# Indoor BSP World-Origin Fix Implementation Plan > **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking. **Goal:** Stop indoor BSP step-down + Path-4 land from writing local-space `ContactPlane`s by passing the cell's actual world rotation + world origin to `BSPQuery.FindCollisions`. **Architecture:** Single-call-site mechanical fix at `TransitionTypes.cs:1442`. Decompose `cellPhysics.WorldTransform` once, pass the rotation as `localToWorld` and the translation as `worldOrigin`. Mirrors the existing correct pattern at `:1808` for object BSP queries. **Tech Stack:** C# .NET 10, xUnit, `System.Numerics.Matrix4x4.Decompose`, existing `BSPQuery` / `Transition` / `CellPhysics` types. **Spec:** [`docs/superpowers/specs/2026-05-20-indoor-bsp-worldorigin-fix-design.md`](../specs/2026-05-20-indoor-bsp-worldorigin-fix-design.md) --- ## File Structure **Files to modify:** - `src/AcDream.Core/Physics/TransitionTypes.cs` — Single call site at `:1442`. Add 8-10 lines for `Matrix4x4.Decompose` + updated arg list. **Files to extend:** - `tests/AcDream.Core.Tests/Physics/BSPQueryTests.cs` — Add one regression test (~50 lines including fixture builder) at the end of the file. Verifies `BSPQuery.FindCollisions` with `path.StepDown=true` + non-identity `localToWorld` + non-zero `worldOrigin` writes a world-space `ContactPlane`. **No files created.** No files deleted (Bug A's `TryFindIndoorWalkablePlane` removal is a separate slice — out of scope for this plan). --- ## Task 1: Add regression test — BSPQuery.FindCollisions Path 3 with translated cell This test verifies the BSPQuery API's correctness when called with non-identity world transforms — it documents the expected behavior and guards against future regressions in `BSPQuery`. It will already pass before the fix at `:1442` (because `BSPQuery` itself is correct when called correctly), but it locks in the contract. **Files:** - Modify: `tests/AcDream.Core.Tests/Physics/BSPQueryTests.cs` — append a new test method after the existing `FindWalkableSphere_SteepPoly_RejectedByWalkableAllowance` test (the last one in the file, around line 421). - [ ] **Step 1: Write the failing test** Append to `tests/AcDream.Core.Tests/Physics/BSPQueryTests.cs` (after the last test method, before the closing `}` of the class): ```csharp // ========================================================================= // FindCollisions — world-origin / world-rotation correctness (spec 2026-05-20) // ========================================================================= /// /// Build a single-leaf BSP with one horizontal floor polygon at the given /// cell-local Z. Vertex array forms a 4x4 m square centered at cell-local /// (0, 0). /// private static (PhysicsBSPNode root, Dictionary resolved) BuildSingleFloorBsp(float floorZ) { var verts = new[] { new Vector3(-2f, -2f, floorZ), new Vector3( 2f, -2f, floorZ), new Vector3( 2f, 2f, floorZ), new Vector3(-2f, 2f, floorZ), }; var root = new PhysicsBSPNode { Type = BSPNodeType.Leaf, BoundingSphere = new Sphere { Origin = new Vector3(0f, 0f, floorZ), Radius = 3f, }, }; root.Polygons.Add(0); var resolved = new Dictionary { [0] = new ResolvedPolygon { Vertices = verts, Plane = new Plane(Vector3.UnitZ, -floorZ), NumPoints = 4, SidesType = CullMode.None, }, }; return (root, resolved); } [Fact] public void FindCollisions_StepDown_TranslatedWorldOrigin_WritesWorldSpacePlane() { // Cell is translated +94 m in world Z (i.e., the cell-local floor at // Z=0 sits at world Z=94). This mirrors the Holtburg cottage scenario // captured in launch-cp-probe.log (cell 0xA9B40150, floor world // Z≈94.02). var (root, resolved) = BuildSingleFloorBsp(floorZ: 0f); var transition = new Transition(); transition.SpherePath.WalkableAllowance = PhysicsGlobals.FloorZ; transition.SpherePath.WalkInterp = 1.0f; transition.SpherePath.StepDown = true; transition.SpherePath.StepDownAmt = 0.5f; // Foot sphere in cell-local space: just above the floor. var localSphere = new Sphere { Origin = new Vector3(0f, 0f, 0.48f), Radius = 0.48f, }; var state = BSPQuery.FindCollisions( root, resolved, transition, localSphere, localSphere1: null, localCurrCenter: localSphere.Origin, localSpaceZ: Vector3.UnitZ, scale: 1.0f, localToWorld: Quaternion.Identity, engine: null, worldOrigin: new Vector3(0f, 0f, 94f)); // Path 3 step-down should fire and adjust the sphere onto the floor. Assert.Equal(TransitionState.Adjusted, state); // ContactPlane must be in world space: normal stays (0,0,1) since the // cell rotation is identity; D = -world_floor_Z = -94. Assert.True(transition.CollisionInfo.ContactPlaneValid); Assert.Equal(1.0f, transition.CollisionInfo.ContactPlane.Normal.Z, precision: 3); Assert.Equal(-94.0f, transition.CollisionInfo.ContactPlane.D, precision: 2); } ``` - [ ] **Step 2: Run the test to verify it passes** Run: ```powershell dotnet test tests/AcDream.Core.Tests/AcDream.Core.Tests.csproj -c Debug --nologo --filter "FullyQualifiedName~FindCollisions_StepDown_TranslatedWorldOrigin" ``` Expected: ``` Passed! - Failed: 0, Passed: 1, Skipped: 0, Total: 1 ``` If it fails, examine the assertion output. The most likely failure mode: `TransitionState.OK` instead of `Adjusted` — means the step-down didn't adjust onto the floor. Adjust `StepDownAmt` / sphere position to ensure the sphere center is within `radius` of the floor plane so `find_walkable` accepts the contact. - [ ] **Step 3: Commit** ```powershell git add tests/AcDream.Core.Tests/Physics/BSPQueryTests.cs git commit -m "test(physics): BSPQuery.FindCollisions writes world-space plane with translated origin Regression test for indoor BSP world-origin fix (Bug B). Verifies that BSPQuery.FindCollisions with path.StepDown=true and a non-zero worldOrigin parameter writes a world-space ContactPlane to CollisionInfo (not a cell-local-space one). Passes before the call-site fix at TransitionTypes.cs:1442 because BSPQuery itself is correct when called with the right args — it's the caller that was passing the defaults. This test locks in the BSPQuery contract so the relationship between worldOrigin/localToWorld input and ContactPlane.D output cannot regress silently. Spec: docs/superpowers/specs/2026-05-20-indoor-bsp-worldorigin-fix-design.md. Co-Authored-By: Claude Opus 4.7 (1M context) " ``` --- ## Task 2: Apply the call-site fix Decompose `cellPhysics.WorldTransform` and pass the rotation + translation to `BSPQuery.FindCollisions`. This is the actual bug fix. **Files:** - Modify: `src/AcDream.Core/Physics/TransitionTypes.cs:1442` — the BSP collision call inside the indoor branch of `FindEnvCollisions`. Replace the 10-arg invocation with a Decompose + 11-arg invocation including `localToWorld` + `worldOrigin`. - [ ] **Step 1: Read the current call site for exact context match** Read `src/AcDream.Core/Physics/TransitionTypes.cs` lines 1430-1455 to confirm the exact whitespace and surrounding code. (We need the exact `old_string` for the Edit tool.) - [ ] **Step 2: Apply the edit** Use Edit on `src/AcDream.Core/Physics/TransitionTypes.cs`: `old_string`: ```csharp // Use the full 6-path BSP dispatcher for retail-faithful collision. // Use pre-resolved polygons (vertices+planes computed at cache time). var cellState = BSPQuery.FindCollisions( cellPhysics.BSP.Root, cellPhysics.Resolved, this, localSphere, localSphere1, localCurrCenter, Vector3.UnitZ, // local space Z is up 1.0f, // scale = 1.0 for cell geometry Quaternion.Identity, engine); // engine needed for Path 5 step-up ``` `new_string`: ```csharp // Use the full 6-path BSP dispatcher for retail-faithful collision. // Use pre-resolved polygons (vertices+planes computed at cache time). // // 2026-05-20 (Bug B fix): pass the cell's world rotation + // translation so the BSP's internal find_walkable / // step_sphere_down / Path-4 land write world-space ContactPlanes // (NOT cell-local). The prior call passed Quaternion.Identity // and defaulted worldOrigin = Vector3.Zero — which corrupted // every Path 3 + Path 4 CP write inside an indoor cell with // D ≈ 0 instead of D = -world_floor_Z. Mirrors the existing // correct pattern at the FindObjCollisions call site. // // Retail oracle: BSPTREE::find_collisions (decomp // acclient_2013_pseudo_c.txt:323924) calls Plane::localtoglobal // (:323921) before set_contact_plane. Our TransformNormal + // TransformVertices + BuildWorldPlane chain is the equivalent // — it just needs the right rotation + origin. Quaternion cellRotation; Vector3 cellOrigin; if (Matrix4x4.Decompose(cellPhysics.WorldTransform, out _, out cellRotation, out cellOrigin)) { // Clean decompose — use the extracted rotation + translation. } else { // Matrix has shear or other non-decomposable parts. EnvCell // WorldTransform is always rigid rotation + translation per // the dat format, so this branch should never fire. Log a // one-shot warning + fall back to identity rotation + // .Translation so we degrade to "translation-only" instead // of the original "both broken". Console.WriteLine(System.FormattableString.Invariant( $"[indoor-bsp] WARN cellPhysics.WorldTransform did not decompose cleanly for cell 0x{sp.CheckCellId:X8} — falling back to identity rotation")); cellRotation = Quaternion.Identity; cellOrigin = cellPhysics.WorldTransform.Translation; } var cellState = BSPQuery.FindCollisions( cellPhysics.BSP.Root, cellPhysics.Resolved, this, localSphere, localSphere1, localCurrCenter, Vector3.UnitZ, // local space Z is up 1.0f, // scale = 1.0 for cell geometry cellRotation, engine, // engine needed for Path 5 step-up worldOrigin: cellOrigin); ``` - [ ] **Step 3: Build to verify the change compiles** Run: ```powershell dotnet build -c Debug ``` Expected: `Build succeeded.` with 0 errors. Warnings unchanged from baseline (3 pre-existing xUnit warnings). - [ ] **Step 4: Run the regression test (Task 1's) to verify it still passes** Run: ```powershell dotnet test tests/AcDream.Core.Tests/AcDream.Core.Tests.csproj -c Debug --no-build --nologo --filter "FullyQualifiedName~FindCollisions_StepDown_TranslatedWorldOrigin" ``` Expected: ``` Passed! - Failed: 0, Passed: 1, Skipped: 0, Total: 1 ``` (The Task 1 test exercises `BSPQuery` directly; this fix is at the caller, so the test still passes.) --- ## Task 3: Run the broader physics test suite — confirm no regressions Verify the existing 8-failure baseline is unchanged (2 BSPStepUp + 6 MotionInterpreter pre-existing failures, all unrelated to this fix). - [ ] **Step 1: Run all physics tests** Run: ```powershell dotnet test tests/AcDream.Core.Tests/AcDream.Core.Tests.csproj -c Debug --no-build --nologo --filter "FullyQualifiedName~Physics" ``` Expected: ``` Failed! - Failed: 8, Passed: ...(at least 405), Skipped: 0, Total: ... ``` The 8 failures are the documented baseline. If you see 9+ failures or different failure names, the fix introduced a regression — investigate before continuing. - [ ] **Step 2: Cross-check the failures match the baseline** Verify the failed test names match this set (no new failures, no new passes that were previously failing): Expected failing tests: ``` AcDream.Core.Tests.Physics.MotionInterpreterTests.GetMaxSpeed_WalkForward_ReturnsWalkAnimSpeed AcDream.Core.Tests.Physics.MotionInterpreterTests.GetMaxSpeed_Idle_ReturnsZero AcDream.Core.Tests.Physics.MotionInterpreterTests.GetMaxSpeed_WalkBackward_ReturnsWalkAnimSpeedTimesBackwardsFactor AcDream.Core.Tests.Physics.MotionInterpreterTests.GetMaxSpeed_* (3 more) AcDream.Core.Tests.Physics.BSPStepUpTests.C3_Path6_AirborneMoverHitsSteepSlope_SetsCollide AcDream.Core.Tests.Physics.BSPStepUpTests.* (1 more) ``` If the failing-test list has changed, stop and investigate. The fix should not affect motion-interpreter or step-up behavior. --- ## Task 4: Commit the fix - [ ] **Step 1: Stage the modified file** ```powershell git add src/AcDream.Core/Physics/TransitionTypes.cs git status ``` Expected `git status`: ``` Changes to be committed: modified: src/AcDream.Core/Physics/TransitionTypes.cs ``` (Only `TransitionTypes.cs` should be staged. If the test file appears, it was already committed in Task 1.) - [ ] **Step 2: Commit with the spec's commit message** ```powershell git commit -m "fix(physics): pass cell world-transform to indoor BSP collision Indoor cell BSP queries at TransitionTypes.cs:1442 were calling BSPQuery.FindCollisions with Quaternion.Identity + defaulted Vector3.Zero worldOrigin. Inside the BSP, Path 3 (step_sphere_down) and Path 4 (land-on-surface) use those params to build the world-space ContactPlane. Result: planes written with D ~ 0 instead of the cell's world floor Z (e.g. -94.02 for Holtburg cottages). 320 corrupt CP writes per Holtburg session per the [cp-write] probe. Fix: decompose cellPhysics.WorldTransform once at the call site, pass the rotation as localToWorld and the translation as worldOrigin. Mirrors the existing correct pattern at :1808 (FindObjCollisions, passes obj.Rotation + obj.Position). Retail oracle: BSPTREE::find_collisions (acclient_2013_pseudo_c.txt:323924) calls Plane::localtoglobal at :323921 before set_contact_plane. Our TransformNormal + TransformVertices + BuildWorldPlane chain is the equivalent — it just needs the right rotation + origin. Spec: docs/superpowers/specs/2026-05-20-indoor-bsp-worldorigin-fix-design.md. Evidence: launch-cp-probe.log capture 2026-05-20, [cp-write] probe. Co-Authored-By: Claude Opus 4.7 (1M context) " ``` - [ ] **Step 3: Verify commit landed cleanly** ```powershell git log --oneline -3 ``` Expected: top of log shows the fix commit, followed by the regression-test commit from Task 1, followed by `865634f docs(spec): indoor BSP world-origin / world-rotation fix (Bug B)`. --- ## Task 5: Hand off to user for visual verification The fix's acceptance test is visual + probe-equivalence. The user drives the client and confirms (a) `[cp-write] caller=BSPQuery.StepSphereDown:1123` lines now show correct world-Z D values, and (b) indoor walking visual scenarios behave better. - [ ] **Step 1: Confirm graceful-logout state** Before launching, check no stale acdream client is running (per CLAUDE.md's logout-before-reconnect rules). Run: ```powershell Get-Process -Name AcDream.App -ErrorAction SilentlyContinue ``` If a process is listed, close it gracefully first: ```powershell $proc = Get-Process -Name AcDream.App -ErrorAction SilentlyContinue if ($proc) { $proc.CloseMainWindow() | Out-Null $proc.WaitForExit(5000) | Out-Null } Start-Sleep -Seconds 3 ``` - [ ] **Step 2: Tell the user the launch command** Show the user (do NOT auto-launch — user retains control here): > Fix landed. Ready for visual verification. Launch with the probe flags on: > > ```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_DEVTOOLS = "1" > $env:ACDREAM_PROBE_INDOOR_BSP = "1" > $env:ACDREAM_PROBE_CONTACT_PLANE = "1" > dotnet run --project src\AcDream.App\AcDream.App.csproj --no-build -c Debug 2>&1 | Tee-Object -FilePath "launch-cp-probe-postfix.log" > ``` > > Walk these scenarios (~30 seconds each): > 1. **Cottage entry** (outdoor → indoor) > 2. **Indoor standstill** for ~10 seconds (stationary case — may still glitch; that's Bug A, expected) > 3. **2nd-floor walking** (primary success criterion for Bug B) > 4. **Cellar descent** > 5. **Single-floor cottage walk** (regression check) > > Then close the window (CloseMainWindow path for graceful logout). I'll grep the new log for the `StepSphereDown:1123` lines and confirm the D values are now correct. - [ ] **Step 3: Read + analyze the post-fix log** After the user closes the window, run: ```powershell Get-Content launch-cp-probe-postfix.log -Encoding Unicode | Out-File launch-cp-probe-postfix.utf8.log -Encoding utf8 ``` Then use Bash: ```bash echo "=== StepSphereDown D distribution (post-fix) ===" grep -E 'caller=BSPQuery\.StepSphereDown' launch-cp-probe-postfix.utf8.log | grep -oE 'D=[-0-9.]+' | sort | uniq -c | sort -rn | head -10 echo "=== Caller distribution (compare to pre-fix) ===" grep -oE 'caller=[A-Za-z_.:0-9]+' launch-cp-probe-postfix.utf8.log | sort | uniq -c | sort -rn | head -10 echo "=== indoor-walkable result distribution (should be ~same; Bug A still active) ===" grep -oE '\[indoor-walkable\].*result=[A-Z]+' launch-cp-probe-postfix.utf8.log | grep -oE 'result=[A-Z]+' | sort | uniq -c ``` Expected: - StepSphereDown D values cluster around realistic floor Z values (-94.0, -94.02, etc., depending on the cell), NOT D=-0.000. - StepSphereDown caller count is similar to pre-fix (~320) OR much lower (the `Plane`-equality suppression in the property setter hides duplicate writes; if seed and BSP-write both produce the same world plane, only the seed shows up). - indoor-walkable MISS/HIT ratio still ~99% MISS (Bug A unchanged). - [ ] **Step 4: Hand off to the user with the assessment** Tell the user one of: **On success (D values now correct):** > Probe-equivalence verified — StepSphereDown D values are now world-Z (e.g. -94.02), not -0.000. Bug B closed. Visual report? If 2nd-floor walking is stabler but stationary cases (cellar entry, indoor standstill) still glitch, that's Bug A — next slice. If you saw the M2-critical indoor scenarios work end-to-end, we can decide whether to ship Bug A as a follow-up phase or punt to post-M2 polish. **On failure (D values still wrong):** > StepSphereDown D values are still wrong (showing X / -0.000 / etc.). The Decompose path either didn't fire or extracted the wrong values. Investigate: check what `cellPhysics.WorldTransform` actually looks like for the affected cells (might need a one-shot `[cell-transform]` probe). --- ## Self-review (run after writing this plan) - **Spec coverage:** Plan covers the spec's Fix section (Task 2), Verification section (Task 3 + Task 5), and the call-site change (Task 2). The risk R1 (cell scale) is acknowledged in-spec but no plan task — fine, deferred. Risk R2 (Decompose returns false) handled inline in Task 2's `else` branch. Risk R3 + R4 informational; no plan task needed. - **Placeholder scan:** No TBD/TODO. Every code block is complete. Commands have exact expected output strings. - **Type consistency:** `cellRotation` (Quaternion), `cellOrigin` (Vector3), `cellPhysics.WorldTransform` (Matrix4x4) — consistent across Task 2. - **Test coverage:** Task 1 covers BSPQuery API regression. Visual verification (Task 5) covers the call-site fix. Acceptable per project convention for one-line mechanical fixes with probe evidence. - **Bug A is explicitly out of scope.** Plan acknowledges it (Task 5 step 4) and defers to a future slice.