profile: per-term legacy FI/TN sample profiler (L76); passage/support is ~75% of field time

Opt-in at build time (VOXELFORGE_PROFILE_LEGACY_TERMS=1; compiled out by default, ~2% when on).
Per legacy sample: passage/support composer ~1.05 us vs primitive scan ~0.19 us, boundary
band ~0.06 us, noise ~0.01 us. Resolved-passage constants are cached at field binding
(arithmetic order unchanged); whole-view effect within noise. Per-tile hashes identical to L75
in all 24 compiler x worker x view comparisons; fast tier PASS; Linux UE host builds.
R40 researcher notes attached.

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

Standalone/Research/WorldAssemblerM3/Linux76/RunTimingPairsL76.py

@@ -0,0 +1,102 @@
+#!/usr/bin/env python3
+"""Run three interleaved whole-view timing pairs for L75 and L76 Clang builds."""
+from __future__ import annotations
+
+import json
+import os
+import re
+import statistics
+import subprocess
+import time
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parents[4]
+OUT = ROOT / os.environ.get("VOXELFORGE_L76_TIMING_OUT", "Saved/Linux/l76/timing")
+DATA = ROOT / "Standalone/data/owner_world.json"
+BINARIES = {
+    "before": ROOT / "Saved/Linux/l75/bin/VoxelForgeCoreHeadless-l75-clang",
+    "after": ROOT / "Standalone/bin/linux/VoxelForgeCoreHeadless-l76-clang",
+}
+CAMERAS = {
+    0: (8.0, 16.0, -372.2626953125),
+    1: (25.8369140625, 3.19921875, -737.0),
+    2: (19.166015625, -14.2001953125, -753.3740234375),
+    3: (-20.0625, -5.068359375, -900.353515625),
+}
+ORDERS = (("before", "after"), ("after", "before"), ("before", "after"))
+PIPELINE = re.compile(r"\[StreamPipeline\] (.*)")
+PAIR = re.compile(r"([a-zA-Z0-9_]+)=([^ ]+)")
+
+
+def run(strate: int, pair: int, mode: str) -> dict:
+    label = f"strate{strate}-pair{pair}-{mode}"
+    log = OUT / f"{label}.log"
+    camera = ",".join(f"{value:.12f}" for value in CAMERAS[strate]) + ",0,0"
+    command = [
+        "taskset", "-c", "0-11", "prlimit", "--as=6442450944", "--", "timeout",
+        "1740s", str(BINARIES[mode]), str(DATA), "--world-assembler-prototype",
+        "--stream-benchmark", "--stream-pipeline", "--force-generate", "--workers=8",
+        "--clip-radius=3", "--max-clip-level=8", "--max-level=8", f"--camera={camera}",
+    ]
+    started = time.monotonic()
+    with log.open("w", encoding="utf-8") as output:
+        result = subprocess.run(command, cwd=ROOT, stdout=output,
+                                stderr=subprocess.STDOUT, check=False, timeout=1740)
+    content = log.read_text(encoding="utf-8", errors="replace")
+    match = PIPELINE.search(content)
+    stamp = re.search(r"^\[VoxelForgeSourceStamp\] sha256=(\S+)$", content, re.M)
+    if result.returncode != 0 or match is None:
+        raise SystemExit(f"timing run failed or summary missing; see {log}")
+    pipeline = dict(PAIR.findall(match.group(1)))
+    row = {
+        "strate": strate,
+        "pair": pair,
+        "mode": mode,
+        "exit_code": result.returncode,
+        "process_wall_s": round(time.monotonic() - started, 3),
+        "whole_view_ready_s": float(pipeline["whole_view_ready"].removesuffix("s")),
+        "stream_wall_s": float(pipeline["stream_wall"].removesuffix("s")),
+        "whole_tiles": int(pipeline["whole_tiles"].split("/")[0]),
+        "source_stamp": stamp.group(1) if stamp else None,
+        "log": str(log.relative_to(ROOT)),
+    }
+    print("[L76TimingPairRun] " + json.dumps(row, sort_keys=True), flush=True)
+    return row
+
+
+def main() -> int:
+    OUT.mkdir(parents=True, exist_ok=True)
+    missing = [str(path) for path in [DATA, *BINARIES.values()] if not path.is_file()]
+    if missing:
+        raise SystemExit("missing input: " + ", ".join(missing))
+    rows = []
+    for strate in range(4):
+        for pair, order in enumerate(ORDERS, 1):
+            for mode in order:
+                rows.append(run(strate, pair, mode))
+    summary = []
+    for strate in range(4):
+        group = [row for row in rows if row["strate"] == strate]
+        before = [row["whole_view_ready_s"] for row in group if row["mode"] == "before"]
+        after = [row["whole_view_ready_s"] for row in group if row["mode"] == "after"]
+        summary.append({
+            "strate": strate,
+            "pairs": len(before),
+            "before_s": [round(value, 3) for value in before],
+            "after_s": [round(value, 3) for value in after],
+            "before_median_s": round(statistics.median(before), 3),
+            "after_median_s": round(statistics.median(after), 3),
+            "change_pct": round(100.0 * (statistics.median(after)
+                / statistics.median(before) - 1.0), 2),
+        })
+    result = {"runs": rows, "summary": summary}
+    (OUT / "summary.json").write_text(json.dumps(result, indent=2) + "\n",
+                                      encoding="utf-8")
+    for row in summary:
+        print("[L76TimingPairSummary] " + json.dumps(row, sort_keys=True), flush=True)
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())