wip(step1): collision/upload clocks behind default-off switches -- partial, stopped on low memory

Compiled and run (cap 14 / 12 / 8), then stopped: another app held 12.5 GB, free memory fell
under the 6 GB launch floor and processes failed to start (STATUS_DLL_INIT_FAILED).

Measured so far (owner world, 120 s windows):
- 343 L0 tiles, request->collision-ready p50/p95: cap 14 = 262/440 ms, cap 8 = 196/238 ms;
  scheduler queue wait p95 141 ms -> 0.9 ms. Initial support tile at cap 14: RMC submit->body
  7.47 s, first check->ready 9.73 s; at cap 12: 0.33 s / 2.54 s; at cap 8 a 3,949-tri tile
  reached body update 2.8 ms after RMC submission. Waiting, not cooking, dominates.
- NOT confirmed: a capsule sweep hitting the exact target body (the 0.75 ms hit was another
  component); the 10 ms core-cook and 150 ms/27-tile thresholds are unscored.
- CMC cannot take a same-frame density floor: FindFloor/ComputeFloorDist trace the collision
  scene. Underfoot digs (100-dig test), upload throughput (render-enabled caps 4/8/16) and the
  8x per-sample question are not run. Per-sample profiling was fully disabled in these runs, so
  it does not explain the 8x.
Switches (all default off): voxel.Step1GenerationCap, Step1PauseGenerationAfterSeconds,
Step1MaxMeshApplies, Step1PrequeueVisibleLOD0, Step1UploadDisableCollision, Step1CollisionProbe,
Step1CoreCookBenchmark; harness -EnableRender. Also: plan step 3b, AVX2 need not match scalar.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MmSoF64BbRFmk9C3p1VsBJ

CODEMAP.md

@@ -297,6 +297,7 @@ casse cette arithmetique *structurellement* — `BeginPlay` loggue une **Error**
 | `RegenerateAllChunks()` | 530 | Bumps epoch, unloads all → Tick reloads. CallInEditor button. |
 | `ValidateDeterminism()` | — | **F2 CallInEditor button (PIE)**: re-samples boundary points under left- vs right-chunk cache warm-ups + a same-alignment repeat; any non-zero delta = window-invariance regression (§8.4). Run after every "bit-identical" hot-path refactor. |
 | `GetMaxConcurrentTasks()` | — | T2.d — asset `MaxConcurrentTasks` capped to logical cores − 2 (all three budget checks use it). |
+| `GetActiveGenerationTaskCount()` | — | Normal mode returns the existing pending count. With `voxel.Step1PrequeueVisibleLOD0>0`, completed held results are excluded from active worker admission so a full render corpus can be generated before the upload release. |
 | `PostEditChangeProperty` | 1000 | Editor live-edit hook. |
 | `OnObjectModifiedInEditor` | 1022 | Regenerates when a strate asset is edited (if `bLiveEditStrates`). |
 | `EndPlay` | 1118 | Sets `bShuttingDown`, **waits for `ActiveTaskCount`→0**, unbinds delegate. |
@@ -306,7 +307,7 @@ casse cette arithmetique *structurellement* — `BeginPlay` loggue une **Error**
 | `GetPlayerPosition` | 4831 | Pawn position or zero. |
 | `AdvanceHeadlessDigMotionTest` / `RecordHeadlessDigMotionFrame` | 3060 / 3217 | Explicit `-voxel.TestDigMotion=1` repro: digs eight times beside a walking pawn, records each frame's vertical velocity, gate, support tile/readiness, movement mode, then digs underfoot and requires ordinary falling. The accompanying gap audit is scoped to the dig session. |
 | `UpdateVisualStalenessAudit` | 5034 | Test-only camera-frustum coverage audit: tracks up to 24 real pre-skirt isosurface points per visible component, then counts frames where no visible tile component covers a previously visible, still-desired point (excluding edited bounds). `voxel.TestVisualGapInjectEarlyHide=1` hides a valid component for three frames and must be caught. `voxel.TestGapAuditLegacyHandoff=1` restores old handoff culling for A/B baselines. |
-| `ProcessPendingChunks` | 7435 | Drains critical, edited, near, then ordinary result queues under the per-frame budget; reads the per-request cancellation token before removing its map entry, drops obsolete/aborted results, then applies each live result via `ApplyTileResult`. Collision profiling timestamps the result's arrival here to separate worker completion from game-thread apply wait. |
+| `ProcessPendingChunks` | 7435 | Drains critical, edited, near, then ordinary result queues under the per-frame budget; reads the per-request cancellation token before removing its map entry, drops obsolete/aborted results, then applies each live result via `ApplyTileResult`. Collision profiling timestamps the result's arrival here to separate worker completion from game-thread apply wait. Step 1's `voxel.Step1PrequeueVisibleLOD0` holds completed results until the requested non-empty L0 count is ready, then releases them through this same drain. |
 | `ApplyTileResult` | — | **Shared game-thread apply** for one `FChunkResult` (async drain + sync carve): discards stale generation epochs and keys no longer desired, marks loaded, ingests capture, EMPTY releases the tile's existing component (a re-gen can flip content→empty on band change — old geometry must not linger), else `ApplyMeshToTile`. Returns true iff a visible mesh uploaded (counts the budget). Doesn't touch `PendingTiles` (caller's). |
 | `FVoxelStackSampler` / `FScopedVoxelStackRegistration` (`VoxelStackSampler.h/.cpp`) | — | **Diagnostic raw stack sampler, off by default.** A sampler thread captures registered generation workers' stacks (`CaptureThreadStackBackTrace`) every N µs and tags each with the tile's LOD. It writes bounded raw PCs to CSV plus a symbolization-free summary under `Saved/`; symbol resolution is deferred until after process exit so the measured process never initializes/calls DbgHelp for this diagnostic. Lifecycle teardown is serialized and registration TLS is session-tagged. Registration is per tile TASK in `LoadTile` (and the export's tasks), never per sample; disabled costs one relaxed atomic load. Game `-voxel.SampleStacks=<us>`, commandlet `-samplestacks[=us]`. |
 | Room-cache performance (2026-09-13): `VF_FindPlayerFitPointForRoomMemoized` / `GPlayerFitMemo` (`VoxelCaveMorphology.cpp`), `voxel.TileCacheWindow` + `VoxelGenLOD::TileOriginVoxels/TileCellsPerAxis` (`VoxelGenerator.h`), `FChunkSDFSpatialIndex` | — | **Player-fit memo:** exact 97-word key, process-wide, `voxel.PlayerFitMemo`. **Tile cache window:** the room cache covers the requesting tile's footprint plus a fixed collect margin. It is set via `TGuardValue` in `GenerateMesh`/classify, and is window-invariant by construction (the margin does not grow with the tile). **LOD-gated:** fused path at LOD ≥ `voxel.TileCacheWindowMinLOD` (3), op-stack at LOD ≥ `voxel.TileCacheWindowOpStackMinLOD` (4); lower LODs keep the 4-chunk worker window, because the tile window slowed LOD0 evaluation ~6%. Strates whose authored terrain ops exceed the proven 256-voxel extent (or are malformed/unloaded) fall back to the legacy window (`VF_ComputeTerrainOpEnvelope`). `voxel.SpatialIndex` is -1 auto (off at fused LOD0, on elsewhere), 0 or 1. **Spatial index:** ordered XY buckets over cache primitives, exact rejection. The `static_assert` in `VoxelStrateTypes.h` ties `VF_STRATE_PARAM_FIELDS` to `FStrateGenerationParams` (83 fields + 8 B padding). |
@@ -329,8 +330,10 @@ casse cette arithmetique *structurellement* — `BeginPlay` loggue une **Error**
 | `RegisterStreamingAnchor` / `UnregisterStreamingAnchor` | — | **BlueprintCallable §9.3:** add/remove an actor as a streaming anchor (`EVoxelAnchorPolicy` CollisionOnly/FullVisual + XY/ZBelow/ZAbove box). Idempotent; forces a rebuild next Tick. §9.4: CollisionOnly tiles cook collision but are hidden (no draw/VSM) unless the player clipmap wants them too. |
 | `LoadTile` | 9033 | Budget check → `UE::Tasks::Launch` background gen+mesh; RAII task guard. Worker runs `Generator->ClassifyTile` first (T1.d): AllSolid/AllAir ⇒ skip `GenerateMesh`, tile stays empty (capture tiles always generate). It carries `GenerationEpoch`/desired epoch and checks `bShuttingDown`, generation pause, and its read-only cancellation token between expensive stages; obsolete work returns through `ProcessQueue`. STRATE CONTENT CUT: tiles ≥ `StrateContentCutMinLevel` pass the player-strate band (`MeshBandChunkLo/Hi` → voxels) to `GenerateMesh` + stamp it on `FChunkResult::BandChunkLo/Hi`; band change re-queues via `BandRemeshQueue` (see `UpdateChunksAroundPosition`). `voxel.TestFullResClipLevels` is a measurement-only runtime override; default -1 uses the authored setting. TOO-COARSE SKIP: if one cell is taller than the band (`Step > band height` — level ≥7 territory) the tile is enqueued EMPTY without launching a task (cell-granular cut could only render garbage). §8.10. |
 | `UnloadTile` | — | Clears tile state; marks any matching generation request obsolete without removing its pending slot, so a late result cannot clear a replacement request; the component is PARKED in the pool (T2.c), not destroyed. |
-| `ApplyMeshToTile` | 9838 | Upload geometry. One component per tile (clipmap keeps count low; supersedes the old region batching); worker-built streams (T1.f) → `CreateSectionGroup(MoveTemp)`. Reuses the component's existing `URealtimeMesh` (no per-apply mesh alloc). **F17: two polygroups** (0 ground / 1 sky-cap, per-triangle class from the mesher) → RMC auto-section per non-empty group; slot 0 = override/default material, slot 1 = `CeilingMaterial` (fallback ground); config gated by `FChunkResult::bHasGroundTris/bHasCeilingTris`. Takes `FChunkResult&`; strate lookups clamp Z into `Result.BandChunkLo/Hi` (strate content cut) — ground at clamped bottom chunk, cap at clamped top (mid = gap fallback). Collision level-0 only (T1.c) both groups; shadow per SECTION: ground casts at level≤1, cap never. Ordinary same-tile re-cooks retain the installed body while it is valid. A carve intersecting the pawn's current support tile and capsule bounds suppresses that old body until the replacement cook is installed. `voxel.ProfileCollisionCookStages` reports generation/apply waits, combined RMC time, completion hops, triangle/skirt counts and collision settings. Routes each terrain base through shared MIDs; disabled volume MIDs bind neutral `VolP*` and null `VolTex*`. **§9.4:** `SetVisibility(false)` when the tile is in `CollisionOnlyTiles` (anchor-only, hidden — collision still cooks). §8.10 + ARCHITECTURE SurfaceWorld row. |
-| `HandleRealtimeMeshCollisionBodyUpdated` / `HandleTileCollisionCookComplete` | 6964 / 7192 | Correlate RMC body-install event and collision-future completion. `voxel.ProfileCollisionCookStages=1` logs worker queue/gen, result wait, apply/upload/config submission, RMC submit→body update, body event→future, future→game-thread hop, submit frames, pending VoxelForge cooks, priority, collision flags, and triangle/skirt totals. RMC's internal end-of-frame, async-pool wait, and cook remain one combined interval because they are inside the external RMC plugin. |
+| `ApplyMeshToTile` | 9838 | Upload geometry. One component per tile (clipmap keeps count low; supersedes the old region batching); worker-built streams (T1.f) → `CreateSectionGroup(MoveTemp)`. Reuses the component's existing `URealtimeMesh` (no per-apply mesh alloc). **F17: two polygroups** (0 ground / 1 sky-cap, per-triangle class from the mesher) → RMC auto-section per non-empty group; slot 0 = override/default material, slot 1 = `CeilingMaterial` (fallback ground); config gated by `FChunkResult::bHasGroundTris/bHasCeilingTris`. Takes `FChunkResult&`; strate lookups clamp Z into `Result.BandChunkLo/Hi` (strate content cut) — ground at clamped bottom chunk, cap at clamped top (mid = gap fallback). Collision level-0 only (T1.c) both groups; shadow per SECTION: ground casts at level≤1, cap never. Ordinary same-tile re-cooks retain the installed body while it is valid. A carve intersecting the pawn's current support tile and capsule bounds suppresses that old body until the replacement cook is installed. `voxel.ProfileCollisionCookStages` reports generation/apply waits, combined RMC time, completion hops, triangle/skirt counts and collision settings. With `voxel.Step1PrequeueVisibleLOD0>0`, logs apply frame and waits for `GetLastRenderTime` to advance for first-visible frame; `voxel.Step1UploadDisableCollision=1` isolates render upload. Routes each terrain base through shared MIDs; disabled volume MIDs bind neutral `VolP*` and null `VolTex*`. **§9.4:** `SetVisibility(false)` when the tile is in `CollisionOnlyTiles` (anchor-only, hidden — collision still cooks). §8.10 + ARCHITECTURE SurfaceWorld row. |
+| `HandleRealtimeMeshCollisionBodyUpdated` / `HandleTileCollisionCookComplete` / `PollStep1SupportSweepProbes` | 6964 / 7192 / — | Correlate RMC body-install event and collision-future completion. `voxel.ProfileCollisionCookStages=1` logs worker queue/gen, result wait, apply/upload/config submission, RMC submit→body update, body event→future, future→game-thread hop, submit frames, pending VoxelForge cooks, priority, collision flags, and triangle/skirt totals. `voxel.Step1CollisionProbe=1` adds the support component's physics-state-ready timestamp and polls a real downward capsule sweep until that component is hit. RMC's end-frame dequeue, async worker start, geometry extraction and core cook remain inside the external plugin and are not individually timestampable from this module. |
+| `FVoxelStep1CoreCookWork` / `FStep1CoreCookPoolOwner` | — | Optional `voxel.Step1CoreCookBenchmark=1` copies critical L0 streams after meshing, appends collision triangles and calls RMC's public `CookComplexMesh` on a dedicated one-thread high-priority pool. It records queue delay, extraction and core cook separately. The benchmark sidecar is not installed as the tile BodySetup and is disabled by default. |
+| Step 1 measurement CVars | — | `voxel.Step1GenerationCap=-1` uses the normal cap (`0` pauses, positive values cap workers); `voxel.Step1PauseGenerationAfterSeconds=0` disables the timed pause; `voxel.Step1MaxMeshApplies=0` uses the asset cap; `voxel.Step1PrequeueVisibleLOD0=0` disables the held upload corpus; `voxel.Step1UploadDisableCollision=0`, `voxel.Step1CollisionProbe=0`, and `voxel.Step1CoreCookBenchmark=0`. All default off. |
 | `AcquireTileComponent` / `ReleaseTileComponent` | — | **T2.c component pool** (`TileComponentPool`, bounded): park on unload (geometry+collision stripped, hidden, stays registered), pop on apply — no `NewObject`/`RegisterComponent`/GC churn during travel & regen. §8.10. |
 | `GetStrateAtPosition` | 8351 | Gameplay query → strate index. |
 | `GetBiomeAtWorldLocation` | — | **BlueprintCallable** biome probe at a world point (undoes actor xf → voxel → `Generator::QueryBiomeAt`). Returns `FVoxelBiomeQuery` for BP debug ("what biome / how many decos under the cursor?"). |