research: L118 passage-tile designs (hash-exact, no readiness gain; kept as patch)

Tagged the passage bucket: per-tile prepareSweptTubeBase dominates (0.47-0.92 s summed per view),
smooth-min second. Segment lower-bound pruning (-17% pairs) and deferred fallback floor work stayed
hash-exact but moved near-ready <3%. Still +17..+26% vs L109.

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

Standalone/Research/WorldAssemblerM3/Linux118/RunL118HashMatrix.py

@@ -0,0 +1,84 @@
+#!/usr/bin/env python3
+"""Compare L118 owner4 hashes to L115 at W1/W8/W12 under Clang and GCC."""
+from __future__ import annotations
+
+import json
+import re
+import subprocess
+import time
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[4]
+OUT = ROOT / "Saved/Linux/l118/hashes"
+DATA = ROOT / "Standalone/data/owner_world.json"
+BASELINE = ROOT / "Saved/Linux/l115/hashes/summary.json"
+BINARIES = {
+    "clang": ROOT / "Saved/Linux/l118/bin/VoxelForgeCoreHeadless-l118-clang",
+    "gcc": ROOT / "Saved/Linux/l118/bin/VoxelForgeCoreHeadless-l118-gcc",
+}
+HASH = re.compile(r"^\[Pipeline(?:FullDetailHash|WholeViewHash|LODHash|ExactQueryHash)\].*$", re.M)
+STAMP = re.compile(r"^\[VoxelForgeSourceStamp\] sha256=(\S+)$", re.M)
+
+
+def run(workers: int, compiler: str) -> dict:
+    OUT.mkdir(parents=True, exist_ok=True)
+    label = f"owner4-w{workers}-{compiler}"
+    log = OUT / f"{label}.log"
+    layout = OUT / f"{label}.layout.json"
+    command = [
+        "taskset", "-c", "0-11", "prlimit", "--as=6442450944", "--",
+        "timeout", "1740s", str(BINARIES[compiler]), str(DATA),
+        "--workers=" + str(workers), "--world-assembler-prototype", "--stream-benchmark",
+        "--stream-pipeline", "--force-generate", "--clip-radius=3",
+        "--max-clip-level=8", "--max-level=8", "--stream-hash",
+        f"--resolved-layout-output={layout}",
+    ]
+    started = time.monotonic()
+    with log.open("w", encoding="utf-8") as stream:
+        result = subprocess.run(command, cwd=ROOT, stdout=stream,
+                                stderr=subprocess.STDOUT, check=False, timeout=1740)
+    content = log.read_text(encoding="utf-8", errors="replace")
+    hashes = HASH.findall(content)
+    if result.returncode or len(hashes) != 12:
+        raise SystemExit(f"hash run failed or incomplete: {label}; exit={result.returncode} "
+                         f"hashes={len(hashes)} log={log}")
+    row = {"workers": workers, "compiler": compiler, "exit_code": result.returncode,
+           "hashes": hashes,
+           "source_stamp": (STAMP.search(content).group(1) if STAMP.search(content) else None),
+           "elapsed_s": round(time.monotonic() - started, 3),
+           "log": str(log.relative_to(ROOT))}
+    print("[L118HashRun] " + json.dumps(row, sort_keys=True), flush=True)
+    return row
+
+
+def main() -> int:
+    if not DATA.is_file() or not BASELINE.is_file() or any(not path.is_file()
+                                                           for path in BINARIES.values()):
+        raise SystemExit("missing L118 hash input or L115 reference")
+    reference = json.loads(BASELINE.read_text(encoding="utf-8"))["runs"]
+    reference = [row for row in reference if row["dataset"] == "owner4"
+                 and row["recipe"] == "surface-world"]
+    rows = [run(workers, compiler) for workers in (1, 8, 12)
+            for compiler in ("clang", "gcc")]
+    comparisons = []
+    for row in rows:
+        matches = [old for old in reference if old["workers"] == row["workers"]
+                   and old["compiler"] == row["compiler"]]
+        if len(matches) != 1:
+            raise SystemExit(f"expected one L115 reference for W{row['workers']}/{row['compiler']}")
+        match = row["hashes"] == matches[0]["hashes"]
+        comparisons.append({"workers": row["workers"], "compiler": row["compiler"],
+                            "matches_l115": match, "l115_log": matches[0]["log"],
+                            "l118_log": row["log"]})
+        if not match:
+            raise SystemExit(f"L118 hash mismatch versus L115 at W{row['workers']}/{row['compiler']}")
+    summary = {"runs": rows, "comparisons": comparisons,
+               "l115_hashes_identical": len({tuple(r["hashes"]) for r in reference}) == 1,
+               "candidate_matches_l115_all_workers_and_compilers": True}
+    (OUT / "summary.json").write_text(json.dumps(summary, indent=2) + "\n",
+                                      encoding="utf-8")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())