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+# A8.F Swept-Sphere Camera Collision — 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 the 3rd-person camera eye from clipping through walls by sweeping a 0.3 m collision sphere from the head-pivot to the desired eye and publishing the stopped position — porting retail's `SmartBox::update_viewer` spring arm. This stabilizes the A8.F indoor-visibility decisions (which key off the eye) and fixes the flap / missing-wall symptoms.
+
+**Architecture:** A narrow `ICameraCollisionProbe` is injected into `RetailChaseCamera`. After the camera damps the desired eye and before it publishes, it asks the probe to sweep `pivot→eye`. The concrete `PhysicsCameraCollisionProbe` wraps the existing `PhysicsEngine.ResolveWithTransition`, which already collides against both indoor cell walls (`FindEnvCollisions`) and outdoor/baked GfxObj shells (`FindObjCollisions`). Gated by `CameraDiagnostics.CollideCamera` (default ON).
+
+**Tech Stack:** C# / .NET 10, Silk.NET, xUnit. Spec: `docs/superpowers/specs/2026-05-29-a8f-camera-collision-design.md`.
+
+**Reference (read before starting):**
+- Spec: `docs/superpowers/specs/2026-05-29-a8f-camera-collision-design.md`
+- Camera: `src/AcDream.App/Rendering/RetailChaseCamera.cs` (eye `:113`, damp `:131`, publish `:136`, fade `:367`)
+- Engine: `src/AcDream.Core/Physics/PhysicsEngine.cs:589` (`ResolveWithTransition`, returns `sp.CheckPos` as `.Position` at `:846`/`:865`)
+- Sphere convention: `src/AcDream.Core/Physics/TransitionTypes.cs:517-547` (`InitPath` sets `LocalSphere[0].Origin = (0,0,radius)`)
+- Player self-skip: `src/AcDream.App/Input/PlayerMovementController.cs` (`CellId` `:133`, `LocalEntityId` `:144`)
+
+---
+
+## Task 1: Add `CameraDiagnostics.CollideCamera` flag
+
+**Files:**
+- Modify: `src/AcDream.Core/Rendering/CameraDiagnostics.cs`
+- Test: `tests/AcDream.Core.Tests/Rendering/CameraDiagnosticsTests.cs`
+
+- [ ] **Step 1: Write the failing test**
+
+Add to `CameraDiagnosticsTests.cs` (inside the `CameraDiagnosticsTests` class):
+
+```csharp
+ [Fact]
+ public void CollideCamera_DefaultOn_AndPersistsRuntimeChanges()
+ {
+ CameraDiagnostics.CollideCamera = true;
+ Assert.True(CameraDiagnostics.CollideCamera);
+
+ CameraDiagnostics.CollideCamera = false;
+ Assert.False(CameraDiagnostics.CollideCamera);
+
+ CameraDiagnostics.CollideCamera = true; // reset so other tests aren't poisoned
+ }
+```
+
+- [ ] **Step 2: Run test to verify it fails**
+
+Run: `dotnet test tests/AcDream.Core.Tests/AcDream.Core.Tests.csproj --filter "FullyQualifiedName~CameraDiagnosticsTests.CollideCamera_DefaultOn"`
+Expected: FAIL — compile error, `CollideCamera` does not exist.
+
+- [ ] **Step 3: Add the property**
+
+In `CameraDiagnostics.cs`, add after the `UseRetailChaseCamera` property (after line 28):
+
+```csharp
+ ///
+ /// When true (default), the chase camera sweeps a 0.3 m collision
+ /// sphere from the head-pivot to the desired eye and stops it at the
+ /// first wall (retail SmartBox::update_viewer spring arm), so
+ /// the eye never sits behind/inside geometry. Initial state from
+ /// ACDREAM_CAMERA_COLLIDE; default-on if unset, off only when
+ /// explicitly set to "0".
+ ///
+ public static bool CollideCamera { get; set; } =
+ Environment.GetEnvironmentVariable("ACDREAM_CAMERA_COLLIDE") != "0";
+```
+
+- [ ] **Step 4: Run test to verify it passes**
+
+Run: `dotnet test tests/AcDream.Core.Tests/AcDream.Core.Tests.csproj --filter "FullyQualifiedName~CameraDiagnosticsTests.CollideCamera_DefaultOn"`
+Expected: PASS.
+
+- [ ] **Step 5: Commit**
+
+```bash
+git add src/AcDream.Core/Rendering/CameraDiagnostics.cs tests/AcDream.Core.Tests/Rendering/CameraDiagnosticsTests.cs
+git commit -m "feat(render): Phase A8.F — add CameraDiagnostics.CollideCamera flag (default on)"
+```
+
+---
+
+## Task 2: Camera-collision probe interface + `PhysicsCameraCollisionProbe`
+
+**Files:**
+- Create: `src/AcDream.App/Rendering/ICameraCollisionProbe.cs`
+- Create: `src/AcDream.App/Rendering/PhysicsCameraCollisionProbe.cs`
+- Test: `tests/AcDream.App.Tests/Rendering/PhysicsCameraCollisionProbeTests.cs`
+
+- [ ] **Step 1: Write the failing test**
+
+Create `tests/AcDream.App.Tests/Rendering/PhysicsCameraCollisionProbeTests.cs`:
+
+```csharp
+using System.Numerics;
+using AcDream.App.Rendering;
+using AcDream.Core.Physics;
+using Xunit;
+
+namespace AcDream.App.Tests.Rendering;
+
+public class PhysicsCameraCollisionProbeTests
+{
+ // The probe must convert the desired eye path (where the SPHERE CENTER
+ // should travel) into the foot-capsule path InitPath expects (which offsets
+ // sphere0 up by radius), then invert it on the result. Verify the round trip.
+ [Fact]
+ public void SpherePathOffset_RoundTrips()
+ {
+ var p = new Vector3(10f, 20f, 30f);
+ const float r = 0.3f;
+
+ var path = PhysicsCameraCollisionProbe.ToSpherePath(p, r);
+ Assert.Equal(p.Z - r, path.Z, 5);
+ Assert.Equal(p.X, path.X, 5);
+ Assert.Equal(p.Y, path.Y, 5);
+
+ var back = PhysicsCameraCollisionProbe.FromSpherePath(path, r);
+ Assert.Equal(p.X, back.X, 5);
+ Assert.Equal(p.Y, back.Y, 5);
+ Assert.Equal(p.Z, back.Z, 5);
+ }
+
+ // cellId == 0 means "no starting cell" — the probe must short-circuit and
+ // return the desired eye without touching the engine.
+ [Fact]
+ public void SweepEye_NoStartingCell_ReturnsDesiredEyeUnchanged()
+ {
+ var probe = new PhysicsCameraCollisionProbe(new PhysicsEngine());
+ var pivot = new Vector3(0f, 0f, 1.5f);
+ var eye = new Vector3(-2f, 0f, 2.2f);
+
+ var result = probe.SweepEye(pivot, eye, cellId: 0, selfEntityId: 0);
+
+ Assert.Equal(eye, result);
+ }
+}
+```
+
+- [ ] **Step 2: Run test to verify it fails**
+
+Run: `dotnet test tests/AcDream.App.Tests/AcDream.App.Tests.csproj --filter "FullyQualifiedName~PhysicsCameraCollisionProbeTests"`
+Expected: FAIL — `ICameraCollisionProbe` / `PhysicsCameraCollisionProbe` do not exist.
+
+- [ ] **Step 3: Create the interface**
+
+Create `src/AcDream.App/Rendering/ICameraCollisionProbe.cs`:
+
+```csharp
+using System.Numerics;
+
+namespace AcDream.App.Rendering;
+
+///
+/// Sweeps a small sphere from the camera pivot (player head) toward the
+/// desired eye and returns the stopped (non-penetrating) eye. The seam that
+/// lets collide its eye without depending on
+/// the physics engine directly (and stay unit-testable with a fake).
+///
+public interface ICameraCollisionProbe
+{
+ ///
+ /// Roll a collision sphere from to
+ /// ; return the position it reaches without
+ /// penetrating geometry. Returns unchanged
+ /// when nothing blocks the path or when is 0.
+ ///
+ Vector3 SweepEye(Vector3 pivot, Vector3 desiredEye, uint cellId, uint selfEntityId);
+}
+```
+
+- [ ] **Step 4: Create the implementation**
+
+Create `src/AcDream.App/Rendering/PhysicsCameraCollisionProbe.cs`:
+
+```csharp
+using System.Numerics;
+using AcDream.Core.Physics;
+
+namespace AcDream.App.Rendering;
+
+///
+/// backed by the player's swept-sphere
+/// engine. Ports retail's SmartBox::update_viewer (0x00453ce0): sweep
+/// the 0.3 m viewer_sphere from the head-pivot to the desired eye via a
+/// CTransition and use the stopped position. Reusing
+/// collides against indoor
+/// cell walls (FindEnvCollisions) AND outdoor/baked GfxObj shells
+/// (FindObjCollisions) in one faithful path.
+///
+public sealed class PhysicsCameraCollisionProbe : ICameraCollisionProbe
+{
+ /// Retail viewer_sphere radius (acclient :93314).
+ public const float ViewerSphereRadius = 0.3f;
+
+ private readonly PhysicsEngine _physics;
+
+ public PhysicsCameraCollisionProbe(PhysicsEngine physics) => _physics = physics;
+
+ public Vector3 SweepEye(Vector3 pivot, Vector3 desiredEye, uint cellId, uint selfEntityId)
+ {
+ // No starting cell → nothing to sweep against; keep the desired eye.
+ if (cellId == 0) return desiredEye;
+
+ // SpherePath.InitPath puts sphere0's center at pathPos + (0,0,radius)
+ // (the player foot-capsule convention). Retail's viewer_sphere center is
+ // (0,0,0), so shift the path DOWN by the radius to make the SPHERE CENTER
+ // travel pivot→eye, then add it back to the swept stop position.
+ Vector3 begin = ToSpherePath(pivot, ViewerSphereRadius);
+ Vector3 end = ToSpherePath(desiredEye, ViewerSphereRadius);
+
+ var r = _physics.ResolveWithTransition(
+ currentPos: begin,
+ targetPos: end,
+ cellId: cellId,
+ sphereRadius: ViewerSphereRadius,
+ sphereHeight: 0f, // single sphere (no head sphere)
+ stepUpHeight: 0f, // no step-up for a camera
+ stepDownHeight: 0f, // no step-down / ground snap
+ isOnGround: false, // no contact-plane / walkable semantics
+ body: null, // no cross-frame persistence
+ moverFlags: ObjectInfoState.None, // all targets collide; also keeps
+ // camera sweeps out of the #98
+ // IsPlayer capture filter
+ movingEntityId: selfEntityId); // skip the player's own ShadowEntry
+
+ return FromSpherePath(r.Position, ViewerSphereRadius);
+ }
+
+ /// Eye/pivot point → InitPath path point (subtract the sphere-center offset).
+ internal static Vector3 ToSpherePath(Vector3 spherePoint, float radius)
+ => spherePoint - new Vector3(0f, 0f, radius);
+
+ /// InitPath path point → eye point (add the sphere-center offset back).
+ internal static Vector3 FromSpherePath(Vector3 pathPoint, float radius)
+ => pathPoint + new Vector3(0f, 0f, radius);
+}
+```
+
+- [ ] **Step 5: Run test to verify it passes**
+
+Run: `dotnet test tests/AcDream.App.Tests/AcDream.App.Tests.csproj --filter "FullyQualifiedName~PhysicsCameraCollisionProbeTests"`
+Expected: PASS (both tests).
+
+- [ ] **Step 6: Commit**
+
+```bash
+git add src/AcDream.App/Rendering/ICameraCollisionProbe.cs src/AcDream.App/Rendering/PhysicsCameraCollisionProbe.cs tests/AcDream.App.Tests/Rendering/PhysicsCameraCollisionProbeTests.cs
+git commit -m "feat(render): Phase A8.F — PhysicsCameraCollisionProbe (swept-sphere eye via ResolveWithTransition)"
+```
+
+---
+
+## Task 3: Wire the probe into `RetailChaseCamera`
+
+**Files:**
+- Modify: `src/AcDream.App/Rendering/RetailChaseCamera.cs` (property, `Update` signature, sweep call)
+- Test: `tests/AcDream.App.Tests/Rendering/RetailChaseCameraTests.cs`
+
+- [ ] **Step 1: Write the failing tests**
+
+Add to `RetailChaseCameraTests.cs` (inside the class). These need a fake probe and exercise `Update`:
+
+```csharp
+ // ── Camera collision (A8.F) ───────────────────────────────────────
+
+ private sealed class FakeProbe : ICameraCollisionProbe
+ {
+ public int Calls;
+ public Vector3 ReturnEye;
+ public Vector3 SweepEye(Vector3 pivot, Vector3 desiredEye, uint cellId, uint selfEntityId)
+ {
+ Calls++;
+ return ReturnEye;
+ }
+ }
+
+ [Fact]
+ public void Update_WithProbeAndFlagOn_PublishesCollidedEye()
+ {
+ CameraDiagnostics.CollideCamera = true;
+ var collided = new Vector3(1f, 2f, 3f);
+ var probe = new FakeProbe { ReturnEye = collided };
+ var cam = new RetailChaseCamera { CollisionProbe = probe };
+
+ cam.Update(
+ playerPosition: Vector3.Zero, playerYaw: 0f, playerVelocity: Vector3.Zero,
+ isOnGround: true, contactPlaneNormal: Vector3.UnitZ, dt: 1f / 60f,
+ cellId: 0x100, selfEntityId: 0x5);
+
+ Assert.True(probe.Calls >= 1);
+ Assert.Equal(collided, cam.Position);
+ }
+
+ [Fact]
+ public void Update_FlagOff_DoesNotConsultProbe()
+ {
+ CameraDiagnostics.CollideCamera = false;
+ var probe = new FakeProbe { ReturnEye = new Vector3(99f, 99f, 99f) };
+ var cam = new RetailChaseCamera { CollisionProbe = probe };
+
+ cam.Update(
+ playerPosition: Vector3.Zero, playerYaw: 0f, playerVelocity: Vector3.Zero,
+ isOnGround: true, contactPlaneNormal: Vector3.UnitZ, dt: 1f / 60f,
+ cellId: 0x100, selfEntityId: 0x5);
+
+ Assert.Equal(0, probe.Calls);
+ Assert.NotEqual(new Vector3(99f, 99f, 99f), cam.Position);
+
+ CameraDiagnostics.CollideCamera = true; // reset
+ }
+
+ [Fact]
+ public void Update_NullProbe_DoesNotThrow()
+ {
+ CameraDiagnostics.CollideCamera = true;
+ var cam = new RetailChaseCamera { CollisionProbe = null };
+
+ // Should run with no collision and publish a valid view.
+ cam.Update(
+ playerPosition: Vector3.Zero, playerYaw: 0f, playerVelocity: Vector3.Zero,
+ isOnGround: true, contactPlaneNormal: Vector3.UnitZ, dt: 1f / 60f,
+ cellId: 0x100, selfEntityId: 0x5);
+
+ Assert.NotEqual(default, cam.View);
+ }
+```
+
+- [ ] **Step 2: Run tests to verify they fail**
+
+Run: `dotnet test tests/AcDream.App.Tests/AcDream.App.Tests.csproj --filter "FullyQualifiedName~RetailChaseCameraTests.Update_"`
+Expected: FAIL — `CollisionProbe` property and the `cellId`/`selfEntityId` `Update` parameters do not exist.
+
+- [ ] **Step 3: Add the `CollisionProbe` property**
+
+In `RetailChaseCamera.cs`, add to the public tunables region (after the `PivotHeight` property, around line 53):
+
+```csharp
+ ///
+ /// Optional spring-arm collision probe. When set (and
+ /// is true), the damped eye
+ /// is swept from the head-pivot and stopped at the first wall. Null leaves
+ /// the eye uncollided (the default for tests and the legacy path).
+ ///
+ public ICameraCollisionProbe? CollisionProbe { get; init; }
+```
+
+- [ ] **Step 4: Extend the `Update` signature**
+
+In `RetailChaseCamera.cs`, change the `Update` signature (line 86-92) to add two optional params at the end:
+
+```csharp
+ public void Update(
+ Vector3 playerPosition,
+ float playerYaw,
+ Vector3 playerVelocity,
+ bool isOnGround,
+ Vector3 contactPlaneNormal,
+ float dt,
+ uint cellId = 0,
+ uint selfEntityId = 0)
+```
+
+- [ ] **Step 5: Insert the sweep between damp and publish**
+
+In `RetailChaseCamera.cs`, between the end of the damping block (line 133 `}`) and the `// 6. Publish renderer surface.` comment (line 135), insert:
+
+```csharp
+
+ // 5b. Spring-arm collision (A8.F). Retail SmartBox::update_viewer
+ // (0x00453ce0) sweeps viewer_sphere from the head-pivot to the
+ // desired eye and uses the stopped position. Keeps the eye out of
+ // walls so the A8.F camera-cell + portal side-tests stay stable.
+ // A null probe or disabled flag leaves the eye unchanged.
+ if (CameraDiagnostics.CollideCamera && CollisionProbe is not null)
+ _dampedEye = CollisionProbe.SweepEye(pivotWorld, _dampedEye, cellId, selfEntityId);
+```
+
+(The fade at step 7, line 140, already reads `_dampedEye`, so it now uses the collided eye automatically.)
+
+- [ ] **Step 6: Run tests to verify they pass**
+
+Run: `dotnet test tests/AcDream.App.Tests/AcDream.App.Tests.csproj --filter "FullyQualifiedName~RetailChaseCameraTests"`
+Expected: PASS (the new `Update_*` tests plus all existing `Heading_*` / `BuildBasis_*` tests).
+
+- [ ] **Step 7: Commit**
+
+```bash
+git add src/AcDream.App/Rendering/RetailChaseCamera.cs tests/AcDream.App.Tests/Rendering/RetailChaseCameraTests.cs
+git commit -m "feat(render): Phase A8.F — RetailChaseCamera consumes the camera-collision probe"
+```
+
+---
+
+## Task 4: Wire the probe in `GameWindow`
+
+**Files:**
+- Modify: `src/AcDream.App/Rendering/GameWindow.cs` (two camera constructions, one `Update` call)
+
+No unit test — `GameWindow` wiring is verified by build + the visual acceptance in Task 7.
+
+- [ ] **Step 1: Inject the probe at the first construction site**
+
+In `GameWindow.cs`, the construction around line 10693 currently reads:
+
+```csharp
+ _retailChaseCamera = new AcDream.App.Rendering.RetailChaseCamera
+ {
+ Aspect = _chaseCamera.Aspect,
+ };
+```
+
+Change it to:
+
+```csharp
+ _retailChaseCamera = new AcDream.App.Rendering.RetailChaseCamera
+ {
+ Aspect = _chaseCamera.Aspect,
+ CollisionProbe = new AcDream.App.Rendering.PhysicsCameraCollisionProbe(_physicsEngine),
+ };
+```
+
+- [ ] **Step 2: Inject the probe at the second construction site**
+
+In `GameWindow.cs`, the construction around line 10826 currently reads:
+
+```csharp
+ _retailChaseCamera = new AcDream.App.Rendering.RetailChaseCamera
+ {
+ Aspect = _window!.Size.X / (float)_window.Size.Y,
+ };
+```
+
+Change it to:
+
+```csharp
+ _retailChaseCamera = new AcDream.App.Rendering.RetailChaseCamera
+ {
+ Aspect = _window!.Size.X / (float)_window.Size.Y,
+ CollisionProbe = new AcDream.App.Rendering.PhysicsCameraCollisionProbe(_physicsEngine),
+ };
+```
+
+- [ ] **Step 3: Pass cell + self-entity into the per-frame `Update`**
+
+In `GameWindow.cs`, the camera update around line 6862 currently ends with `dt: (float)dt);`. Change the call to:
+
+```csharp
+ _retailChaseCamera!.Update(result.RenderPosition, _playerController.Yaw,
+ playerVelocity: _playerController.BodyVelocity,
+ isOnGround: result.IsOnGround,
+ contactPlaneNormal: _playerController.ContactPlane.Normal,
+ dt: (float)dt,
+ cellId: _playerController.CellId,
+ selfEntityId: _playerController.LocalEntityId);
+```
+
+- [ ] **Step 4: Build to verify the wiring compiles**
+
+Run: `dotnet build`
+Expected: build succeeds (0 errors).
+
+- [ ] **Step 5: Commit**
+
+```bash
+git add src/AcDream.App/Rendering/GameWindow.cs
+git commit -m "feat(render): Phase A8.F — wire camera-collision probe + cell/self id into GameWindow"
+```
+
+---
+
+## Task 5: Add the live-toggle menu item
+
+**Files:**
+- Modify: `src/AcDream.App/Rendering/GameWindow.cs` (the `Camera` ImGui menu, ~line 7934)
+
+- [ ] **Step 1: Add the checkbox menu item**
+
+In `GameWindow.cs`, the `Camera` menu (around line 7934) currently reads:
+
+```csharp
+ if (ImGuiNET.ImGui.BeginMenu("Camera"))
+ {
+ if (_cameraController is not null)
+ {
+ string flyLabel = _cameraController.IsFlyMode
+ ? "Exit Free-Fly Mode" : "Enter Free-Fly Mode";
+ if (ImGuiNET.ImGui.MenuItem(flyLabel, "Ctrl+Shift+F"))
+ ToggleFlyOrChase();
+ }
+ ImGuiNET.ImGui.EndMenu();
+ }
+```
+
+Insert the toggle before `ImGuiNET.ImGui.EndMenu();`:
+
+```csharp
+ if (ImGuiNET.ImGui.BeginMenu("Camera"))
+ {
+ if (_cameraController is not null)
+ {
+ string flyLabel = _cameraController.IsFlyMode
+ ? "Exit Free-Fly Mode" : "Enter Free-Fly Mode";
+ if (ImGuiNET.ImGui.MenuItem(flyLabel, "Ctrl+Shift+F"))
+ ToggleFlyOrChase();
+ }
+ // A8.F: spring-arm camera collision (live A/B toggle).
+ if (ImGuiNET.ImGui.MenuItem("Collide Camera (spring arm)", "",
+ AcDream.Core.Rendering.CameraDiagnostics.CollideCamera))
+ AcDream.Core.Rendering.CameraDiagnostics.CollideCamera =
+ !AcDream.Core.Rendering.CameraDiagnostics.CollideCamera;
+ ImGuiNET.ImGui.EndMenu();
+ }
+```
+
+- [ ] **Step 2: Build to verify**
+
+Run: `dotnet build`
+Expected: build succeeds (0 errors).
+
+- [ ] **Step 3: Commit**
+
+```bash
+git add src/AcDream.App/Rendering/GameWindow.cs
+git commit -m "feat(render): Phase A8.F — Camera menu toggle for spring-arm collision"
+```
+
+---
+
+## Task 6: Correct the prior camera spec's collision note
+
+**Files:**
+- Modify: `docs/superpowers/specs/2026-05-18-retail-chase-camera-design.md` (lines 454-457)
+
+- [ ] **Step 1: Mark the stale note as superseded**
+
+In `2026-05-18-retail-chase-camera-design.md`, replace the bullet at lines 454-457:
+
+```markdown
+- **Camera-vs-world collision.** Retail's per-frame update doesn't
+ raycast world geometry (see investigation report 2026-05-18 in chat).
+ The auto-fade handles "camera passes through player"; we don't
+ attempt "camera collides with wall" — same as retail.
+```
+
+with:
+
+```markdown
+- **Camera-vs-world collision.** ~~Retail's per-frame update doesn't
+ raycast world geometry; we don't attempt "camera collides with wall"
+ — same as retail.~~ **SUPERSEDED 2026-05-29:** this was a research
+ error — retail DOES collide the camera in `SmartBox::update_viewer`
+ (0x00453ce0), which the earlier pass missed by tracing only the
+ desired-eye producer. Implemented as a swept-sphere spring arm; see
+ `docs/superpowers/specs/2026-05-29-a8f-camera-collision-design.md`.
+```
+
+- [ ] **Step 2: Commit**
+
+```bash
+git add docs/superpowers/specs/2026-05-18-retail-chase-camera-design.md
+git commit -m "docs(render): Phase A8.F — supersede the old 'no camera collision' note"
+```
+
+---
+
+## Task 7: Full verification + acceptance
+
+**Files:** none (verification only).
+
+- [ ] **Step 1: Full build**
+
+Run: `dotnet build`
+Expected: 0 errors.
+
+- [ ] **Step 2: Full test suite**
+
+Run: `dotnet test`
+Expected: green. Note the App.Tests baseline should increase by the new camera tests; no regressions in Core/Net.
+
+- [ ] **Step 3: Visual verification (the real acceptance — requires the user)**
+
+Launch against the live ACE server with the A8.F branch on (PowerShell):
+
+```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_A8_INDOOR_BRANCH="1"
+dotnet run --project src\AcDream.App\AcDream.App.csproj --no-build -c Debug 2>&1 | Tee-Object -FilePath "a8f-cameracollide.log"
+```
+
+Walk `+Acdream` into a Holtburg cottage and down into its cellar, panning the camera through walls and crossing the doorway inside↔outside. Confirm:
+- the flap is gone — walls/ground stay solid while panning and while crossing the doorway;
+- back walls no longer go missing when looking through a window from outside;
+- the player fades (rather than the camera sitting inside the player mesh) when backed into a corner.
+
+Then toggle `Collide Camera (spring arm)` off via the Camera menu (or relaunch with `ACDREAM_CAMERA_COLLIDE=0`) and confirm the flap returns — proving the fix is what closed it.
+
+- [ ] **Step 4: Update the roadmap / milestones on visual pass**
+
+After the user confirms the visual result, update the A8.F entry in `CLAUDE.md` (the M1.5 "currently working toward" block) and `docs/plans/2026-04-11-roadmap.md` shipped table to note the swept-sphere camera collision shipped + visual-verified, and move/close the related A8.F flap notes. Commit:
+
+```bash
+git add CLAUDE.md docs/plans/2026-04-11-roadmap.md
+git commit -m "docs(render): Phase A8.F — camera collision shipped + visual-verified"
+```
+
+---
+
+## Notes for the implementer
+
+- **Do not** re-implement collision in the probe. The whole point of reusing
+ `ResolveWithTransition` is that the env+obj sweep is already tested. The probe
+ is param-marshalling + the z-offset round trip.
+- **Self-skip is load-bearing.** The sweep starts at the player's head, inside
+ the player's own 0.48 m collision sphere / ShadowEntry. Passing
+ `selfEntityId` (= `LocalEntityId`) is what stops the eye from snapping onto
+ the head every frame. If the eye appears glued to the player, this is the
+ first thing to check.
+- **Slide vs hard-stop (open question).** Reusing the transition gives the
+ player path's edge-slide (the eye glides along a wall, no jitter). If visual
+ verification shows the eye behaving oddly, read retail's `find_valid_position`
+ and match its stop/slide semantics — but do not change the architecture for it.
+- **If the eye hugs/penetrates in a tight room**, the spec's optional
+ `AdjustPosition` fallback (spec §7) is the escalation; add it only if needed.
diff --git a/docs/superpowers/specs/2026-05-29-a8f-camera-collision-design.md b/docs/superpowers/specs/2026-05-29-a8f-camera-collision-design.md
index 2c77fc8..0cc1a21 100644
--- a/docs/superpowers/specs/2026-05-29-a8f-camera-collision-design.md
+++ b/docs/superpowers/specs/2026-05-29-a8f-camera-collision-design.md
@@ -130,9 +130,13 @@ public interface ICameraCollisionProbe
public Vector3 SweepEye(Vector3 pivot, Vector3 desiredEye, uint cellId, uint selfEntityId)
{
if (cellId == 0) return desiredEye; // no starting cell → can't sweep
+ // InitPath offsets sphere0's center up by radius (foot-capsule convention),
+ // but retail's viewer_sphere center is (0,0,0). Shift the path down by radius
+ // so the SPHERE CENTER travels pivot→eye, then add it back to the result.
+ var zoff = new Vector3(0f, 0f, 0.3f);
var r = _physics.ResolveWithTransition(
- currentPos: pivot,
- targetPos: desiredEye,
+ currentPos: pivot - zoff,
+ targetPos: desiredEye - zoff,
cellId: cellId,
sphereRadius: 0.3f, // retail viewer_sphere radius
sphereHeight: 0f, // single sphere (no head sphere)
@@ -144,7 +148,7 @@ public Vector3 SweepEye(Vector3 pivot, Vector3 desiredEye, uint cellId, uint sel
// camera sweeps out of the #98
// IsPlayer capture filter
movingEntityId: selfEntityId); // skip the player's own ShadowEntry
- return r.Position; // = sp.CheckPos, the swept stop position
+ return r.Position + zoff; // r.Position = sp.CheckPos (path pt); + zoff = eye
}
```
@@ -234,11 +238,13 @@ inside the player mesh) when backed into a corner.
- probe returns a pulled-in eye → published `Position`/`View` use the collided
eye; fade increases.
- `CollideCamera = false` → probe never consulted.
-- `PhysicsCameraCollisionProbe` against fixtures (reuse the issue-#98 cell +
- GfxObj fixtures already in the test tree):
- - clear path → eye unchanged;
- - wall/shell between pivot and desiredEye → eye stops short (does not penetrate);
- - `selfEntityId` set → sweep does not collide with the player's own ShadowEntry.
+- `PhysicsCameraCollisionProbe` deterministic units (no heavy fixture setup):
+ - `ToSpherePath`/`FromSpherePath` z-offset round-trip;
+ - `cellId == 0` guard → returns `desiredEye` unchanged.
+ Collision correctness itself (eye stops at a wall/shell; self-skip) is already
+ covered by the exhaustive `ResolveWithTransition` / `BSPQuery` suites and is
+ confirmed end-to-end by the visual acceptance below — re-proving it at the probe
+ layer would duplicate that coverage with brittle fixture wiring.
**Visual (acceptance):** with `ACDREAM_A8_INDOOR_BRANCH=1`, walk into a Holtburg
cottage and its cellar:
@@ -263,9 +269,12 @@ Compare `ACDREAM_CAMERA_COLLIDE=0` vs default to confirm the flag isolates the f
retail's `find_valid_position` during implementation and confirm whether it
slides or hard-stops; match it. Both keep the eye out of walls, so this does
not change the architecture.
-2. **`sphereHeight: 0f`.** Confirm `SpherePath.InitPath` with height 0 yields a
- single sphere (no degenerate coincident head sphere). If not, pass a tiny
- height or a single-sphere init.
+2. **`sphereHeight: 0f` — RESOLVED.** `SpherePath.InitPath` with height 0 yields a
+ single sphere (`NumSphere = 1`, `TransitionTypes.cs:534-537`). It also offsets
+ sphere0's center to `pathPos + (0,0,radius)` (foot-capsule convention) whereas
+ retail's `viewer_sphere` center is (0,0,0); the probe compensates with the
+ `ToSpherePath`/`FromSpherePath` z-shift (§5.1) so the sphere center travels
+ pivot→eye.
3. **Probe construction order.** The `PhysicsEngine` must exist before the
`RetailChaseCamera` constructions at `GameWindow.cs:10693/:10826`; confirm
lifetime ordering or make the probe field settable post-construction.