diff --git a/packages/engine-ts/src/ClimatePhysics.generated.ts b/packages/engine-ts/src/ClimatePhysics.generated.ts
index 245650a5..7ce487dc 100644
--- a/packages/engine-ts/src/ClimatePhysics.generated.ts
+++ b/packages/engine-ts/src/ClimatePhysics.generated.ts
@@ -56,7 +56,7 @@ export function idealTerrain(
   tile: TileState,
   spec: Record<string, unknown>,
 ): string {
-  const tid = tile.terrain_id
+  const tid = tile.biome_id
   const temp = tile.temperature
   const moist = tile.moisture
   const elev = tile.elevation
@@ -150,7 +150,7 @@ export class ClimatePhysics {
     this.oceanDistCache = new Int32Array(n).fill(20)
     const queue: number[] = []
     for (let i = 0; i < n; i++) {
-      const tid = tiles[i].terrain_id
+      const tid = tiles[i].biome_id
       if (tid === 'ocean' || tid === 'coast' || tid === 'lake' || tid === 'inland_sea') {
         this.oceanDistCache[i] = 0
         queue.push(i)
@@ -586,47 +586,39 @@ export class ClimatePhysics {
   }
 
   private stepTerrainEvolution(grid: GridState): void {
-  const { tiles, width: w, height: h } = grid
-  let up_thresh = Math.floor((this.params as any)["quality_up_threshold"] ?? 10)
-  let down_thresh = Math.floor((this.params as any)["quality_down_threshold"] ?? 5)
+    const { tiles } = grid
+    const up_thresh = this.p('quality_up_threshold', 10)
+    const down_thresh = this.p('quality_down_threshold', 5)
 
-  for (let i = 0; i < tiles.length; i++) {
-    const tile = tiles[i]
-    const { col, row } = tile
-    let tid = tile.biome_id
+    for (let i = 0; i < tiles.length; i++) {
+      const tile = tiles[i]
+      const tid = tile.biome_id
 
-    if (tile.is_natural_wonder) {
-      continue
-    }
-    if (tid === "ocean" || tid === "coast" || tid === "lake" || tid === "volcano") {
-      continue
+      if (tile.is_natural_wonder) continue
+      if (tid === 'ocean' || tid === 'coast' || tid === 'lake' || tid === 'volcano') continue
 
-    }
-    let ideal = idealTerrain(tile, this.spec)
+      const ideal = idealTerrain(tile, this.spec)
 
-    if (ideal === tid) {
-      tile.quality_progress += 1
-      if (tile.quality_progress >= up_thresh) {
-        tile.quality_progress = 0
-        if (tile.quality < 5) {
-          tile.quality += 1
-    } else {
-      tile.quality_progress -= 1
-      if (tile.quality_progress <= -down_thresh) {
-        tile.quality_progress = 0
-        if (tile.quality > 1) {
-          tile.quality -= 1
-        } else {
-          tile.biome_id = ideal
-          tile.quality = 1
+      if (ideal === tid) {
+        tile.quality_progress += 1
+        if (tile.quality_progress >= up_thresh) {
           tile.quality_progress = 0
-
+          if (tile.quality < 5) tile.quality += 1
+        }
+      } else {
+        tile.quality_progress -= 1
+        if (tile.quality_progress <= -down_thresh) {
+          tile.quality_progress = 0
+          if (tile.quality > 1) {
+            tile.quality -= 1
+          } else {
+            tile.biome_id = ideal
+            tile.quality = 1
+            tile.quality_progress = 0
+          }
         }
       }
     }
-      }
-    }
-  }
   }
 
   private stepGlobalStats(grid: GridState): void {
@@ -698,7 +690,7 @@ export class ClimatePhysics {
       const col = Math.floor(hashNoise(ch, 1, turnSeed) * w)
       const row = Math.floor(hashNoise(ch, 2, turnSeed) * (h - 4)) + 2
       const tile = tiles[idx(col, row, w)]
-      if (!tile || tile.terrain_id === 'ocean' || tile.terrain_id === 'coast') return null
+      if (!tile || tile.biome_id === 'ocean' || tile.biome_id === 'coast') return null
       return tile
     }
     const hexDist = (c1: number, r1: number, c2: number, r2: number): number => {
@@ -717,15 +709,15 @@ export class ClimatePhysics {
       const center = pickLand(11)
       const forestTypes = (wf['target_terrain'] as string[]) ??
         ['forest', 'jungle', 'boreal_forest', 'enchanted_forest']
-      if (center && forestTypes.includes(center.terrain_id)) {
+      if (center && forestTypes.includes(center.biome_id)) {
         const radius = (wf['radius'] as number) ?? 2
         const moistLoss = (wf['moisture_loss'] as number) ?? 0.15
         const becomes = (wf['becomes'] as string) ?? 'grassland'
         let burned = 0
         for (const t of tilesInRadius(center.col, center.row, radius)) {
           if (t.is_natural_wonder) continue
-          if (forestTypes.includes(t.terrain_id)) {
-            t.terrain_id = becomes
+          if (forestTypes.includes(t.biome_id)) {
+            t.biome_id = becomes
             t.quality = 1
             t.quality_progress = 0
             t.moisture = Math.max(0.0, t.moisture - moistLoss)
@@ -742,7 +734,7 @@ export class ClimatePhysics {
     if (roll(20) < ((sv['frequency'] as number) ?? 0.00667)) {
       const center = pickLand(21)
       if (center && !center.is_natural_wonder) {
-        center.terrain_id = 'volcano'
+        center.biome_id = 'volcano'
         center.quality = 1
         center.quality_progress = 0
         const svRadius = (sv['radius'] as number) ?? 3
@@ -753,8 +745,8 @@ export class ClimatePhysics {
         let scorched = 0
         for (const t of tilesInRadius(center.col, center.row, svRadius)) {
           if (t === center || t.is_natural_wonder) continue
-          if (t.terrain_id !== 'ocean' && t.terrain_id !== 'coast') {
-            t.terrain_id = (sv['scorched_terrain'] as string) ?? 'desert'
+          if (t.biome_id !== 'ocean' && t.biome_id !== 'coast') {
+            t.biome_id = (sv['scorched_terrain'] as string) ?? 'desert'
             t.moisture = Math.max(0.0, t.moisture - svMoistLoss)
             t.quality = 1
             scorched++
@@ -780,7 +772,7 @@ export class ClimatePhysics {
       if (center && !center.is_natural_wonder) {
         const mtRadius = (mt['heat_radius'] as number) ?? 2
         const heatDelta = (mt['heat_delta'] as number) ?? 0.03
-        center.terrain_id = center.elevation < 0.15 ? 'lake' : 'desert'
+        center.biome_id = center.elevation < 0.15 ? 'lake' : 'desert'
         center.elevation = Math.max(0.0, center.elevation - 0.15)
         center.quality = 1
         for (const t of tilesInRadius(col, row, mtRadius)) t.magic_heat_delta += heatDelta
@@ -799,7 +791,7 @@ export class ClimatePhysics {
         const drRadius = (dr['radius'] as number) ?? 4
         const moistLoss = (dr['moisture_loss'] as number) ?? 0.10
         for (const t of tilesInRadius(center.col, center.row, drRadius)) {
-          if (t.terrain_id !== 'ocean' && t.terrain_id !== 'coast')
+          if (t.biome_id !== 'ocean' && t.biome_id !== 'coast')
             t.moisture = Math.max(0.0, t.moisture - moistLoss)
         }
         events.push({ turn, type: 'drought', col: center.col, row: center.row,
@@ -813,10 +805,10 @@ export class ClimatePhysics {
       const col = Math.floor(hashNoise(51, 1, turnSeed) * w)
       const row = Math.floor(hashNoise(51, 2, turnSeed) * h)
       const center = tiles[idx(col, row, w)]
-      if (center && (center.terrain_id === 'coast' || center.terrain_id === 'ocean')) {
+      if (center && (center.biome_id === 'coast' || center.biome_id === 'ocean')) {
         for (const t of tilesInRadius(col, row, 2)) {
-          if (t.terrain_id === 'coast') t.reef_health = Math.min(1.0, t.reef_health + 0.1)
-          if (t.terrain_id !== 'ocean' && t.terrain_id !== 'coast')
+          if (t.biome_id === 'coast') t.reef_health = Math.min(1.0, t.reef_health + 0.1)
+          if (t.biome_id !== 'ocean' && t.biome_id !== 'coast')
             t.moisture = Math.min(1.0, t.moisture + 0.05)
         }
         events.push({ turn, type: 'algal_bloom', col, row, description: 'Algal bloom' })
@@ -827,13 +819,13 @@ export class ClimatePhysics {
     const ip = cfg['insect_plague'] ?? {}
     if (roll(60) < ((ip['frequency'] as number) ?? 0.04)) {
       const center = pickLand(61)
-      if (center && (center.terrain_id === 'forest' || center.terrain_id === 'jungle' ||
-          center.terrain_id === 'enchanted_forest')) {
+      if (center && (center.biome_id === 'forest' || center.biome_id === 'jungle' ||
+          center.biome_id === 'enchanted_forest')) {
         const ipRadius = (ip['radius'] as number) ?? 3
         for (const t of tilesInRadius(center.col, center.row, ipRadius)) {
           if (t.is_natural_wonder) continue
-          if (t.terrain_id === 'enchanted_forest') { t.terrain_id = 'forest'; t.quality = Math.max(1, t.quality - 1) }
-          else if (t.terrain_id === 'jungle' || t.terrain_id === 'forest') t.quality = Math.max(1, t.quality - 1)
+          if (t.biome_id === 'enchanted_forest') { t.biome_id = 'forest'; t.quality = Math.max(1, t.quality - 1) }
+          else if (t.biome_id === 'jungle' || t.biome_id === 'forest') t.quality = Math.max(1, t.quality - 1)
         }
         events.push({ turn, type: 'insect_plague', col: center.col, row: center.row,
           description: 'Insect plague degrades forest quality' })
@@ -844,7 +836,7 @@ export class ClimatePhysics {
     const mg = cfg['mountain_growth'] ?? {}
     if (roll(70) < ((mg['frequency'] as number) ?? 0.0167)) {
       const center = pickLand(71)
-      if (center && (center.terrain_id === 'hills' || center.terrain_id === 'mountains')) {
+      if (center && (center.biome_id === 'hills' || center.biome_id === 'mountains')) {
         center.elevation = Math.min(1.0, center.elevation + 0.05)
         for (const nb of neighbors(center.col, center.row, w, h))
           tiles[idx(nb.col, nb.row, w)].elevation = Math.min(1.0, tiles[idx(nb.col, nb.row, w)].elevation + 0.02)
@@ -857,11 +849,11 @@ export class ClimatePhysics {
     const er = cfg['erosion'] ?? {}
     if (roll(80) < ((er['frequency'] as number) ?? 0.033)) {
       const center = pickLand(81)
-      if (center && (center.terrain_id === 'mountains' || center.terrain_id === 'hills' ||
-          center.terrain_id === 'volcano') && !center.is_natural_wonder) {
+      if (center && (center.biome_id === 'mountains' || center.biome_id === 'hills' ||
+          center.biome_id === 'volcano') && !center.is_natural_wonder) {
         center.elevation = Math.max(0.0, center.elevation - 0.03)
-        const isVolcano = center.terrain_id === 'volcano'
-        if (isVolcano) center.terrain_id = 'hills'
+        const isVolcano = center.biome_id === 'volcano'
+        if (isVolcano) center.biome_id = 'hills'
         for (const nb of neighbors(center.col, center.row, w, h)) {
           const t = tiles[idx(nb.col, nb.row, w)]
           if (t.elevation < center.elevation) t.moisture = Math.min(1.0, t.moisture + 0.03)
@@ -884,7 +876,7 @@ export class ClimatePhysics {
       const col = Math.floor(hashNoise(ch, 1, turnSeed) * w)
       const row = Math.floor(hashNoise(ch, 2, turnSeed) * (h - 4)) + 2
       const tile = tiles[idx(col, row, w)]
-      if (!tile || tile.terrain_id === 'ocean' || tile.terrain_id === 'coast') return null
+      if (!tile || tile.biome_id === 'ocean' || tile.biome_id === 'coast') return null
       return tile
     }
     const hexDist = (c1: number, r1: number, c2: number, r2: number): number => {
@@ -897,12 +889,12 @@ export class ClimatePhysics {
       tiles.filter(t => hexDist(col, row, t.col, t.row) <= radius)
     if (roll(10) < 0.125) {
       const center = pickLand(11)
-      if (center && ['forest','jungle','boreal_forest','enchanted_forest'].includes(center.terrain_id)) {
+      if (center && ['forest','jungle','boreal_forest','enchanted_forest'].includes(center.biome_id)) {
         let burned = 0
         for (const t of tilesInRadius(center.col, center.row, 2)) {
           if (t.is_natural_wonder) continue
-          if (['forest','jungle','enchanted_forest','boreal_forest'].includes(t.terrain_id)) {
-            t.terrain_id = 'grassland'; t.quality = 1; t.quality_progress = 0
+          if (['forest','jungle','enchanted_forest','boreal_forest'].includes(t.biome_id)) {
+            t.biome_id = 'grassland'; t.quality = 1; t.quality_progress = 0
             t.moisture = Math.max(0.0, t.moisture - 0.15); burned++
           }
         }
@@ -913,12 +905,12 @@ export class ClimatePhysics {
     if (roll(20) < 0.00667) {
       const center = pickLand(21)
       if (center && !center.is_natural_wonder) {
-        center.terrain_id = 'volcano'; center.quality = 1; center.quality_progress = 0
+        center.biome_id = 'volcano'; center.quality = 1; center.quality_progress = 0
         let scorched = 0
         for (const t of tilesInRadius(center.col, center.row, 3)) {
           if (t === center || t.is_natural_wonder) continue
-          if (t.terrain_id !== 'ocean' && t.terrain_id !== 'coast') {
-            t.terrain_id = 'desert'; t.moisture = Math.max(0.0, t.moisture - 0.2); t.quality = 1; scorched++
+          if (t.biome_id !== 'ocean' && t.biome_id !== 'coast') {
+            t.biome_id = 'desert'; t.moisture = Math.max(0.0, t.moisture - 0.2); t.quality = 1; scorched++
           }
         }
         for (const t of tiles) t.magic_heat_delta -= 0.002
@@ -932,7 +924,7 @@ export class ClimatePhysics {
       const row = Math.floor(hashNoise(31, 2, turnSeed) * (h - 4)) + 2
       const center = tiles[idx(col, row, w)]
       if (center && !center.is_natural_wonder) {
-        center.terrain_id = center.elevation < 0.15 ? 'lake' : 'desert'
+        center.biome_id = center.elevation < 0.15 ? 'lake' : 'desert'
         center.elevation = Math.max(0.0, center.elevation - 0.15); center.quality = 1
         for (const t of tilesInRadius(col, row, 2)) t.magic_heat_delta += 0.03
         center.wonder_anchor_strength = 2; center.wonder_anchor_school = 'aether'
@@ -943,7 +935,7 @@ export class ClimatePhysics {
       const center = pickLand(41)
       if (center) {
         for (const t of tilesInRadius(center.col, center.row, 4)) {
-          if (t.terrain_id !== 'ocean' && t.terrain_id !== 'coast')
+          if (t.biome_id !== 'ocean' && t.biome_id !== 'coast')
             t.moisture = Math.max(0.0, t.moisture - 0.10)
         }
         events.push({ turn, type: 'drought', col: center.col, row: center.row, description: 'Regional drought' })
@@ -953,10 +945,10 @@ export class ClimatePhysics {
       const col = Math.floor(hashNoise(51, 1, turnSeed) * w)
       const row = Math.floor(hashNoise(51, 2, turnSeed) * h)
       const center = tiles[idx(col, row, w)]
-      if (center && (center.terrain_id === 'coast' || center.terrain_id === 'ocean')) {
+      if (center && (center.biome_id === 'coast' || center.biome_id === 'ocean')) {
         for (const t of tilesInRadius(col, row, 2)) {
-          if (t.terrain_id === 'coast') t.reef_health = Math.min(1.0, t.reef_health + 0.1)
-          if (t.terrain_id !== 'ocean' && t.terrain_id !== 'coast')
+          if (t.biome_id === 'coast') t.reef_health = Math.min(1.0, t.reef_health + 0.1)
+          if (t.biome_id !== 'ocean' && t.biome_id !== 'coast')
             t.moisture = Math.min(1.0, t.moisture + 0.05)
         }
         events.push({ turn, type: 'algal_bloom', col, row, description: 'Algal bloom' })
@@ -964,18 +956,18 @@ export class ClimatePhysics {
     }
     if (roll(60) < 0.04) {
       const center = pickLand(61)
-      if (center && ['forest','jungle','enchanted_forest'].includes(center.terrain_id)) {
+      if (center && ['forest','jungle','enchanted_forest'].includes(center.biome_id)) {
         for (const t of tilesInRadius(center.col, center.row, 3)) {
           if (t.is_natural_wonder) continue
-          if (t.terrain_id === 'enchanted_forest') { t.terrain_id = 'forest'; t.quality = Math.max(1, t.quality - 1) }
-          else if (t.terrain_id === 'jungle' || t.terrain_id === 'forest') t.quality = Math.max(1, t.quality - 1)
+          if (t.biome_id === 'enchanted_forest') { t.biome_id = 'forest'; t.quality = Math.max(1, t.quality - 1) }
+          else if (t.biome_id === 'jungle' || t.biome_id === 'forest') t.quality = Math.max(1, t.quality - 1)
         }
         events.push({ turn, type: 'insect_plague', col: center.col, row: center.row, description: 'Insect plague' })
       }
     }
     if (roll(70) < 0.0167) {
       const center = pickLand(71)
-      if (center && (center.terrain_id === 'hills' || center.terrain_id === 'mountains')) {
+      if (center && (center.biome_id === 'hills' || center.biome_id === 'mountains')) {
         center.elevation = Math.min(1.0, center.elevation + 0.05)
         for (const nb of neighbors(center.col, center.row, w, h))
           tiles[idx(nb.col, nb.row, w)].elevation = Math.min(1.0, tiles[idx(nb.col, nb.row, w)].elevation + 0.02)
@@ -984,10 +976,10 @@ export class ClimatePhysics {
     }
     if (roll(80) < 0.033) {
       const center = pickLand(81)
-      if (center && ['mountains','hills','volcano'].includes(center.terrain_id) && !center.is_natural_wonder) {
+      if (center && ['mountains','hills','volcano'].includes(center.biome_id) && !center.is_natural_wonder) {
         center.elevation = Math.max(0.0, center.elevation - 0.03)
-        const isVolcano = center.terrain_id === 'volcano'
-        if (isVolcano) center.terrain_id = 'hills'
+        const isVolcano = center.biome_id === 'volcano'
+        if (isVolcano) center.biome_id = 'hills'
         for (const nb of neighbors(center.col, center.row, w, h)) {
           const t = tiles[idx(nb.col, nb.row, w)]
           if (t.elevation < center.elevation) t.moisture = Math.min(1.0, t.moisture + 0.03)
diff --git a/packages/engine-ts/src/MapGenerator.generated.ts b/packages/engine-ts/src/MapGenerator.generated.ts
index a7a3232c..5a134bd1 100644
--- a/packages/engine-ts/src/MapGenerator.generated.ts
+++ b/packages/engine-ts/src/MapGenerator.generated.ts
@@ -163,7 +163,7 @@ interface GenTile {
   axial: Vec2i
   col: number
   row: number
-  terrain_id: string
+  biome_id: string
   elevation: number
   moisture: number
   temperature: number
@@ -183,7 +183,7 @@ interface GenTile {
 function newGenTile(axial: Vec2i, col: number, row: number): GenTile {
   return {
     axial, col, row,
-    terrain_id: '',
+    biome_id: '',
     elevation: 0.0,
     moisture: 0.0,
     temperature: 0.0,
@@ -226,7 +226,7 @@ class GenMap {
   getTilesByTerrain(terrainId: string): Vec2i[] {
     const result: Vec2i[] = []
     for (const tile of this.tiles.values()) {
-      if (tile.terrain_id === terrainId) result.push(tile.axial)
+      if (tile.biome_id === terrainId) result.push(tile.axial)
     }
     return result
   }
@@ -244,14 +244,14 @@ class GenMap {
           temperature: gt?.temperature ?? 0.0,
           moisture: gt?.moisture ?? 0.0,
           elevation: gt?.elevation ?? 0.0,
-          terrain_id: gt?.terrain_id ?? 'ocean',
+          biome_id: gt?.biome_id ?? 'ocean',
           wind_direction: gt?.wind_direction ?? 0,
           wind_speed: gt?.wind_speed ?? 0.5,
           quality: gt?.quality ?? 2,
           quality_progress: gt?.quality_progress ?? 0,
           river_edges: gt?.river_edges ?? [],
           flow_accumulation: gt?.flow_accumulation ?? 0.0,
-          original_terrain_id: '',
+          original_biome_id: '',
           ley_line_count: 0,
           ley_school: '',
           reef_health: 1.0,
@@ -560,7 +560,7 @@ function assignSeaLevel(
 
   for (const tile of gm.tiles.values()) {
     const elev = elevation.get(axialKey(tile.axial)) ?? 0.0
-    tile.terrain_id = elev < seaLevel ? 'ocean' : 'land'
+    tile.biome_id = elev < seaLevel ? 'ocean' : 'land'
   }
 
   smoothCoastlines(gm, genParams)
@@ -578,35 +578,35 @@ function smoothCoastlines(gm: GenMap, params: Record<string, number>): void {
         const nb = gm.getTile({ x: tile.axial.x + dq, y: tile.axial.y + dr })
         if (!nb) continue
         neighborCount++
-        if (!isWaterTerrain(nb.terrain_id)) landCount++
+        if (!isWaterTerrain(nb.biome_id)) landCount++
       }
       const waterCount = neighborCount - landCount
-      if (isWaterTerrain(tile.terrain_id) && landCount >= 5) {
+      if (isWaterTerrain(tile.biome_id) && landCount >= 5) {
         changes.push({ pos: tile.axial, terrain: 'grassland' })
-      } else if (!isWaterTerrain(tile.terrain_id) && waterCount >= 5) {
+      } else if (!isWaterTerrain(tile.biome_id) && waterCount >= 5) {
         changes.push({ pos: tile.axial, terrain: 'ocean' })
       }
     }
     for (const change of changes) {
       const tile = gm.getTile(change.pos)
-      if (tile) tile.terrain_id = change.terrain
+      if (tile) tile.biome_id = change.terrain
     }
   }
 }
 
 function assignCoastTiles(gm: GenMap): void {
   for (const tile of gm.tiles.values()) {
-    if (tile.terrain_id === 'ocean') {
+    if (tile.biome_id === 'ocean') {
       let hasLandNeighbor = false
       for (const [dq, dr] of AXIAL_DIRECTIONS) {
         const nb = gm.getTile({ x: tile.axial.x + dq, y: tile.axial.y + dr })
-        if (nb && !isWaterTerrain(nb.terrain_id)) { hasLandNeighbor = true; break }
+        if (nb && !isWaterTerrain(nb.biome_id)) { hasLandNeighbor = true; break }
       }
-      if (hasLandNeighbor) tile.terrain_id = 'coast'
-    } else if (!isWaterTerrain(tile.terrain_id)) {
+      if (hasLandNeighbor) tile.biome_id = 'coast'
+    } else if (!isWaterTerrain(tile.biome_id)) {
       for (const [dq, dr] of AXIAL_DIRECTIONS) {
         const nb = gm.getTile({ x: tile.axial.x + dq, y: tile.axial.y + dr })
-        if (nb && isWaterTerrain(nb.terrain_id)) { tile.is_coastal = true; break }
+        if (nb && isWaterTerrain(nb.biome_id)) { tile.is_coastal = true; break }
       }
     }
   }
@@ -625,7 +625,7 @@ function placeTectonicRelief(
   // Compute local average elevation (radius 3) for each land tile
   const localAvg = new Map<string, number>()
   for (const tile of gm.tiles.values()) {
-    if (tile.terrain_id === 'ocean' || tile.terrain_id === 'coast') continue
+    if (tile.biome_id === 'ocean' || tile.biome_id === 'coast') continue
     const nearby = hexSpiral(tile.axial, 3)
     let total = 0.0, count = 0
     for (const nb of nearby) {
@@ -637,7 +637,7 @@ function placeTectonicRelief(
 
   const landTiles: Vec2i[] = []
   for (const tile of gm.tiles.values()) {
-    if (tile.terrain_id !== 'ocean' && tile.terrain_id !== 'coast') {
+    if (tile.biome_id !== 'ocean' && tile.biome_id !== 'coast') {
       landTiles.push(tile.axial)
     }
   }
@@ -654,19 +654,19 @@ function placeTectonicRelief(
     let adjOcean = false
     for (const nb of axialNeighbors(axial)) {
       const nbTile = gm.getTile(nb)
-      if (nbTile && (nbTile.terrain_id === 'ocean' || nbTile.terrain_id === 'coast')) {
+      if (nbTile && (nbTile.biome_id === 'ocean' || nbTile.biome_id === 'coast')) {
         adjOcean = true; break
       }
     }
 
     if (!adjOcean && elev > avg * 1.20) {
-      tile.terrain_id = 'mountains'
+      tile.biome_id = 'mountains'
       mountainTiles.push(axial)
     } else if (!adjOcean && elev > avg * 1.10) {
-      tile.terrain_id = 'hills'
+      tile.biome_id = 'hills'
       hillTiles.push(axial)
     } else if (rng.randf() < 0.40) {
-      tile.terrain_id = 'hills'
+      tile.biome_id = 'hills'
       hillTiles.push(axial)
     }
   }
@@ -681,7 +681,7 @@ function placeTectonicRelief(
     const excess = totalRelief - cap
     for (let i = 0; i < Math.min(excess, hillTiles.length); i++) {
       const tile = gm.getTile(hillTiles[i])
-      if (tile) tile.terrain_id = 'land'
+      if (tile) tile.biome_id = 'land'
     }
   }
 }
@@ -718,7 +718,7 @@ function computeMoisture(
   const dist = new Map<string, number>()
   const queue: Vec2i[] = []
   for (const tile of gm.tiles.values()) {
-    if (tile.terrain_id === 'ocean' || tile.terrain_id === 'coast') {
+    if (tile.biome_id === 'ocean' || tile.biome_id === 'coast') {
       dist.set(axialKey(tile.axial), 0)
       queue.push(tile.axial)
     }
@@ -751,7 +751,7 @@ function computeMoisture(
 
   // Rain shadow from mountains
   for (const tile of gm.tiles.values()) {
-    if (tile.terrain_id !== 'mountains') continue
+    if (tile.biome_id !== 'mountains') continue
     const wind = 0  // base direction before quality pass
     const [dq, dr] = AXIAL_DIRECTIONS[wind]
     for (let r = 1; r < 3; r++) {
@@ -784,7 +784,7 @@ function assignTerrainPatches(
 
   let landCount = 0
   for (const tile of gm.tiles.values()) {
-    if (tile.terrain_id === 'land') landCount++
+    if (tile.biome_id === 'land') landCount++
   }
 
   const order: string[] = [
@@ -797,14 +797,14 @@ function assignTerrainPatches(
     if (terrainId === 'tundra' || terrainId === 'snow') {
       const isFrozen = terrainId === 'snow'
       for (const tile of gm.tiles.values()) {
-        if (tile.terrain_id !== 'land') continue
+        if (tile.biome_id !== 'land') continue
         const t = temperature.get(axialKey(tile.axial)) ?? 0.5
         if (isFrozen && t < 0.10) targetCount++
         else if (!isFrozen && t >= 0.10 && t < 0.25) targetCount++
       }
     } else if (terrainId === 'jungle' || terrainId === 'forest' || terrainId === 'boreal_forest') {
       for (const tile of gm.tiles.values()) {
-        if (tile.terrain_id !== 'land') continue
+        if (tile.biome_id !== 'land') continue
         const t = temperature.get(axialKey(tile.axial)) ?? 0.5
         const m = moisture.get(axialKey(tile.axial)) ?? 0.5
         if (terrainId === 'jungle' && t > 0.65 && m >= 0.35) targetCount++
@@ -815,14 +815,14 @@ function assignTerrainPatches(
     } else if (terrainId === 'enchanted_forest') {
       let forestFamilyCount = 0
       for (const tile of gm.tiles.values()) {
-        const tid = tile.terrain_id
+        const tid = tile.biome_id
         if (tid === 'forest' || tid === 'jungle' || tid === 'boreal_forest') forestFamilyCount++
       }
       const baseCount = forestFamilyCount > 0 ? forestFamilyCount : landCount
       targetCount = Math.round(baseCount * (fractions['enchanted_forest'] ?? 0.01))
     } else if (terrainId === 'grassland') {
       for (const tile of gm.tiles.values()) {
-        if (tile.terrain_id === 'land') targetCount++
+        if (tile.biome_id === 'land') targetCount++
       }
     } else if (terrainId === 'volcano') {
       const mtCount = gm.getTilesByTerrain('mountains').length
@@ -836,7 +836,7 @@ function assignTerrainPatches(
 
   // Convert any remaining unclassified 'land' tiles to 'plains'
   for (const tile of gm.tiles.values()) {
-    if (tile.terrain_id === 'land') tile.terrain_id = 'plains'
+    if (tile.biome_id === 'land') tile.biome_id = 'plains'
   }
 }
 
@@ -848,7 +848,7 @@ function expandPatch(
   const eligible: Vec2i[] = []
   const src = terrainId === 'volcano' ? 'mountains' : 'land'
   for (const tile of gm.tiles.values()) {
-    if (tile.terrain_id === src && isEligible(tile.axial, terrainId, gm, elevation, moisture, temperature)) {
+    if (tile.biome_id === src && isEligible(tile.axial, terrainId, gm, elevation, moisture, temperature)) {
       eligible.push(tile.axial)
     }
   }
@@ -861,19 +861,19 @@ function expandPatch(
     const ei = rng.randiRange(0, eligible.length - 1)
     const seedPos = eligible[ei]
     const tile = gm.getTile(seedPos)
-    if (!tile || tile.terrain_id !== src) {
+    if (!tile || tile.biome_id !== src) {
       eligible.splice(ei, 1); continue
     }
-    tile.terrain_id = terrainId
+    tile.biome_id = terrainId
     placed++
 
     for (const nb of axialNeighbors(seedPos)) {
       if (placed >= targetCount) break
       const nbTile = gm.getTile(nb)
-      if (!nbTile || nbTile.terrain_id !== src) continue
+      if (!nbTile || nbTile.biome_id !== src) continue
       if (!isEligible(nb, terrainId, gm, elevation, moisture, temperature)) continue
       if (rng.randf() < 0.65) {
-        nbTile.terrain_id = terrainId
+        nbTile.biome_id = terrainId
         placed++
         eligible.push(nb)
       }
@@ -894,7 +894,7 @@ function isEligible(
     case 'volcano':
       for (const nb of axialNeighbors(axial)) {
         const nbTile = gm.getTile(nb)
-        if (nbTile && nbTile.terrain_id === 'mountains') return false
+        if (nbTile && nbTile.biome_id === 'mountains') return false
       }
       return true
     case 'jungle':         return t > 0.65 && m >= 0.35
@@ -935,7 +935,7 @@ function computeWindMap(gm: GenMap, windParams: Record<string, number>): void {
   // Pass 2: landmass friction
   const frictionLand = params['wind_friction_land'] ?? 0.7
   for (const tile of gm.tiles.values()) {
-    if (tile.terrain_id !== 'ocean' && tile.terrain_id !== 'coast') {
+    if (tile.biome_id !== 'ocean' && tile.biome_id !== 'coast') {
       tile.wind_speed *= frictionLand
     }
   }
@@ -943,7 +943,7 @@ function computeWindMap(gm: GenMap, windParams: Record<string, number>): void {
   // Pass 3: mountain blocking
   const mtCap = params['wind_friction_mountain_downwind'] ?? 0.1
   for (const tile of gm.tiles.values()) {
-    if (tile.terrain_id !== 'mountains') continue
+    if (tile.biome_id !== 'mountains') continue
     const mtDir = tile.wind_direction
     const [dwQ, dwR] = AXIAL_DIRECTIONS[mtDir]
     for (let step = 1; step <= 2; step++) {
@@ -958,7 +958,7 @@ function computeWindMap(gm: GenMap, windParams: Record<string, number>): void {
     for (const faceDir of [faceA, faceB]) {
       const [fq, fr] = AXIAL_DIRECTIONS[faceDir]
       const faceTile = gm.getTile({ x: tile.axial.x + fq, y: tile.axial.y + fr })
-      if (faceTile && faceTile.terrain_id !== 'mountains') {
+      if (faceTile && faceTile.biome_id !== 'mountains') {
         faceTile.wind_direction = faceDir
       }
     }
@@ -1013,11 +1013,11 @@ function bandWindForRow(
 
 function assignQuality(gm: GenMap): void {
   for (const tile of gm.tiles.values()) {
-    if (tile.terrain_id === 'ocean' || tile.terrain_id === 'coast' || tile.terrain_id === 'land') continue
+    if (tile.biome_id === 'ocean' || tile.biome_id === 'coast' || tile.biome_id === 'land') continue
     let same = 0
     for (const nb of axialNeighbors(tile.axial)) {
       const nbTile = gm.getTile(nb)
-      if (nbTile && nbTile.terrain_id === tile.terrain_id) same++
+      if (nbTile && nbTile.biome_id === tile.biome_id) same++
     }
     if (same >= 3) tile.quality = 4
     else if (same >= 1) tile.quality = 2
@@ -1053,7 +1053,7 @@ function computeRainfall(
   const out = new Map<string, number>()
   for (const tile of gm.tiles.values()) {
     const key = axialKey(tile.axial)
-    if (isWaterTerrainHydro(tile.terrain_id)) { out.set(key, 0.0); continue }
+    if (isWaterTerrainHydro(tile.biome_id)) { out.set(key, 0.0); continue }
     const m = moisture.get(key) ?? tile.moisture
     const t = temperature.get(key) ?? tile.temperature
     let base = m * climateMult(t, params)
@@ -1081,7 +1081,7 @@ function applyRainfallBonuses(
   gm: GenMap, params: Record<string, unknown>,
 ): number {
   const sb = (params['source_bonuses'] ?? {}) as Record<string, Record<string, unknown>>
-  const terrain = tile.terrain_id
+  const terrain = tile.biome_id
   const elev = elevation.get(key) ?? tile.elevation
   const temp = temperature.get(key) ?? tile.temperature
 
@@ -1124,7 +1124,7 @@ function applyRainfallBonuses(
 function adjTerrain(axial: Vec2i, terrains: string[], gm: GenMap): boolean {
   for (const [dq, dr] of AXIAL_DIRECTIONS) {
     const nb = gm.getTile({ x: axial.x + dq, y: axial.y + dr })
-    if (nb && terrains.includes(nb.terrain_id)) return true
+    if (nb && terrains.includes(nb.biome_id)) return true
   }
   return false
 }
@@ -1147,7 +1147,7 @@ function depressionFill(
 
   for (const tile of gm.tiles.values()) {
     const key = axialKey(tile.axial)
-    if (isWaterTerrainHydro(tile.terrain_id)) {
+    if (isWaterTerrainHydro(tile.biome_id)) {
       filled.set(key, 0.0)
       flowDir.set(key, -1)
       heapPush(heap, [0.0, tile.axial.x, tile.axial.y])
@@ -1255,7 +1255,7 @@ function detectLakes(
   const seaMin = cfg['inland_sea_min_tiles'] ?? 12
   const lakeTiles = new Set<string>()
   for (const tile of gm.tiles.values()) {
-    if (isWaterTerrainHydro(tile.terrain_id)) continue
+    if (isWaterTerrainHydro(tile.biome_id)) continue
     const key = axialKey(tile.axial)
     const re = elevation.get(key) ?? tile.elevation
     if ((filledElev.get(key) ?? re) - re > depth) lakeTiles.add(key)
@@ -1282,7 +1282,7 @@ function detectLakes(
     const tid = group.length < seaMin ? 'lake' : 'inland_sea'
     for (const key of group) {
       const tile = gm.tiles.get(key)
-      if (tile) { tile.terrain_id = tid; tile.lake_id = nextId }
+      if (tile) { tile.biome_id = tid; tile.lake_id = nextId }
     }
     nextId++
   }
@@ -1300,10 +1300,10 @@ function markRivers(
   for (const axial of topoOrder) {
     const key = axialKey(axial)
     const tile = gm.getTile(axial)
-    if (!tile || isWaterTerrainHydro(tile.terrain_id)) continue
+    if (!tile || isWaterTerrainHydro(tile.biome_id)) continue
     const a = acc.get(key) ?? 0.0
     const temp = temperature.get(key) ?? tile.temperature
-    if (a < riverThresh(temp, tile.terrain_id, rcfg) / density) continue
+    if (a < riverThresh(temp, tile.biome_id, rcfg) / density) continue
     const d = flowDir.get(key) ?? -1
     if (d === -1) continue
     const dsPos: Vec2i = {
@@ -1317,7 +1317,7 @@ function markRivers(
     tile.river_flow[String(d)] = fv
     tile.river_flow['_flow_dir'] = d
     const opp = OPPOSITE_DIR[d]
-    if (!isWaterTerrainHydro(ds.terrain_id)) {
+    if (!isWaterTerrainHydro(ds.biome_id)) {
       if (!ds.river_edges.includes(opp)) ds.river_edges.push(opp)
       ds.river_flow[String(opp)] = fv
     }
@@ -1344,14 +1344,14 @@ function markDeltas(
   const frozenT = (params as Record<string, number>)['frozen_river_temperature'] ?? 0.10
   for (const tile of gm.tiles.values()) {
     const key = axialKey(tile.axial)
-    if (isWaterTerrainHydro(tile.terrain_id) || (acc.get(key) ?? 0) < thresh) continue
+    if (isWaterTerrainHydro(tile.biome_id) || (acc.get(key) ?? 0) < thresh) continue
     const waterDirs: number[] = []
     for (let di = 0; di < 6; di++) {
       const nb = gm.getTile({
         x: tile.axial.x + AXIAL_DIRECTIONS[di][0],
         y: tile.axial.y + AXIAL_DIRECTIONS[di][1],
       })
-      if (nb && isWaterTerrainHydro(nb.terrain_id)) waterDirs.push(di)
+      if (nb && isWaterTerrainHydro(nb.biome_id)) waterDirs.push(di)
     }
     if (waterDirs.length === 0) continue
     const br = Math.min(maxBr - 1, waterDirs.length)
@@ -1371,7 +1371,7 @@ function markDeltas(
         const nbKey = axialKey(nbPos)
         if ((flowDir.get(nbKey) ?? -1) === OPPOSITE_DIR[di]) {
           const up = gm.getTile(nbPos)
-          if (up && !isWaterTerrainHydro(up.terrain_id)) {
+          if (up && !isWaterTerrainHydro(up.biome_id)) {
             const d = waterDirs[br]
             let upFv = acc.get(nbKey) ?? 0.0
             if (up.temperature <= frozenT) upFv = -upFv
@@ -1410,7 +1410,7 @@ function classifySources(
     }
     if (hasUp) continue
 
-    const terrain = tile.terrain_id
+    const terrain = tile.biome_id
     const elev = elevation.get(key) ?? tile.elevation
     const temp = temperature.get(key) ?? tile.temperature
     const moist = moisture.get(key) ?? tile.moisture
diff --git a/packages/engine-ts/src/runner.ts b/packages/engine-ts/src/runner.ts
index 05a95faf..b6f668fe 100644
--- a/packages/engine-ts/src/runner.ts
+++ b/packages/engine-ts/src/runner.ts
@@ -104,7 +104,7 @@ export function encodeSnapshot(
 
     texB[base + 0] = tile.wind_direction / 5
     texB[base + 1] = tile.wind_speed
-    texB[base + 2] = encodeTerrainId(tile.terrain_id)
+    texB[base + 2] = encodeTerrainId(tile.biome_id)
     let riverMask = 0
     for (const e of tile.river_edges) riverMask |= (1 << e)
     texB[base + 3] = riverMask / 63
@@ -141,9 +141,9 @@ export function computeTurnStats(grid: GridState): TurnStats {
   const terrain_counts: Record<string, number> = {}
 
   for (const tile of tiles) {
-    terrain_counts[tile.terrain_id] = (terrain_counts[tile.terrain_id] ?? 0) + 1
-    const isWater = tile.terrain_id === 'ocean' || tile.terrain_id === 'coast' ||
-      tile.terrain_id === 'lake' || tile.terrain_id === 'inland_sea'
+    terrain_counts[tile.biome_id] = (terrain_counts[tile.biome_id] ?? 0) + 1
+    const isWater = tile.biome_id === 'ocean' || tile.biome_id === 'coast' ||
+      tile.biome_id === 'lake' || tile.biome_id === 'inland_sea'
     if (!isWater) {
       landCount++
       tempSum += tile.temperature
@@ -198,7 +198,7 @@ export function applyVolcanicWinterForcing(grid: GridState): void {
   const { tiles } = grid
   const RADIUS = 3
 
-  const volcanos = tiles.filter((t) => t.terrain_id === 'volcano')
+  const volcanos = tiles.filter((t) => t.biome_id === 'volcano')
   for (const volcano of volcanos) {
     const q1 = volcano.col
     const s1 = volcano.row - (volcano.col - (volcano.col & 1)) / 2
diff --git a/packages/engine-ts/src/scenarios.ts b/packages/engine-ts/src/scenarios.ts
index b4c133a5..9ae051a3 100644
--- a/packages/engine-ts/src/scenarios.ts
+++ b/packages/engine-ts/src/scenarios.ts
@@ -115,12 +115,12 @@ const volcanicWinter: ScenarioConfig = {
     for (const { col, row } of volcanicSites) {
       if (col >= 0 && col < w && row >= 0 && row < grid.height) {
         const tile = grid.tiles[idx(col, row, w)]
-        if (tile) tile.terrain_id = 'volcano'
+        if (tile) tile.biome_id = 'volcano'
       }
     }
     // Seed ash cooling delta on volcano-adjacent tiles
     for (const tile of grid.tiles) {
-      if (tile.terrain_id === 'volcano') {
+      if (tile.biome_id === 'volcano') {
         tile.magic_heat_delta = -0.005
       }
     }
diff --git a/packages/engine-ts/src/types.ts b/packages/engine-ts/src/types.ts
index f16c145f..92bf6dc2 100644
--- a/packages/engine-ts/src/types.ts
+++ b/packages/engine-ts/src/types.ts
@@ -7,7 +7,6 @@ export interface TileState {
   temperature: number       // [0, 1]
   moisture: number          // [0, 1]
   elevation: number         // [0, 1]
-  terrain_id: string
   biome_id: string          // computed biome from substrate + climate + flora
   wind_direction: number    // [0, 5] axial direction index
   wind_speed: number        // [0, 1]
@@ -15,7 +14,7 @@ export interface TileState {
   quality_progress: number  // counter toward next quality change
   river_edges: number[]     // edge indices [0-5] where rivers flow
   flow_accumulation: number
-  original_terrain_id: string
+  original_biome_id: string
   ley_line_count: number
   ley_school: LeySchool | ''
   reef_health: number       // [0, 1], relevant for coast tiles