6c3a96b26e
The 2026-06-08 AM "physics rest micro-jitter" diagnosis is refuted with primary
evidence (door-recheck 216K standstill records: 0 position re-snaps; player
byte-stable during the flap). Two adversarial verification sub-agents confirmed:
- Retail roots the render at the camera viewer_cell (swept from the player via
SmartBox::update_viewer 0x453ce0; DrawInside(viewer_cell) 0x453aa0) and toggles
DrawInside / LScape::draw -- so acdream's eye-cell rooting + inside/outside
toggle are RETAIL-FAITHFUL. The locked-design "root at player cell" is wrong.
- The flap is render membership instability, eye-motion-driven: the visible-cell
set oscillates (8<->3) as the eye sweeps monotonically. Root = the
re-enqueue-on-growth DRIFT (PortalVisibilityBuilder.cs:322, MaxReprocessPerCell
=16) re-clipping each grown cell every round -> sub-cm eye jitter flips membership.
Fix (spec, not yet implemented): verbatim port of retail's enqueue-once flood
(ConstructView + AddViewToPortals): enqueue once on first discovery, clip each
cell's portals once, union late growth in place (AddToCell) + draw-reorder
(FixCellList), never re-enqueue. Kills the drift; rooting/camera/seal untouched.
This commit lands VERIFIED GROUNDWORK + design only:
- spec: docs/superpowers/specs/2026-06-08-portal-flood-enqueue-once-port-design.md
- findings: docs/research/2026-06-08-flap-physics-diagnosis-REFUTED-its-render-membership.md
- [pv-input] probe gains rawPlayer + yaw (disambiguates the varying input)
- 4 GREEN physics rest-stability tests (prove rest is bit-stable -> flap not physics)
- apparatus: launch-flap-capture.ps1, analyze_flap_live.py, find_burst.py
- captured fixtures: tests/.../Fixtures/flap-doorway/0xA9B4017{0..5}.json
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
127 lines
8.9 KiB
Markdown
127 lines
8.9 KiB
Markdown
# Handoff/Findings — the "physics rest µm-jitter" flap diagnosis is REFUTED; the flap is a RENDER membership instability at the grazing doorway portal — 2026-06-08 (PM)
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> **Supersedes** `docs/research/2026-06-08-flap-rootcause-physics-rest-handoff.md` (the AM handoff). That
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> handoff asked to be treated as a suspect statement and verified — this session verified it with primary
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> evidence and it does **not** hold. The flap is **not physics** and **not camera drift**. It is the
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> portal-flood **membership flickering non-monotonically at the grazing doorway portal as the camera eye
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> sweeps** (i.e. while you turn the camera at the doorway). This is the SPEC's §2.2 diagnosis
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> (`2026-06-08-portal-flood-membership-stability-design.md`), NOT its refuted §4 enqueue-once fix.
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---
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## 1. What was claimed (AM handoff) vs what the evidence shows
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**AM claim:** the flap's varying input is a **physics resting-position µm jitter** — `_body.Position`
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blips ~1 ULP between ticks at rest → `RenderPosition` (Lerp of physics) jitters → eye jitters → flood
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flips. Fix = physics rest-stability (broaden `kill_velocity`, hold contact plane).
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**Refuted by three independent pieces of primary evidence:**
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### A. The physics body is bit-stable at standstill — it does NOT blip
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`door-recheck-capture.jsonl` (515 MB, 238,342 `ResolveWithTransition` records, captured standing at the
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doorway, cells `0xA9B40170/0171/0174/0175/0031`):
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- **216,300 true-standstill records** (zero velocity, `currentPos==targetPos`).
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- **0** resolve re-snaps (`result.position != input` never happens at standstill).
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- **0** cross-tick `currentPos` drift (the body position is carried forward byte-identically).
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- The `grounded-but-cp=none` contradictory state DOES occur (3.5% of frames) but produces **no** position
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blip.
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Confirmed independently with **4 new deterministic tests** (all GREEN — they PROVE rest is bit-stable):
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- `PlayerMovementControllerTests.Update_AtRestNoInput_RenderPositionBitStableAcrossManyFrames` (flat terrain)
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- `PlayerMovementControllerTests.Update_WalkThenStop_SettlesToBitStableRest` (flat terrain, post-motion)
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- `CellarUpTrajectoryReplayTests.IndoorCellarFloor_AtRestZeroOffset_BodyPositionBitStable` (indoor cell, resolver loop)
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- `CellarUpTrajectoryReplayTests.IndoorCell_FullController_AtRestNoInput_RenderPositionBitStable` (indoor cell, full controller loop)
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### B. On the actual flap frames, the PLAYER position is byte-identical
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`pvinput.log` window 7748–7758 (a clean `flood 6↔2` flap), player `RenderPosition` for **11 consecutive
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frames**: `(155.632858, 13.527222, 94.000000)` — **byte-identical**. The physics output the camera reads
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does not move at all during the flap. (The 1-ULP *player* blip the AM handoff cited is at the **outdoor**
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`flood=1` records — a red herring, not the indoor flap.)
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### C. The EYE moves while the player is still — and the camera DOES settle when idle
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Same window: the eye orbits smoothly ~1 mm/frame (X ↓, Y ↑, Z constant) — a slow **camera rotation**
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around the stationary player. And:
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- Of **888** flood flips in the capture, only **1** had a byte-identical eye (and that one is the
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outdoor→indoor root switch). Every other flip had a moved eye → **the flood is deterministic in the
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eye; it changes only when the eye moves** (matches `Build_IsDeterministic_*`).
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- Longest **indoor byte-identical-eye runs: 203 / 181 / 178 frames (~3.4 s)** — within each, the flood is
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a **single constant value** (no flicker). **61%** of indoor frames have a byte-stable eye.
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- ⇒ The camera **settles** at rest (no boom drift, no spring oscillation). When the eye is still, the
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flood is stable. The flap fires **only while the eye is moving**.
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## 2. The actual mechanism
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When the camera eye **sweeps** through the grazing doorway portal (you turn the camera at the threshold),
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the deep cell cluster `{0172,0173,0174,0175}` flickers in/out — flood `6,6,6,2,2,6,6,6,2,6,2` — i.e.
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**non-monotonic membership across a monotonic eye sweep**. A correct visibility flood would transition
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the deep cluster in/out **once** as the grazing portal closes; instead its clip flips empty↔non-empty as
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the eye crosses and re-crosses the knife-edge. This is the SPEC's §2.2 diagnosis (the grazing portal's
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clip / re-clip drift makes `clippedRegion.Count` flip `0↔N`, dropping the deep cluster on empty-clip
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frames).
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It is **NOT** physics (A, B). It is **NOT** camera drift/oscillation (C: eye byte-stable ~3.4 s when
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idle). It is a **render-side portal-flood membership instability at grazing angles**, surfaced by camera
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rotation.
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## 3. Status of prior fixes / diagnoses
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- **AM physics-rest fix** — would not have fixed the flap (physics rest is already bit-stable). Do not pursue.
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- **SPEC §2.2 diagnosis (grazing-portal membership instability)** — CONFIRMED by this evidence.
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- **SPEC §4 enqueue-once fix** — already refuted in the AM handoff (retail propagates late slices via
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`AddToCell`, decomp :433494; broke `Build_ViewGrowthAfterDoneCell_PropagatesNewSlicesToExit`). So the
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correct fix is a render-side membership stabilization that is monotonic under a sweeping eye **without**
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breaking late-slice propagation — design TBD (brainstorm).
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## 4. Apparatus (this session)
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- 4 GREEN rest-stability tests (above) — keep as regression guards + evidence that physics rest is bit-stable.
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- Analysis scripts (ad-hoc, `/tmp`): door-recheck standstill survey; pvinput flood-flip vs eye/player
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delta buckets; indoor byte-stable-eye-run scan. Re-derivable from `pvinput.log` + `door-recheck-capture.jsonl`.
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- Existing probes `[pv-input]` (`ACDREAM_PROBE_PVINPUT`) and `[render-sig]` remain the live gate.
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## 5. Next step (proposed)
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Brainstorm + design a render-side fix that makes the deep-cluster membership **monotonic/stable as the eye
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sweeps the grazing portal** (candidates: more robust grazing-portal clip, a retail-faithful single-process
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traversal that doesn't re-clip-drift, or matching retail's exact `GetClip`/`polyClipFinish` epsilon). Then
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TDD a builder test that sweeps the eye across the grazing angle and asserts monotonic membership, and
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visual-gate by turning the camera at the cottage doorway.
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## 6. LIVE-CONFIRMED (2026-06-08 PM, targeted doorway capture, user-driven)
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A fresh instrumented capture (`launch-flap-capture.ps1`; `[pv-input]` enhanced with `rawPlayer`=raw
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physics body pos + `yaw`; cells `0170-0175` dumped to `tests/.../Fixtures/flap-doorway/`; 84K frames)
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confirms the diagnosis across every state and decomposes the flap into THREE render sub-issues. **In
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every case the player render-pos AND raw physics-pos are byte-identical (0 µm) — physics is conclusively
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exonerated; the flap is 100% camera-eye-driven.**
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| State (user-driven) | player moves | eye moves | flood |
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|---|---|---|---|
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| Idle, hands fully off | no (0 µm) | **no (0 µm)** | **stable** (no flap) |
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| Turn / walk | no (0 µm) | yes (mm, yaw) | oscillates |
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| Camera smoothing-glide after a turn (yaw byte-constant, eye glides monotonically, decelerating) | no | yes (mm) | **oscillates 8↔3** ← this is the "flickers while idle" the user perceived |
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Key burst (row 11167): **yaw byte-constant**, eye X glides monotonically 155.109→155.435 (18→5 mm/frame,
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decelerating), flood `8→3→8…3→8`. Monotonic eye ⇒ non-monotonic membership ⇒ **render** instability (not
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camera hunting).
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**Three sub-issues (all eye-driven, physics out):**
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- **A — Membership oscillation:** flood non-monotonic as the eye sweeps within a *stable* root.
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outside-looking-in `8↔3`; outdoor-root `17↔33` (21 flips/2500 frames); indoor-root `2↔6`.
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- **B — Root toggle (the big one):** at the threshold, `outRoot` flips outdoor↔indoor as the eye crosses
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the door plane → wholesale visible-set swap **≈18-33 cells ↔ 2 cells** (4 toggles in 2500 frames). This
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is the "two-branch" outdoor-node-vs-indoor-cell root switch the unification was meant to remove — still
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present.
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- **C — Indoor-root under-inclusion:** eye just inside ⇒ `outRoot=n` flood **= 2, stable** for 2438
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frames → outdoors + other rooms missing (the indoor flood does not reach back out the exit portal / to
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adjacent cells). C is B's partner: the swap *to* indoor loses the scene → "textures missing."
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**Fix scope:** core render pipeline (root resolution + flood + grazing-clip), NOT physics, NOT camera.
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Spec §2.2 (membership instability) is right for A; B+C are the threshold root-resolution/flood issues.
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Spec §4 enqueue-once stays refuted. Design needs brainstorming (saga has reverted speculative render
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fixes — see `feedback_render_one_gate`, `feedback_verify_render_seal_before_layering`).
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Apparatus added: `launch-flap-capture.ps1`, `analyze_flap_live.py`, `find_burst.py`, fixtures
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`tests/AcDream.Core.Tests/Fixtures/flap-doorway/0xA9B4017{0..5}.json`, `flap-doorway-resolve.jsonl`.
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**Memory to correct:** `project_indoor_flap_rootcause` (root is render: A membership instability + B
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root-toggle + C indoor under-inclusion, all under a moving camera eye — NOT physics rest, NOT camera
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drift; the "two-branch split" B is still live).
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