import {
  applyLandscapeUnitAdminPartition,
  assignAdminRegionsFromNaturalCompartments,
  lockSmallUrbanComponentsToMunicipality,
  mergeTinyMunicipalities,
  removeMunicipalExclaves,
  smoothAdminRegionsTerrainAware,
  splitOversizedLowlandMunicipalities,
  snapAdminBoundariesToTerrain,
} from "./adminRegions.js";
import { INF, MAP_H, MAP_W, SIZE, MinHeap, clamp, hash2, indexOf, inside, pickEntities, rand, xyOf } from "./mapUtils.js";
import { extractAdminBorderSegments } from "./mapGeneratorHelpers.js";

function changedCellsSince(before, after, prefectureMask, sea) {
  let changed = 0;
  for (let i = 0; i < SIZE; i++) if (prefectureMask[i] && !sea[i] && before[i] !== after[i]) changed++;
  return changed;
}

function municipalityAreaById(adminId, prefectureMask, sea) {
  const area = new Map();
  for (let i = 0; i < SIZE; i++) {
    if (!prefectureMask[i] || sea[i] || adminId[i] < 0) continue;
    area.set(adminId[i], (area.get(adminId[i]) || 0) + 1);
  }
  return area;
}

function maskLandArea(mask, sea) {
  let area = 0;
  for (let i = 0; i < SIZE; i++) if (mask[i] && !sea[i]) area++;
  return area;
}

function compactWholeCompartmentMunicipalities(adminId, centers, prefectureMask, sea, fields = {}) {
  const activeIds = [...new Set([...adminId].filter((id, i) => id >= 0 && prefectureMask[i] && !sea[i]))].sort((a, b) => a - b);
  const idMap = new Map(activeIds.map((id, n) => [id, n]));
  const compactId = new Int16Array(SIZE);
  compactId.fill(-1);
  const stats = activeIds.map(() => ({ sx: 0, sy: 0, count: 0, bestI: -1, bestScore: -INF }));
  for (let i = 0; i < SIZE; i++) {
    if (!prefectureMask[i] || sea[i] || adminId[i] < 0) continue;
    const nextId = idMap.get(adminId[i]);
    if (nextId === undefined) continue;
    compactId[i] = nextId;
    const [x, y] = xyOf(i);
    const row = stats[nextId];
    row.sx += x;
    row.sy += y;
    row.count++;
    const score = (fields.populationDensity?.[i] || 0) * 2.2 + (fields.plain?.[i] || 0) * 0.25 - (fields.slope?.[i] || 0) * 0.2;
    if (score > row.bestScore) { row.bestScore = score; row.bestI = i; }
  }
  const compactCenters = activeIds.map((oldId, newId) => {
    const current = centers[oldId];
    if (current && inside(current.x, current.y) && compactId[indexOf(current.x, current.y)] === newId) {
      return { ...current, originalAdminId: oldId };
    }
    const row = stats[newId];
    const fallback = row.bestI >= 0 ? xyOf(row.bestI) : [Math.round(row.sx / Math.max(1, row.count)), Math.round(row.sy / Math.max(1, row.count))];
    return {
      ...(current || {}),
      x: fallback[0],
      y: fallback[1],
      originalAdminId: oldId,
      generatedOfficePoint: true,
      invisibleLowlandAdminSeed: current?.invisibleLowlandAdminSeed ?? true,
      seedKind: current?.seedKind || "compactedMunicipalityOffice",
    };
  });
  return { adminId: compactId, adminCentersRaw: compactCenters, activeMunicipalityCount: compactCenters.length };
}

function enforceCompartmentMunicipalityOwnership(adminId, compartmentId, compartments, prefectureMask, sea) {
  if (!compartmentId || !compartments) return 0;
  let changed = 0;
  for (const comp of compartments) {
    if (!comp || !comp.cells?.length) continue;
    const counts = new Map();
    for (const i of comp.cells) {
      if (!prefectureMask[i] || sea[i]) continue;
      const id = adminId[i];
      if (id >= 0) counts.set(id, (counts.get(id) || 0) + 1);
    }
    let bestId = -1, bestCount = -1;
    for (const [id, count] of counts) {
      if (count > bestCount || (count === bestCount && id < bestId)) {
        bestId = id;
        bestCount = count;
      }
    }
    if (bestId < 0) continue;
    for (const i of comp.cells) {
      if (!prefectureMask[i] || sea[i] || adminId[i] === bestId) continue;
      adminId[i] = bestId;
      changed++;
    }
  }
  return changed;
}

function buildMunicipalityGraph(adminId, prefectureMask, sea, naturalBarrierScore, populationDensity) {
  const nodes = new Map();
  const edges = new Map();
  for (let i = 0; i < SIZE; i++) {
    if (!prefectureMask[i] || sea[i] || adminId[i] < 0) continue;
    const id = adminId[i];
    if (!nodes.has(id)) nodes.set(id, { id, area: 0, population: 0, sx: 0, sy: 0, touchesOutside: false });
    const node = nodes.get(id);
    const [x, y] = xyOf(i);
    if (x === 0 || y === 0 || x === MAP_W - 1 || y === MAP_H - 1) node.touchesOutside = true;
    for (const [ox, oy] of [[x + 1, y], [x - 1, y], [x, y + 1], [x, y - 1]]) {
      if (!inside(ox, oy)) { node.touchesOutside = true; continue; }
      const oi = indexOf(ox, oy);
      if (!prefectureMask[oi] || sea[oi]) node.touchesOutside = true;
    }
    node.area++;
    node.population += populationDensity?.[i] || 0;
    node.sx += x;
    node.sy += y;
    for (const [nx, ny] of [[x + 1, y], [x, y + 1]]) {
      if (!inside(nx, ny)) continue;
      const ni = indexOf(nx, ny);
      if (!prefectureMask[ni] || sea[ni] || adminId[ni] < 0 || adminId[ni] === id) continue;
      const a = Math.min(id, adminId[ni]);
      const b = Math.max(id, adminId[ni]);
      const key = `${a}:${b}`;
      const edge = edges.get(key) || { a, b, count: 0, barrier: 0 };
      edge.count++;
      edge.barrier += ((naturalBarrierScore?.[i] || 0) + (naturalBarrierScore?.[ni] || 0)) * 0.5;
      edges.set(key, edge);
    }
  }
  for (const node of nodes.values()) {
    node.x = node.sx / Math.max(1, node.area);
    node.y = node.sy / Math.max(1, node.area);
    node.adjacent = new Map();
  }
  for (const edge of edges.values()) {
    edge.barrier /= Math.max(1, edge.count);
    nodes.get(edge.a)?.adjacent.set(edge.b, edge);
    nodes.get(edge.b)?.adjacent.set(edge.a, edge);
  }
  return { nodes, edges };
}

function choosePrefectureMunicipalitySeeds(nodes, seed) {
  const active = [...nodes.values()].filter((node) => node.area > 0).sort((a, b) => b.area - a.area || a.id - b.id);
  const totalArea = active.reduce((sum, node) => sum + node.area, 0);
  const targetCount = clamp(Math.round(totalArea / 7200), 3, 6);
  const seeds = [];
  const first = active.sort((a, b) => (b.population * 1.8 + b.area * 0.08) - (a.population * 1.8 + a.area * 0.08) || a.id - b.id)[0];
  if (first) seeds.push(first);
  while (seeds.length < targetCount) {
    let best = null, bestScore = -INF;
    for (const node of active) {
      if (seeds.includes(node)) continue;
      const nearest = Math.min(...seeds.map((s) => Math.hypot(node.x - s.x, node.y - s.y)));
      const score = nearest * (1.0 + hash2(seed, node.id) * 0.08) + Math.sqrt(node.area) * 0.12 + node.population * 0.28;
      if (score > bestScore) { bestScore = score; best = node; }
    }
    if (!best) break;
    seeds.push(best);
  }
  return seeds;
}

function assignMunicipalitiesToPrefectures(nodes, seeds) {
  const owner = new Map();
  const area = new Map();
  const heap = new MinHeap();
  seeds.forEach((node, id) => {
    owner.set(node.id, id);
    area.set(id, node.area);
    heap.push({ i: node.id, id, f: 0 });
  });
  const totalArea = [...nodes.values()].reduce((sum, node) => sum + node.area, 0);
  const maxArea = Math.max(900, totalArea * 0.30);
  while (heap.length) {
    const cur = heap.pop();
    if (!cur || owner.get(cur.i) !== cur.id) continue;
    const node = nodes.get(cur.i);
    if (!node) continue;
    for (const [nextId, edge] of node.adjacent) {
      if (owner.has(nextId)) continue;
      const next = nodes.get(nextId);
      if (!next) continue;
      const areaPressure = Math.max(0, ((area.get(cur.id) || 0) + next.area - maxArea) / Math.max(1, maxArea));
      const cost = cur.f + 1.0 + edge.barrier * 5.5 + areaPressure * 14 + hash2(cur.id, nextId) * 0.05;
      owner.set(nextId, cur.id);
      area.set(cur.id, (area.get(cur.id) || 0) + next.area);
      heap.push({ i: nextId, id: cur.id, f: cost });
    }
  }
  let fallback = 0;
  for (const id of [...nodes.keys()].sort((a, b) => a - b)) {
    if (!owner.has(id)) owner.set(id, fallback++ % Math.max(1, seeds.length));
  }
  return owner;
}

function repairPrefectureMunicipalityConnectivity(nodes, owner) {
  let changed = 0;
  for (let pass = 0; pass < 8; pass++) {
    let passChanged = 0;
    const prefIds = [...new Set(owner.values())].sort((a, b) => a - b);
    for (const prefId of prefIds) {
      const members = [...nodes.keys()].filter((id) => owner.get(id) === prefId);
      const memberSet = new Set(members);
      const seen = new Set();
      const components = [];
      for (const start of members) {
        if (seen.has(start)) continue;
        const queue = [start];
        const comp = [];
        seen.add(start);
        for (let q = 0; q < queue.length; q++) {
          const cur = queue[q];
          comp.push(cur);
          for (const next of nodes.get(cur)?.adjacent.keys() || []) {
            if (!memberSet.has(next) || seen.has(next)) continue;
            seen.add(next);
            queue.push(next);
          }
        }
        components.push(comp);
      }
      if (components.length <= 1) continue;
      components.sort((a, b) => b.length - a.length);
      for (const comp of components.slice(1)) {
        const neighborCounts = new Map();
        for (const id of comp) {
          for (const next of nodes.get(id)?.adjacent.keys() || []) {
            const nOwner = owner.get(next);
            if (nOwner !== prefId) neighborCounts.set(nOwner, (neighborCounts.get(nOwner) || 0) + 1);
          }
        }
        let best = -1, bestCount = -1;
        for (const [id, count] of neighborCounts) if (count > bestCount || (count === bestCount && id < best)) { best = id; bestCount = count; }
        if (best < 0) continue;
        for (const id of comp) owner.set(id, best);
        passChanged += comp.length;
      }
    }
    changed += passChanged;
    if (!passChanged) break;
  }
  return changed;
}

function repairPrefectureMunicipalityEnclaves(nodes, owner, maxPasses = 6) {
  let changed = 0;
  for (let pass = 0; pass < maxPasses; pass++) {
    let passChanged = 0;
    const prefIds = [...new Set(owner.values())].filter((id) => id >= 0).sort((a, b) => a - b);
    for (const prefId of prefIds) {
      const members = [...nodes.keys()].filter((id) => owner.get(id) === prefId);
      const memberSet = new Set(members);
      const seen = new Set();
      for (const start of members) {
        if (seen.has(start)) continue;
        const queue = [start];
        const comp = [];
        seen.add(start);
        let touchesOutside = false;
        const boundaryPrefs = new Map();
        for (let q = 0; q < queue.length; q++) {
          const cur = queue[q];
          comp.push(cur);
          const node = nodes.get(cur);
          if (node?.touchesOutside) touchesOutside = true;
          for (const next of node?.adjacent.keys() || []) {
            const nextOwner = owner.get(next);
            if (nextOwner === prefId) {
              if (!seen.has(next)) { seen.add(next); queue.push(next); }
            } else if (nextOwner >= 0) {
              boundaryPrefs.set(nextOwner, (boundaryPrefs.get(nextOwner) || 0) + 1);
            }
          }
        }
        if (touchesOutside || boundaryPrefs.size !== 1) continue;
        const [targetPref] = boundaryPrefs.keys();
        if (targetPref < 0 || targetPref === prefId) continue;
        for (const id of comp) owner.set(id, targetPref);
        passChanged += comp.length;
      }
    }
    changed += passChanged;
    if (!passChanged) break;
  }
  return changed;
}

function repairPrefectureCellEnclavesFromGrid(adminId, owner, prefectureMask, sea, maxPasses = 5) {
  let changed = 0;
  const dirs = [[1,0],[-1,0],[0,1],[0,-1]];
  for (let pass = 0; pass < maxPasses; pass++) {
    const prefId = new Int16Array(SIZE);
    prefId.fill(-1);
    for (let i = 0; i < SIZE; i++) {
      if (!prefectureMask[i] || sea[i] || adminId[i] < 0) continue;
      prefId[i] = owner.get(adminId[i]) ?? -1;
    }
    const seen = new Uint8Array(SIZE);
    let passChanged = 0;
    for (let i = 0; i < SIZE; i++) {
      if (seen[i] || prefId[i] < 0) continue;
      const id = prefId[i];
      const queue = [i];
      const comp = [];
      seen[i] = 1;
      let touchesOutside = false;
      const boundaryCounts = new Map();
      const adminCounts = new Map();
      for (let q = 0; q < queue.length; q++) {
        const cur = queue[q];
        comp.push(cur);
        const aid = adminId[cur];
        if (aid >= 0) adminCounts.set(aid, (adminCounts.get(aid) || 0) + 1);
        const [x, y] = xyOf(cur);
        if (x === 0 || y === 0 || x === MAP_W - 1 || y === MAP_H - 1) touchesOutside = true;
        for (const [dx, dy] of dirs) {
          const nx = x + dx, ny = y + dy;
          if (!inside(nx, ny)) { touchesOutside = true; continue; }
          const ni = indexOf(nx, ny);
          if (!prefectureMask[ni] || sea[ni]) { touchesOutside = true; continue; }
          const nid = prefId[ni];
          if (nid === id) {
            if (!seen[ni]) { seen[ni] = 1; queue.push(ni); }
          } else if (nid >= 0) {
            boundaryCounts.set(nid, (boundaryCounts.get(nid) || 0) + 1);
          }
        }
      }
      if (touchesOutside || boundaryCounts.size !== 1) continue;
      const [targetPref] = boundaryCounts.keys();
      if (targetPref < 0 || targetPref === id) continue;
      for (const aid of adminCounts.keys()) {
        if (owner.get(aid) !== targetPref) { owner.set(aid, targetPref); passChanged++; }
      }
    }
    changed += passChanged;
    if (!passChanged) break;
  }
  return changed;
}

function repairAdminSingleOwnerEnclaves(adminId, prefectureMask, sea, maxPasses = 5) {
  let changed = 0;
  const dirs = [[1,0],[-1,0],[0,1],[0,-1]];
  for (let pass = 0; pass < maxPasses; pass++) {
    const seen = new Uint8Array(SIZE);
    let passChanged = 0;
    for (let i = 0; i < SIZE; i++) {
      if (seen[i] || !prefectureMask[i] || sea[i] || adminId[i] < 0) continue;
      const id = adminId[i];
      const queue = [i];
      const comp = [];
      seen[i] = 1;
      let touchesOutside = false;
      const boundaryCounts = new Map();
      for (let q = 0; q < queue.length; q++) {
        const cur = queue[q];
        comp.push(cur);
        const [x, y] = xyOf(cur);
        if (x === 0 || y === 0 || x === MAP_W - 1 || y === MAP_H - 1) touchesOutside = true;
        for (const [dx, dy] of dirs) {
          const nx = x + dx, ny = y + dy;
          if (!inside(nx, ny)) { touchesOutside = true; continue; }
          const ni = indexOf(nx, ny);
          if (!prefectureMask[ni] || sea[ni]) { touchesOutside = true; continue; }
          const nid = adminId[ni];
          if (nid === id) {
            if (!seen[ni]) { seen[ni] = 1; queue.push(ni); }
          } else if (nid >= 0) {
            boundaryCounts.set(nid, (boundaryCounts.get(nid) || 0) + 1);
          }
        }
      }
      if (touchesOutside || boundaryCounts.size !== 1) continue;
      const [targetId] = boundaryCounts.keys();
      if (targetId < 0 || targetId === id) continue;
      for (const ci of comp) adminId[ci] = targetId;
      passChanged += comp.length;
    }
    changed += passChanged;
    if (!passChanged) break;
  }
  return changed;
}

function lockCompactUrbanAreasToDominantAdmin(adminId, prefectureMask, sea, landuse, populationDensity, maxCells = 950) {
  if (!landuse || !populationDensity) return 0;
  const seen = new Uint8Array(SIZE);
  const dirs = [[1,0],[-1,0],[0,1],[0,-1]];
  let changed = 0;
  const isUrban = (i) => !sea[i] && prefectureMask[i] && (populationDensity[i] > 0.34 || [2, 3, 4, 7, 8].includes(landuse[i]));
  for (let i = 0; i < SIZE; i++) {
    if (seen[i] || !isUrban(i) || adminId[i] < 0) continue;
    const queue = [i];
    const comp = [];
    seen[i] = 1;
    const counts = new Map();
    for (let q = 0; q < queue.length; q++) {
      const cur = queue[q];
      comp.push(cur);
      const id = adminId[cur];
      if (id >= 0) counts.set(id, (counts.get(id) || 0) + 1 + (populationDensity[cur] || 0) * 2.0);
      const [x, y] = xyOf(cur);
      for (const [dx, dy] of dirs) {
        const nx = x + dx, ny = y + dy;
        if (!inside(nx, ny)) continue;
        const ni = indexOf(nx, ny);
        if (seen[ni] || !isUrban(ni)) continue;
        seen[ni] = 1;
        queue.push(ni);
      }
    }
    if (comp.length < 8 || comp.length > maxCells || counts.size <= 1 || counts.size > 7) continue;
    let best = -1, bestScore = -INF;
    let total = 0;
    for (const [id, score] of counts) {
      total += score;
      if (score > bestScore || (score === bestScore && id < best)) { best = id; bestScore = score; }
    }
    if (best < 0 || bestScore / Math.max(1, total) < 0.38) continue;
    for (const ci of comp) {
      if (adminId[ci] !== best) { adminId[ci] = best; changed++; }
    }
  }
  return changed;
}

function mergeTinyMunicipalityPrefectures(nodes, owner) {
  let changed = 0;
  for (let pass = 0; pass < 6; pass++) {
    const areaByPref = new Map();
    for (const node of nodes.values()) {
      const pref = owner.get(node.id);
      areaByPref.set(pref, (areaByPref.get(pref) || 0) + node.area);
    }
    const totalArea = [...areaByPref.values()].reduce((sum, value) => sum + value, 0);
    const minArea = Math.max(520, totalArea / Math.max(1, areaByPref.size) * 0.34);
    const tiny = [...areaByPref.entries()]
      .filter(([, area]) => area > 0 && area < minArea && areaByPref.size > 4)
      .sort((a, b) => a[1] - b[1] || a[0] - b[0])[0];
    if (!tiny) break;
    const [tinyPref] = tiny;
    const neighborScores = new Map();
    for (const node of nodes.values()) {
      if (owner.get(node.id) !== tinyPref) continue;
      for (const [nextId, edge] of node.adjacent) {
        const nextPref = owner.get(nextId);
        if (nextPref === tinyPref || nextPref < 0) continue;
        const score = (neighborScores.get(nextPref) || 0) + edge.count * (0.6 + edge.barrier);
        neighborScores.set(nextPref, score);
      }
    }
    let best = -1, bestScore = -INF;
    for (const [pref, score] of neighborScores) {
      if (score > bestScore || (score === bestScore && pref < best)) { best = pref; bestScore = score; }
    }
    if (best < 0) break;
    for (const node of nodes.values()) if (owner.get(node.id) === tinyPref) { owner.set(node.id, best); changed++; }
  }
  return changed;
}


function splitOversizedCompartmentMunicipalities(adminId, centers, compartments, prefectureMask, sea, fields = {}, seed = 0) {
  if (!compartments?.length) return { changedCells: 0, splitMunicipalities: 0, addedCenters: 0 };
  const compOwner = new Int16Array(compartments.length);
  compOwner.fill(-1);
  for (const comp of compartments) {
    if (!comp || !comp.cells?.length) continue;
    const counts = new Map();
    for (const i of comp.cells) {
      if (!prefectureMask[i] || sea[i]) continue;
      const id = adminId[i];
      if (id >= 0) counts.set(id, (counts.get(id) || 0) + 1);
    }
    let best = -1, bestCount = -1;
    for (const [id, count] of counts) if (count > bestCount || (count === bestCount && id < best)) { best = id; bestCount = count; }
    compOwner[comp.id] = best;
  }
  const byOwner = new Map();
  for (const comp of compartments) {
    if (!comp || !comp.cells?.length) continue;
    const owner = compOwner[comp.id];
    if (owner < 0) continue;
    if (!byOwner.has(owner)) byOwner.set(owner, []);
    byOwner.get(owner).push(comp);
  }
  const areas = [...byOwner.values()].map((list) => list.reduce((sum, comp) => sum + comp.area, 0)).sort((a, b) => a - b);
  if (!areas.length) return { changedCells: 0, splitMunicipalities: 0, addedCenters: 0 };
  const median = areas[Math.floor(areas.length / 2)] || 1;
  const total = areas.reduce((sum, value) => sum + value, 0);
  const maxArea = Math.max(360, Math.min(total * 0.11, Math.max(median * 2.65, total / Math.max(12, Math.round(total / 520)))));
  let changedCells = 0;
  let splitMunicipalities = 0;
  let addedCenters = 0;
  const elevation = fields.elevation;
  const slope = fields.slope;
  const ridgeField = fields.ridgeField;
  const plain = fields.plain;
  const agriculture = fields.agriculture;
  const basinField = fields.basinField;
  const coastalLowland = fields.coastalLowland;
  const populationDensity = fields.populationDensity;
  for (const [owner, list] of [...byOwner.entries()].sort((a, b) => a[0] - b[0])) {
    const area = list.reduce((sum, comp) => sum + comp.area, 0);
    if (area <= maxArea || list.length < 4) continue;
    const desiredParts = clamp(Math.ceil(area / Math.max(1, maxArea)), 2, 9);
    const splitCount = desiredParts - 1;
    if (splitCount <= 0) continue;
    const candidates = list.map((comp) => {
      let sx = 0, sy = 0, n = 0, score = 0, bestI = -1, bestScore = -INF;
      for (const i of comp.cells) {
        if (!prefectureMask[i] || sea[i]) continue;
        const [x, y] = xyOf(i);
        sx += x; sy += y; n++;
        const cellScore =
          (plain?.[i] || 0) * 0.22 +
          (agriculture?.[i] || 0) * 0.24 +
          (basinField?.[i] || 0) * 0.14 +
          (coastalLowland?.[i] || 0) * 0.10 +
          (populationDensity?.[i] || 0) * 0.24 -
          (slope?.[i] || 0) * 0.20 -
          (ridgeField?.[i] || 0) * 0.18 -
          Math.max(0, (elevation?.[i] || 0) - 0.62) * 0.38;
        score += cellScore;
        if (cellScore > bestScore) { bestScore = cellScore; bestI = i; }
      }
      const [x, y] = bestI >= 0 ? xyOf(bestI) : [Math.round(sx / Math.max(1, n)), Math.round(sy / Math.max(1, n))];
      return { comp, x, y, score: score / Math.max(1, n) + Math.sqrt(comp.area) * 0.025 + hash2(seed + owner, comp.id) * 0.03 };
    }).sort((a, b) => b.score - a.score || a.comp.id - b.comp.id);
    const newSeeds = [];
    for (const cand of candidates) {
      if (newSeeds.length >= splitCount) break;
      if (newSeeds.every((s) => Math.hypot(s.x - cand.x, s.y - cand.y) >= 9)) newSeeds.push(cand);
    }
    if (!newSeeds.length) continue;
    const seedIds = newSeeds.map((cand) => {
      const id = centers.length;
      centers.push({ x: cand.x, y: cand.y, score: cand.score, invisibleLowlandAdminSeed: true, seedKind: "oversizedMunicipalitySplit", splitFromAdminId: owner });
      addedCenters++;
      return id;
    });
    const oldCenter = centers[owner] || candidates[0] || { x: list[0].x || 0, y: list[0].y || 0, score: 0 };
    const owners = [{ id: owner, x: oldCenter.x, y: oldCenter.y, score: oldCenter.score || 0 }, ...newSeeds.map((cand, k) => ({ id: seedIds[k], x: cand.x, y: cand.y, score: cand.score }))];
    const targetArea = area / Math.max(1, owners.length);
    const claimedArea = new Map(owners.map((entry) => [entry.id, 0]));
    for (const cand of candidates) {
      let bestSeed = owner;
      let bestCost = INF;
      for (const entry of owners) {
        const d = Math.hypot(cand.x - entry.x, cand.y - entry.y);
        const pressure = Math.max(0, ((claimedArea.get(entry.id) || 0) + cand.comp.area - targetArea * 1.25) / Math.max(1, targetArea));
        const cost = d + pressure * 18 - cand.score * 2.5 + hash2(entry.id, cand.comp.id) * 0.05;
        if (cost < bestCost) { bestCost = cost; bestSeed = entry.id; }
      }
      claimedArea.set(bestSeed, (claimedArea.get(bestSeed) || 0) + cand.comp.area);
      if (bestSeed === owner) continue;
      for (const i of cand.comp.cells) {
        if (!prefectureMask[i] || sea[i]) continue;
        if (adminId[i] !== bestSeed) { adminId[i] = bestSeed; changedCells++; }
      }
    }
    splitMunicipalities++;
  }
  return { changedCells, splitMunicipalities, addedCenters, maxArea };
}

function extractPrefectureBordersFromMunicipalities(adminId, municipalityToPrefectureId, prefectureMask, sea) {
  const segments = [];
  for (let y = 0; y < MAP_H; y++) {
    for (let x = 0; x < MAP_W; x++) {
      const i = indexOf(x, y);
      if (!prefectureMask[i] || sea[i] || adminId[i] < 0) continue;
      const aPref = municipalityToPrefectureId[adminId[i]] ?? -1;
      if (x + 1 < MAP_W) {
        const ni = indexOf(x + 1, y);
        const bPref = !sea[ni] && adminId[ni] >= 0 ? municipalityToPrefectureId[adminId[ni]] ?? -1 : -1;
        if (prefectureMask[ni] && bPref >= 0 && aPref >= 0 && bPref !== aPref && adminId[ni] !== adminId[i]) segments.push([[x + 1, y], [x + 1, y + 1]]);
      }
      if (y + 1 < MAP_H) {
        const ni = indexOf(x, y + 1);
        const bPref = !sea[ni] && adminId[ni] >= 0 ? municipalityToPrefectureId[adminId[ni]] ?? -1 : -1;
        if (prefectureMask[ni] && bPref >= 0 && aPref >= 0 && bPref !== aPref && adminId[ni] !== adminId[i]) segments.push([[x, y + 1], [x + 1, y + 1]]);
      }
    }
  }
  return segments;
}

function generatePrefecturesFromMunicipalities(context, adminResult) {
  const { adminId } = adminResult;
  const { prefectureMask, sea, naturalBarrierScore, populationDensity, seed } = context;
  const graph = buildMunicipalityGraph(adminId, prefectureMask, sea, naturalBarrierScore, populationDensity);
  const seeds = choosePrefectureMunicipalitySeeds(graph.nodes, seed + 91001);
  const owner = assignMunicipalitiesToPrefectures(graph.nodes, seeds);
  const changedForTinyMerge = mergeTinyMunicipalityPrefectures(graph.nodes, owner);
  let changedForConnectivity = repairPrefectureMunicipalityConnectivity(graph.nodes, owner);
  let changedForEnclaveRepair = repairPrefectureMunicipalityEnclaves(graph.nodes, owner);
  changedForConnectivity += repairPrefectureMunicipalityConnectivity(graph.nodes, owner);
  changedForEnclaveRepair += repairPrefectureCellEnclavesFromGrid(adminId, owner, prefectureMask, sea);
  changedForConnectivity += repairPrefectureMunicipalityConnectivity(graph.nodes, owner);
  const maxAdminId = Math.max(-1, ...[...graph.nodes.keys()]);
  const municipalityToPrefectureId = new Int16Array(maxAdminId + 1);
  municipalityToPrefectureId.fill(-1);
  for (const [admin, pref] of owner) municipalityToPrefectureId[admin] = pref;
  const prefectureRegionId = new Int16Array(SIZE);
  prefectureRegionId.fill(-1);
  for (let i = 0; i < SIZE; i++) {
    if (!prefectureMask[i] || sea[i] || adminId[i] < 0) continue;
    prefectureRegionId[i] = municipalityToPrefectureId[adminId[i]] ?? -1;
  }
  const regionalPrefectureBorders = extractPrefectureBordersFromMunicipalities(adminId, municipalityToPrefectureId, prefectureMask, sea);
  const areaByPref = new Map();
  const popByPref = new Map();
  for (const node of graph.nodes.values()) {
    const pref = owner.get(node.id);
    areaByPref.set(pref, (areaByPref.get(pref) || 0) + node.area);
    popByPref.set(pref, (popByPref.get(pref) || 0) + node.population);
  }
  const totalArea = [...areaByPref.values()].reduce((sum, value) => sum + value, 0);
  return {
    prefectureRegionId,
    municipalityToPrefectureId,
    regionalPrefectureBorders,
    regionalDebug: {
      prefecturesGeneratedAfterMunicipalities: true,
      prefectureSource: "municipality-boundary-union",
      municipalityGraphNodeCount: graph.nodes.size,
      municipalityGraphEdgeCount: graph.edges.size,
      prefectureMunicipalitySeedCount: seeds.length,
      prefectureTinyMergeChangedMunicipalities: changedForTinyMerge,
      prefectureConnectivityRepairChangedMunicipalities: changedForConnectivity,
      prefectureEnclaveRepairChangedMunicipalities: changedForEnclaveRepair,
      finalRegionalMaxAreaShare: totalArea ? Math.max(0, ...areaByPref.values()) / totalArea : 0,
      finalRegionalTinyPrefectureCount: [...areaByPref.values()].filter((area) => area < 520).length,
      finalRegionalPrefectureBorderCount: regionalPrefectureBorders.length,
      regionalPrefectureBordersRebuiltFromFinalId: true,
    },
  };
}

function isProtectedAdminSeed(seed) {
  if (!seed) return false;
  if (seed.seedKind === "capital" || seed.protectedCity?.isPrefecturalCapital) return true;
  if (seed.seedKind === "modernCity" && (seed.protectedCity?.population || seed.population || 0) >= 180000) return true;
  if (seed.seedKind === "port" && seed.portClass === "major") return true;
  if (seed.seedKind === "satelliteCity" && (seed.protectedSatellite?.population || seed.population || 0) >= 60000) return true;
  return false;
}

function buildSeedLifecycle(adminCenters, adminId, prefectureMask, sea, minArea = 80) {
  const areaById = municipalityAreaById(adminId, prefectureMask, sea);
  const lifecycle = adminCenters.map((center, id) => {
    const protectedSeed = isProtectedAdminSeed(center);
    const area = areaById.get(id) || 0;
    const enoughArea = area >= (protectedSeed ? 28 : minArea);
    return {
      id,
      protected: protectedSeed,
      area,
      state: enoughArea || protectedSeed ? "survived" : "pending",
    };
  });
  return lifecycle;
}

function activeSeedIds(seedLifecycle) {
  return new Set(seedLifecycle.filter((seed) => seed.state === "survived" || seed.protected).map((seed) => seed.id));
}

function dominantCompartmentOwners(compartments, adminId) {
  const owner = new Int16Array(compartments.length);
  owner.fill(-1);
  for (const unit of compartments) {
    if (!unit || unit.area === 0) continue;
    const counts = new Map();
    for (const i of unit.cells) {
      const id = adminId[i];
      if (id >= 0) counts.set(id, (counts.get(id) || 0) + 1);
    }
    let bestId = -1, best = -1;
    for (const [id, count] of counts) if (count > best) { best = count; bestId = id; }
    owner[unit.id] = bestId;
  }
  return owner;
}

function applyCompartmentOwners(adminId, compartments, owner) {
  for (const unit of compartments) {
    if (!unit || unit.area === 0) continue;
    const id = owner[unit.id];
    if (id < 0) continue;
    for (const i of unit.cells) adminId[i] = id;
  }
}

function absorbSeedCompartments(adminId, compartments, seedLifecycle) {
  const owner = dominantCompartmentOwners(compartments, adminId);
  const absorbed = new Set(seedLifecycle.filter((seed) => seed.state === "absorbed").map((seed) => seed.id));
  let changed = 0;
  for (const unit of compartments) {
    if (!unit || unit.area === 0 || !absorbed.has(owner[unit.id])) continue;
    let bestId = -1, bestScore = -INF;
    for (const [neighborId, edge] of unit.adjacent) {
      const candidate = owner[neighborId];
      if (candidate < 0 || absorbed.has(candidate)) continue;
      const neighbor = compartments[neighborId];
      const score = edge.count * 2 - (edge.target / Math.max(1, edge.count)) * 2 + (neighbor?.area || 0) * 0.002;
      if (score > bestScore) { bestScore = score; bestId = candidate; }
    }
    if (bestId < 0) continue;
    owner[unit.id] = bestId;
    changed += unit.area;
  }
  applyCompartmentOwners(adminId, compartments, owner);
  return changed;
}

function splitOversizedLowlandsWithPendingSeeds(adminId, prefectureMask, sea, fields, compartments, adminCenters, seedLifecycle, settlements = []) {
  const { plain, agriculture, basinField, coastalLowland, valleyField, ridgeField, slope, elevation } = fields;
  const areaById = municipalityAreaById(adminId, prefectureMask, sea);
  const areas = [...areaById.values()].sort((a, b) => a - b);
  const median = areas.length ? areas[Math.floor(areas.length / 2)] : 0;
  if (!median) return { changedCells: 0, splitMunicipalities: 0, pendingSeedsUsed: 0 };
  const owner = dominantCompartmentOwners(compartments, adminId);
  const unitsByOwner = new Map();
  for (const unit of compartments) {
    if (!unit || unit.area === 0 || owner[unit.id] < 0) continue;
    if (!unitsByOwner.has(owner[unit.id])) unitsByOwner.set(owner[unit.id], []);
    unitsByOwner.get(owner[unit.id]).push(unit);
  }
  const pending = seedLifecycle.filter((seed) => seed.state === "pending" && !seed.protected);
  let changedCells = 0;
  let splitMunicipalities = 0;
  let pendingSeedsUsed = 0;
  for (const [id, units] of unitsByOwner) {
    const area = areaById.get(id) || 0;
    if (area < Math.max(260, median * 1.45) || units.length < 6) continue;
    let lowland = 0, rough = 0;
    for (const unit of units) {
      for (const i of unit.cells) {
        lowland += (plain[i] || 0) * 0.38 + (agriculture[i] || 0) * 0.20 + basinField[i] * 0.22 + coastalLowland[i] * 0.22 + valleyField[i] * 0.10;
        rough += ridgeField[i] * 0.48 + slope[i] * 0.34 + Math.max(0, elevation[i] - 0.58) * 0.30;
      }
    }
    if (lowland / area < 0.26 || rough / area > 0.48) continue;
    const localPending = pending.filter((seed) => {
      const center = adminCenters[seed.id];
      if (!center || !inside(center.x, center.y)) return false;
      const centerOwner = adminId[indexOf(center.x, center.y)];
      return centerOwner === id || Math.hypot(center.x - (adminCenters[id]?.x || center.x), center.y - (adminCenters[id]?.y || center.y)) < 28;
    });
    const localSettlements = settlements.filter((p) => p && inside(p.x, p.y) && adminId[indexOf(p.x, p.y)] === id);
    if (localPending.length === 0 || localPending.length + localSettlements.length < 2) continue;
    let municipalitySplit = false;
    for (const seed of localPending.slice(0, 3)) {
      const center = adminCenters[seed.id];
      if (!center) continue;
      const targetArea = clamp(95 + (center.score || 0.5) * 60, 90, 180);
      let claimed = 0;
      const candidates = units
        .filter((unit) => owner[unit.id] === id && unit.classId !== 8 && unit.classId !== 9)
        .map((unit) => ({
          unit,
          score: Math.hypot(unit.x - center.x, unit.y - center.y) - (unit.lowlandFitness || 0) * 8 - (unit.urbanWeight || 0) * 3,
        }))
        .sort((a, b) => a.score - b.score);
      if (candidates.length < 2) continue;
      for (const { unit } of candidates) {
        if (claimed >= targetArea && claimed >= 2) break;
        owner[unit.id] = seed.id;
        claimed += unit.area;
        changedCells += unit.area;
      }
      if (claimed >= 45) {
        seed.state = "survived";
        seed.area = claimed;
        pendingSeedsUsed++;
        municipalitySplit = true;
      }
    }
    if (municipalitySplit) splitMunicipalities++;
  }
  applyCompartmentOwners(adminId, compartments, owner);
  return { changedCells, splitMunicipalities, pendingSeedsUsed };
}

function promotePendingSeedsForMunicipalityCount(adminId, prefectureMask, sea, fields, compartments, adminCenters, seedLifecycle, targetMinCount = 20) {
  const { plain, agriculture, basinField, coastalLowland, valleyField, ridgeField, slope, elevation } = fields;
  let areaById = municipalityAreaById(adminId, prefectureMask, sea);
  let currentCount = areaById.size;
  if (currentCount >= targetMinCount) return { changedCells: 0, promotedSeeds: 0 };
  const owner = dominantCompartmentOwners(compartments, adminId);
  let changedCells = 0;
  let promotedSeeds = 0;
  const pending = seedLifecycle
    .filter((seed) => seed.state === "pending" && !seed.protected)
    .sort((a, b) => (adminCenters[b.id]?.score || 0) - (adminCenters[a.id]?.score || 0));
  for (const seed of pending) {
    if (currentCount >= targetMinCount) break;
    const center = adminCenters[seed.id];
    if (!center || !inside(center.x, center.y)) continue;
    const existingArea = areaById.get(seed.id) || 0;
    if (existingArea >= 12) {
      seed.state = "survived";
      seed.area = existingArea;
      promotedSeeds++;
      continue;
    }
    const candidates = compartments
      .filter((unit) => {
        if (!unit || unit.area === 0) return false;
        const currentOwner = owner[unit.id];
        if (currentOwner < 0 || currentOwner === seed.id) return false;
        const ownerArea = areaById.get(currentOwner) || 0;
        if (ownerArea < 90) return false;
        const lowlandFit = (unit.lowlandFitness || 0) + (unit.basinIdentity || 0) * 0.15 + (unit.coastalExposure || 0) * 0.15;
        if (lowlandFit < 0.26) return false;
        return Math.hypot(unit.x - center.x, unit.y - center.y) < 36;
      })
      .map((unit) => ({
        unit,
        score: Math.hypot(unit.x - center.x, unit.y - center.y) - (unit.lowlandFitness || 0) * 6 - (unit.urbanWeight || 0) * 2,
      }))
      .sort((a, b) => a.score - b.score);
    if (candidates.length === 0) continue;
    let claimed = 0;
    for (const { unit } of candidates) {
      const currentOwner = owner[unit.id];
      if ((areaById.get(currentOwner) || 0) - unit.area < 70) continue;
      owner[unit.id] = seed.id;
      areaById.set(currentOwner, (areaById.get(currentOwner) || 0) - unit.area);
      areaById.set(seed.id, (areaById.get(seed.id) || 0) + unit.area);
      claimed += unit.area;
      changedCells += unit.area;
      if (claimed >= 55) break;
    }
    if (claimed >= 25) {
      seed.state = "survived";
      seed.area = areaById.get(seed.id) || claimed;
      promotedSeeds++;
      currentCount++;
    }
  }
  applyCompartmentOwners(adminId, compartments, owner);
  return { changedCells, promotedSeeds };
}

function restoreSurvivedSeedsByCompartment(adminId, prefectureMask, sea, compartments, adminCenters, seedLifecycle, targetMinCount = 20) {
  const areaById = municipalityAreaById(adminId, prefectureMask, sea);
  let currentCount = areaById.size;
  if (currentCount >= targetMinCount) return { changedCells: 0, restoredSeeds: 0 };
  const owner = dominantCompartmentOwners(compartments, adminId);
  let changedCells = 0;
  let restoredSeeds = 0;
  const missing = seedLifecycle
    .filter((seed) => (seed.state === "survived" || seed.protected) && (areaById.get(seed.id) || 0) === 0)
    .sort((a, b) => (b.protected ? 1 : 0) - (a.protected ? 1 : 0));
  for (const seed of missing) {
    if (currentCount >= targetMinCount) break;
    const center = adminCenters[seed.id];
    if (!center || !inside(center.x, center.y)) continue;
    const candidates = compartments
      .filter((unit) => {
        if (!unit || unit.area === 0 || unit.classId === 8 || unit.classId === 9) return false;
        const currentOwner = owner[unit.id];
        if (currentOwner < 0 || currentOwner === seed.id) return false;
        if ((areaById.get(currentOwner) || 0) - unit.area < 25) return false;
        return Math.hypot(unit.x - center.x, unit.y - center.y) < 90 && ((unit.lowlandFitness || 0) > 0.08 || seed.protected);
      })
      .map((unit) => ({
        unit,
        score: Math.hypot(unit.x - center.x, unit.y - center.y) - (unit.lowlandFitness || 0) * 6 - (unit.urbanWeight || 0) * 2 + (unit.classId === 8 || unit.classId === 9 ? 20 : 0),
      }))
      .sort((a, b) => a.score - b.score);
    if (candidates.length === 0) continue;
    const unit = candidates[0].unit;
    const oldOwner = owner[unit.id];
    if ((areaById.get(oldOwner) || 0) - unit.area < 25) continue;
    owner[unit.id] = seed.id;
    const claimed = unit.area;
    areaById.set(oldOwner, (areaById.get(oldOwner) || 0) - claimed);
    changedCells += claimed;
    areaById.set(seed.id, claimed);
    seed.area = claimed;
    restoredSeeds++;
    currentCount++;
  }
  applyCompartmentOwners(adminId, compartments, owner);
  return { changedCells, restoredSeeds };
}

function municipalityCountBoundsForRegion(landCells, meta = {}) {
  // Use the same administrative density curve for the highlighted prefecture
  // and neighboring prefectures.  Only clipped slivers get a low floor.
  let min = 1;
  if (landCells >= 360) min = 2;
  if (landCells >= 750) min = 4;
  if (landCells >= 1400) min = 7;
  if (landCells >= 2400) min = 11;
  if (landCells >= 3800) min = 16;
  if (landCells >= 5600) min = 22;
  const max = clamp(Math.round(landCells / 160 + 6), Math.max(min, 4), 72);
  return { min, max };
}

function computeTargetMunicipalityCount({ prefectureMask, sea, elevation, slope, ridgeField, coastalLowland, basinField, modernCities, markets, ports, satelliteCities, villages, adminRegionMeta = {} }) {
  let landCells = 0;
  let habitableCells = 0;
  let lowlandCells = 0;
  let coastlineComplexity = 0;
  let mountainCells = 0;
  for (let y = 1; y < MAP_H - 1; y++) {
    for (let x = 1; x < MAP_W - 1; x++) {
      const i = indexOf(x, y);
      if (!prefectureMask[i] || sea[i]) continue;
      landCells++;
      if (slope[i] < 0.42 && ridgeField[i] < 0.55 && (!elevation || elevation[i] < 0.72)) habitableCells++;
      if ((coastalLowland[i] > 0.20 || basinField[i] > 0.24) && slope[i] < 0.36 && ridgeField[i] < 0.52) lowlandCells++;
      if (ridgeField[i] > 0.52 || slope[i] > 0.48) mountainCells++;
      for (const [nx, ny] of [[x + 1, y], [x - 1, y], [x, y + 1], [x, y - 1]]) {
        const ni = indexOf(nx, ny);
        if (sea[ni]) {
          coastlineComplexity += 1 + coastalLowland[i] * 0.8;
          break;
        }
      }
    }
  }
  const independentSatellites = (satelliteCities || []).filter((p) => p.municipalityClass === "independentSatelliteMunicipality").length;
  const settlementWeight = modernCities.length * 1.7 + markets.length * 1.15 + ports.length * 0.8 + independentSatellites * 0.7 + villages.length * 0.32;
  const basinBonus = Math.min(8, [...basinField].filter((v, i) => prefectureMask[i] && !sea[i] && v > 0.34).length / 520);
  const mountainRatio = landCells ? mountainCells / landCells : 0;
  const lowlandBonus = Math.min(7, lowlandCells / 430);
  const rawTarget = Math.round(habitableCells / 175 + settlementWeight + coastlineComplexity * 0.03 + basinBonus * 0.65 + lowlandBonus * 1.15 - mountainRatio * 1.8);
  const { min, max } = municipalityCountBoundsForRegion(landCells, adminRegionMeta);
  return clamp(rawTarget, min, max);
}

function lowlandAdminSeedScore(i, { elevation, slope, ridgeField, plain, basinField, coastalLowland, settlementScore, populationDensity, roadInfluence, railInfluence2, stationInfluence, landuse }) {
  const lowRelief = clamp((0.70 - elevation[i]) * 1.35) + clamp((0.34 - slope[i]) * 1.55) + clamp((0.48 - ridgeField[i]) * 1.10);
  const landuseFit = [1, 2, 3, 4, 7, 8].includes(landuse[i]) ? 0.40 : landuse[i] === 5 || landuse[i] === 6 ? 0.12 : 0;
  return clamp(
    lowRelief * 0.25 +
    plain[i] * 0.28 +
    basinField[i] * 0.24 +
    coastalLowland[i] * 0.24 +
    settlementScore[i] * 0.30 +
    populationDensity[i] * 0.32 +
    roadInfluence[i] * 0.16 +
    railInfluence2[i] * 0.16 +
    (stationInfluence?.[i] || 0) * 0.18 +
    landuseFit -
    Math.max(0, elevation[i] - 0.62) * 1.2 -
    Math.max(0, ridgeField[i] - 0.54) * 0.9
  );
}

function buildLowlandAdminSeeds({
  seed,
  targetMunicipalityCount,
  prefectureMask,
  sea,
  elevation,
  slope,
  ridgeField,
  plain,
  basinField,
  coastalLowland,
  settlementScore,
  populationDensity,
  roadInfluence,
  railInfluence2,
  stationInfluence,
  landuse,
  modernCities,
  satelliteCities,
  markets,
  ports,
  newTowns,
  stations,
}) {
  const fields = { elevation, slope, ridgeField, plain, basinField, coastalLowland, settlementScore, populationDensity, roadInfluence, railInfluence2, stationInfluence, landuse };
  function validLowlandPoint(p, strict = true) {
    if (!p || !inside(p.x, p.y)) return false;
    const i = indexOf(p.x, p.y);
    if (!prefectureMask[i] || sea[i]) return false;
    const score = lowlandAdminSeedScore(i, fields);
    const mountain = elevation[i] > 0.70 || slope[i] > 0.52 || ridgeField[i] > 0.62;
    return score >= (strict ? 0.34 : 0.24) && (!mountain || p.isPrefecturalCapital || (p.population || 0) >= 220000 || p.portClass === "major");
  }
  const realSeeds = [];
  for (const city of modernCities || []) {
    if (!validLowlandPoint(city, !city.isPrefecturalCapital)) continue;
    if ((city.population || 0) < 45000) continue;
    const i = indexOf(city.x, city.y);
    realSeeds.push({ x: city.x, y: city.y, score: 1.35 + (city.population || 0) / 650000 + lowlandAdminSeedScore(i, fields), population: city.population || 0, protectedCity: city, seedKind: city.isPrefecturalCapital ? "capital" : "modernCity" });
  }
  for (const city of satelliteCities || []) {
    if (city.municipalityClass !== "independentSatelliteMunicipality" || !validLowlandPoint(city, false)) continue;
    const i = indexOf(city.x, city.y);
    realSeeds.push({ x: city.x, y: city.y, score: 0.92 + (city.population || 0) / 260000 + lowlandAdminSeedScore(i, fields), population: city.population || 0, protectedSatellite: city, seedKind: "satelliteCity" });
  }
  for (const p of [...(markets || []), ...(ports || []), ...(newTowns || [])]) {
    if (!validLowlandPoint(p, true)) continue;
    const i = indexOf(p.x, p.y);
    const portBonus = p.portClass === "major" ? 0.45 : p.portClass === "regional" ? 0.26 : 0;
    realSeeds.push({ x: p.x, y: p.y, score: 0.74 + lowlandAdminSeedScore(i, fields) + portBonus + (p.population || 0) / 420000, population: p.population || 0, portClass: p.portClass, source: p, seedKind: p.portClass ? "port" : "marketTown" });
  }
  const picked = pickEntities(realSeeds, {
    max: targetMunicipalityCount,
    minDistance: 5 + Math.floor(rand(seed, 1302) * 3),
    threshold: 0.62,
    seed: seed + 1300,
    jitter: 0.025,
  });
  const invisibleCandidates = [];
  for (let y = 2; y < MAP_H - 2; y++) {
    for (let x = 2; x < MAP_W - 2; x++) {
      const i = indexOf(x, y);
      if (!prefectureMask[i] || sea[i]) continue;
      const score = lowlandAdminSeedScore(i, fields) + hash2(x, y, seed + 1311) * 0.045;
      if (score < 0.48) continue;
      const insideDenseCore = modernCities.some((city) => (city.population || 0) >= 180000 && Math.hypot(city.x - x, city.y - y) < Math.max(5, (city.coreRadius || 4) * 1.7));
      if (insideDenseCore) continue;
      invisibleCandidates.push({ x, y, score, invisibleLowlandAdminSeed: true, seedKind: "invisibleLowland" });
    }
  }
  if (picked.length < targetMunicipalityCount) {
    const extra = pickEntities(invisibleCandidates, {
      max: targetMunicipalityCount - picked.length,
      minDistance: 5,
      threshold: 0.48,
      seed: seed + 1304,
      jitter: 0.02,
    });
    for (const p of extra) if (picked.every((q) => Math.hypot(p.x - q.x, p.y - q.y) >= 4)) picked.push(p);
  }
  if (picked.length < Math.min(targetMunicipalityCount, 20)) {
    const relaxed = pickEntities(invisibleCandidates, {
      max: Math.min(targetMunicipalityCount, 20) - picked.length,
      minDistance: 4,
      threshold: 0.38,
      seed: seed + 1305,
      jitter: 0.02,
    });
    for (const p of relaxed) if (picked.length < targetMunicipalityCount && picked.every((q) => Math.hypot(p.x - q.x, p.y - q.y) >= 3.5)) picked.push(p);
  }
  return picked.slice(0, targetMunicipalityCount);
}

function estimateUrbanComponentArea(city, prefectureMask, sea, landuse, populationDensity) {
  if (!city || !inside(city.x, city.y)) return 0;
  const start = indexOf(city.x, city.y);
  if (!prefectureMask[start] || sea[start]) return 0;
  const radius = Math.ceil(Math.max(7, (city.urbanRadius || 6) * 1.7));
  const seen = new Uint8Array(SIZE);
  const queue = [start];
  seen[start] = 1;
  let area = 0;
  for (let q = 0; q < queue.length; q++) {
    const cur = queue[q];
    const [x, y] = xyOf(cur);
    const d = Math.hypot(x - city.x, y - city.y);
    if (d > radius) continue;
    const urban = (landuse[cur] >= 2 && landuse[cur] <= 4) || landuse[cur] === 7 || landuse[cur] === 8 || populationDensity[cur] > 0.18;
    if (!urban) continue;
    area++;
    for (const [dx, dy] of [[1, 0], [-1, 0], [0, 1], [0, -1]]) {
      const nx = x + dx, ny = y + dy;
      if (!inside(nx, ny)) continue;
      const ni = indexOf(nx, ny);
      if (seen[ni] || !prefectureMask[ni] || sea[ni]) continue;
      seen[ni] = 1;
      queue.push(ni);
    }
  }
  return area;
}

function terrainSeparationBetween(a, b, ridgeField, river, flowAccum, populationDensity, landuse) {
  if (!a || !b) return { separatedByBarrier: false, ruralGap: false, averageDensity: 0, maxBarrier: 0 };
  const steps = Math.max(1, Math.ceil(Math.hypot(a.x - b.x, a.y - b.y)));
  let maxBarrier = 0;
  let lowUrbanRun = 0;
  let bestLowUrbanRun = 0;
  let densitySum = 0;
  for (let s = 0; s <= steps; s++) {
    const t = s / steps;
    const x = Math.round(a.x + (b.x - a.x) * t);
    const y = Math.round(a.y + (b.y - a.y) * t);
    if (!inside(x, y)) continue;
    const i = indexOf(x, y);
    const barrier = Math.max(ridgeField[i] * 0.95, river[i] * 0.85, flowAccum[i] * 0.42);
    maxBarrier = Math.max(maxBarrier, barrier);
    densitySum += populationDensity[i];
    const urban = (landuse[i] >= 2 && landuse[i] <= 4) || landuse[i] === 7 || populationDensity[i] > 0.20;
    if (urban) lowUrbanRun = 0;
    else {
      lowUrbanRun++;
      bestLowUrbanRun = Math.max(bestLowUrbanRun, lowUrbanRun);
    }
  }
  return {
    separatedByBarrier: maxBarrier > 0.56,
    ruralGap: bestLowUrbanRun >= 4,
    averageDensity: densitySum / (steps + 1),
    maxBarrier,
  };
}

function classifySatelliteMunicipalities(satelliteCities, modernCities, prefectureMask, sea, landuse, populationDensity, roadInfluence, railInfluence2, ridgeField, river, flowAccum) {
  let independent = 0;
  let attached = 0;
  for (const sat of satelliteCities || []) {
    if (!sat || !inside(sat.x, sat.y) || !prefectureMask[indexOf(sat.x, sat.y)] || sea[indexOf(sat.x, sat.y)]) continue;
    const parent = modernCities[sat.parentCityIndex] || modernCities.slice().sort((a, b) => Math.hypot(a.x - sat.x, a.y - sat.y) - Math.hypot(b.x - sat.x, b.y - sat.y))[0];
    const parentDistance = parent ? Math.hypot(parent.x - sat.x, parent.y - sat.y) : 99;
    const separation = terrainSeparationBetween(sat, parent, ridgeField, river, flowAccum, populationDensity, landuse);
    const urbanArea = estimateUrbanComponentArea(sat, prefectureMask, sea, landuse, populationDensity);
    const i = indexOf(sat.x, sat.y);
    const continuousUrban = parent && parentDistance < Math.max(10, (parent.urbanRadius || 12) + (sat.urbanRadius || 5) + 5) && separation.averageDensity > 0.14 && !separation.ruralGap && !separation.separatedByBarrier;
    const newTownLike = landuse[i] === 7 || (railInfluence2[i] > 0.22 && roadInfluence[i] > 0.12 && (sat.population || 0) < 70000);
    let municipalityClass = "independentSatelliteMunicipality";
    if (continuousUrban && (sat.population || 0) < 90000) municipalityClass = "suburbanDistrictMergedWithParent";
    else if (newTownLike && (sat.population || 0) < 85000 && !separation.separatedByBarrier) municipalityClass = "newTownDistrict";
    else if ((sat.population || 0) < 42000 && urbanArea < 55 && !separation.separatedByBarrier) municipalityClass = "smallTownAttachedToRuralMunicipality";
    else if ((sat.population || 0) >= 60000 && urbanArea >= 42 && (separation.separatedByBarrier || separation.ruralGap || parentDistance > 15)) municipalityClass = "independentSatelliteMunicipality";

    sat.municipalityClass = municipalityClass;
    sat.parentX = parent?.x;
    sat.parentY = parent?.y;
    sat.parentAdminHint = -1;
    sat.distinctUrbanComponentArea = urbanArea;
    sat.separatedByBarrier = separation.separatedByBarrier || separation.ruralGap;
    sat.satelliteMinArea = clamp(90 + Math.sqrt(sat.population || 24000) * 0.62 + (sat.urbanRadius || 5) * 12, 80, 360);
    if (municipalityClass === "independentSatelliteMunicipality") independent++;
    else attached++;
  }
  return { independent, attached };
}

function expandSatelliteMunicipalityCatchment(adminId, satellite, targetAdmin, context) {
  const { prefectureMask, sea, elevation, slope, river, ridgeField, valleyField, basinField, coastalLowland, flowAccum, landuse, populationDensity, roadInfluence, railInfluence2, stationInfluence, modernCities } = context;
  if (!satellite || targetAdmin < 0 || !inside(satellite.x, satellite.y)) return 0;
  const start = indexOf(satellite.x, satellite.y);
  if (!prefectureMask[start] || sea[start]) return 0;
  const targetAreaBase = clamp(90 + Math.sqrt(satellite.population || 24000) * 0.8 + (satellite.urbanRadius || 5) * 18, 120, 520);
  const targetArea = satellite.municipalityClass === "smallTownAttachedToRuralMunicipality"
    ? Math.min(130, targetAreaBase * 0.55)
    : satellite.municipalityClass === "suburbanDistrictMergedWithParent" || satellite.municipalityClass === "newTownDistrict"
      ? Math.min(190, targetAreaBase * 0.62)
      : targetAreaBase;
  const maxCost = satellite.municipalityClass === "independentSatelliteMunicipality" ? 46 : 32;
  const heap = new MinHeap();
  const best = new Float32Array(SIZE);
  best.fill(INF);
  heap.push({ i: start, f: 0 });
  best[start] = 0;
  const claimed = [];
  while (heap.length > 0 && claimed.length < targetArea) {
    const cur = heap.pop();
    if (!cur || cur.f > best[cur.i] + 1e-5 || cur.f > maxCost) continue;
    const [x, y] = xyOf(cur.i);
    const d = Math.hypot(x - satellite.x, y - satellite.y);
    if (!prefectureMask[cur.i] || sea[cur.i]) continue;
    let invadesOtherCore = false;
    for (const city of modernCities || []) {
      if (!city || (city.population || 0) < 140000) continue;
      if (Math.hypot(city.x - satellite.x, city.y - satellite.y) < 4) continue;
      if (Math.hypot(city.x - x, city.y - y) <= Math.max(3.5, (city.coreRadius || 4) * 1.25)) {
        invadesOtherCore = true;
        break;
      }
    }
    if (invadesOtherCore) continue;
    const compatible = d <= (satellite.urbanRadius || 5) * 1.25 ||
      [2, 3, 4, 7, 8].includes(landuse[cur.i]) ||
      populationDensity[cur.i] > 0.12 ||
      roadInfluence[cur.i] > 0.12 ||
      railInfluence2[cur.i] > 0.10 ||
      stationInfluence?.[cur.i] > 0.10 ||
      basinField[cur.i] > 0.22 ||
      valleyField[cur.i] > 0.24 ||
      coastalLowland[cur.i] > 0.20;
    if (!compatible && claimed.length > targetArea * 0.55) continue;
    claimed.push(cur.i);
    for (const [dx, dy, step] of [[1, 0, 1], [-1, 0, 1], [0, 1, 1], [0, -1, 1], [1, 1, 1.41], [-1, 1, 1.41], [1, -1, 1.41], [-1, -1, 1.41]]) {
      const nx = x + dx, ny = y + dy;
      if (!inside(nx, ny)) continue;
      const ni = indexOf(nx, ny);
      if (!prefectureMask[ni] || sea[ni]) continue;
      const barrier = ridgeField[ni] * 5.2 + Math.max(0, elevation[ni] - 0.58) * 4.0 + slope[ni] * 2.2 + (river[ni] > 0.55 || flowAccum[ni] > 0.70 ? 7.5 : river[ni] > 0.30 ? 2.8 : 0);
      const living = ([2, 3, 4, 7, 8].includes(landuse[ni]) ? 2.2 : 0) + populationDensity[ni] * 2.0 + roadInfluence[ni] * 0.85 + railInfluence2[ni] * 0.95 + (stationInfluence?.[ni] || 0) * 1.2 + basinField[ni] * 0.42 + valleyField[ni] * 0.48 + coastalLowland[ni] * 0.32;
      const distanceCost = Math.hypot(nx - satellite.x, ny - satellite.y) / Math.max(7, (satellite.urbanRadius || 5) * 1.9);
      const nd = cur.f + Math.max(0.28, 1.05 + barrier - living + distanceCost) * step;
      if (nd < best[ni]) {
        best[ni] = nd;
        heap.push({ i: ni, f: nd });
      }
    }
  }
  let changed = 0;
  for (const i of claimed) {
    if (adminId[i] !== targetAdmin) changed++;
    adminId[i] = targetAdmin;
  }
  return changed;
}

function cityMinimumMunicipalityArea(city) {
  const populationArea = Math.sqrt(city.population || 0) * 0.72;
  const footprintArea = (city.urbanFootprintCells || 0) * 0.42;
  return clamp(95 + populationArea + footprintArea, 130, (city.population || 0) >= 450000 ? 780 : 520);
}

function enforceCityMunicipalityCatchments(adminId, cities, context) {
  const { prefectureMask, sea, elevation, slope, river, ridgeField, valleyField, basinField, coastalLowland, flowAccum, landuse, populationDensity, roadInfluence, railInfluence2, stationInfluence } = context;
  const areaById = municipalityAreaById(adminId, prefectureMask, sea);
  let changed = 0;
  let protectedCities = 0;
  let tooSmall = 0;
  for (const city of cities || []) {
    if (!city || (city.population || 0) < 95000 || !inside(city.x, city.y)) continue;
    const start = indexOf(city.x, city.y);
    if (!prefectureMask[start] || sea[start]) continue;
    const targetAdmin = adminId[start];
    if (targetAdmin < 0) continue;
    protectedCities++;
    const minArea = cityMinimumMunicipalityArea(city);
    if ((areaById.get(targetAdmin) || 0) >= minArea) continue;
    tooSmall++;
    const heap = new MinHeap();
    const best = new Float32Array(SIZE);
    best.fill(INF);
    heap.push({ i: start, f: 0 });
    best[start] = 0;
    const claimed = [];
    const maxCost = (city.population || 0) >= 450000 ? 78 : 56;
    let projectedArea = areaById.get(targetAdmin) || 0;
    while (heap.length > 0 && projectedArea < minArea) {
      const cur = heap.pop();
      if (!cur || cur.f > best[cur.i] + 1e-5 || cur.f > maxCost) continue;
      const [x, y] = xyOf(cur.i);
      if (!prefectureMask[cur.i] || sea[cur.i]) continue;
      const d = Math.hypot(x - city.x, y - city.y);
      const compatible = d <= Math.max(5, (city.coreRadius || 3) * 2.0) ||
        [2, 3, 4, 7, 8].includes(landuse[cur.i]) ||
        populationDensity[cur.i] > 0.10 ||
        roadInfluence[cur.i] > 0.10 ||
        railInfluence2[cur.i] > 0.10 ||
        (stationInfluence?.[cur.i] || 0) > 0.10 ||
        valleyField[cur.i] > 0.22 ||
        basinField[cur.i] > 0.20 ||
        coastalLowland[cur.i] > 0.18;
      if (!compatible && claimed.length > minArea * 0.55) continue;
      claimed.push(cur.i);
      if (adminId[cur.i] !== targetAdmin) projectedArea++;
      for (const [dx, dy, step] of [[1, 0, 1], [-1, 0, 1], [0, 1, 1], [0, -1, 1], [1, 1, 1.41], [-1, 1, 1.41], [1, -1, 1.41], [-1, -1, 1.41]]) {
        const nx = x + dx, ny = y + dy;
        if (!inside(nx, ny)) continue;
        const ni = indexOf(nx, ny);
        if (!prefectureMask[ni] || sea[ni]) continue;
        const majorBarrier = river[ni] > 0.62 || flowAccum[ni] > 0.74 || ridgeField[ni] > 0.70;
        const barrier = ridgeField[ni] * 5.4 + Math.max(0, elevation[ni] - 0.60) * 4.4 + slope[ni] * 2.6 + (majorBarrier ? 8.5 : river[ni] > 0.34 ? 2.6 : 0);
        const fit = ([2, 3, 4, 7, 8].includes(landuse[ni]) ? 2.4 : 0) + populationDensity[ni] * 2.2 + roadInfluence[ni] * 0.88 + railInfluence2[ni] * 0.92 + (stationInfluence?.[ni] || 0) * 1.15 + valleyField[ni] * 0.56 + basinField[ni] * 0.42 + coastalLowland[ni] * 0.34;
        const nd = cur.f + Math.max(0.30, 1.05 + barrier - fit + Math.hypot(nx - city.x, ny - city.y) / Math.max(8, (city.urbanRadius || 7) * 2.1)) * step;
        if (nd < best[ni]) {
          best[ni] = nd;
          heap.push({ i: ni, f: nd });
        }
      }
    }
    for (const i of claimed) {
      const old = adminId[i];
      if (old === targetAdmin) continue;
      if (old >= 0) areaById.set(old, Math.max(0, (areaById.get(old) || 0) - 1));
      adminId[i] = targetAdmin;
      areaById.set(targetAdmin, (areaById.get(targetAdmin) || 0) + 1);
      changed++;
    }
    city.municipalityMinArea = minArea;
  }
  return { changed, protectedCities, tooSmall };
}

function generateAdminLayoutForMask({
  seed,
  prefectureMask,
  sea,
  elevation,
  slope,
  river,
  ridgeField,
  naturalBarrierScore,
  valleyField,
  basinField,
  coastalLowland,
  flowAccum,
  plain,
  agriculture,
  settlementScore,
  populationDensity,
  stationInfluence,
  roadInfluence,
  railInfluence2,
  villageInfluence,
  landuse,
  modernCities,
  satelliteCities,
  newTowns,
  markets,
  villages,
  ports,
  stations,
  industrialZones,
  logisticsParks,
  naturalCompartmentId,
  naturalCompartments,
  adminRegionMeta = {},
  adminProgress = null,
}) {
  const boundaryRidgeField = naturalBarrierScore
    ? Float32Array.from(ridgeField, (value, i) => clamp(value * 0.72 + naturalBarrierScore[i] * 0.46))
    : ridgeField;
  adminProgress?.({ status: "admin-step", regionId: adminRegionMeta.regionId, step: "classify satellites" });
  const satelliteClassificationDebug = classifySatelliteMunicipalities(satelliteCities, modernCities, prefectureMask, sea, landuse, populationDensity, roadInfluence, railInfluence2, boundaryRidgeField, river, flowAccum);
  const targetMunicipalityCount = computeTargetMunicipalityCount({ prefectureMask, sea, elevation, slope, ridgeField: boundaryRidgeField, coastalLowland, basinField, modernCities, markets, ports, satelliteCities, villages, adminRegionMeta });
  const compartmentMultiplier = clamp(4.6 + rand(seed, 1320) * 2.4, 4.6, 7.0);
  const regionLandArea = adminRegionMeta.landArea || maskLandArea(prefectureMask, sea);
  const minCompartmentTarget = clamp(Math.round(Math.max(targetMunicipalityCount * 3.4, regionLandArea / 78)), 22, 150);
  const maxCompartmentTarget = clamp(Math.round(Math.max(targetMunicipalityCount * 6.0, regionLandArea / 36)), minCompartmentTarget, 320);
  let targetCompartmentCount = clamp(Math.round(targetMunicipalityCount * compartmentMultiplier), minCompartmentTarget, maxCompartmentTarget);
  let adminCentersRaw = buildLowlandAdminSeeds({
    seed,
    targetMunicipalityCount,
    prefectureMask,
    sea,
    elevation,
    slope,
    ridgeField: boundaryRidgeField,
    plain,
    basinField,
    coastalLowland,
    settlementScore,
    populationDensity,
    roadInfluence,
    railInfluence2,
    stationInfluence,
    landuse,
    modernCities,
    satelliteCities,
    markets,
    ports,
    newTowns,
    stations,
  });
  if (adminCentersRaw.length < targetMunicipalityCount) targetCompartmentCount = Math.max(targetCompartmentCount, minCompartmentTarget);
  adminProgress?.({ status: "admin-step", regionId: adminRegionMeta.regionId, step: "natural compartments", targetMunicipalityCount, targetCompartmentCount, seedCount: adminCentersRaw.length });
  const compartmentAssignment = assignAdminRegionsFromNaturalCompartments(prefectureMask, sea, elevation, slope, river, boundaryRidgeField, valleyField, basinField, coastalLowland, flowAccum, plain, agriculture, populationDensity, landuse, adminCentersRaw, {
    seed,
    targetMunicipalityCount,
    targetCompartmentCount,
    maxNaturalCompartmentArea: Math.max(32, Math.round(maskLandArea(prefectureMask, sea) / Math.max(1, targetCompartmentCount) * 1.65)),
    naturalCompartmentId,
    naturalCompartments,
    naturalBarrierScore,
    progress: (step) => adminProgress?.({ status: "admin-step", regionId: adminRegionMeta.regionId, step }),
  });
  const adminId = compartmentAssignment.adminId;
  if (naturalCompartmentId && naturalCompartments) {
    const oversizedCompartmentSplit = splitOversizedCompartmentMunicipalities(adminId, adminCentersRaw, compartmentAssignment.compartments, prefectureMask, sea, {
      elevation, slope, ridgeField: boundaryRidgeField, plain, agriculture, basinField, coastalLowland, populationDensity,
    }, seed + 21900);
    const changedAfterFinalCompartmentOwnership = enforceCompartmentMunicipalityOwnership(adminId, compartmentAssignment.compartmentId, compartmentAssignment.compartments, prefectureMask, sea);
    const changedAfterUrbanUnification = lockCompactUrbanAreasToDominantAdmin(adminId, prefectureMask, sea, landuse, populationDensity, 980);
    const changedAfterAdminEnclaveRepair = repairAdminSingleOwnerEnclaves(adminId, prefectureMask, sea, 6);
    const compacted = compactWholeCompartmentMunicipalities(adminId, adminCentersRaw, prefectureMask, sea, { populationDensity, plain, slope });
    const adminBorders = extractAdminBorderSegments(compacted.adminId, prefectureMask);
    const actualMunicipalityCount = compacted.activeMunicipalityCount;
    const adminDebug = {
      ...compartmentAssignment.debug,
      sharedNaturalCompartmentLayer: true,
      skippedLegacyCellCleanupForHierarchy: true,
      targetMunicipalityCount,
      actualMunicipalityCount,
      finalMunicipalityCount: actualMunicipalityCount,
      candidateSeedCount: adminCentersRaw.length,
      municipalOfficePointCount: compacted.adminCentersRaw.length,
      seedCellRevivalCount: 0,
      survivedSeedCount: compacted.activeMunicipalityCount,
      pendingSeedCount: 0,
      absorbedSeedCount: Math.max(0, adminCentersRaw.length - compacted.activeMunicipalityCount),
      targetNaturalCompartmentCount: targetCompartmentCount,
      naturalCompartmentCount: compartmentAssignment.debug?.naturalCompartmentCount || naturalCompartments.filter((unit) => unit && unit.area > 0).length,
      compartmentCount: compartmentAssignment.debug?.naturalCompartmentCount || naturalCompartments.filter((unit) => unit && unit.area > 0).length,
      changedAfterCompartmentAssignment: compartmentAssignment.debug?.naturalCompartmentCount || 0,
      changedAfterFinalCompartmentOwnership,
      changedAfterUrbanUnification,
      changedAfterAdminEnclaveRepair,
      changedAfterOversizedCompartmentSplit: oversizedCompartmentSplit.changedCells,
      oversizedCompartmentMunicipalitiesSplit: oversizedCompartmentSplit.splitMunicipalities,
      oversizedCompartmentSplitAddedCenters: oversizedCompartmentSplit.addedCenters,
      oversizedCompartmentSplitMaxArea: oversizedCompartmentSplit.maxArea || 0,
      finalTinyMunicipalityCount: [...municipalityAreaById(compacted.adminId, prefectureMask, sea).values()].filter((area) => area > 0 && area < 8).length,
      compartmentBorders: compartmentAssignment.debug?.compartmentBorders || [],
      borderNaturalBarrierAverage: compartmentAssignment.debug?.finalBorderNaturalBarrierAverage || 0,
      voronoiLikeRate: compartmentAssignment.debug?.voronoiLikeRateAfter || 0,
    };
    return {
      adminCentersRaw: compacted.adminCentersRaw,
      adminId: compacted.adminId,
      adminBorders,
      adminDebug,
      naturalCompartmentId: compartmentAssignment.compartmentId,
      naturalCompartments: compartmentAssignment.compartments,
    };
  }
  let previousSnapshot = new Int16Array(adminId);
  const adminDebug = {
    changedAfterSmooth: 0,
    changedAfterUrbanLock: 0,
    changedAfterSmallUrbanLock: 0,
    changedAfterInitialMerge: 0,
    changedAfterInitialExclaveRemoval: 0,
    changedAfterLandscapePartition: 0,
    changedAfterSnap: 0,
    changedAfterOversizedRuralSplit: 0,
    changedAfterFinalExclaveRemoval: 0,
    changedAfterFinalMerge: 0,
    targetMunicipalityCount,
    actualMunicipalityCount: 0,
    municipalityCountReason: "habitable cells, settlement weight, coastline complexity, basin/lowland bonus, and mountain-ratio adjustment",
    changedAfterCompartmentAssignment: compartmentAssignment.debug?.naturalCompartmentCount || 0,
    oversizedRuralSplits: 0,
    oversizedLowlandSplits: 0,
    ruralSplitsAccepted: 0,
    ruralSplitsRejected: 0,
    targetNaturalCompartmentCount: targetCompartmentCount,
    compartmentMultiplier,
    lowlandAdminSeedCount: adminCentersRaw.filter((p) => p.invisibleLowlandAdminSeed).length,
    lowlandAdminSeeds: adminCentersRaw.filter((p) => p.invisibleLowlandAdminSeed).map((p) => ({ x: p.x, y: p.y })),
    realAdminSeedCount: adminCentersRaw.filter((p) => !p.invisibleLowlandAdminSeed).length,
    highMountainAdminSeedCount: adminCentersRaw.filter((p) => {
      const i = indexOf(p.x, p.y);
      return elevation[i] > 0.70 || slope[i] > 0.52 || boundaryRidgeField[i] > 0.62;
    }).length,
    candidateSeedCount: adminCentersRaw.length,
    protectedSeedCount: adminCentersRaw.filter(isProtectedAdminSeed).length,
    survivedSeedCount: 0,
    pendingSeedCount: 0,
    absorbedSeedCount: 0,
    pendingSeedsUsedForLowlandSplit: 0,
    finalMunicipalityCount: 0,
    finalTinyMunicipalityCount: 0,
    seedCellRevivalCount: 0,
    satelliteMunicipalitiesCreated: adminCentersRaw.filter((p) => p.protectedSatellite).length,
    satelliteMunicipalitiesMerged: 0,
    satelliteMunicipalitiesExpanded: 0,
    satelliteMunicipalitiesTooSmall: 0,
    averageSatelliteMunicipalityArea: 0,
    minSatelliteMunicipalityArea: 0,
    satelliteMunicipalityAreaByNameOrIndex: {},
    independentSatelliteMunicipalities: satelliteClassificationDebug.independent,
    attachedSatelliteDistricts: satelliteClassificationDebug.attached,
    satelliteMunicipalityStats: satelliteClassificationDebug,
    ...compartmentAssignment.debug,
  };
  adminProgress?.({ status: "admin-step", regionId: adminRegionMeta.regionId, step: "seed lifecycle" });
  const seedLifecycle = buildSeedLifecycle(adminCentersRaw, adminId, prefectureMask, sea, 35);
  const pendingSplitDebug = splitOversizedLowlandsWithPendingSeeds(adminId, prefectureMask, sea, {
    plain, agriculture, basinField, coastalLowland, valleyField, ridgeField: boundaryRidgeField, slope, elevation,
  }, compartmentAssignment.compartments, adminCentersRaw, seedLifecycle, [...(satelliteCities || []), ...newTowns, ...markets, ...villages, ...ports]);
  adminDebug.changedAfterPendingSeedLowlandSplit = pendingSplitDebug.changedCells;
  adminDebug.pendingSeedsUsedForLowlandSplit = pendingSplitDebug.pendingSeedsUsed;
  adminDebug.oversizedLowlandSplits += pendingSplitDebug.splitMunicipalities;
  const pendingPromotionDebug = promotePendingSeedsForMunicipalityCount(adminId, prefectureMask, sea, {
    plain, agriculture, basinField, coastalLowland, valleyField, ridgeField: boundaryRidgeField, slope, elevation,
  }, compartmentAssignment.compartments, adminCentersRaw, seedLifecycle, Math.min(24, targetMunicipalityCount));
  adminDebug.changedAfterPendingSeedCountRepair = pendingPromotionDebug.changedCells;
  adminDebug.pendingSeedsPromotedForCount = pendingPromotionDebug.promotedSeeds;
  let areaAfterPendingSplit = municipalityAreaById(adminId, prefectureMask, sea);
  for (const seedState of seedLifecycle) {
    if (seedState.state !== "pending") continue;
    seedState.area = areaAfterPendingSplit.get(seedState.id) || 0;
    if (seedState.area >= 35) seedState.state = "survived";
    else seedState.state = "absorbed";
  }
  adminDebug.changedAfterAbsorbingSeeds = absorbSeedCompartments(adminId, compartmentAssignment.compartments, seedLifecycle);
  let activeAdminIds = activeSeedIds(seedLifecycle);
  function markChanged(field) {
    adminDebug[field] = changedCellsSince(previousSnapshot, adminId, prefectureMask, sea);
    previousSnapshot = new Int16Array(adminId);
  }
  adminProgress?.({ status: "admin-step", regionId: adminRegionMeta.regionId, step: "smooth boundaries" });
  smoothAdminRegionsTerrainAware(adminId, prefectureMask, sea, elevation, slope, river, boundaryRidgeField, valleyField, populationDensity, landuse, 2);
  markChanged("changedAfterSmooth");

  function lockUrbanClusterToMunicipality(city, radius, allowSuburban = true) {
    if (!city || !prefectureMask[indexOf(city.x, city.y)]) return;
    let bestAdmin = -1;
    let bestD = INF;
    adminCentersRaw.forEach((center, id) => {
      if (!activeAdminIds.has(id)) return;
      const d = Math.hypot(center.x - city.x, center.y - city.y);
      if (d < bestD) { bestD = d; bestAdmin = id; }
    });
    if (bestAdmin < 0) return;
    const r = Math.ceil(radius);
    for (let dy = -r; dy <= r; dy++) {
      for (let dx = -r; dx <= r; dx++) {
        const x = city.x + dx;
        const y = city.y + dy;
        if (!inside(x, y)) continue;
        const i = indexOf(x, y);
        if (!prefectureMask[i] || sea[i]) continue;
        const d = Math.hypot(dx, dy);
        if (d > radius) continue;
        const urban = landuse[i] === 2 || landuse[i] === 3 || (allowSuburban && (landuse[i] === 4 || landuse[i] === 7 || landuse[i] === 8));
        if (urban || populationDensity[i] > 0.22) adminId[i] = bestAdmin;
      }
    }
  }
  for (const city of modernCities) {
    const radius = (city.population || 0) >= 500000
      ? clamp(17 + Math.sqrt(city.population) / 120, 20, 38)
      : clamp(5 + Math.sqrt(city.population || 70000) / 210, 6, 11);
    lockUrbanClusterToMunicipality(city, radius, true);
  }
  for (const sat of satelliteCities || []) {
    if (!prefectureMask[indexOf(sat.x, sat.y)]) continue;
    let bestAdmin = -1;
    if (sat.municipalityClass === "independentSatelliteMunicipality") {
      let bestD = INF;
      adminCentersRaw.forEach((center, id) => {
        if (!activeAdminIds.has(id)) return;
        const d = Math.hypot(center.x - sat.x, center.y - sat.y);
        if (d < bestD) { bestD = d; bestAdmin = id; }
      });
    } else if (inside(sat.parentX ?? -1, sat.parentY ?? -1)) {
      bestAdmin = adminId[indexOf(sat.parentX, sat.parentY)];
    }
    if (bestAdmin < 0) continue;
    sat.parentAdminHint = bestAdmin;
    const changed = expandSatelliteMunicipalityCatchment(adminId, sat, bestAdmin, {
      prefectureMask, sea, elevation, slope, river, ridgeField: boundaryRidgeField, valleyField, basinField, coastalLowland, flowAccum,
      landuse, populationDensity, roadInfluence, railInfluence2, stationInfluence, modernCities,
    });
    if (changed > 0 && sat.municipalityClass === "independentSatelliteMunicipality") adminDebug.satelliteMunicipalitiesExpanded++;
  }
  markChanged("changedAfterUrbanLock");
  lockSmallUrbanComponentsToMunicipality(adminId, prefectureMask, sea, landuse, populationDensity, 520);
  lockSmallUrbanComponentsToMunicipality(adminId, prefectureMask, sea, landuse, populationDensity, 620);
  markChanged("changedAfterSmallUrbanLock");
  const activeAdminCenters = () => adminCentersRaw.filter((_, id) => activeAdminIds.has(id));
  mergeTinyMunicipalities(adminId, prefectureMask, sea, populationDensity, modernCities, 120, { satelliteCities, satelliteStats: adminDebug, satelliteMinArea: 100, protectedPoints: activeAdminCenters() });
  markChanged("changedAfterInitialMerge");
  adminProgress?.({ status: "admin-step", regionId: adminRegionMeta.regionId, step: "topology cleanup" });
  removeMunicipalExclaves(adminId, prefectureMask, sea, adminCentersRaw, modernCities, 180);
  markChanged("changedAfterInitialExclaveRemoval");
  // The initial compartment graph assignment is now the primary natural partition.
  // Re-running the older raw landscape-unit pass here collapses lowland seeds into a few broad owners.
  markChanged("changedAfterLandscapePartition");
  adminProgress?.({ status: "admin-step", regionId: adminRegionMeta.regionId, step: "split oversized municipalities" });
  // The older oversized-lowland pass rebuilds natural compartments a second time.
  // The current pipeline already performs pending-seed lowland splitting on the active
  // compartment graph above, so keep the full admin layout while avoiding the duplicate
  // high-cost recomputation.
  const oversizedSplitDebug = {
    changedCells: 0,
    splitMunicipalities: 0,
    rejectedMunicipalities: 0,
    skippedDuplicateCompartmentRebuild: true,
    skippedForVisibleFragment: false,
  };
  adminDebug.changedAfterOversizedRuralSplit = oversizedSplitDebug.changedCells;
  adminDebug.oversizedRuralMunicipalitiesSplit = oversizedSplitDebug.splitMunicipalities;
  adminDebug.oversizedRuralSplits = oversizedSplitDebug.splitMunicipalities;
  adminDebug.oversizedLowlandSplits = oversizedSplitDebug.splitMunicipalities;
  adminDebug.ruralSplitsAccepted = oversizedSplitDebug.splitMunicipalities;
  adminDebug.ruralSplitsRejected = oversizedSplitDebug.rejectedMunicipalities || 0;
  adminDebug.oversizedSplitSkippedForVisibleFragment = Boolean(oversizedSplitDebug.skippedForVisibleFragment);
  adminDebug.oversizedSplitSkippedDuplicateCompartmentRebuild = Boolean(oversizedSplitDebug.skippedDuplicateCompartmentRebuild);
  previousSnapshot = new Int16Array(adminId);
  adminProgress?.({ status: "admin-step", regionId: adminRegionMeta.regionId, step: "terrain snap" });
  snapAdminBoundariesToTerrain(adminId, prefectureMask, sea, elevation, slope, river, boundaryRidgeField, valleyField, flowAccum, populationDensity, landuse, adminCentersRaw, [...modernCities, ...satelliteCities, ...ports, ...industrialZones, ...logisticsParks], 2);
  markChanged("changedAfterSnap");
  removeMunicipalExclaves(adminId, prefectureMask, sea, adminCentersRaw, [...modernCities, ...activeAdminCenters()], 360);
  markChanged("changedAfterFinalExclaveRemoval");
  mergeTinyMunicipalities(adminId, prefectureMask, sea, populationDensity, modernCities, 80, { satelliteCities, satelliteStats: adminDebug, satelliteMinArea: 90, protectedPoints: activeAdminCenters() });
  markChanged("changedAfterFinalMerge");

  for (const sat of satelliteCities || []) {
    if (sat.municipalityClass !== "independentSatelliteMunicipality" || !inside(sat.x, sat.y)) continue;
    const targetAdmin = adminId[indexOf(sat.x, sat.y)];
    if (targetAdmin < 0) continue;
    expandSatelliteMunicipalityCatchment(adminId, sat, targetAdmin, {
      prefectureMask, sea, elevation, slope, river, ridgeField: boundaryRidgeField, valleyField, basinField, coastalLowland, flowAccum,
      landuse, populationDensity, roadInfluence, railInfluence2, stationInfluence, modernCities,
    });
  }
  const cityCatchmentDebug = enforceCityMunicipalityCatchments(adminId, modernCities, {
    prefectureMask, sea, elevation, slope, river, ridgeField: boundaryRidgeField, valleyField, basinField, coastalLowland, flowAccum,
    landuse, populationDensity, roadInfluence, railInfluence2, stationInfluence,
  });
  adminDebug.changedAfterCityMunicipalityCatchment = cityCatchmentDebug.changed;
  adminDebug.protectedCityMunicipalityCount = cityCatchmentDebug.protectedCities;
  adminDebug.tooSmallCityMunicipalityCountBeforeRepair = cityCatchmentDebug.tooSmall;
  snapAdminBoundariesToTerrain(adminId, prefectureMask, sea, elevation, slope, river, boundaryRidgeField, valleyField, flowAccum, populationDensity, landuse, adminCentersRaw, [...modernCities, ...activeAdminCenters()], 2);
  removeMunicipalExclaves(adminId, prefectureMask, sea, adminCentersRaw, [...modernCities, ...activeAdminCenters()], 260);
  const finalPromotionDebug = promotePendingSeedsForMunicipalityCount(adminId, prefectureMask, sea, {
    plain, agriculture, basinField, coastalLowland, valleyField, ridgeField: boundaryRidgeField, slope, elevation,
  }, compartmentAssignment.compartments, adminCentersRaw, seedLifecycle, Math.min(22, targetMunicipalityCount));
  adminDebug.changedAfterFinalPendingSeedCountRepair = finalPromotionDebug.changedCells;
  adminDebug.pendingSeedsPromotedForCount += finalPromotionDebug.promotedSeeds;
  const restoredSeedDebug = restoreSurvivedSeedsByCompartment(adminId, prefectureMask, sea, compartmentAssignment.compartments, adminCentersRaw, seedLifecycle, Math.min(22, targetMunicipalityCount));
  adminDebug.changedAfterSurvivedSeedCompartmentRestore = restoredSeedDebug.changedCells;
  adminDebug.survivedSeedsRestoredByCompartment = restoredSeedDebug.restoredSeeds;
  let finalAreaBySeed = municipalityAreaById(adminId, prefectureMask, sea);
  for (const seedState of seedLifecycle) {
    seedState.area = finalAreaBySeed.get(seedState.id) || 0;
    if (!seedState.protected && seedState.state === "pending" && seedState.area < 25) seedState.state = "absorbed";
  }
  absorbSeedCompartments(adminId, compartmentAssignment.compartments, seedLifecycle);
  activeAdminIds = activeSeedIds(seedLifecycle);
  adminDebug.changedAfterFinalCompartmentOwnership = enforceCompartmentMunicipalityOwnership(adminId, compartmentAssignment.compartmentId, compartmentAssignment.compartments, prefectureMask, sea);
  removeMunicipalExclaves(adminId, prefectureMask, sea, adminCentersRaw, [...modernCities, ...activeAdminCenters()], 220);
  adminDebug.changedAfterPostCompartmentExclaveRemoval = enforceCompartmentMunicipalityOwnership(adminId, compartmentAssignment.compartmentId, compartmentAssignment.compartments, prefectureMask, sea);
  adminDebug.changedAfterUrbanUnification = lockCompactUrbanAreasToDominantAdmin(adminId, prefectureMask, sea, landuse, populationDensity, 980);
  adminDebug.changedAfterAdminEnclaveRepair = repairAdminSingleOwnerEnclaves(adminId, prefectureMask, sea, 6);
  adminDebug.changedAfterFinalCompartmentOwnership += enforceCompartmentMunicipalityOwnership(adminId, compartmentAssignment.compartmentId, compartmentAssignment.compartments, prefectureMask, sea);

  const areaById = municipalityAreaById(adminId, prefectureMask, sea);
  const satelliteAreas = [];
  (satelliteCities || []).forEach((sat, index) => {
    if (!inside(sat.x, sat.y) || !prefectureMask[indexOf(sat.x, sat.y)]) return;
    const id = adminId[indexOf(sat.x, sat.y)];
    const area = areaById.get(id) || 0;
    const key = sat.name || `satellite-${index}`;
    adminDebug.satelliteMunicipalityAreaByNameOrIndex[key] = area;
    if (sat.municipalityClass === "independentSatelliteMunicipality" && (area < Math.max(120, sat.satelliteMinArea || 0) || ((sat.population || 0) >= 60000 && area < 150))) {
      sat.municipalityClass = "smallTownAttachedToRuralMunicipality";
      adminDebug.satelliteMunicipalitiesTooSmall++;
      return;
    }
    if (sat.municipalityClass === "independentSatelliteMunicipality") {
      satelliteAreas.push(area);
      if (area < 80) adminDebug.satelliteMunicipalitiesTooSmall++;
    }
  });
  adminDebug.averageSatelliteMunicipalityArea = satelliteAreas.length ? satelliteAreas.reduce((sum, value) => sum + value, 0) / satelliteAreas.length : 0;
  adminDebug.minSatelliteMunicipalityArea = satelliteAreas.length ? Math.min(...satelliteAreas) : 0;
  adminDebug.satelliteMunicipalitiesIndependent = satelliteAreas.length;
  const landscapeDebug = applyLandscapeUnitAdminPartition.lastDebug || {};
  Object.assign(adminDebug, landscapeDebug);
  adminDebug.targetNaturalCompartmentCount = compartmentAssignment.debug?.targetNaturalCompartmentCount || targetCompartmentCount;
  adminDebug.naturalCompartmentCount = compartmentAssignment.debug?.naturalCompartmentCount || adminDebug.naturalCompartmentCount || adminDebug.compartmentCount || 0;
  adminDebug.compartmentCount = adminDebug.naturalCompartmentCount;
  adminDebug.averageCompartmentsPerMunicipality = compartmentAssignment.debug?.averageCompartmentsPerMunicipality || adminDebug.averageCompartmentsPerMunicipality || 0;
  adminDebug.singleCompartmentMunicipalityRatio = compartmentAssignment.debug?.singleCompartmentMunicipalityRatio ?? adminDebug.singleCompartmentMunicipalityRatio ?? 0;
  adminDebug.actualMunicipalityCount = new Set([...adminId].filter((id, i) => id >= 0 && prefectureMask[i] && !sea[i])).size;
  adminDebug.averageCompartmentsPerMunicipality = adminDebug.actualMunicipalityCount ? adminDebug.naturalCompartmentCount / adminDebug.actualMunicipalityCount : 0;
  adminDebug.survivedSeedCount = seedLifecycle.filter((seed) => seed.state === "survived").length;
  adminDebug.pendingSeedCount = seedLifecycle.filter((seed) => seed.state === "pending").length;
  adminDebug.absorbedSeedCount = seedLifecycle.filter((seed) => seed.state === "absorbed").length;
  adminDebug.finalMunicipalityCount = adminDebug.actualMunicipalityCount;
  adminDebug.finalTinyMunicipalityCount = [...areaById.values()].filter((area) => area > 0 && area < 8).length;
  adminDebug.seedLifecycle = seedLifecycle.map((seed) => ({ id: seed.id, state: seed.state, protected: seed.protected, area: seed.area }));
  adminDebug.borderNaturalBarrierAverage = adminDebug.finalBorderNaturalBarrierAverage ?? 0;
  adminDebug.voronoiLikeRate = adminDebug.voronoiLikeRateAfter ?? 0;
  adminProgress?.({ status: "admin-step", regionId: adminRegionMeta.regionId, step: "extract borders" });
  const adminBorders = extractAdminBorderSegments(adminId, prefectureMask);


  return {
    adminCentersRaw,
    adminId,
    adminBorders,
    adminDebug,
    naturalCompartmentId: compartmentAssignment.compartmentId,
    naturalCompartments: compartmentAssignment.compartments,
  };
}


export function generateAdminLayout(context) {
  const layout = generateAdminLayoutForMask(context);
  return { ...layout, ...generatePrefecturesFromMunicipalities(context, layout) };
}