# Handoff — Verbatim port of retail `find_cell_list` (the R1 "flap" fix) — 2026-06-02 > **Canonical pickup for the next (fresh) session.** Read this FIRST, then the linked > design docs. This session shipped **R1 — the per-cell `DrawInside` render redesign** (the > interior seal works: the cellar is solid), and that render redesign **exposed a pre-existing > cell-MEMBERSHIP ping-pong** — the visual "flap" the user sees at every cottage threshold. The > render is **correct**; the membership answer it consumes is **unstable**. The next job is a > **verbatim port of retail `CObjCell::find_cell_list`'s containing-cell pick** to make > membership stable. --- ## 0. THE MANDATE + the new authorization (user, 2026-06-02 — non-negotiable) - The standing render mandate is unchanged: **fully working outdoor + indoor + dungeon rendering, no shortcuts/bandaids, port from retail, architecturally-correct even if slower.** (See the master render handoff + design spec, §13 links.) - **NEW, EXPLICIT authorization (this is the key enabler):** *"You are allowed to break whatever you want in the code to get the engine and membership working, it's OK!"* — i.e. **do the faithful verbatim port even if it breaks other physics/movement tests or behavior.** Don't tiptoe around the #98-area accumulated logic. Get the membership right, faithfully; fix any breakage afterward. Run the physics suite to SEE what breaks (eyes open), don't avoid the port. - The user also clarified the fidelity split: **physics/membership = strict, line-by-line faithful decomp port** (this task); **rendering = retail-structured orchestration over the kept WorldBuilder pipeline** (already done in R1 — do NOT re-port rendering from decomp). - The user is **tired of probe-driven debug cycles** — do NOT ask them to run manual probe walks. Diagnose from existing data + the existing apparatus (trajectory-replay harness, auto-logging probes); verify the fix with a **normal visual test** (their eyes) + the deterministic harness. --- ## 1. THE MENTAL MODEL (render vs membership) — internalize this first Two separate systems, in a strict producer→consumer relationship: 1. **Membership** (physics, `AcDream.Core.Physics`): every tick, answers ONE question — *"which cell (room/space) is the player standing in?"* → a single `currentCell` per tick. The world is carved into cells: cellar `0174`, stairs `0175`, main room `0171` (+ sub-cells `0172`/`0173`), vestibule `0170`, outdoors `0031` (note: low id `0x31 < 0x100` ⇒ outdoor landcell). 2. **Render** (`AcDream.App.Rendering`): `draw(currentCell)` — strictly **downstream**. If `currentCell` is jittery, render faithfully redraws the jitter. **The flap = render correctly drawing an oscillating membership answer.** Proof it's membership, not render: when membership is **stable** (standing still in the cellar) the render seals perfectly (solid walls/floor, no bleed — user confirmed). The flap appears **only** at the boundaries where the `[cell-transit]` log shows the cell answer oscillating. **Fix membership → render goes stable; the seal already works.** > Confidence note (honest): *very high* the flap is membership (the cellar-seals proof + the > flap-tracks-cell-flips evidence). NOT a claimed 100% that zero render residual exists — a single > *clean* outdoor→indoor transition has never been observed (the ping-pong masks it), so a small > render tear on a genuine one-time crossing *could* exist. If so it's separate + isolated, and > becomes visible once membership is stable. The membership fix is unambiguously the right next > step regardless. --- ## 2. WHAT THIS SESSION SHIPPED (commit ledger, branch `claude/thirsty-goldberg-51bb9b`) | SHA | What | Keep? | |---|---|---| | `7aca79f` | R0 — locked render-redesign **design spec** (brainstorm outcome) | ✅ authority | | `ce7404b` | R1 **implementation plan** (per-cell DrawInside, TDD) | ✅ authority | | `cf85ea4` | R1 Task 1 — `InteriorEntityPartition` (3-bucket entity split, TDD, 3 tests) | ✅ correct | | `4b75c68` | R1 Task 2 — `InteriorRenderer` per-cell `DrawInside` loop | ✅ correct | | `c4fd711` | R1 Task 3 — **binary render decision** in `GameWindow.OnRender` (indoor = DrawInside only) | ✅ correct | | `58822fe` | R1 Task 4 — repurpose the `WbDrawDispatcher.cs:1756` `ParentCellId==null` bypass (#78) | ✅ correct | | `5ca2f44` | **membership pre-check approximation** (current-cell-first explicit check) | ⚠️ **REPLACE** (see §5) | Working tree is **clean** at `5ca2f44` (untracked = session screenshots + launch logs only). R1 (the render redesign) is done and **proven correct by the visual gate** (cellar seals). The only open R1 blocker is the membership flap (this handoff). **Design + plan docs (read after this handoff):** - Design spec: [`docs/superpowers/specs/2026-06-02-render-pipeline-redesign-design.md`](../superpowers/specs/2026-06-02-render-pipeline-redesign-design.md) - R1 plan: [`docs/superpowers/plans/2026-06-02-render-r1-per-cell-drawinside.md`](../superpowers/plans/2026-06-02-render-r1-per-cell-drawinside.md) - Master render handoff: [`docs/research/2026-06-02-render-pipeline-redesign-handoff.md`](2026-06-02-render-pipeline-redesign-handoff.md) - Retail render reference: [`docs/research/2026-06-02-retail-render-pipeline-full-reference.md`](2026-06-02-retail-render-pipeline-full-reference.md) --- ## 3. THE PROVEN DIAGNOSIS (the flap = membership ping-pong) Captured from the user's R1 walk (`ACDREAM_PROBE_CELL`, `[cell-transit]` lines). **59 cell transitions in one cottage walk** (a clean walk should be ~6–8) — oscillating at every boundary: - **Stairs ↔ cellar** (`0175 ↔ 0174`) at ~(154.3, 9.4, 93.1). Crucially, the **foot Z oscillates ~0.2 m/tick** (93.07 ↔ 93.27; low Z = cellar, high Z = stairs). ⇒ membership is faithfully following a *bouncing position* — this looks like a **SEPARATE stairs/ramp physics instability** (step-up/step-down, #98 family), not (only) the pick. **See §8 — do not conflate.** - **Room ↔ room** (`0171 ↔ 0173 ↔ 0172`) at **constant Z = 94.0**, tiny X/Y movement. ⇒ pure membership-**pick** non-determinism (the unordered HashSet). This is the verbatim-port target. - **Vestibule ↔ outdoors** (`0170 ↔ 0031`) at ~(155, 16). `0031` is an outdoor landcell, so each flip swings the binary render decision to the *outdoor* path → the full sky/world/NPCs flash ("bluish background"). Fixed by the same current-first hysteresis (vestibule wins while it contains you). The `[vis]` log confirms the mechanism: as the root cell flips, the `OutsideView` + visible-cell set flip with it (e.g. room `0171` → `outside(polys=0)` sealed vs stairs `0175` → `outside(polys=1)` sky-through-portal), so the through-door landscape appears/disappears = the flap. Evidence files (this session, may still be present in the worktree root): `launch-r1.log`, `launch-fix.log` (UTF-16 — read with `Select-String` / ripgrep `--encoding utf-16-le`, NOT GNU grep). --- ## 4. ROOT CAUSE + the verbatim retail target ### 4.1 acdream (the bug) `CellTransit.BuildCellSetAndPickContaining` (`src/AcDream.Core/Physics/CellTransit.cs`, the body of `FindCellSet`): - The candidate set is an **unordered `HashSet`** (declared ~line 433). - The current cell IS added first (~line 447, indoor seed) — **but `HashSet` does not preserve insertion order**, and the set's contents churn tick-to-tick at a boundary, so the enumeration can surface a neighbour before the current cell. - The pick (the `foreach (uint candId in candidates)` interior pass, ~lines 544–562 post-`5ca2f44`): iterates the HashSet in arbitrary order, returns the **first** interior cell whose `CellBSP` contains the sphere center (interior-wins). Outdoor fallback = a `gx/gy` XY-column computation (NOT retail's `point_in_cell` on landcells — acdream landcells have no `point_in_cell`). - The player's `CellId` is set from this: `ResolveWithTransition` (`PhysicsEngine.cs:608`) returns the swept `sp.CurCellId` (lines 880/901), which `FindEnvCollisions` (`TransitionTypes.cs:1958`) sets from `FindCellSet`; `PlayerMovementController.cs:1296` does `UpdateCellId(resolveResult.CellId, "resolver")`. **A1 (swept membership) IS ported — the divergence is purely the pick ordering.** ### 4.2 retail (the verbatim source) — `CObjCell::find_cell_list @ 0x52b4e0` (pc:308742–308831) Reads verbatim this session. The structure: ```c // edi = arg4 = the CELLARRAY (an ORDERED DArray) num_cells = 0; added_outside = 0; objcell_id = arg1->objcell_id; // the CURRENT cell cell0 = (objcell_id >= 0x100) ? CEnvCell::GetVisible(objcell_id) : CLandCell::GetVisible(objcell_id); if (objcell_id >= 0x100) CELLARRAY::add_cell(edi, objcell_id, cell0); // CURRENT at INDEX 0 (pc:308766) else CLandCell::add_all_outside_cells(arg1, arg2, arg3, edi); // expand: for each cell already in the array, call its find_transit_cells (vtable[0x80]) (pc:308782) for (i = 0; i < edi->num_cells; i++) if (edi->cells[i].cell) edi->cells[i].cell->vtable[0x80](arg1, arg2, arg3, edi, arg6); // THE PICK (pc:308788–308825): iterate the array IN ORDER from index 0, interior-wins-break *arg5 = nullptr; for (i = 0; i < edi->num_cells; i++) { cell = edi->cells[i].cell; if (cell) { // point relative to the cell's block offset: Vector3 p = arg3->center - LandDefs::get_block_offset(arg1->objcell_id, cell->cell_id); if (cell->vtable[0x84](&p) != 0) { // point_in_cell (pc:308810) *arg5 = cell; // set result on ANY containing cell if ((int16_t)cell->cell_id >= 0x100) { // interior? arg6->hits_interior_cell = 1; break; // INTERIOR-WINS — stop } } } } // (then do_not_load_cells prune, pc:308829+ — out of scope for the flap) ``` **The load-bearing facts:** (a) the current cell is at **index 0**; (b) the pick iterates **in order** and **breaks on the first interior-containing cell**. So **the current cell is tested FIRST — if you're still inside it, it wins and the search stops.** That ordered, current-first iteration IS the hysteresis: *you stay in your current cell until the center genuinely leaves it, never flipping to an overlapping neighbour.* acdream's unordered `HashSet` discarded that ordering. > `CELLARRAY::add_cell` definition was not located by grep (`void CELLARRAY::add_cell(` → no match; > only call sites at pc:279012/288076/308766/309860/309960/310030/310054/310208/317064/317218). > Behaviorally it appends to the ordered array; treat the candidate collection as **ordered + > deduped** (the HashSet already dedups; an ordered-dedup collection is the faithful model). The > fresh session can locate add_cell via Ghidra MCP (`/decompile_function`) or `acclient.h` (CELLARRAY > = `acclient.h:31574`) if exact dedup semantics are wanted. ### 4.3 The fix (the fresh session's task) Replace the unordered `HashSet` candidate set with an **ordered, deduped collection** (mirror retail `CELLARRAY`: current cell at index 0, neighbours in BFS add-order, unique) and port the pick **verbatim**: iterate from index 0; for each **interior** cell, `point_in_cell` via `BSPQuery.PointInsideCellBsp(cell.CellBSP.Root, localCenter)`; first interior-containing → return (break). This is the current-first hysteresis that stops the ping-pong. - Thread the new ordered-collection type through the methods that build candidates: `BuildCellSetAndPickContaining`, `FindTransitCellsSphere`, `AddAllOutsideCells`, `CheckBuildingTransit` (they currently take `HashSet candidates`). Changing the type is the invasive part the user authorized. - **Honest scope:** the **interior** pick is fully verbatim-portable. The **outdoor fallback** (the `gx/gy` XY-column) stays an acdream adaptation — acdream landcells lack retail's `CLandCell::point_in_cell` (they're a terrain grid). Mark it clearly. The flap is all interior/boundary, so the verbatim interior pick covers it. - Suggested collection: a small `CellArray` class — `List` (order) + `HashSet` (O(1) dedup); `Add(id)` appends iff new; ordered enumeration; `Contains`; `Count`. Exposes its list as `IReadOnlyCollection` for the `out cellSet` return. --- ## 5. REPLACE the committed pre-check approximation (`5ca2f44`) `5ca2f44` added an **explicit current-cell-first pre-check** in `BuildCellSetAndPickContaining` (before the interior-pass `foreach`): if the current cell is interior and its `CellBSP` contains the center, return it. This achieves the *property* but NOT retail's ordered-array *structure*, and it still diverges on the multi-neighbour edge (hash-order among non-current candidates). **The user wants this replaced by the verbatim ordered-`CELLARRAY` port (§4.3).** When you implement the ordered pick, **delete the pre-check** (it becomes redundant). - **Keep** the regression guard test added in `5ca2f44`: `CellTransitFindCellSetTests.TwoOverlappingCells_CurrentCellWinsTheStraddle` (two-direction `[Theory]`). It documents the current-cell-first invariant and passes under the verbatim port. Note: it does **not** go RED against the bug statically (the HashSet happens to enumerate the current cell first when the set is small/unchurned — see §7), so it's a guard, not the RED repro. The real verification is the harness + the visual flap gate. --- ## 6. THE WORKFLOW for the fresh session (this is a PHYSICS port) Per CLAUDE.md's mandatory faithful-port workflow (the triangle-Z / frame-swap lessons): 1. **Grep named — DONE.** `find_cell_list` found at pc:308742. 2. **Read decomp — DONE.** §4.2 has the verbatim pseudo-C of the pick. 3. **WRITE PSEUDOCODE** (the step skipped this session): translate retail `find_cell_list`'s candidate-build + ordered pick to readable pseudocode in `docs/research/*_pseudocode.md` before porting. This catches misreads. 4. **PORT FAITHFULLY** line-by-line (§4.3): ordered `CellArray` + in-order current-first interior-wins pick. Same control flow as retail. Don't "improve." 5. **CONFORMANCE TEST**: extend `CellTransitFindCellSetTests` — a multi-neighbour straddle where the current cell wins by *order* (not just by containment), and an indoor↔outdoor straddle (vestibule stays vestibule while it contains you). 6. **VERIFY** (no manual probe walks): the deterministic harness (`CellTransitFindCellSetTests`, `CellarUpTrajectoryReplayTests`, `DoorBugTrajectoryReplayTests`), then **run the FULL physics suite to see breakage** (`dotnet test tests/AcDream.Core.Tests`), then the **visual flap gate** (user walks normally; `ACDREAM_PROBE_CELL` auto-logs so you can confirm the transition count drops 59 → ~6–8 without asking them to do anything extra). **Superpowers:** you may go straight to `superpowers:writing-plans` → `superpowers:executing-plans` for the port (the design is clear — a heavy `brainstorming` pass is probably unnecessary). Use `superpowers:systematic-debugging` if the flap doesn't fully clear and you need to chase a residual. Use `superpowers:test-driven-development` for the conformance tests. --- ## 7. WHY the static unit test alone won't catch it (important nuance) The pre-check / the bug interplay: `.NET HashSet` with a small, unchurned set tends to enumerate in insertion order, and the current cell is added first — so a *static* single-tick test where the current cell contains the center already returns the current cell (the `TwoOverlappingCells` guard PASSES even against the unfixed pick). The production ping-pong is **dynamic** — it arises from (a) the candidate set's contents churning tick-to-tick (reordering the enumeration), and/or (b) the foot position genuinely oscillating across a boundary (the stairs Z-jitter, §8). The **ordered `CELLARRAY`** removes (a) by construction (deterministic current-first order every tick). (b) is the separate physics issue. ⇒ verify dynamically (harness + visual), not just by the static guard. --- ## 8. The SEPARATE stairs-physics suspicion (don't conflate with the pick) On the stairs the foot **Z oscillated ~0.2 m/tick** while membership flipped `0175↔0174`. The room flips were at **constant Z** (pure pick). So: - The **room/vestibule** flips → fixed by the verbatim current-first pick (this task). - The **stairs** flip may be a **separate physics-movement instability** (step-up/step-down on the cellar stairs/ramp — the #98 family: "stuck at the last step", `Transition.AdjustOffset` / `DoStepUp`). The current-first hysteresis will *dampen* it if the wobble stays inside the current cell's BSP, but if the Z-oscillation is large enough to cross the cell boundary it will persist. - **If the stairs still flap after the membership port lands and the room/door flaps are gone**, that's the physics-movement target (a #98-area follow-up) — diagnose it the same evidence-first way (the existing `ACDREAM_CAPTURE_RESOLVE` + the trajectory-replay harness; the user's cellar-stairs is the repro). Do not block the membership port on it. --- ## 9. KEEP / DON'T-REDO (avoid re-litigating settled work) **KEEP (correct, do not reopen for the flap):** - All R1 render code: `InteriorEntityPartition`, `InteriorRenderer` (per-cell DrawInside loop), the binary decision in `GameWindow.OnRender`, the `WbDrawDispatcher` gate fix. The cellar seals — render is correct. - `PortalVisibilityBuilder`, `ClipFrameAssembler`/`ClipFrame`, `EnvCellRenderer`, `TerrainModernRenderer`, the WB mesh pipeline. The render design spec + R1 plan. - The swept-membership chain (A1): `ResolveWithTransition` returning `sp.CurCellId`. Do NOT revert to a static `ResolveCellId` re-derive. - The `5ca2f44` regression test (`TwoOverlappingCells_CurrentCellWinsTheStraddle`). **DON'T:** - Don't reopen R1's render code chasing the flap — the flap is membership. - Don't re-port *rendering* from the decomp (use the WB pipeline — CLAUDE.md). - Don't add a render-side debounce/grace-period for the flap (bandaid — forbidden). - Don't ask the user for manual probe walks (diagnose from existing data + harness; verify visually). --- ## 10. TEST STATE (baseline for regression judgement) - **Pre-existing Core failures (NOT yours — verified):** the handoff's "5" — 2 step-up gaps (incl. an A6.P4 door regression) + 3 door-collision apparatus / A6.P5. The **2 `DoorBugTrajectoryReplayTests` failures** (`TransientState live=0x87 harness=0x83`, e.g. `LiveCompare_DoorBlocksFromOutside_Tick22760`) were **verified pre-existing this session** (they fail without the membership change too). Plus the documented PhysicsResolveCapture/PhysicsDiagnostics **static-leak flakiness** (8–19 failures across runs of identical code). ⇒ the deterministic **membership net** (`CellTransit|FindEnvCollisions|CellGraph|Doorway|Cellar|DoorBug`) is the reliable signal: it was **66 pass + 2 pre-existing DoorBug** with the pre-check. - `tests/AcDream.App.Tests`: **174 green** (incl. `InteriorEntityPartitionTests` ×3, the flipped `EntityClipTests` gate test). - **Breakage is authorized** (§0): when the verbatim port lands, run the full physics suite, diff the failure set against this baseline, and fix genuinely-new breakage (the port may legitimately change membership-dependent test expectations — update them with retail-cited reasoning, don't pin wrong values). --- ## 11. After the membership port: the remaining render arc Once the flap is gone and the seal holds, resume the R1→R7 plan (design spec §7): - **R1b** — per-cell particles (#104): "particles bleed through the ground when looking out the door" — Scene-pass particles aren't cell-clipped (needs a cell link on `ParticleEmitter`; the per-cell `DrawInside` loop makes this tractable). - **R2** — outside-looking-in (`DrawPortal`): "interior walls are transparent when looking in a window/door from outside" — no outdoor→interior portal render yet. - **R3** — dungeons. **R4** — polish (the `CullMode.Landblock→None` winding; remove dormant WB two-pipe scaffolding `Building`/`BuildingLoader`; conformance). - The cottage seal (R1) is **not signed off** until the flap is gone — the membership port is the R1 gate's remaining blocker. --- ## 12. KEY FILES + ANCHORS (quick index) ``` MEMBERSHIP (the task) src/AcDream.Core/Physics/CellTransit.cs FindCellSet (entry, ~388 single-sphere, ~412 multi-sphere) BuildCellSetAndPickContaining (the candidate build + pick — THE function to port) ~433 candidates = new HashSet() ← the unordered set to replace ~447 candidates.Add(currentCellId) ← current added first (indoor seed) ~520 the 5ca2f44 pre-check ← DELETE when the ordered pick lands ~544 foreach interior pass (the pick) ← port verbatim (ordered, current-first) ~558 gx/gy outdoor fallback ← acdream adaptation (landcells lack point_in_cell) FindTransitCellsSphere / AddAllOutsideCells / CheckBuildingTransit ← take `HashSet candidates` (re-type) src/AcDream.Core/Physics/TransitionTypes.cs:1958 ← FindEnvCollisions calls FindCellSet (the swept membership) src/AcDream.Core/Physics/PhysicsEngine.cs:608/880/901← ResolveWithTransition returns swept sp.CurCellId src/AcDream.App/Input/PlayerMovementController.cs:1296 ← UpdateCellId(resolveResult.CellId, "resolver") tests/AcDream.Core.Tests/Physics/CellTransitFindCellSetTests.cs ← conformance home (+ the kept guard) (line numbers ≈ — shifted by 5ca2f44's ~22 lines; grep by method name) RETAIL DECOMP (the verbatim source) CObjCell::find_cell_list 0x52b4e0 pc:308742 (pick = 308788–308825; add_cell @308766; point_in_cell vtable[0x84] @308810; find_transit_cells vtable[0x80] @308782) CEnvCell::find_transit_cells 0x52c820 pc:309968 acclient.h: CELLARRAY 31574 ; CELLINFO 31925 ; SPHEREPATH 32625 Ghidra MCP (port 8081, patchmem.gpr) for /decompile_function on add_cell if exact dedup wanted. RENDER (correct — context only) src/AcDream.App/Rendering/InteriorRenderer.cs ← per-cell DrawInside loop src/AcDream.App/Rendering/InteriorEntityPartition.cs ← 3-bucket entity split src/AcDream.App/Rendering/GameWindow.cs (OnRender ~7530)← the binary decision src/AcDream.App/Rendering/Wb/WbDrawDispatcher.cs:~1744 ← EntityPassesVisibleCellGate (gate fix) ``` --- ## 13. RUNNING THE CLIENT + apparatus (no manual probe walks) Per CLAUDE.md "Running the client" (PowerShell; `+Acdream` spawns at/near the Holtburg cottage): ```powershell $env:ACDREAM_DAT_DIR="$env:USERPROFILE\Documents\Asheron's Call"; $env:ACDREAM_LIVE="1" $env:ACDREAM_TEST_HOST="127.0.0.1"; $env:ACDREAM_TEST_PORT="9000" $env:ACDREAM_TEST_USER="testaccount"; $env:ACDREAM_TEST_PASS="testpassword" $env:ACDREAM_PROBE_CELL="1" # auto-logs [cell-transit]; lets you confirm the count drops, no manual walk dotnet run --project src\AcDream.App\AcDream.App.csproj --no-build -c Debug *>&1 | Tee-Object -FilePath launch.log ``` - Build green BEFORE launching. Logs are UTF-16 (`Select-String` / ripgrep `--encoding utf-16-le`). - A client from THIS session may still be running (graceful close clears ACE in ~3–5s; a hard kill leaves the session stuck ~3 min — see CLAUDE.md). Close gracefully before relaunching. - Verify the flap visually (user's eyes) + the `[cell-transit]` count. Walk: outside `0031` → door `0170` → room `0171` → stairs `0175` → cellar `0174`, and back. Room/door flap should be GONE. --- ## 14. PICKUP PROMPT (copy-paste for the fresh session) ``` VERBATIM PORT of retail CObjCell::find_cell_list's containing-cell pick — to fix the cell-MEMBERSHIP ping-pong that the R1 render redesign exposed (the cottage "flap"). Continue on branch claude/thirsty-goldberg-51bb9b (do NOT branch/worktree; do NOT push without asking; NEVER git stash/gc — a shared stash is under investigation). PowerShell on Windows; launch logs are UTF-16 (Select-String / ripgrep --encoding utf-16-le, NOT GNU grep). AUTHORIZATION (user, explicit): you may BREAK ANY physics/movement code or tests to get the engine + membership working faithfully — breakage is OK, fix later. Do the faithful line-by-line port; don't tiptoe around the #98-area logic. Run the physics suite to SEE what breaks. The user is tired of probe walks — diagnose from existing data + the deterministic trajectory-replay harness; verify with a normal VISUAL test (their eyes) + the auto-logging ACDREAM_PROBE_CELL. READ FIRST (in order): 1. docs/research/2026-06-02-membership-verbatim-port-handoff.md (THIS handoff — full diagnosis, the verbatim retail source §4.2, the fix §4.3, replace-the-pre-check §5, workflow §6, KEEP §9). 2. docs/superpowers/specs/2026-06-02-render-pipeline-redesign-design.md (the render redesign — context; render is CORRECT + downstream of membership). 3. docs/superpowers/plans/2026-06-02-render-r1-per-cell-drawinside.md (R1 plan — what shipped). THE JOB: - Replace the UNORDERED HashSet candidate set in CellTransit.BuildCellSetAndPickContaining with an ORDERED, deduped collection (retail CELLARRAY: current cell at index 0, BFS add-order) and port the pick VERBATIM: iterate from index 0, point_in_cell per interior cell, first interior-containing wins (break) — retail find_cell_list pc:308788-308825. This is the current-first hysteresis that stops the ping-pong. Thread the new type through FindTransitCellsSphere/AddAllOutsideCells/CheckBuildingTransit. - DELETE the 5ca2f44 current-first pre-check (the ordered pick supersedes it). KEEP its regression test (TwoOverlappingCells_CurrentCellWinsTheStraddle). - Outdoor fallback (gx/gy XY-column) stays an acdream adaptation (landcells lack point_in_cell) — mark it. WORKFLOW (physics port — mandatory): grep named (done) → read decomp (done, §4.2) → WRITE PSEUDOCODE (docs/research/) → PORT FAITHFULLY line-by-line → CONFORMANCE TEST → run full physics suite (see breakage vs the §10 baseline; fix new breakage) → VISUAL flap gate (room/door flap GONE; [cell-transit] count 59→~6-8). Use superpowers:writing-plans → executing-plans; test-driven-development for conformance. PROVEN, DON'T RE-LITIGATE: the flap is MEMBERSHIP not render (cellar seals when membership is stable; flap tracks the [cell-transit] ping-pong). R1 render is correct — do NOT reopen it. The 2 DoorBug TransientState failures are PRE-EXISTING (verified). The stairs flip additionally shows the foot Z oscillating ~0.2m/tick = a SEPARATE physics issue (#98 family, §8) — if it persists after the membership port (room/door fixed), that's the next target; don't block on it. GOAL: stable membership → the R1 seal holds with no flap. Then resume R1b (particles) → R2 (outside-looking-in) → R3/R4 per the design spec. ```