wip(assembler): round L19 -- strate ceilings closed at every LOD; ledges diagnosed

The shared boundary-cap path now emits a cap wherever the field is solid just below a strate's
configured top (it previously required a solid-to-air crossing there) and checks a 5x5 perimeter
grid before suppressing a fallback cap. Strict audit: 0 misses / 0 edge gaps, LOD0-8.
farHorizonVersion 3 -> 4. SurfaceWorld LOD0-2, full detail and exact queries unchanged; 28/28
matrix plus 14/14 crossing; route parity and proofs pass.
Ledges: the lower stratum's terrain at the FI/SW interface, seen through the FI void, sampled at
0.5/1/2 m at LOD1-3 (up to 1.5 m / 7.7 m ring steps). Fix deferred to the units/layers round.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CSFYgsdW8ejZSyiMf4qRSX

Standalone/Research/WorldAssemblerM3/Linux19/RunAuditsL19.py

@@ -0,0 +1,79 @@
+#!/usr/bin/env python3
+"""Run the L9 uniform-block proof and L13 route parity audits."""
+import os
+import signal
+import subprocess
+import time
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[4]
+OUT = ROOT / "Saved/Linux/l19-audits"
+OUT.mkdir(parents=True, exist_ok=True)
+if not os.sched_getaffinity(0).issubset(set(range(12))):
+    raise SystemExit("run under taskset -c 0-11")
+BINARIES = {
+    "clang-off": ROOT / "Standalone/bin/linux/VoxelForgeCoreHeadless-linux19-clang",
+    "gcc-default": ROOT / "Standalone/bin/linux/VoxelForgeCoreHeadless-linux19-gcc",
+}
+RECIPES = {
+    "floating-islands": ("-22,-19,-22.8,0,-4", "--recipe=floating-islands"),
+    "surface-world": ("0,-35,-487.94,0,-22", "--recipe=surface-world"),
+}
+passed = True
+for recipe, (camera, recipe_flag) in RECIPES.items():
+    for compiler, binary in BINARIES.items():
+        name = f"{recipe}-{compiler}"
+        logfile = OUT / f"{name}.log"
+        command = ["prlimit", "--as=6442450944", "--", str(binary),
+            str(ROOT / "Standalone/data/owner_world.json"),
+            "--world-assembler-prototype", "--stream-benchmark", "--stream-pipeline",
+            "--stream-hash", "--force-generate", "--clip-radius=3", "--max-clip-level=8",
+            "--workers=12", f"--camera={camera}", recipe_flag,
+            "--audit-uniform-block-proofs", "--audit-route-parity"]
+        started = time.monotonic()
+        peak_rss = 0
+        timed_out = False
+        with logfile.open("w", encoding="utf-8") as stream:
+            process = subprocess.Popen(command, stdout=stream, stderr=subprocess.STDOUT,
+                                       start_new_session=True)
+            while process.poll() is None:
+                pending, seen = [process.pid], set()
+                while pending:
+                    pid = pending.pop()
+                    if pid in seen:
+                        continue
+                    seen.add(pid)
+                    try:
+                        pending.extend(int(value) for value in
+                            Path(f"/proc/{pid}/task/{pid}/children").read_text().split())
+                        for line in Path(f"/proc/{pid}/status").read_text().splitlines():
+                            if line.startswith("VmRSS:"):
+                                peak_rss = max(peak_rss, int(line.split()[1]))
+                                break
+                    except (FileNotFoundError, PermissionError, ProcessLookupError, ValueError):
+                        pass
+                if time.monotonic() - started > 900:
+                    os.killpg(process.pid, signal.SIGTERM)
+                    try:
+                        process.wait(timeout=5)
+                    except subprocess.TimeoutExpired:
+                        os.killpg(process.pid, signal.SIGKILL)
+                        process.wait()
+                    timed_out = True
+                    passed = False
+                    break
+                time.sleep(0.1)
+            code = process.wait()
+        elapsed = time.monotonic() - started
+        log = logfile.read_text(encoding="utf-8", errors="replace")
+        route_lines = [line for line in log.splitlines() if line.startswith("[RouteParityAudit]")]
+        proof_lines = [line for line in log.splitlines() if line.startswith("[UniformBlockProofAudit]")]
+        route_ok = bool(route_lines) and route_lines[-1].endswith("status=PASS")
+        proof_ok = bool(proof_lines) and "violations=0" in proof_lines[-1]
+        ok = code == 0 and not timed_out and route_ok and proof_ok
+        passed &= ok
+        print(f"[AuditRun] {name} exit={code} seconds={elapsed:.3f} peak_rss_kib={peak_rss} "
+              f"route={route_ok} proofs={proof_ok} status={'PASS' if ok else 'FAIL'}", flush=True)
+print(f"[AuditSummary] rows={len(RECIPES)*len(BINARIES)} expected=4 "
+      f"result={'PASS' if passed else 'FAIL'} path={OUT}", flush=True)
+raise SystemExit(0 if passed else 1)