streaming: restore same-level refill; early admission on by default; fixed UE harness (L172)

Scheduler stable-sorts the whole level and checks capacity per admission (refill when slots free mid-pass); regression
test with the old partial-sort path as negative control. Harness repoints Source/Standalone/uplugin together, records
root HEAD/status, builds baselines from fresh worktrees, gates on DWARF struct sizes (480/480/480).
Frame-resolution arrival: A/A p90 36.8 ms; fixed-on vs fixed-off -12.2 ms median (4/10 slower). 30 m/s: near 43.3 ->
55.3%, far holes 1.8 -> 0%, p99 <= 7.46 ms, worst <= 12.3 ms.
Defaults: StreamingFastTravelWaitForAllCriticalTiles=0, StreamingFastTravelApplyBudgetMilliseconds=1.0,
StreamingIncrementalDesiredSet=1, CoreRegionConcurrentAdmission=1, StreamingFastTravelForwardFirst=0,
StreamingRebuildOnCoreRegionCompletion=1, StreamingCoreDesiredCacheByCenter=0, audits 0.
Source/: VoxelWorld.cpp, VoxelStreamingAdmissionOrder.h (new).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016dhxM43dnWvUu2B5Ph1iG1

Standalone/Research/WorldAssemblerM3/Linux172/RunStreamingAdmissionOrderTest.py

@@ -0,0 +1,59 @@
+#!/usr/bin/env python3
+from __future__ import annotations
+
+import argparse
+import os
+from pathlib import Path
+import shutil
+import subprocess
+
+
+ROOT = Path(__file__).resolve().parents[4]
+SOURCE = ROOT / "Source/VoxelForge/Private/VoxelWorld.cpp"
+HEADER_DIR = ROOT / "Source/VoxelForge/Private"
+TEST_SOURCE = Path(__file__).with_name("TestStreamingAdmissionOrder.cpp")
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--out", type=Path, required=True)
+    args = parser.parse_args()
+    output = args.out.resolve()
+    output.mkdir(parents=True, exist_ok=True)
+
+    source = SOURCE.read_text(encoding="utf-8")
+    required = (
+        "VoxelStreamingAdmissionOrder::StableSortCandidates(",
+        "LevelTiles.GetData(), LevelTiles.GetData() + LevelTiles.Num()",
+        "VoxelStreamingAdmissionOrder::AdmitInOrder(LevelTiles",
+    )
+    if any(token not in source for token in required):
+        raise SystemExit("VoxelWorld.cpp is not using the tested sort/admission helpers")
+    if ("LevelSubmissionCount" in source or "LevelTiles.SetNum" in source
+            or "std::partial_sort(" in source):
+        raise SystemExit("pass-start truncation returned to the production scheduler")
+
+    compiler = os.environ.get("CXX") or shutil.which("clang++-19") or shutil.which("clang++")
+    if not compiler:
+        raise SystemExit("clang++ is required for the streaming admission regression")
+    executable = output / "StreamingAdmissionOrderTest"
+    build_log = output / "streaming-admission-order-build.log"
+    run_log = output / "streaming-admission-order.log"
+    command = [compiler, "-std=c++20", "-O1", "-Wall", "-Wextra", "-Werror",
+               f"-I{HEADER_DIR}", str(TEST_SOURCE), "-o", str(executable)]
+    built = subprocess.run(command, cwd=ROOT, text=True, capture_output=True, check=False)
+    build_log.write_text(built.stdout + built.stderr, encoding="utf-8")
+    if built.returncode != 0:
+        raise SystemExit(f"admission regression compile failed; see {build_log}")
+    ran = subprocess.run([str(executable)], cwd=ROOT, text=True, capture_output=True,
+                         check=False)
+    run_log.write_text(ran.stdout + ran.stderr, encoding="utf-8")
+    if ran.returncode != 0:
+        raise SystemExit(f"admission regression failed; see {run_log}")
+    print(ran.stdout.strip())
+    print(f"[StreamingAdmissionOrder] production_source_guard=PASS build_log={build_log}")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())