docs(research): record step 1 verdicts in the build plan

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

RESEARCH-SPEED-2026-09.md

@@ -32,6 +32,7 @@ The ~2 µs sample is an end-to-end `GetDensityAt` cost, not a Perlin operation.
 The steps below describe **future plugin experiments**. This research pass makes no `Source/` change and does not run Unreal. Use the same machine, fixed seeds/layouts, cold world caches, and 20 spawn/teleport trials per UE gate; report the **maximum** as well as median because 20 trials are too few for a meaningful p99. Preserve gameplay while replacing one pipeline stage at a time.
 
 1. **Day-one falsification: stage the existing collision and upload clocks.** Add timestamps for collision request, RMC end-of-frame dequeue, `GThreadPool` worker start, geometry extraction end, `CookComplexMesh` start/end, game-thread `ApplyCollisionUpdate` start/end, physics-state ready and first successful capsule sweep. Keep existing generation, mesh and gameplay behavior while profiling. Test one ~4,000-triangle tile and the pawn's current 3³=27-tile support neighborhood, idle at the current 14 generation tasks, and with the generation cap reduced to 12. If the cook's queue wait dominates, test a dedicated priority cook dispatched directly after player-support mesh extraction; compare its core cook and install times with RMC's route. In parallel, prequeue a 341-tile render corpus and run caps 4/8/16 with the same 2 ms drain guard; record visible applies/s, game/render/RHI clocks and first-visible frame. **Pass the cook shortcut only if** core cook p95 ≤10 ms, the 27-tile player support is ready ≤150 ms after meshes exist under load, and an edit-time field override can switch floor/support within the first simulated/rendered frame with zero invented velocity in 100 repeated underfoot digs. If any edit test fails, implement field-aware Mover as the player authority; if the shortcut passes all tests, use prioritized cooks for steady terrain plus field queries while an edit's cook is pending. **Pass the ungrouped upload path only if** it sustains ≥525 visible applies/s at 60 Hz with game-thread drain ≤2 ms/frame and no render/RHI backlog. These are decision thresholds, not existing measurements.
+   **Step 1 results (2026-09-30, commit `41b001b`):** core cook **1.50 ms p50 / 2.28 ms p95** (passes); through RMC's collision route the same support bodies were ready **8.5–10.8 s** after their meshes existed (fails): the wait is RMC's path, not Chaos, so player-support collision must bypass it. CMC with a field override: **883 false-support frames in 100 underfoot digs** (fails): step 4 is **field-aware Mover**. Uploads: cap 16 = **639 applies/s**, drain p95 2.22 ms (misses 2 ms by 0.22 ms), no render/RHI backlog, so tune the drain and **do not group yet**. The "8× per-sample gap" was a denominator artefact: 263 ns was export *wall* time with 15 workers on a shared lattice (≈3.4 µs CPU per sample); the real per-sample CPU cost is ~2–3.4 µs in both paths, so the 12–16× reduction target stands.
 2. **Standalone exact-float evaluator ablation.** Extract representative *real* TunnelNetwork and composer plans, including warped rooms, passages, stratum transitions, route floors and diff edits, into `Saved/Research` only. Keep the plugin's active evaluator and worlds untouched. Compare baseline point API to a prepared float region/brick API at the same lattice coordinates and op order. The reference is the chosen **new-world float definition**, not old-season geometry. **Pass:** zero 16-bit quantized-value disagreements and zero route/capsule regression across at least five seeds; ≤**600 ms** for the full 259³ cold ring on six workers before certificates. Record candidate visits, cache checks and worker CPU. Failure means local compilation did not remove enough work; investigate before rewriting numeric math.
 3. **Add certificates, shared lattice and contouring.** Prove final-sign bounds after all writers and edits; classify 8³ bricks, evaluate uncertain ones, share global corners, and mesh them with today's marching-cubes table. Keep the old tile route as a versioned reference while the new route is validated. **Pass:** zero false-uniform bricks and zero sign mismatch at all 17,373,979 ring lattice sites for the test corpus, cold worker generation ≤**350 ms**, and max render-visible/full ring ≤**900 ms** in the later UE gate. If certification consumes more time than it saves, fall back to evaluating uncertain regions without that proof; do not repeat the archived 0.588→2.057 s interval-control mistake.
 3b. **AVX2 check against the new norm (owner's request, 2026-09-29).** Once step 3's brick evaluator is the baseline, try an explicit 8-lane AVX2 version of its hot loop (the plugin's current noise path is 4-lane SSE4.1). **The owner does not require AVX2 to match the scalar path bit for bit** (clarified 2026-09-29): only the shipped product must be deterministic across players' machines. If adopted, the AVX2 path *is* the canonical world definition (FMA allowed, as long as it is always used), and every machine must run that same path: require AVX2 at startup rather than falling back to a scalar path that would produce a different world. **Keep it only if** it is faster on the step-3 corpus and the AVX2 path gives the same lattice hash on two runs and on two different AVX2 CPU models; otherwise record the number and drop it. The round-two integer AVX2 probe (4.25–5.86× over its own scalar) is the reference for what explicit vectorisation can buy.