profile: in-process SIGPROF sampler + exclusive route/phase census (L77); closes to 0.1%

Opt-in (L77 build + --linux77-profile; compiled out by default, 0.02% handler cost).
FI/TN cost account closes against direct grid-fill timing within 0.15% (LOD0-2 bins within 1.4%).
Passage carving = 66% of LOD0-2 CPU (52-54% whole view), passage support 10-14%, base packed
+ analytic field ~3%. Hotspots: value noise 17%, lower_bound in VisitNearestPassageSpatialNode
14%, ApplyResolvedStratePassageCarves 6.5%. LOD0/1 complete LAST (4.1/4.6 s) while LOD2 is
ready at 2.2 s.

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

Standalone/Research/WorldAssemblerM3/Linux77/RunLinux77.py

@@ -0,0 +1,92 @@
+#!/usr/bin/env python3
+"""Cold production-path samples and controls for Linux77."""
+from __future__ import annotations
+
+import json
+import re
+import subprocess
+import sys
+import time
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parents[4]
+OUT = ROOT / "Saved/Linux/l77"
+DATA = ROOT / "Standalone/data/owner_world.json"
+BINARIES = {
+    "clean": ROOT / "Standalone/bin/linux/VoxelForgeCoreHeadless-l76-clang",
+    "clean_default": ROOT / "Standalone/bin/linux/VoxelForgeCoreHeadless-l77-clean-clang",
+    "l77_off": ROOT / "Standalone/bin/linux/VoxelForgeCoreHeadless-l77-clang",
+    "profile": ROOT / "Standalone/bin/linux/VoxelForgeCoreHeadless-l77-clang",
+}
+CAMERAS = {
+    "FI": (25.8369140625, 3.19921875, -737.0),
+    "TN": (19.166015625, -14.2001953125, -753.3740234375),
+}
+KV = re.compile(r"([a-zA-Z0-9_]+)=([^ ]+)")
+PIPELINE = re.compile(r"^\[StreamPipeline\] (.*)$", re.M)
+STAMP = re.compile(r"^\[VoxelForgeSourceStamp\] sha256=(\S+)$", re.M)
+
+
+def run(world: str, mode: str, replicate: int = 1) -> dict:
+    camera = ",".join(f"{value:.12f}" for value in CAMERAS[world]) + ",0,0"
+    name = f"{world.lower()}-{mode}-r{replicate}"
+    log = OUT / f"{name}.log"
+    command = [
+        "taskset", "-c", "0-11", "prlimit", "--as=6442450944", "--", "timeout", "1740s",
+        str(BINARIES[mode]), str(DATA), "--world-assembler-prototype", "--stream-benchmark",
+        "--stream-pipeline", "--workers=8", "--clip-radius=3", "--max-clip-level=8",
+        "--max-level=8", f"--camera={camera}", "--profile-lod-work",
+    ]
+    if mode == "profile":
+        command.append("--linux77-profile")
+    start = 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)
+    if result.returncode != 0 or match is None:
+        raise SystemExit(f"run failed or summary missing: {name} exit={result.returncode}; see {log}")
+    pipeline = dict(KV.findall(match.group(1)))
+    row = {
+        "world": world,
+        "mode": mode,
+        "replicate": replicate,
+        "exit_code": result.returncode,
+        "process_wall_s": round(time.monotonic() - start, 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.search(content).group(1) if STAMP.search(content) else None,
+        "sampler_samples": sum(1 for line in content.splitlines()
+                                if line.startswith("[L77Sample]")),
+        "sampler_header": next((line for line in content.splitlines()
+                                 if line.startswith("[L77Sampler] action=stop")), None),
+        "log": str(log.relative_to(ROOT)),
+    }
+    print("[Linux77Run] " + 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))
+    if len(sys.argv) > 1 and sys.argv[1] == "--clean-control":
+        schedule = [("FI", "clean_default", 14), ("TN", "clean_default", 14),
+                    ("FI", "clean_default", 15), ("TN", "clean_default", 15)]
+        output_name = "final-clean-runs2.json"
+    else:
+        schedule = [("FI", "profile", 12), ("TN", "profile", 12),
+                    ("FI", "profile", 13), ("TN", "profile", 13)]
+        output_name = "final-runs3.json"
+    rows = [run(*item) for item in schedule]
+    (OUT / output_name).write_text(
+        json.dumps(rows, indent=2) + "\n", encoding="utf-8")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())