passages: XY-smooth spline with planned height profile + open-air half-pipe (L112, v219)

Dense centripetal spline in XY, height piecewise-linear on the planner's certified profile,
radius/floor depth blended; open air = floor slab + 1 m side walls, no roof; audits sample the
generated centreline. All walk audits pass (grades <= 15 deg, headroom, shell, mouths, ripple);
Clang/GCC W1/W8/W12 deterministic; fast tier PASS; Linux UE builds. Chevron rings gone.
Open issues: jagged spikes along the half-pipe wall tops, visible step lines on the trough
floor; near-ready +7..+10% vs L109 (candidate list p95 4 -> 22). Not merged.

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

Standalone/Research/WorldAssemblerM3/Linux112/RunL112Captures.py

@@ -0,0 +1,839 @@
+#!/usr/bin/env python3
+"""Capture L109 and L112 routes, every open-air section, and verified 4 m wall views."""
+from __future__ import annotations
+
+import json
+import math
+import re
+from array import array
+import struct
+import subprocess
+import sys
+import time
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[4]
+RESEARCH = Path(__file__).resolve().parent
+CAPTURES = RESEARCH / "captures"
+SAVED = ROOT / "Saved/Linux/l112/captures"
+DATA = ROOT / "Standalone/data/owner_world.json"
+BINARIES = {
+    "before": ROOT / "Saved/Linux/l109/bin-final/VoxelForgeCoreHeadless-l109-clang",
+    "after": ROOT / "Saved/Linux/l112/bin-clang/VoxelForgeCoreHeadless-l112-clang",
+}
+LAYOUTS = {
+    "before": ROOT / "Saved/Linux/l109/audit-layout-final-stamp.json",
+    "after": ROOT / "Saved/Linux/l112/audit-layout-candidate.json",
+}
+AUDIT_LOGS = {
+    "before": ROOT / "Saved/Linux/l109/audit-owner4-final-stamp.log",
+    "after": ROOT / "Saved/Linux/l112/audit-owner-clang.log",
+}
+RENDERERS = {
+    "before": ROOT / "Saved/Linux/l109/bin-final/VoxelForgeOffscreenCapture-l109-clang",
+    "after": ROOT / "Saved/Linux/l112/bin-clang/VoxelForgeOffscreenCapture-l112-clang",
+}
+SECTION = re.compile(
+    r"^\[PassageOpenAirSection\] id=(\S+) section=(\d+) start_m=([\d.]+) "
+    r"end_m=([\d.]+) samples=(\d+) midpoint_xyz_m=\(([^)]*)\) "
+    r"midpoint_radius_m=([\d.]+)", re.M)
+DRAWN = re.compile(r"drawn_triangles=(\d+)")
+QUALITY_METRICS = re.compile(r"stddev_luma=([\d.]+).*coverage_luma_gt12=([\d.]+)")
+
+
+def vector(text: str) -> tuple[float, float, float]:
+    return tuple(float(value) for value in text.split(","))
+
+
+def add(a, b):
+    return tuple(x + y for x, y in zip(a, b))
+
+
+def sub(a, b):
+    return tuple(x - y for x, y in zip(a, b))
+
+
+def mul(a, scale):
+    return tuple(x * scale for x in a)
+
+
+def norm(a):
+    length = math.sqrt(sum(x * x for x in a))
+    if length <= 1.0e-9:
+        return (0.0, 1.0, 0.0)
+    return tuple(value / length for value in a)
+
+
+def angles(camera, target):
+    delta = sub(target, camera)
+    horizontal = math.hypot(delta[0], delta[1])
+    return (math.degrees(math.atan2(delta[0], delta[1])),
+            math.degrees(math.atan2(delta[2], horizontal)))
+
+
+def fmt(values) -> str:
+    return ",".join(f"{value:.6f}" for value in values)
+
+
+def mesh_triangle_count(mesh: Path) -> int:
+    """Read only the VFMSH headers and count indexed triangles."""
+    with mesh.open("rb") as stream:
+        magic = stream.read(8)
+        materials = magic == b"VFMSH002"
+        if magic not in (b"VFMSH001", b"VFMSH002"):
+            raise RuntimeError(f"unsupported mesh scene header: {mesh}")
+        version, _voxel_um, tile_count = struct.unpack("<3I", stream.read(12))
+        if version != (2 if materials else 1):
+            raise RuntimeError(f"mesh scene version mismatch: {mesh}")
+        stream.seek(40, 1)
+        triangles = 0
+        for _ in range(tile_count):
+            stream.seek(16, 1)
+            surface_count, _skirts, vertex_count, index_count, mask_count = struct.unpack(
+                "<5I", stream.read(20))
+            triangles += index_count // 3
+            stream.seek(vertex_count * 24 + (10 * vertex_count if materials else 0)
+                        + index_count * 4 + mask_count, 1)
+        if stream.read(1):
+            raise RuntimeError(f"trailing data in mesh scene: {mesh}")
+    return triangles
+
+
+def dot(a, b):
+    return sum(x * y for x, y in zip(a, b))
+
+
+def closest_point_triangle(point, a, b, c):
+    def closest_segment(start, end, first_weight, second_weight):
+        edge = sub(end, start)
+        length_squared = dot(edge, edge)
+        t = (min(1.0, max(0.0, dot(sub(point, start), edge) / length_squared))
+             if length_squared > 1.0e-16 else 0.0)
+        position = add(start, mul(edge, t))
+        weights = [0.0, 0.0, 0.0]
+        weights[first_weight], weights[second_weight] = 1.0 - t, t
+        return position, tuple(weights)
+
+    ab, ac = sub(b, a), sub(c, a)
+    cross = ((ab[1] * ac[2] - ab[2] * ac[1]),
+             (ab[2] * ac[0] - ab[0] * ac[2]),
+             (ab[0] * ac[1] - ab[1] * ac[0]))
+    if dot(cross, cross) <= 1.0e-16:
+        candidates = [closest_segment(a, b, 0, 1),
+                      closest_segment(b, c, 1, 2),
+                      closest_segment(c, a, 2, 0)]
+        return min(candidates, key=lambda candidate:
+                   dot(sub(candidate[0], point), sub(candidate[0], point)))
+    ap = sub(point, a)
+    d1, d2 = dot(ab, ap), dot(ac, ap)
+    if d1 <= 0.0 and d2 <= 0.0:
+        return a, (1.0, 0.0, 0.0)
+    bp = sub(point, b)
+    d3, d4 = dot(ab, bp), dot(ac, bp)
+    if d3 >= 0.0 and d4 <= d3:
+        return b, (0.0, 1.0, 0.0)
+    vc = d1 * d4 - d3 * d2
+    if vc <= 0.0 and d1 >= 0.0 and d3 <= 0.0:
+        denominator = d1 - d3
+        if denominator <= 1.0e-16:
+            return a, (1.0, 0.0, 0.0)
+        v = d1 / denominator
+        return add(a, mul(ab, v)), (1.0 - v, v, 0.0)
+    cp = sub(point, c)
+    d5, d6 = dot(ab, cp), dot(ac, cp)
+    if d6 >= 0.0 and d5 <= d6:
+        return c, (0.0, 0.0, 1.0)
+    vb = d5 * d2 - d1 * d6
+    if vb <= 0.0 and d2 >= 0.0 and d6 <= 0.0:
+        denominator = d2 - d6
+        if denominator <= 1.0e-16:
+            return a, (1.0, 0.0, 0.0)
+        w = d2 / denominator
+        return add(a, mul(ac, w)), (1.0 - w, 0.0, w)
+    va = d3 * d6 - d5 * d4
+    if va <= 0.0 and d4 - d3 >= 0.0 and d5 - d6 >= 0.0:
+        denominator = (d4 - d3) + (d5 - d6)
+        if denominator <= 1.0e-16:
+            return b, (0.0, 1.0, 0.0)
+        w = (d4 - d3) / denominator
+        edge = sub(c, b)
+        return add(b, mul(edge, w)), (0.0, 1.0 - w, w)
+    face_denominator = va + vb + vc
+    if face_denominator <= 1.0e-16:
+        candidates = [closest_segment(a, b, 0, 1),
+                      closest_segment(b, c, 1, 2),
+                      closest_segment(c, a, 2, 0)]
+        return min(candidates, key=lambda candidate:
+                   dot(sub(candidate[0], point), sub(candidate[0], point)))
+    denominator = 1.0 / face_denominator
+    v, w = vb * denominator, vc * denominator
+    weights = (1.0 - v - w, v, w)
+    closest = tuple(weights[0] * a[axis] + weights[1] * b[axis]
+                    + weights[2] * c[axis] for axis in range(3))
+    return closest, weights
+
+
+def nearest_surface_anchor(mesh: Path, point, margin_m=200.0, *,
+                           preferred_normal=None, minimum_alignment=-1.0) -> dict:
+    """Return the nearest point on a VFMSH surface triangle and its normal."""
+    best_distance_sq = float("inf")
+    best_position = best_normal = None
+    with mesh.open("rb") as stream:
+        magic = stream.read(8)
+        materials = magic == b"VFMSH002"
+        if magic not in (b"VFMSH001", b"VFMSH002"):
+            raise RuntimeError(f"unsupported mesh scene header: {mesh}")
+        version, voxel_um, tile_count = struct.unpack("<3I", stream.read(12))
+        if version != (2 if materials else 1):
+            raise RuntimeError(f"mesh scene version mismatch: {mesh}")
+        stream.seek(40, 1)
+        for _ in range(tile_count):
+            key = struct.unpack("<4i", stream.read(16))
+            surface_count, _skirts, vertex_count, index_count, mask_count = struct.unpack(
+                "<5I", stream.read(20))
+            extent = (32 << key[3]) * voxel_um / 1_000_000.0
+            origin = (key[0] * extent, key[1] * extent, key[2] * extent)
+            if any(point[axis] < origin[axis] - margin_m or
+                   point[axis] > origin[axis] + extent + margin_m for axis in range(3)):
+                stream.seek(vertex_count * 24 + (10 * vertex_count if materials else 0)
+                            + index_count * 4 + mask_count, 1)
+                continue
+            positions = array("f")
+            positions.frombytes(stream.read(vertex_count * 12))
+            normals = array("f")
+            normals.frombytes(stream.read(vertex_count * 12))
+            if materials:
+                stream.seek(vertex_count * 10, 1)
+            indices = array("I")
+            indices.frombytes(stream.read(index_count * 4))
+            stream.seek(mask_count, 1)
+            if struct.pack("=I", 1) != struct.pack("<I", 1):
+                positions.byteswap()
+                normals.byteswap()
+                indices.byteswap()
+            def vertex(index):
+                offset = index * 3
+                return tuple(float(positions[offset + axis]) for axis in range(3))
+            def vertex_normal(index):
+                offset = index * 3
+                return tuple(float(normals[offset + axis]) for axis in range(3))
+            for index in range(0, index_count - 2, 3):
+                triangle = (indices[index], indices[index + 1], indices[index + 2])
+                if any(vertex_index >= surface_count or vertex_index >= vertex_count
+                       for vertex_index in triangle):
+                    continue
+                a, b, c = (vertex(vertex_index) for vertex_index in triangle)
+                position, weights = closest_point_triangle(point, a, b, c)
+                delta = sub(position, point)
+                distance_sq = dot(delta, delta)
+                if distance_sq >= best_distance_sq:
+                    continue
+                raw_normals = [vertex_normal(vertex_index) for vertex_index in triangle]
+                raw_normal = tuple(sum(weights[corner] * raw_normals[corner][axis]
+                    for corner in range(3)) for axis in range(3))
+                if dot(raw_normal, raw_normal) < 1.0e-10:
+                    raw_normal = (
+                        (b[1] - a[1]) * (c[2] - a[2]) - (b[2] - a[2]) * (c[1] - a[1]),
+                        (b[2] - a[2]) * (c[0] - a[0]) - (b[0] - a[0]) * (c[2] - a[2]),
+                        (b[0] - a[0]) * (c[1] - a[1]) - (b[1] - a[1]) * (c[0] - a[0]))
+                    if dot(raw_normal, raw_normal) < 1.0e-10:
+                        continue
+                candidate_normal = norm(raw_normal)
+                if preferred_normal is not None:
+                    alignment = dot(candidate_normal, preferred_normal)
+                    if abs(alignment) < minimum_alignment:
+                        continue
+                    if alignment < 0.0:
+                        candidate_normal = mul(candidate_normal, -1.0)
+                best_distance_sq = distance_sq
+                best_position = position
+                best_normal = candidate_normal
+    if best_position is None:
+        raise RuntimeError(f"no nearby surface vertices in mesh scene: {mesh}")
+    return {"position_m": best_position, "normal": best_normal,
+            "distance_m": math.sqrt(best_distance_sq)}
+
+
+def sanitize(value: str) -> str:
+    return re.sub(r"[^A-Za-z0-9_-]+", "-", value).strip("-").replace("/", "-")
+
+
+def route_height_at_xy(route, x, y):
+    if not route:
+        return None
+    if len(route) == 1:
+        point = route[0]
+        return point[2], (x - point[0]) ** 2 + (y - point[1]) ** 2
+    best = (float("inf"), None)
+    for a, b in zip(route, route[1:]):
+        dx, dy = b[0] - a[0], b[1] - a[1]
+        length_sq = dx * dx + dy * dy
+        t = min(1.0, max(0.0, ((x - a[0]) * dx + (y - a[1]) * dy) / length_sq)) \
+            if length_sq > 1.0e-12 else 0.0
+        px, py = a[0] + t * dx, a[1] + t * dy
+        distance_sq = (x - px) ** 2 + (y - py) ** 2
+        if distance_sq < best[0]:
+            best = (distance_sq, a[2] + (b[2] - a[2]) * t)
+    return best[1], best[0]
+
+
+def upper_mouth_floor_depth(layout: dict, passage: dict, controls) -> float:
+    scale = layout["core_voxel_size_um"] / 256.0 / 1_000_000.0
+    authored = max(0.0, controls[0][0][2] - passage["upper_mouth_q"][2] * scale + 1.13)
+    stratum = next((row for row in layout["strates"]
+                    if row["strate_index"] == passage["upper_strate_index"]), None)
+    if stratum is None or stratum["generator_kind"] != "FloatingIslands":
+        return authored
+    route = [tuple(value * scale for value in anchor["values"][:3])
+             for anchor in stratum.get("anchors", [])
+             if anchor.get("kind") == "route_point" and len(anchor.get("values", [])) >= 3]
+    projected = route_height_at_xy(route, controls[0][0][0], controls[0][0][1])
+    if projected is None or projected[1] > (controls[0][1] + 2.0) ** 2:
+        return authored
+    route_depth = max(0.0, controls[0][0][2] - projected[0] + 1.13)
+    return max(authored, route_depth)
+
+
+def route_controls(layout: dict, passage: dict, *, adjust_upper_mouth=False):
+    scale = layout["core_voxel_size_um"] / 256.0 / 1_000_000.0
+    controls = [(tuple(value * scale for value in row["position_q"]),
+                 row["radius_q"] * scale) for row in passage["control_points"]]
+    lower_q = passage["lower_mouth_q"]
+    player_center_above_floor_q = round(
+        1.13 * 256.0 * 1_000_000.0 / layout["core_voxel_size_um"])
+    lower_index = next((index for index, row in enumerate(passage["control_points"])
+                        if row["position_q"][0] == lower_q[0]
+                        and row["position_q"][1] == lower_q[1]
+                        and row["position_q"][2] - row["radius_q"]
+                            + player_center_above_floor_q == lower_q[2]), None)
+    if lower_index is None:
+        raise RuntimeError(f"{passage['stable_id']}: lower mouth control is unbound")
+    if lower_index < 1:
+        raise RuntimeError(f"{passage['stable_id']}: incomplete route controls")
+    if adjust_upper_mouth:
+        controls[0] = (controls[0][0], max(controls[0][1],
+            upper_mouth_floor_depth(layout, passage, controls)))
+    return controls, lower_index
+
+
+def route_for(layout: dict, passage: dict) -> list[tuple[tuple[float, float, float], float]]:
+    controls, lower_index = route_controls(layout, passage)
+    return controls[:lower_index + 1]
+
+
+def spline_knot_span(a, b):
+    return max(1.0e-6, math.sqrt(math.sqrt((b[0] - a[0]) ** 2
+                                           + (b[1] - a[1]) ** 2)))
+
+
+def spline_point(controls, span, t):
+    as_point = lambda index: (*controls[index][0], controls[index][1])
+    p0, p1, p2, p3 = (as_point(max(0, span - 1)), as_point(span),
+                       as_point(span + 1), as_point(min(span + 2, len(controls) - 1)))
+    dt0, dt1, dt2 = (spline_knot_span(p0, p1), spline_knot_span(p1, p2),
+                     spline_knot_span(p2, p3))
+    t2, t3 = t * t, t * t * t
+    result = [0.0] * 4
+    for axis in (0, 1, 3):
+        m1 = dt1 * ((p1[axis] - p0[axis]) / dt0
+                    - (p2[axis] - p0[axis]) / (dt0 + dt1)
+                    + (p2[axis] - p1[axis]) / dt1)
+        m2 = dt1 * ((p2[axis] - p1[axis]) / dt1
+                    - (p3[axis] - p1[axis]) / (dt1 + dt2)
+                    + (p3[axis] - p2[axis]) / dt2)
+        result[axis] = ((2 * t3 - 3 * t2 + 1) * p1[axis]
+                        + (-2 * t3 + 3 * t2) * p2[axis]
+                        + (t3 - 2 * t2 + t) * m1 + (t3 - t2) * m2)
+    result[2] = p1[2] + (p2[2] - p1[2]) * t
+    result[3] = min(max(result[3], min(p1[3], p2[3])), max(p1[3], p2[3]))
+    return result
+
+
+def smooth_route(layout: dict, passage: dict):
+    """Mirror PassageSpline::BuildSegments from the runtime shared sampler."""
+    scale = layout["core_voxel_size_um"] / 256.0 / 1_000_000.0
+    planned_floor_profile = [
+        (row["position_q"][2] - row["radius_q"]) * scale
+        for row in passage["control_points"]]
+    controls, route_end = route_controls(layout, passage, adjust_upper_mouth=True)
+    result = []
+    along = 0.0
+    arc_steps = 32
+    for span in range(route_end):
+        arc = [0.0]
+        previous = spline_point(controls, span, 0.0)
+        for step in range(1, arc_steps + 1):
+            current = spline_point(controls, span, step / arc_steps)
+            arc.append(arc[-1] + math.hypot(current[0] - previous[0],
+                                             current[1] - previous[1]))
+            previous = current
+        segment_count = max(1, math.ceil(arc[-1]))
+        points = [spline_point(controls, span, 0.0)]
+        parameters = [0.0]
+        for segment in range(1, segment_count + 1):
+            target = min(arc[-1], arc[-1] * segment / segment_count)
+            upper = next(index for index in range(1, len(arc))
+                         if arc[index] >= target)
+            lower = upper - 1
+            width = arc[upper] - arc[lower]
+            fraction = min(1.0, max(0.0, (target - arc[lower]) / width)) if width > 1e-12 else 0.0
+            t = (lower + fraction) / arc_steps
+            points.append(spline_point(controls, span, t))
+            parameters.append(t)
+        sampled_arc = [0.0]
+        for a, b in zip(points, points[1:]):
+            sampled_arc.append(sampled_arc[-1] + math.hypot(b[0] - a[0], b[1] - a[1]))
+        horizontal_length = sampled_arc[-1]
+        for index, point in enumerate(points):
+            progress = sampled_arc[index] / horizontal_length if horizontal_length > 1e-12 else parameters[index]
+            point[2] = controls[span][0][2] + (controls[span + 1][0][2]
+                       - controls[span][0][2]) * progress
+            point.append(planned_floor_profile[span]
+                         + (planned_floor_profile[span + 1]
+                            - planned_floor_profile[span]) * progress)
+        if not result:
+            result.append((tuple(points[0][:3]), points[0][3], 0.0, points[0][4]))
+        for a, b in zip(points, points[1:]):
+            length = math.dist(a[:3], b[:3])
+            along += length
+            result.append((tuple(b[:3]), b[3], along, b[4]))
+    return result
+
+
+def derived_smooth_route(route, passage, layout):
+    total = route[-1][2]
+    interior_radii = [radius for _, radius, distance, _ in route
+                      if distance >= 10.0 and total - distance >= 10.0]
+    body_depth = max(0.5, min(interior_radii or [radius for _, radius, _, _ in route]) - 0.23)
+    result = []
+    for point, radius, distance, planned_floor in route:
+        local_radius_depth = max(0.0, radius - 0.23)
+        tube_depth = min(body_depth, local_radius_depth)
+        center = (point[0], point[1], planned_floor + tube_depth)
+        result.append((center, radius, distance, planned_floor))
+    return result, body_depth
+
+
+def route_lengths(route):
+    lengths = [((b[2] - a[2]) if len(a) > 2 and len(b) > 2
+                else math.dist(a[0], b[0])) for a, b in zip(route, route[1:])]
+    prefix = [0.0]
+    for length in lengths:
+        prefix.append(prefix[-1] + length)
+    return lengths, prefix
+
+
+def at_distance(route, lengths, prefix, distance):
+    distance = max(0.0, min(distance, prefix[-1]))
+    for index, length in enumerate(lengths):
+        if distance <= prefix[index + 1] or index + 1 == len(lengths):
+            t = 0.0 if length <= 1.0e-9 else (distance - prefix[index]) / length
+            a, b = route[index], route[index + 1]
+            return (tuple(a[0][axis] + (b[0][axis] - a[0][axis]) * t
+                          for axis in range(3)),
+                    a[1] + (b[1] - a[1]) * t)
+    return route[-1]
+
+
+def tangent_at(route, lengths, prefix, distance):
+    before = at_distance(route, lengths, prefix, max(0.0, distance - 0.25))[0]
+    after = at_distance(route, lengths, prefix, min(prefix[-1], distance + 0.25))[0]
+    return norm(sub(after, before))
+
+
+def derived_route(route, passage, layout):
+    """Apply L109's fixed-depth floor offset to raw layout controls."""
+    lengths, prefix = route_lengths(route)
+    total = prefix[-1]
+    body_radii = [radius for index, (_, radius) in enumerate(route)
+                  if prefix[index] >= 10.0 and total - prefix[index] >= 10.0]
+    body_depth = max(0.5, min(body_radii or [radius for _, radius in route]) - 0.23)
+    scale = layout["core_voxel_size_um"] / 256.0 / 1_000_000.0
+    upper_z = passage["upper_mouth_q"][2] * scale
+    lower_z = passage["lower_mouth_q"][2] * scale
+    upper_target = max(0.0, route[0][0][2] - upper_z + 1.13)
+    lower_target = max(0.0, route[-1][0][2] - lower_z + 1.13)
+    transformed = []
+    for index, (point, radius) in enumerate(route):
+        local_radius_depth = max(0.0, radius - 0.23)
+        mouth_distance = max(0.0, min(prefix[index], total - prefix[index]))
+        u = max(0.0, min(1.0, mouth_distance / 5.0))
+        ramp = u * u * (3.0 - 2.0 * u)
+        target = upper_target if prefix[index] <= total * 0.5 else lower_target
+        mouth_depth = max(0.0, min(radius, target))
+        route_depth = mouth_depth + (local_radius_depth - mouth_depth) * ramp
+        tube_depth = min(body_depth, local_radius_depth)
+        transformed.append(((point[0], point[1], point[2] - route_depth + tube_depth),
+                            radius))
+    return transformed, body_depth
+
+
+def make_views(layout: dict, audit_sections: list[dict], *, use_derived_shape: bool,
+               use_spline: bool,
+               include_open_air: bool = True) -> list[dict]:
+    views = []
+    passages = sorted(layout["passages"], key=lambda item: item["stable_id"])
+    for passage in passages:
+        raw_route = smooth_route(layout, passage) if use_spline else route_for(layout, passage)
+        if use_derived_shape:
+            route, body_depth = (derived_smooth_route(raw_route, passage, layout)
+                                 if use_spline else derived_route(raw_route, passage, layout))
+        else:
+            route = raw_route
+            body_depth = max(point[1] for point in route)
+        def floor_depth(radius: float) -> float:
+            if not use_derived_shape:
+                return radius
+            return min(body_depth, max(0.0, radius - 0.23))
+        lengths, prefix = route_lengths(route)
+        total = prefix[-1]
+        passage_id = passage["stable_id"]
+        safe_id = sanitize(passage_id)
+
+        for end_name, distance, outward_sign in (
+                ("upper-mouth", 0.0, -1.0), ("lower-mouth", total, 1.0)):
+            center, radius = at_distance(route, lengths, prefix, distance)
+            tangent = tangent_at(route, lengths, prefix, distance)
+            outward = mul(tangent, outward_sign)
+            floor_z = center[2] - floor_depth(radius)
+            eye = (center[0] + outward[0] * 4.5,
+                   center[1] + outward[1] * 4.5,
+                   floor_z + 1.55)
+            if end_name == "lower-mouth":
+                eye = add(eye, add(mul(outward, 5.0), (0.0, 0.0, 2.0)))
+            target = (center[0] - outward[0] * 2.0,
+                      center[1] - outward[1] * 2.0,
+                      floor_z + 1.45)
+            yaw, pitch = angles(eye, target)
+            views.append({"name": f"{safe_id}-{end_name}", "passage": passage_id,
+                          "kind": "mouth", "station": end_name,
+                          "camera": eye, "target": target, "yaw": yaw, "pitch": pitch,
+                          "focus": center, "center_z": center[2]})
+
+        for fraction in (0.25, 0.50, 0.75):
+            distance = total * fraction
+            center, radius = at_distance(route, lengths, prefix, distance)
+            tangent = tangent_at(route, lengths, prefix, distance)
+            depth = floor_depth(radius)
+            floor_z = center[2] - depth
+            horizontal = norm((-tangent[1], tangent[0], 0.0))
+            eye = (center[0] + horizontal[0] * 0.75,
+                   center[1] + horizontal[1] * 0.75, floor_z + 1.60)
+            target_center, target_radius = at_distance(route, lengths, prefix,
+                min(total, distance + 14.0))
+            target_depth = floor_depth(target_radius)
+            target = (target_center[0] + horizontal[0] * 2.35,
+                      target_center[1] + horizontal[1] * 2.35,
+                      target_center[2] - target_depth + 1.80)
+            yaw, pitch = angles(eye, target)
+            views.append({"name": f"{safe_id}-station-{int(fraction * 100)}",
+                          "passage": passage_id, "kind": "station",
+                          "station": f"{int(fraction * 100)}%", "camera": eye,
+                          "target": target, "yaw": yaw, "pitch": pitch,
+                          "focus": center, "center_z": center[2],
+                          "route_distance_m": distance,
+                          "route_length_m": total,
+                          "requested_route_distance_m": distance})
+
+        if not include_open_air:
+            continue
+        for section in (item for item in audit_sections if item["passage"] == passage_id):
+            distance = 0.5 * (section["start_m"] + section["end_m"])
+            center, radius = (section["midpoint"], section["radius_m"])
+            tangent = tangent_at(route, lengths, prefix, distance)
+            side = norm((-tangent[1], tangent[0], 0.0))
+            depth = floor_depth(radius)
+            section_id = section["section"]
+            interior_eye = (center[0], center[1], center[2] - depth + 1.25)
+            interior_target = add(interior_eye, mul(tangent, 7.0))
+            side_eye = add(center, add(mul(side, radius + 5.0), (0.0, 0.0, 1.2)))
+            oblique_eye = add(center, add(mul(side, -(radius + 3.5)), (0.0, 0.0, 4.0)))
+            targets = (add(center, (0.0, 0.0, 0.1)),
+                       add(center, mul(tangent, 2.0)), interior_target)
+            for view_index, (eye, target) in enumerate(zip(
+                    (side_eye, oblique_eye, interior_eye), targets), start=1):
+                yaw, pitch = angles(eye, target)
+                views.append({"name": f"{safe_id}-openair-{section_id}-view-{view_index}",
+                              "passage": passage_id, "kind": "open-air",
+                              "station": f"section-{section_id}/view-{view_index}",
+                              "camera": eye, "target": target, "yaw": yaw,
+                              "pitch": pitch, "focus": center,
+                              "center_z": center[2], "open_air_section": section_id,
+                              "route_distance_m": distance,
+                              "requested_route_distance_m": distance,
+                              "route_length_m": total})
+            floor_z = center[2] - depth
+            outside_target = add(center, add(mul(side, radius), (0.0, 0.0, -depth + 0.5)))
+            outside_eye = add(outside_target, mul(side, 4.0))
+            interior_radius = math.sqrt(max(0.0, radius * radius
+                - max(0.0, depth - 0.5) ** 2))
+            inside_target = add(center, add(mul(side, interior_radius),
+                                            (0.0, 0.0, -depth + 0.5)))
+            inside_eye = add(inside_target,
+                add(mul(side, -1.0), mul(tangent, math.sqrt(15.0))))
+            for closeup, eye, target in (("outside", outside_eye, outside_target),
+                                         ("interior-wall", inside_eye, inside_target)):
+                yaw, pitch = angles(eye, target)
+                views.append({"name": f"{safe_id}-openair-{section_id}-4m-{closeup}",
+                              "passage": passage_id, "kind": "open-air-close",
+                              "station": f"section-{section_id}/4m-{closeup}",
+                              "camera": eye, "target": target, "yaw": yaw,
+                              "pitch": pitch, "focus": center, "center_z": center[2],
+                              "open_air_section": section_id, "closeup_side": closeup,
+                              "closeup_preferred_normal": side if closeup == "outside"
+                                  else mul(side, -1.0),
+                              "camera_target_distance_m": math.dist(eye, target),
+                              "route_distance_m": distance,
+                              "requested_route_distance_m": distance,
+                              "route_length_m": total})
+    return views
+
+
+def run_process(name: str, command: list[str], log: Path, *, allow_failure=False) -> str:
+    wrapped = ["taskset", "-c", "0-11", "prlimit", "--as=6442450944", "--",
+               "timeout", "1740s", *map(str, command)]
+    started = time.monotonic()
+    with log.open("w", encoding="utf-8") as stream:
+        result = subprocess.run(wrapped, cwd=ROOT, stdout=stream,
+                                stderr=subprocess.STDOUT, check=False, timeout=1740)
+    if result.returncode and not allow_failure:
+        raise RuntimeError(f"{name}: exit={result.returncode} log={log}")
+    print(f"[L112CaptureProcess] name={name} elapsed_s={time.monotonic()-started:.2f} "
+          f"exit={result.returncode} log={log.relative_to(ROOT)}", flush=True)
+    return log.read_text(encoding="utf-8", errors="replace")
+
+
+def capture(variant: str, view: dict, layout: dict) -> dict:
+    variant_saved = SAVED / variant
+    variant_saved.mkdir(parents=True, exist_ok=True)
+    variant_capture = CAPTURES / variant
+    variant_capture.mkdir(parents=True, exist_ok=True)
+    scene = variant_saved / f"{view['name']}.vfmesh"
+    image = variant_capture / f"{view['name']}.png"
+    candidates = [(view["camera"], view["target"], view["focus"],
+                   view.get("route_distance_m"), 0.0, "requested")]
+    if variant == "before" and view["kind"] not in ("mouth", "open-air-close"):
+        passage = next(item for item in layout["passages"]
+                       if item["stable_id"] == view["passage"])
+        route = route_for(layout, passage)
+        lengths, prefix = route_lengths(route)
+        total = prefix[-1]
+        eye_offset = sub(view["camera"], view["focus"])
+        target_offset = sub(view["target"], view["focus"])
+        requested = view["route_distance_m"]
+        for delta in (5, -5, 10, -10, 20, -20, 35, -35, 50, -50, 75, -75,
+                      100, -100, 150, -150, 200, -200):
+            distance = max(0.0, min(total, requested + delta))
+            if abs(distance - requested) < 0.01:
+                continue
+            center, _radius = at_distance(route, lengths, prefix, distance)
+            candidates.append((add(center, eye_offset), add(center, target_offset), center,
+                               distance, distance - requested, "route-offset"))
+
+    attempt_errors = []
+    for attempt_index, (probe_camera, probe_target, probe_focus, route_distance,
+                        route_adjustment, attempt_kind) in enumerate(candidates):
+        suffix = "" if attempt_index == 0 else f"-attempt-{attempt_index:02d}"
+        headless_log = variant_saved / f"{view['name']}{suffix}-mesh.log"
+        render_log = variant_saved / f"{view['name']}{suffix}-render.log"
+        quality_log = variant_saved / f"{view['name']}{suffix}-quality.log"
+        yaw, pitch = angles(probe_camera, probe_target)
+        camera = (*probe_camera, yaw, pitch)
+        export_command = [
+            str(BINARIES[variant]), str(DATA), "--world-assembler-prototype",
+            "--stream-benchmark", "--stream-pipeline", "--workers=12",
+            "--clip-radius=3", "--max-clip-level=0", "--max-level=0", "--force-generate",
+            "--recipe=surface-world", f"--camera={fmt(camera)}",
+            "--render-distance-chunks=1", f"--mesh-export={scene}",
+        ]
+        export_output = run_process(f"{variant}-{view['name']}{suffix}-mesh", export_command,
+                                    headless_log)
+        if "status=PASS" not in export_output or not scene.is_file():
+            raise RuntimeError(f"{variant}-{view['name']}: missing successful scene export")
+        source_triangles = mesh_triangle_count(scene)
+        if source_triangles <= 0:
+            attempt_errors.append(f"{attempt_kind}@{route_distance}: empty mesh")
+            if variant == "after" or view["kind"] == "mouth":
+                break
+            continue
+
+        actual_camera, actual_target = probe_camera, probe_target
+        actual_focus = probe_focus
+        surface_distance = None
+        closeup_surface_distance = None
+        closeup_anchor_offset = None
+        closeup_normal_alignment = None
+        closeup_distance = None
+        if view["kind"] == "open-air-close":
+            try:
+                wall_anchor = nearest_surface_anchor(scene, probe_target, margin_m=5.0,
+                    preferred_normal=view["closeup_preferred_normal"],
+                    minimum_alignment=0.25)
+                closeup_surface_distance = wall_anchor["distance_m"]
+                closeup_anchor_offset = closeup_surface_distance
+                closeup_normal_alignment = dot(wall_anchor["normal"],
+                    view["closeup_preferred_normal"])
+                if closeup_surface_distance > 5.0:
+                    raise RuntimeError(f"{variant}-{view['name']}: nearest wall surface is "
+                        f"{closeup_surface_distance:.3f} m from the route-local target")
+                actual_target = wall_anchor["position_m"]
+                actual_camera = add(actual_target, mul(wall_anchor["normal"], 4.0))
+                closeup_distance = math.dist(actual_camera, actual_target)
+                if abs(closeup_distance - 4.0) > 0.02:
+                    raise RuntimeError(f"{variant}-{view['name']}: camera-to-wall distance is "
+                                       f"{closeup_distance:.3f} m, expected 4 m")
+            except RuntimeError as error:
+                raise RuntimeError(f"{variant}-{view['name']}: could not verify the 4 m wall "
+                                   f"view: {error}") from error
+        if attempt_kind == "route-offset":
+            anchor = nearest_surface_anchor(scene, probe_focus)
+            surface_distance = anchor["distance_m"]
+            actual_camera = add(anchor["position_m"], mul(anchor["normal"], 12.0))
+            actual_target = anchor["position_m"]
+            actual_focus = anchor["position_m"]
+        actual_yaw, actual_pitch = angles(actual_camera, actual_target)
+        render_command = [
+            str(RENDERERS[variant]), str(scene), str(image), "--size=1920x1080",
+            f"--camera-m={fmt(actual_camera)}", f"--yaw-deg={actual_yaw:.6f}",
+            f"--pitch-deg={actual_pitch:.6f}", "--shade=readable", "--headlamp=on",
+            "--height-tint=on", f"--height-center-m={actual_focus[2]:.6f}",
+            "--height-range-m=32",
+        ]
+        render_output = run_process(f"{variant}-{view['name']}{suffix}-render", render_command,
+                                    render_log)
+        drawn = DRAWN.search(render_output)
+        if drawn is None or int(drawn.group(1)) <= 0 or not image.is_file():
+            attempt_errors.append(f"{attempt_kind}@{route_distance}: no drawn geometry")
+            if variant == "after" or view["kind"] == "mouth":
+                break
+            continue
+        quality = run_process(f"{variant}-{view['name']}{suffix}-quality", [
+            "python3", "-B", str(ROOT / "Standalone/Tools/verify/capture_quality.py"),
+            str(image)], quality_log, allow_failure=True)
+        quality_status = "pass"
+        if "status=PASS" not in quality:
+            metrics = QUALITY_METRICS.search(quality)
+            coverage = float(metrics.group(2)) if metrics else 0.0
+            if coverage >= 0.001:
+                quality_status = "low_contrast_geometry_visible"
+            else:
+                attempt_errors.append(f"{attempt_kind}@{route_distance}: no visible pixel coverage")
+                if variant == "after" or view["kind"] == "mouth":
+                    break
+                continue
+
+        row = {**view, "variant": variant, "capture": str(image.relative_to(RESEARCH)),
+               "scene": str(scene.relative_to(ROOT)), "drawn_triangles": int(drawn.group(1)),
+               "source_triangles": source_triangles, "verified": True,
+               "pixel_quality_status": quality_status,
+               "route_distance_actual_m": route_distance,
+               "route_station_adjustment_m": route_adjustment,
+               "closeup_camera_target_distance_m": closeup_distance,
+               "closeup_target_surface_distance_m": closeup_surface_distance,
+               "closeup_predicted_target_offset_m": closeup_anchor_offset,
+               "closeup_wall_normal_alignment": closeup_normal_alignment,
+               "fallback_kind": attempt_kind if attempt_kind != "requested" else None,
+               "fallback_surface_distance_m": surface_distance,
+               "camera_actual_m": actual_camera, "target_actual_m": actual_target,
+               "logs": [str(headless_log.relative_to(ROOT)),
+                        str(render_log.relative_to(ROOT)),
+                        str(quality_log.relative_to(ROOT))]}
+        print("[L112Capture] " + json.dumps(row, sort_keys=True), flush=True)
+        return row
+    raise RuntimeError(f"{variant}-{view['name']}: no verified image; "
+                       + "; ".join(attempt_errors))
+
+
+def main() -> int:
+    if any(not path.is_file() for path in (*BINARIES.values(), *RENDERERS.values(),
+                                            *LAYOUTS.values(), *AUDIT_LOGS.values())):
+        raise SystemExit("missing L109 capture binary, layout, or audit log")
+    all_rows = []
+    variants = ("before", "after")
+    if "--after-only" in sys.argv[1:]:
+        prior_log = SAVED.parent / "captures-before-first.log"
+        if not prior_log.is_file():
+            raise SystemExit(f"missing reusable L109 capture rows: {prior_log}")
+        for line in prior_log.read_text(encoding="utf-8", errors="replace").splitlines():
+            if line.startswith("[L112Capture] ") or line.startswith("[L109Capture] "):
+                all_rows.append(json.loads(line.split(" ", 1)[1]))
+        if not all_rows or any(row["variant"] != "before" for row in all_rows):
+            raise SystemExit("saved L109 capture rows are incomplete")
+        variants = ("after",)
+    sections_by_variant = {}
+    for variant in ("before", "after"):
+        sections = []
+        for passage, section, start, end, samples, midpoint, radius in SECTION.findall(
+                AUDIT_LOGS[variant].read_text(encoding="utf-8", errors="replace")):
+            sections.append({"passage": passage, "section": int(section),
+                             "start_m": float(start), "end_m": float(end),
+                             "samples": int(samples), "midpoint": vector(midpoint),
+                             "radius_m": float(radius)})
+        if not sections:
+            raise SystemExit(f"no open-air sections found in the {variant} passage audit")
+        sections_by_variant[variant] = sections
+        if variant not in variants:
+            continue
+        if variant == "after" and variants == ("after",):
+            expected_before = 15 + 5 * len(sections_by_variant["before"])
+            if len(all_rows) != expected_before or any(
+                    row.get("variant") != "before" or not row.get("verified")
+                    for row in all_rows):
+                raise RuntimeError("saved L109 capture rows do not cover every required view")
+        layout = json.loads(LAYOUTS[variant].read_text(encoding="utf-8"))
+        include_open_air = True
+        views = make_views(layout, sections, use_derived_shape=True,
+                           use_spline=variant == "after",
+                           include_open_air=include_open_air)
+        expected = 5 * len(layout["passages"])
+        if include_open_air:
+            expected += 5 * len(sections)
+        if len(views) != expected:
+            raise RuntimeError(f"unexpected camera count: {len(views)} != {expected}")
+        print(f"[L112CapturePlan] variant={variant} passage_views={5*len(layout['passages'])} "
+              f"open_air_sections={len(sections) if include_open_air else 0} "
+              f"open_air_views={5*len(sections) if include_open_air else 0} "
+              f"total={len(views)}", flush=True)
+        for view in views:
+            all_rows.append(capture(variant, view, layout))
+    CAPTURES.mkdir(parents=True, exist_ok=True)
+    (CAPTURES / "capture-index.json").write_text(
+        json.dumps({"open_air_sections_by_variant": sections_by_variant,
+            "captures": all_rows}, indent=2) + "\n",
+        encoding="utf-8")
+    lines = ["# L112 passage captures", "",
+             "Each PNG was rendered from its own exported mesh. The renderer reported visible "
+             "triangles, and each decoded image met the pixel coverage floor. "
+             "`low_contrast_geometry_visible` marks images that met this floor below the "
+             "preferred contrast target.", ""]
+    for variant in ("before", "after"):
+        lines.extend([f"## {variant.title()}", ""])
+        for row in all_rows:
+            if row["variant"] != variant:
+                continue
+            flag = " **OPEN AIR**" if row["kind"] == "open-air" else ""
+            quality_note = (f"; {row['pixel_quality_status']}"
+                            if row["pixel_quality_status"] != "pass" else "")
+            lines.append(f"- [{row['station']}]({variant}/{Path(row['capture']).name}) — "
+                         f"{row['passage']}{flag}; {row['drawn_triangles']} visible triangles"
+                         f"{quality_note}")
+        lines.append("")
+    (CAPTURES / "INDEX.md").write_text("\n".join(lines), encoding="utf-8")
+    failures = [row for row in all_rows if not row["verified"]]
+    closeups = [row for row in all_rows if row["kind"] == "open-air-close"]
+    closeups_ok = (len(closeups) == 2 * sum(1 for row in all_rows
+        if row["kind"] == "open-air" and row["station"].endswith("view-1"))
+        and all(row["verified"] and abs(row["closeup_camera_target_distance_m"] - 4.0) <= 0.02
+                and row["closeup_target_surface_distance_m"] <= 5.0
+                and row["closeup_wall_normal_alignment"] >= 0.25
+                and row["drawn_triangles"] > 0
+                and row["pixel_quality_status"] in
+                    ("pass", "low_contrast_geometry_visible") for row in closeups))
+    print(f"[L112CaptureSummary] captures={len(all_rows)} verified={len(all_rows)-len(failures)} "
+          f"failed={len(failures)} 4m_closeups={len(closeups)} closeups_verified="
+          f"{str(closeups_ok).lower()}", flush=True)
+    return 1 if failures or not closeups_ok else 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())