WB upstream is net-negative (the `e279c46` road-check attempt over-suppressed scenery elsewhere, reverted `677a726`); visible impact = a handful of trees a few meters off | The same WB-upstream class could hide a *larger* placement divergence elsewhere; revisit only via a coherent ACME-style per-vertex filter port | `CLandBlock::get_land_scenes`; ACME GameScene.cs:1074 per-vertex road filter |
| AP-32 | Cell shells DRAW +0.02 m above the dat EnvCell origin (`ShellDrawLiftZ`, z-fight vs coplanar terrain); retail draws at the origin verbatim. Split invariant: PHYSICS + visibility graph UNLIFTED (f35cb8b, **#119**-residual), every DRAW-space consumer of portal/cell geometry LIFTED (OutsideView color gate via `Build(drawLiftZ)`, seal/punch fans — **#130**) | `src/AcDream.App/Rendering/GameWindow.cs:5604` (const at `PortalVisibilityBuilder.ShellDrawLiftZ`) | Shell floors coplanar with terrain z-fight in our z-buffered frame; the 2 cm lift is the documented stand-in | A new draw-space consumer of portal/cell polygons that forgets the lift re-opens a 2 cm seam at horizontal aperture edges (the #130 top-edge strip, ~7 px at 2.4 m); a visibility consumer that picks up the LIFTED transform re-opens the #119-residual horizontal-portal side-cull | retail draws cell geometry at the dat EnvCell origin (no lift) |
| AP-33 | Interior-root look-in cells (**#124** sub-pass) draw their statics + DYNAMICS + emitters WHOLE — no per-part/per-object viewcone check; retail viewconeCheck's each vs the installed view (the **#131** portal closure: a server object in a look-in cell drew nowhere — dynamics-last culls cells absent from the main cone, and post-seal it z-fails anyway) | `src/AcDream.App/Rendering/RetailPViewRenderer.cs` (`DrawBuildingLookIns`) | The main viewcone has no entries for look-in cells; over-include is the safe direction (z-correct, repainted outside apertures by the root's shells); look-in cell counts are small (~1-3 cells) | A few wasted draws on content outside the doorway region (repainted); no under-draw direction remains | `viewconeCheck` 0x0054c250; nested `DrawCells` objects pc:432878 |
| AP-34 | Landscape-stage alpha deferral is a TWO-PHASE slice split (statics-early / dynamics+particles+weather-late around the **#124** look-ins) + outdoor-root attached scene emitters moved to the post-frame pass, not retail's single deferred alpha flush. Residual: building exteriors' / outside-stage dynamics' own translucent MESH batches still draw within their stage draw call (before later stage content) | `src/AcDream.App/Rendering/RetailPViewRenderer.cs` (`DrawLandscapeThroughOutsideView` late loop) + `GameWindow` post-frame Scene pass | The MDI dispatcher draws translucency inside each Draw call; a faithful FlushAlphaList port needs a global deferred alpha list across all landscape draws — the split covers the user-visible cases (#131 portal swirl, #132 candle flame indoors + outdoors) | Translucent landscape content drawn early and screen-overlapped by content drawn later in the stage gets overpainted (no depth self-protection) — the portal-swirl/candle-flame class re-appears in the residual configurations | `D3DPolyRender::FlushAlphaList` (DrawCells pc:432722) |
| AP-36 | Dungeon streaming gate triggers on the player's CURRENT cell being a sealed EnvCell (`CurrCell.IsEnv && !SeenOutside`), an approximation of ACE's full landblock `IsDungeon` (all-heights-zero + NumCells>0 + Buildings.Count==0). The retail BEHAVIOR (a dungeon loads no adjacent landblocks) is faithful — only the runtime TRIGGER is the cheap cell predicate instead of classifying the center landblock. **#135 pre-collapse:** at login/teleport the same collapse is triggered EARLY (the instant the streaming center is recentered onto the spawn/dest cell) via `IsSealedDungeonCell` reading the EnvCell **dat** `SeenOutside` flag — because the physics `CurrCell` is null until placement, which waits for hydration; without the early trigger the full 25×25 ocean-grid window loads then unloads (the ~30 s login FPS ramp) | `src/AcDream.App/Rendering/GameWindow.cs:6895` (per-frame predicate) + `:IsSealedDungeonCell` + `:OnLiveEntitySpawnedLocked`/`:OnLivePositionUpdated` (login/teleport pre-collapse hooks) + `src/AcDream.App/Streaming/StreamingController.cs` (collapse/expand/`PreCollapseToDungeon`) | The predicate is already computed for sun/sky gating (playerInsideCell) and exactly matches for sealed dungeons vs windowed building interiors (SeenOutside=true → not gated); no landblock re-classification needed. The dat-flag read is the same `EnvCellFlags.SeenOutside` the hydrated `ObjCell.SeenOutside` is built from (`EnvCell.cs:72`/`PhysicsDataCache.cs:224`), so the pre-collapse decision matches the eventual per-frame gate exactly | A dungeon cell that reports SeenOutside (an entrance cell open to the surface) briefly un-collapses and re-streams the window; a hypothetical windowless building back-room (IsEnv && !SeenOutside but HasBuildings) would wrongly collapse its outdoor neighbors; a sealed-dungeon entrance cell that is itself SeenOutside is simply MISSED by the early trigger and falls back to the existing late collapse (no worse than before #135) | ACE `LandblockManager.GetAdjacentIDs` (dungeons→empty) Landblock.cs:577-582; `IsDungeon` Landblock.cs:1264-1277 |
| AP-43 | Per-object torch (point/spot) lighting is gated on the OBJECT's own cell: an object selects the static wall-torches ONLY when its `ParentCellId` is an EnvCell (`(id & 0xFFFF) >= 0x0100`); outdoor objects (building exterior shells with null ParentCellId, outdoor scenery, outdoor creatures) get the SUN + ambient and NO torches. This is the faithful port of retail's `useSunlight` gate — `DrawMeshInternal` (0x0059f398) calls `minimize_object_lighting` only `if (Render::useSunlight == 0)`, and the outdoor landscape stage runs `useSunlightSet(1)` (`PView::DrawCells` 0x005a485a, before `LScape::draw`) so outdoor objects are never torch-lit (closes the Holtburg meeting-hall facade torch-flood — A7 Fix D round 2, the dat's intensity-100 `falloff 6` orange torches were washing the exterior shell). **Residual approximation:** the sun/no-sun half is a per-FRAME global keyed on the PLAYER being inside a cell (`UpdateSunFromSky` zeroes the sun when `playerInsideCell`), NOT retail's per-draw-STAGE `useSunlight` toggle. So a mixed-stage frame (standing in a doorway / look-in) lights through-aperture objects with the player's regime, not the object's stage regime | `src/AcDream.App/Rendering/Wb/WbDrawDispatcher.cs` (`IndoorObjectReceivesTorches` + `ComputeEntityLightSet`); sun half `src/AcDream.App/Rendering/GameWindow.cs:10421` (`UpdateSunFromSky`) | The visible case — player OUTSIDE, looking at an outdoor building/scenery — is now exactly faithful (sun+ambient, no torches); player INSIDE a cell gets torches with the sun globally killed = faithful indoor regime. Cross-aperture mismatch only affects objects seen THROUGH a doorway from the other lighting context | A through-aperture interior object viewed from outside gets the sun (player outside) instead of retail's indoor torches-no-sun; an outdoor object viewed from inside gets no sun (player inside) instead of retail's sunlit outside stage — doorway/look-in frames only, not the standalone outdoor or indoor case | `useSunlight` gate `DrawMeshInternal` 0x0059f398; `useSunlightSet` 0x0054d450; outside stage `PView::DrawCells` 0x005a485a (`useSunlightSet(1)`); `minimize_object_lighting` 0x0054d480; `config_hardware_light` Range=falloff×`rangeAdjust`(1.5) 0x0059ad30 |
| AP-35 | Point/spot lights are now PER-VERTEX Gouraud (`pointContribution` ~line 153 of `mesh_modern.vert`) matching retail's `SetStaticLightingVertexColors` bake path. Half-Lambert wrap (`(1/1.5)·(N·D + 0.5·d)`) AND norm distance attenuation (`distsq>1 ? distsq·d : d`) ARE ported (A7 Fix A, `aa94ced`). Point-light sum clamped to [0,1] on its own accumulator before adding ambient+sun (A7 Fix D D-1, mirrors retail's per-vertex bake clamp). CPU oracle: `src/AcDream.Core/Lighting/LightBake.cs`, locked by `tests/AcDream.Core.Tests/Lighting/LightBakeConformanceTests.cs`. **Residual (two parts):** (a) acdream lights in-shader each frame (per-frame GPU evaluate); retail bakes into the vertex buffer ONCE — an architecture/performance difference; the wrap + norm + clamp formula is the same, but bake-once is cheaper for static geometry; (b) acdream's `SelectForObject` keeps only the 8 NEAREST reaching point/spot lights per object/cell (`MaxLightsPerObject=8`, see AP-16), whereas retail's bake sums ALL reaching static lights per vertex — a surface reached by >8 point lights is dimmer in acdream than retail's bake result (rare in practice; a room has a handful of torches) | `src/AcDream.App/Rendering/Shaders/mesh_modern.vert` (`pointContribution` ~line 153; wrap ~line 163; norm ~line 167; point-sum clamp line 210) | Per-vertex Gouraud + wrap + norm + clamp all match retail. The two residuals are: (a) per-frame GPU vs bake-once — architecture/perf only; (b) 8-light cap dimming when >8 lights reach one surface — rare. `LightInfoLoader.cs:81` folds static_light_factor 1.3 into Range | (a) A new frame-time consumer bypassing `accumulateLights` would need to replicate the wrap + norm formula; per-frame GPU re-evaluate has higher per-frame cost than bake for static geometry. (b) A densely lit scene (>8 torches reaching one wall) renders dimmer than retail — see AP-16 for the 8-cap ownership | `calc_point_light` 0x0059c8b0 (line 0x0059c9a2 ramp; 0x0059c925 wrap); `SetStaticLightingVertexColors` 0x0059cfe0; static_light_factor 0x00820e24 |
| AP-37 | LayoutDesc importer collapses the dat's nested meter structure (Type-7 meter → two Type-3 container children → three Type-3 image-slice grandchildren each) into `UiMeter`'s programmatic 3-slice fields (`BackLeft..FrontRight`) + reuses `UiMeter.DrawHBar`'s scissor-fill, instead of building those child nodes generically and porting `UIElement_Meter::DrawChildren`. Vitals number elements are meter children (not recursed); `VitalsController` attaches a centered `UiText` child for the cur/max number (Task 8 landed — retail `gmVitalsUI` uses `UIElement_Text`), so `UiMeter.Label` is no longer used for vitals (`UiText.Centered` reuses the meter's former centering formula → pixel-identical, user-confirmed). The inheritance `Merge` treats Width/Height==0 as "inherit from base", diverging from format-doc §12 rule 2 (documented inline in `ElementReader.cs`) | `src/AcDream.App/UI/Layout/DatWidgetFactory.cs` (`BuildMeter`/`SliceIds`) + `src/AcDream.App/UI/Layout/LayoutImporter.cs` (`BuildWidget` meter-child skip) | Reuses the tested `UiMeter` render that already visually matches retail's stacked vitals bars; the full nested-element + `DrawChildren` scissor port is deferred to Plan 2. Locked by the conformance fixture (`tests/AcDream.App.Tests/UI/Layout/fixtures/vitals_2100006C.json`) | A LayoutDesc whose meter structure differs from the vitals 2-container/3-slice shape renders an empty/wrong meter — no oracle diff until the Plan-2 port lands | `UIElement_Meter::DrawChildren` @0x46fbd0; `docs/research/2026-06-15-layoutdesc-format.md` |
| AP-38 | Chat transcript renders pre-split `ChatLog` lines 1:1; no in-element word-wrap at the panel's current pixel width | `src/AcDream.App/UI/UiText.cs` | Retail does in-element wrap via `UIElement_Text::SizeToFit`; our pre-split lines are always shorter than 440 px in practice; a line that overflows clips at the edge rather than wrapping | Very long server system messages (server shutdowns, broadcast announcements) clip rather than wrapping — no information loss, just visual truncation | `UIElement_Text::SizeToFit` @0x467980; `gmMainChatUI` layout |
| AP-39 | Chat lines carry one color per `ChatKind` (per-line solid color); retail `UIElement_Text` supports per-glyph styled runs (bold, different hue per segment) | `src/AcDream.App/UI/UiText.cs:13` | Retail glyph-run parsing lives inside keystone.dll with no PDB/decomp; per-line per-kind coloring is the correct tonal palette and covers all existing chat types | Chat lines retail renders with multiple colors or bold names (e.g. "PlayerName says: text") render as one flat color; subtle visual difference but functionally complete | `UIElement_Text` glyph-run styling (keystone.dll, no decomp) |
| AP-40 | Single default translucency for the chat window chrome; no focused/unfocused opacity transition; dat font face/size taken from the vitals `vitalsDatFont` (same dat font, not a chat-specific size lookup) | `src/AcDream.App/Rendering/GameWindow.cs` (chatController binding line) | Retail fades the chat window to ~80% alpha when unfocused (`gmMainChatUI::UpdateAlpha @0x4cdea0`); the opacity animation deferred to the Plan-2 window-manager input integration; sharing `vitalsDatFont` is safe — retail uses the same AC-default font for both | The chat window is always fully opaque/same-font rather than subtly fading when idle; no wrong text, but the focused/unfocused breathing rhythm is absent | `gmMainChatUI::UpdateAlpha` @0x4cdea0; `UCF::SetAceFont @0x4d3940` |
| AP-41 | Scrollbar thumb 3-slice cap fallback only: single-tile draw (`0x06004C63`) used only when `ThumbTopSprite`/`ThumbBotSprite` are unset; the chat controller passes all three cap ids so the 3-slice path is drawn in practice | `src/AcDream.App/UI/UiScrollbar.cs:35` | The fallback single-tile path is unreachable when caps are bound (chat controller always sets them); the 3-slice path is the active code path | Only if a future caller omits the cap ids will the fallback fire — no visual regression in the chat window | `UIElement_Scrollbar::UpdateLayout @0x4710d0`; cap sprites `0x06004C60` (top) + `0x06004C66` (bottom) from base layout `0x2100003E` |
| AP-42 | `UiMenu` item model is flat (label + opaque payload, single-level popup); retail `UIElement_Menu::MakePopup @0x46d310` supports hierarchical nested submenus via recursive popup chain | `src/AcDream.App/UI/UiMenu.cs` | The chat talk-focus menu is single-level (14 rows, 2 columns, no submenu); hierarchy is latent and unreachable through the chat window — no behavioral difference in the current usage | A future menu with nested submenus would render flat (only the top-level items drawn, no drill-down) | `UIElement_Menu::MakePopup` @0x46d310 |
| AP-45 | `PublicUpdatePropertyInt (0x02CE)` sequence byte parsed-past but not honored; last update wins (no freshness check against sequence number) | `src/AcDream.Core.Net/Messages/PublicUpdatePropertyInt.cs` | Loopback ACE rarely reorders; latest-wins matches `PrivateUpdateVital`/`UpdatePosition`'s existing non-sequence behavior. Sequence tracking added when needed alongside TS-26. | A reordered 0x02CE on a real network could apply a stale UiEffects value — item icon temporarily shows the wrong effect state, corrected on next update | `PublicUpdatePropertyInt` sequence byte (ACE GameMessagePublicUpdatePropertyInt) |
| AP-46 | Health-meter gate approximation: retail shows the health meter for `IsPlayer() || pet_owner || ClientCombatSystem::ObjectIsAttackable()` (full PK/faction logic); acdream's `GameWindow.IsHealthBarTarget` uses the server PWD bits `BF_ATTACKABLE (0x10)` OR `BF_PLAYER (0x8)` | `src/AcDream.App/Rendering/GameWindow.cs` (`IsHealthBarTarget`) → `SelectedObjectController` | The PWD `BF_ATTACKABLE`/`BF_PLAYER` bits distinguish monsters + players (bar) from friendly/vendor NPCs (name-only) for the M1.5 dev loop; the pet case and the full ObjectIsAttackable PK/faction refinement (free-PK, PK-vs-PK, PKLite) are not ported | A PK/faction edge (e.g. a hostile-flagged player whose `BF_ATTACKABLE` is unset, or a pet) could show/hide the bar where retail differs — no impact on the non-PK PvE dev loop | `ClientCombatSystem::ObjectIsAttackable` acclient_2013_pseudo_c.txt:375385; `BF_ATTACKABLE` acclient.h:6437 |

---

## 4. Temporary stopgap (TS) — 31 rows

| # | Divergence | Where (file:line) | Why it is safe / justified | Risk if assumption breaks | Retail oracle |
|---|---|---|---|---|---|
| TS-1 | PrecipiceSlide context missing — conservative stop-at-edge instead of retail's EdgeSlide → PrecipiceSlide / CliffSlide | `src/AcDream.Core/Physics/TransitionTypes.cs:1254` | Awaiting the next L.2c slice; a diagnostic records which ingredient (precipice context / steep plane / EdgeSlide flag) is missing | Player stops dead at precipice edges where retail slides along/over — visible mismatch at cliff and roof edges | retail EdgeSlide → PrecipiceSlide chain |
| TS-2 | `BspOnlyDispatch` reduces retail's `(HAS_PHYSICS_BSP_PS && !pvpTargetPlayer && !missileIgnore)` to the flag test alone (M1.5 scope: no PK, no missiles) | `src/AcDream.Core/Physics/TransitionTypes.cs:660` | Both omitted terms are genuinely false pre-M2; comment directs wiring them with PK (M2+) and missiles (F.3) | If PK or missiles land without the terms, flagged entities get BSP-only where retail tests cyl+sphere — pass-through / wrong blocking in PvP/missile interactions | `FindObjCollisions` pc:276861; HAS_PHYSICS_BSP_PS acclient.h:2833 |
| TS-3 | `FramesStationaryFall` accounting absent (`moved = true` unconditionally in the accepted-move branch) | `src/AcDream.Core/Physics/TransitionTypes.cs:3691` | Explicitly deferred to the full physics port | A body wedged falling-in-place never triggers retail's stuck-fall escalation — indefinite falling-animation wedges | CPhysicsObj frames_stationary_fall |
| TS-4 | Path-6 steep-poly slide-tangent shortcut: airborne hits on >FloorZ polys skip retail's SetCollide → Path-4 → ContactPlane landing chain, returning Slid in place | `src/AcDream.Core/Physics/BSPQuery.cs:2001` | Deliberate deviation: our faithful port DID wedge (missing step_up_slide / cliff_slide details on grounded-steep); validated against the 2026-04-30 retail cdb trace (retail body didn't wedge). Filed L.5+ for retail-strict | Airborne steep contact never commits Contact / lands as retail — roof-bounce trajectories, landing events, grounded-steep transitions diverge | `BSPTREE::find_collisions` SetCollide pc:323783-323821 |
| TS-5 | `CanJump` always true — burden/stamina gating deferred (stat plumbing incomplete pre-M2) | `src/AcDream.Core/Physics/PlayerWeenie.cs:44` | Marked deferred; harmless until stats matter | Client launches jumps retail refuses (exhausted/overburdened) — server rejection / rubber-band; divergent jump availability vs retail muscle memory | CMotionInterp jump path stamina/burden inquiry |
| TS-6 | Weather particle emission suppressed — all weathery DayGroups map to Overcast (correct fog/cloud tone, no precipitation); retail's camera-attached weather subsystem not yet located in the decomp | `src/AcDream.Core/World/WeatherState.cs:200` | Decomp research verified the sky loop never reads `DefaultPesObjectId`; an earlier name-based rain spawn regressed (rained where retail didn't, 2026-04-23) — inventing a name→rain path is forbidden until the real subsystem is found | Rainy/snowy/stormy days never show retail's precipitation effects (permanent missing visuals until the subsystem is found and ported) | FUN_00508010 / FUN_0051bed0→FUN_0051bfb0 (negative findings) |
| TS-7 | SkyObject `weather_enabled` gate not honored — weather-flagged sky objects (bit 0x04) always instantiate | `src/AcDream.Core/World/SkyDescLoader.cs:50` | No weather_enabled toggle exists yet; IsWeather flag parsed + documented as the gate to wire | Weather-only sky meshes (rain cylinders) appear where retail-with-weather-off suppresses them | `GameSky::MakeObject` 0x00506ee0, guard at decomp:268630 |
| TS-8 | `MagicUpdateEnchantment` (0x02C2) records carry no StatMod — mid-session buffs don't move vital max until relog (**#7/#12**) | `src/AcDream.Core/Spells/Spellbook.cs:150` | The wire parser hasn't been extended to the full ~60-64 byte Enchantment payload; PlayerDescription's block IS parsed | Vitals HUD percent reads differently from retail for the whole session after any buff cast | `EnchantAttribute` 0x00594570; holtburger magic/types.rs |
| TS-9 | MP3 (0x55) and MS-ADPCM (0x02) waves undecoded — affected sounds skipped; retail decoded both via winmm ACM | `src/AcDream.Core/Audio/WaveDecoder.cs:33` | Managed decoder (NAudio or similar) deferred; PCM covers the vast majority of ~3500 waves | Any MP3 (common for music-ish clips) or ADPCM cue plays as silence where retail plays it | winmm ACM path (r05 §2.1) |
| TS-10 | Setup lights anchored at entity root — per-light Frames not transformed through the animated part chain | `src/AcDream.Core/Lighting/LightInfoLoader.cs:31` | Per-part world transforms aren't exposed to the lighting layer; awaiting animation hook integration | A carried torch glows from the character origin, not the hand, and doesn't track swing/idle animations | LightInfo.ViewSpaceLocation per-part Frame (r13 §1) |
| TS-11 | `CreateBlockingParticleHook` consumed as a no-op; no sequencer implements the pause retail performs (consistent with the missing pending_motions chain, 2026-06-04 deep-dive) | `src/AcDream.Core/Vfx/ParticleHookSink.cs:112` | Responsibility assigned to the (future) sequencer layer when the sink was written | Animations retail pauses on a particle (cast/effect beats) run straight through — visual beat desynced from the effect | retail sequencer blocking-particle handling (r04 §6) |
| TS-12 | Animated entities' emitters use rest-pose part transforms anchored at entity root; retail attaches to the live animated part (per-tick refresh deferred; statics fixed by C.1.5b/#56) | `src/AcDream.Core/Vfx/ParticleHookSink.cs:80` (+ :20) | The renderer doesn't expose per-part world transforms to VFX; root + precomputed matrices reproduce retail placement for everything that doesn't animate | Effects hooked to animated parts (swinging hand, nodding head) emit from the rest pose / float at spawn offsets instead of tracking motion | `ParticleEmitter::UpdateParticles` 0x0051d2d4 |
| TS-13 | `DefaultScriptHook` / `DefaultScriptPartHook` / `CallPESHook` animation hooks dropped (no OnHook case); blocker comment predates PhysicsScriptRunner (C.1.5a) and may be STALE | `src/AcDream.Core/Vfx/ParticleHookSink.cs:130` | Originally blocked on PhysicsScript dat exposure; spawn-time DefaultScript firing landed via EntityScriptActivator, the animation-frame path never did | VFX retail triggers from specific animation frames (mid-animation script calls) never appear | CallPES / DefaultScript hook dispatch (r04 §6) |
| TS-14 | Setup `Flatten` ignores ParentIndex part hierarchy (treats every placement as root-local); still in production use (GameWindow hydration, SkyRenderer) | `src/AcDream.Core/Meshing/SetupMesh.cs:15` | Most Setups are flat single-level rigs where root-local equals composed; hierarchical composition deferred ("Phase 3") | Any Setup with genuinely nested parts renders them at wrong offsets — mis-assembled multi-part objects in the Flatten paths | retail Setup ParentIndex chain composition |
| TS-15 | No distance-driven degrade (LOD): always close-detail slot 0; plus the **#47** static `Degrades[0]` swap for 34-part humanoids only (structural sentinel detector) | `src/AcDream.Core/Meshing/GfxObjDegradeResolver.cs:57` (+ `src/AcDream.App/Rendering/GameWindow.cs:2608`) | LOD plumbing doesn't exist; slot 0 is correct for player + nearby NPCs; #47 closed the visible low-detail-arms bug without porting UpdateViewerDistance | Distant objects render max-detail (perf + wrong visuals where far meshes intentionally differ/hide parts); a future 34-part non-humanoid matching the sentinel gets the wrong mesh swap | `CPhysicsPart::UpdateViewerDistance` 0x0050E030; ::Draw 0x0050D7A0; ::LoadGfxObjArray 0x0050DCF0 |
| TS-16 | Click picking is Stage A only: ray-vs-fixed-radius spheres (0.7–1.0 m) + screen rect matched to the indicator; retail's per-polygon refine deferred (**#71**); rect-over-circle is a user-approved UX divergence | `src/AcDream.Core/Selection/WorldPicker.cs:199` | Stage B only needed if visual testing surfaces Stage-A over-picks; sphere/rect + cell-BSP occlusion adequate so far | Clicks near (not on) an entity still select it; fixed radii can mis-prioritize overlapping candidates vs retail's polygon-accurate test | `CPolygon::polygon_hits_ray` 0x0054c889 |
| TS-17 | AttackConditions suffix always empty in combat chat — formatting ported, wire bitflag not plumbed (Phase I.7 follow-up) | `src/AcDream.Core/Chat/CombatChatTranslator.cs:233` | Only the wire plumbing is missing; the holtburger-ported formatter is ready | Combat log omits "[Sneak Attack]"-style suffixes retail displays — hidden combat-mechanic feedback | holtburger chat.rs:588-595 |
| TS-18 | `LandCell.BuildingCellId` (CSortCell building bridge) declared but never populated — always null in Stage 1 | `src/AcDream.Core/World/Cells/LandCell.cs:19` | Cell graph shipped in stages; population is explicitly membership Stage 2 (the outdoor→indoor entry path the physics digest flags as unvalidated) | Cell-graph paths that should discover a building's EnvCells from the outdoor cell silently find nothing — the doorway-entry bug class | CSortCell (acclient.h:31880) |
| TS-19 | Legacy non-retail ChaseCamera (invented pitch/distance, K-fix12 airborne Z-pin) retained behind `ACDREAM_RETAIL_CHASE=0` / DebugPanel toggle; both update every frame | `src/AcDream.App/Rendering/ChaseCamera.cs:49` | Diagnostic before/after comparison path, "pending the follow-up deletion commit" | When toggled on, the eye diverges from retail's spring-arm — and the render roots at the VIEWER cell, so a non-retail eye changes the render root near doorways, masking or manufacturing flap symptoms during debugging | `CameraManager::UpdateCamera` (retail path in RetailChaseCamera.cs) |
| TS-20 | GfxObj polys drawn by dictionary iteration, not DrawingBSP traversal (**#113**): physics/no-draw polys referenced by no BSP node render as visible surfaces; the `CollectDrawingBspPolygonIds` filter exists (:1004) but is NOT applied (naive walk made doors disappear, `e46d3d9` un-applied, user-gated 2026-06-11) | `src/AcDream.App/Rendering/Wb/ObjectMeshManager.cs:1027` | Correct fix is full BSP-traversal-order drawing per the holistic port handoff (docs/research/2026-06-11-building-render-holistic-port-handoff.md); the id filter must first be diagnosed on a door GfxObj (Issue113PhantomStairsDumpTests) | Phantom geometry visible NOW (Holtburg meeting-hall "staircase" wall ramp 0x010014C3; 8 orphan polys on hill cottage 0x01000827); draw order also diverges from retail's BSP order | D3DPolyRender drawing-BSP traversal; ConstructMesh 0x0059dfa0 |
| TS-21 | Default run/jump skills 200/300 tuned to feel until the first PlayerDescription lands; "we don't parse yet" comment is STALE (K-fix7 parses PD → SetCharacterSkills) | `src/AcDream.App/Input/PlayerMovementController.cs:341` | Defaults rule only pre-PD or on PD parse failure; jump bumped 200→300 on user complaint (3.01 m max felt too low) | Any window with defaults live predicts run/jump speeds the server disagrees with — observer rubber-banding, local snap-backs | retail height = (skill/(skill+1300))×22.2 + 0.05 |
| TS-22 | `adjust_motion` not ported — backward (×−0.65) / strafe (×−1) translation hand-mirrored at controller call sites; `get_state_velocity` returns (0,0,0) for backward/strafe-left | `src/AcDream.App/Input/PlayerMovementController.cs:1021` | Duplication exists because LeaveGround through the unported path wiped strafe/backward jump velocity (straight-up backward jumps) | Any NEW `get_state_velocity` consumer during backward/strafe motion silently gets zero velocity (the exact prior bug class); hand-mirrored formulas can drift from the grounded block they copy | FUN_00528010 (adjust_motion); FUN_00528960 |
| TS-23 | PK/PKLite/Impenetrable mover bits never set (PlayerKillerStatus not parsed from PD); moverFlags always `IsPlayer ∣ EdgeSlide` | `src/AcDream.App/Input/PlayerMovementController.cs:1128` | Non-PK pair walks through other non-PK players — retail's default for ACE's character-creation defaults too | On a PK/PKLite character, local client lets players walk through where retail collides — prediction vs server disagree the moment PvP statuses enter play | PWD._bitfield acclient.h:6431-6463; pc:406898-406918 |
| TS-24 | RawMotionState command list always empty (bits 11-31 = 0) — discrete motion events (emotes, one-shots) never packed outbound | `src/AcDream.Core.Net/Messages/MoveToState.cs:34` | Discrete client-initiated motions aren't implemented yet; documented builder scope | When player-triggered emotes land, they silently never broadcast — observers see idle while the local client animates | RawMotionState pack (holtburger types.rs) |
| TS-25 | `FlagCurrentStyle` (stance, bit 0x2) never written to outbound MoveToState | `src/AcDream.Core.Net/Messages/MoveToState.cs:130` | Stance switching is M2 combat scope | Once combat-mode switching ships, mid-stance MoveToStates omit the style — server/observers keep the stale stance, wrong cycle family for every subsequent movement | RawMotionFlags CurrentStyle 0x2 (holtburger) |
| TS-26 | UpdatePosition's four u16 sequence numbers parsed but never checked for freshness; retail rejects stale/out-of-order packets | `src/AcDream.Core.Net/Messages/UpdatePosition.cs:30` | Loopback ACE rarely reorders, so the gap is invisible in the dev loop | On a real network, a reordered/post-teleport straggler applies as-is — remotes snap backward / flicker; a teleport-vs-position race renders an entity in the wrong cell | PositionPack trailer (ACE PositionPack.cs::Write) |
| TS-27 | Retransmit handling absent: `RetransmitRequests`/`RejectRetransmit` parsed, but nothing re-sends lost outbound or requests missing inbound sequences (class-doc gap list otherwise stale — ack/position/chat exist) | `src/AcDream.Core.Net/WorldSession.cs:29` | Deferred since the one-shot test harness; dev loop is loopback (no loss) | On any lossy link a dropped fragment is gone forever — entities never spawn, chat vanishes, reassembly stalls; server retransmit requests ignored until session timeout. Stale doc list also misleads readers | PacketHeaderFlags RequestRetransmit 0x1000 / Retransmission 0x1 |
| TS-28 | LoginComplete sent on PlayerCreate (0xF746) arrival; retail sends it after the portal-space transition animation finishes (no such animation exists yet) | `src/AcDream.Core.Net/Messages/GameActionLoginComplete.cs:30` | acdream has no portal-space animation; "InWorld" phrasing in the file is slightly stale (trigger is PlayerCreate) | Server flips the character out of the loading state and pushes initial updates while the client may still be streaming — server logic assuming retail's load-screen duration fires against a half-initialized client | retail post-EnterWorld flow (holtburger messages.rs:391-422) |
| TS-29 | Background music (MIDI) + ambient loops not ported: PlayMusic/StopMusic no-op; StartAmbient reserves a handle that never plays | `src/AcDream.App/Audio/OpenAlAudioEngine.cs:331` | Explicitly outside R5 audio-phase scope; a landblock-attached ambient system is planned separately | Silent world where retail has music/atmosphere; code trusting StartAmbient's handle to mean "playing" is already subtly wrong (StopAmbient looks up a never-created source) | retail MIDI + ambient system (r05) |
| TS-30 | Numbered chat tabs (element ids `0x10000522`–`0x10000525`) render as clickable buttons but do not switch channel filter or affect the transcript — tab state is a no-op | `src/AcDream.App/UI/Layout/ChatWindowController.cs:210` | Retail's tab switching routes transcript lines by chat channel (`gmMainChatUI::gmScrollWindow` sub-windows per tab); the tab wiring is D.5 scope | Tab clicks produce no visible transcript change; retail would filter to the selected channel — all chat always shows in all tabs | `gmMainChatUI::PostInit` tab setup @0x4ce2a0; holtburger chat tab handling |
| TS-31 | Squelch toggle absent (no `/squelch` slash command, no clickable name-tags to silence); retail's squelch list filters incoming chat lines | `src/AcDream.Core/Chat/ChatLog.cs` | Squelch is a social / moderation feature deferred to post-M1.5; the data structure (`ChatLog`) has no squelch set today | Any player can spam all clients; clickable-name-tag contextual menu (used in retail to squelch, tell, add-to-friends) is absent | `ChatFilter::IsSquelched`; retail right-click player name → Squelch menu |
| TS-32 | `ClientObjectTable` has no pre-queue for a child `CreateObject` that arrives before its parent (out-of-order PARENTED create); such objects are ingested as root objects and their `ContainerId` links a not-yet-known container. Retail's `null_object_table` + `null_weenie_object_table` hold unresolvable objects until the parent arrives | `src/AcDream.Core/Items/ClientObjectTable.cs` (`Ingest`) | PD↔`CreateObject` ordering is handled (upsert semantics); out-of-order PARENTED creates are observed only at high packet loss or in vendor/corpse multi-object bursts on non-loopback links; deferred to D.5.5+ | A container's child object arriving before the container is ingested as a root item — it won't appear in `GetContents` until the next `RecordMembership` or a move event corrects the parent link | `CObjectMaint::null_object_table` / `null_weenie_object_table` (acclient.h / named-retail pc) |

---

## 5. Unclear (UN) — 5 rows

These rows have a missing, contradictory, or never-argued justification.
They are the highest-priority audits: each needs either a recorded
equivalence argument (promote to AD/AP) or a fix.

| # | Divergence | Where (file:line) | Recorded justification (deficient) | Risk if assumption breaks | Retail oracle |
|---|---|---|---|---|---|
| UN-1 | `CheckOtherCells` iterates the overlap set SORTED by cell id; retail walks the CELLARRAY in build order — and the loop halts on the first non-OK result, so order is behavior-bearing | `src/AcDream.Core/Physics/CellTransit.cs:1718` | Justified only as "deterministic order for greppable probe logs" — no equivalence argument vs retail's array order recorded | A sphere straddling two cells that would each return a different non-OK result halts on a different cell than retail — different collision normal / slide direction at multi-cell straddles | `CTransition::check_other_cells` pc:272717-272798 |
| UN-3 | AdminEnvirons fog-override RGB tints hardcoded with no retail constant cited (RedFog 0.60/0.05/0.05 etc.); Snapshot replaces fog COLOR only, keeping keyframe distances on an unverified assumption | `src/AcDream.Core/World/WeatherState.cs:350` | Enum semantics cite ACE EnvironChangeType + r12 §5.2; no source for the RGB values or the color-only override scope | A server-forced fog event renders the wrong hue and/or wrong density vs what retail clients showed for the same packet | AdminEnvirons 0xEA60; ACE EnvironChangeType.cs |
| UN-4 | GfxObj double-sided/negative-surface handling keeps WB's legacy logic (cull-mode double-siding, no reversed-winding duplicate, different neg-surface predicate) while the CellStruct path follows the retail-cited `ConstructMesh` reading | `src/AcDream.App/Rendering/Wb/ObjectMeshManager.cs:1059` (CellStruct contrast :1396-1410) | No recorded justification on the GfxObj side — it is the unmodified WB extraction; the retail citation was added only to the CellStruct path | GfxObj models retail draws via duplicated-reversed-winding get wrong back-face lighting (normals not inverted) or missing/extra negative faces — dark or absent faces from behind | `D3DPolyRender::ConstructMesh` 0x0059dfa0 |
| UN-5 | Run multiplier applied to backward (and strafe) speed while the wire reports speed 1.0; the 0.65 backward factor IS retail's, the runMul on top is justified only by feel ("~2.4× ratio felt wrong"); strafe cites holtburger, backward cites nothing | `src/AcDream.App/Input/PlayerMovementController.cs:909` | Feel fix (K-fix3); no retail citation for run-scaling backward movement | If retail does NOT run-scale backward, the local body moves up to ~2.4× faster backward than the wire declares — observers dead-reckon slower and see lag/teleport when backing up at run | adjust_motion FUN_00528010 (0.65 only); holtburger common.rs (sidestep) |
| UN-6 | Fixed 200 ms sleep between ConnectRequest and ConnectResponse; retail inserts no delay. Annotated only as "with 200ms race delay"; the 2026-06-04 audit flagged it, the follow-up refuted "forbidden workaround" but wrote no fuller rationale back | `src/AcDream.Core.Net/WorldSession.cs:484` | Presumed ACE port+1 listener race guard — four words, no citation | Every login eats a flat 200 ms; if the race needs longer on a loaded server, the handshake fails intermittently (ConnectResponse ignored → CharacterList never arrives, exit-29 shape) with no retry — a timing constant masking an unconfirmed root cause | (none recorded) |
| UN-7 | Outdoor OBJECT point lighting uses `calc_point_light` (wrap/norm + per-channel cap, `~1/d²`) for ALL meshes including static buildings, but retail's object path is unconfirmed — `config_hardware_light` (0x0059ad30) sets D3D-FF point lights (`Diffuse=color×intensity`, `Attenuation=(0,1,0)`⇒`1/d`, `Range=falloff×1.5`, `material.diffuse=white`) yet that math would blow walls WHITE while retail stays DIM, so static buildings may instead use the `SetStaticLightingVertexColors` bake. Model + the brightness-scaling factor both UNRESOLVED (issue #140 / Fix D) | `src/AcDream.App/Rendering/Shaders/mesh_modern.vert` (`pointContribution`); `src/AcDream.Core/Lighting/LightManager.cs` (`SelectForObject`) | Fix A/B ported calc_point_light + per-object selection for objects without confirming retail uses that model for static buildings; cdb captured the D3D-FF path but it contradicts the observed dim result | Outdoor buildings blow out warm near torches (the #140 meeting-hall symptom); whichever model is wrong, the object torch contribution is too strong | `config_hardware_light` 0x0059ad30; `SetStaticLightingVertexColors` 0x0059cfe0; `rangeAdjust=1.5` 0x00820cc4 — see docs/research/2026-06-18-lighting-a7-fixABC-shipped-fixD-handoff.md |

---

## 6. Retire-next shortlist

Temporary-stopgap + unclear rows, ordered by risk (symptom severity ×
likelihood the guarding assumption breaks). Items below the line are
phase-gated — they carry their trigger in their row and should land
WITH that phase, not before.

1. **TS-20 — GfxObj DrawingBSP traversal (#113)** — phantom geometry is visible in Holtburg RIGHT NOW; the holistic port handoff already specs the fix; first diagnose the id filter against a door GfxObj.
2. **TS-27 — Retransmit handling** — sole hard blocker for any non-loopback play; failure mode is silent permanent stalls (entities never spawn). Also fix the stale class-doc gap list while there.
3. **TS-4 — Path-6 steep slide-tangent shortcut** — landing/contact state diverges on every airborne-steep hit; the L.5+ retail-strict followup is already filed with the missing-ingredient analysis.
4. **UN-5 — Backward/strafe run multiplier** — potential ~2.4× local-vs-wire speed mismatch on a common input (S at run); one cdb session against retail answers it.
5. **UN-1 — CheckOtherCells iteration order** — behavior-bearing halt order with a log-cosmetics justification; trivial to fix (iterate CELLARRAY build order, sort only in probe output).
6. **TS-1 — PrecipiceSlide stop-at-edge** — visible movement mismatch at every cliff/roof edge; diagnostic already records which ingredient is missing.
7. **TS-22 — adjust_motion port** — active bug-class generator: any new `get_state_velocity` consumer during backward/strafe silently gets zero velocity.
8. **TS-26 — Position sequence freshness** — real-network correctness; pairs naturally with TS-27 in one transport-hardening pass.
9. **UN-6 — 200 ms ConnectResponse sleep** — unexplained constant on every login with an intermittent-failure shape; either find the ACE race and cite it, or replace with an acknowledged-ready check.
10. **UN-4 — GfxObj sides/negative-surface logic** — diagnose against the retail-cited CellStruct interpretation on a known double-sided GfxObj; promote to AP with a citation or align it.
11. **TS-8 — MagicUpdateEnchantment StatMod parse (#7/#12)** — vitals wrong for the whole session after any buff; parser shape is known from holtburger.
12. **TS-13 — CallPES/DefaultScript animation hooks** — the blocker comment is stale since C.1.5a shipped PhysicsScriptRunner; possibly a cheap wire-up now.
13. **UN-3 — AdminEnvirons tints** — invented RGB constants + unverified color-only scope; one decomp lookup against the 0xEA60 handler.
14. **TS-19 — Legacy ChaseCamera deletion** — already marked "pending the follow-up deletion commit"; its continued existence can mask or manufacture flap symptoms during debugging.

**Phase-gated (do WITH the phase, flagged here so they aren't forgotten):**
M2 combat must land TS-2 (BspOnlyDispatch terms), TS-5 (CanJump gating),
TS-23 (PK bits), TS-25 (stance in MoveToState), TS-17 (AttackConditions),
and revisit AP-13 (ComputeDamage) + AP-24 (jump-charge constant via the
0x0056ADE0 decompile). Emote work must land TS-24 (command-list packing).
Membership Stage 2 must land TS-18 (BuildingCellId).
The audio phase lands TS-9/TS-29; the animation-hook layer lands
TS-10/TS-11/TS-12/TS-13/TS-14.

---

*Maintenance: this register is part of the definition of done for any
phase that adds or removes a divergence. Sources merged 2026-06-12:
5-area code sweep, `docs/architecture/worldbuilder-inventory.md`,
`docs/ISSUES.md` accepted-divergence entries (#96, #49, #50).*