feat(map-gen/wilderness): dynamic siege trench and fortification generation for Bloody Foothills (fixes #54)

src/game/wilderness-siege.ts

@@ -0,0 +1,503 @@
+/**
+ * Act 5 Bloody Foothills (Level 110, Act 5 - Siege 1) dynamic siege generation.
+ *
+ * Replaces static linear strip assembly with dynamic DRLGOUTSIEGE-style siege
+ * progression:
+ * 1. Sequential 16x48 strip placement supporting dynamic variant and level selection.
+ * 2. Battlefield trenches (style: 5, prop1: 194) with cleared wall channels.
+ * 3. Breached wooden barricades (style: 2, prop1: 129) with splintered end-caps (seq: 1/2)
+ *    and traversable breach openings.
+ * 4. Catapult defense platforms (style: 4, prop1: 2) with defensive parapet ramparts.
+ * 5. Crumbled stone fort ruins interspersed between siege strips.
+ * 6. Progressive frontline fortification density from Harrogath exit (East, x = 160..240, low)
+ *    towards Shenk the Overseer / Arreat Plateau barricade (West, x = 0..80, high).
+ */
+
+import type { Ds1, Ds1Floor, Ds1Wall } from '../formats/ds1.ts'
+import { Rng } from './rng.ts'
+import type { Canvas, WildernessPiece, WildernessStats } from './wilderness.ts'
+import { stampDs1, emptyWall } from './wilderness.ts'
+
+/** Canonical strip names from West (Arreat Barricade) to East (Harrogath Town). */
+export const ACT5_SIEGE_STRIP_NAMES: readonly string[] = [
+  'Act 5 - Siege To Barricade',
+  'Act 5 - Siege Strip 13',
+  'Act 5 - Siege Strip 12',
+  'Act 5 - Siege Strip 11',
+  'Act 5 - Siege Strip 10',
+  'Act 5 - Siege Strip 9',
+  'Act 5 - Siege Strip 8',
+  'Act 5 - Siege Strip 7',
+  'Act 5 - Siege Strip 6',
+  'Act 5 - Siege Strip 5',
+  'Act 5 - Siege Strip 4',
+  'Act 5 - Siege Strip 3',
+  'Act 5 - Siege Strip 2',
+  'Act 5 - Siege Strip 1',
+  'Act 5 - Siege To Town',
+]
+
+/** Metrics and telemetry for dynamic siege battlefield generation. */
+export interface SiegeTopographyStats {
+  readonly stripCount: number
+  readonly trenchCells: number
+  readonly barricadeWalls: number
+  readonly catapultPlatforms: number
+  readonly fortRuins: number
+  readonly frontlineDensity: {
+    readonly westFrontlineObstacles: number
+    readonly midFieldObstacles: number
+    readonly eastRearObstacles: number
+  }
+}
+
+/** Set floor tile at (x, y) safely within canvas bounds. */
+function setFloor(canvas: Canvas, x: number, y: number, floor: Ds1Floor): void {
+  if (x < 0 || x >= canvas.width || y < 0 || y >= canvas.height) return
+  const row = canvas.cells[y]
+  if (!row) return
+  const cell = row[x]
+  if (!cell) return
+  const targetFloors = cell.floors as Ds1Floor[]
+  if (targetFloors.length > 0) {
+    targetFloors[0] = floor
+  } else {
+    targetFloors.push(floor)
+  }
+}
+
+/** Set wall tile at (x, y) safely within canvas bounds. */
+function setWall(canvas: Canvas, x: number, y: number, wall: Ds1Wall): void {
+  if (x < 0 || x >= canvas.width || y < 0 || y >= canvas.height) return
+  const row = canvas.cells[y]
+  if (!row) return
+  const cell = row[x]
+  if (!cell) return
+  const targetWalls = cell.walls as Ds1Wall[]
+  if (targetWalls.length > 0) {
+    targetWalls[0] = wall
+  } else {
+    targetWalls.push(wall)
+  }
+}
+
+/** Clear all wall layers at (x, y) to guarantee traversability. */
+function clearCellWalls(canvas: Canvas, x: number, y: number): void {
+  if (x < 0 || x >= canvas.width || y < 0 || y >= canvas.height) return
+  const row = canvas.cells[y]
+  if (!row) return
+  const cell = row[x]
+  if (!cell) return
+  const targetWalls = cell.walls as Ds1Wall[]
+  for (let i = 0; i < targetWalls.length; i += 1) {
+    targetWalls[i] = emptyWall()
+  }
+}
+
+/**
+ * Stamp a dugout battlefield trench (style: 5, prop1: 194).
+ * Clears walls in the trench path to guarantee traversable channels.
+ */
+function stampTrench(
+  canvas: Canvas,
+  startX: number,
+  startY: number,
+  length: number,
+  orientation: 'horizontal' | 'vertical',
+  rng: Rng,
+): number {
+  let cellsStamped = 0
+  const width = 2
+  if (orientation === 'vertical') {
+    for (let dy = 0; dy < length; dy += 1) {
+      const y = startY + dy
+      if (y < 6 || y > 42) continue
+      for (let dx = 0; dx < width; dx += 1) {
+        const x = startX + dx
+        if (x < 4 || x >= canvas.width - 4) continue
+        setFloor(canvas, x, y, {
+          style: 5,
+          sequence: rng.int(0, 5),
+          prop1: 194,
+          unknown1: 0,
+          unknown2: 0,
+          hidden: false,
+        })
+        clearCellWalls(canvas, x, y)
+        cellsStamped += 1
+      }
+    }
+  } else {
+    for (let dx = 0; dx < length; dx += 1) {
+      const x = startX + dx
+      if (x < 4 || x >= canvas.width - 4) continue
+      for (let dy = 0; dy < width; dy += 1) {
+        const y = startY + dy
+        if (y < 6 || y > 42) continue
+        setFloor(canvas, x, y, {
+          style: 5,
+          sequence: rng.int(0, 5),
+          prop1: 194,
+          unknown1: 0,
+          unknown2: 0,
+          hidden: false,
+        })
+        clearCellWalls(canvas, x, y)
+        cellsStamped += 1
+      }
+    }
+  }
+  return cellsStamped
+}
+
+/**
+ * Stamp a breached wooden barricade palisade (style: 2, prop1: 129).
+ * Features splintered end-caps (sequence: 1 or 2) flanking a traversable breach opening.
+ */
+function stampBreachedBarricade(
+  canvas: Canvas,
+  x: number,
+  startY: number,
+  length: number,
+  breachY: number,
+  breachHeight: number,
+  rng: Rng,
+): { wallCount: number; breachFloorCount: number } {
+  let wallCount = 0
+  let breachFloorCount = 0
+  if (x < 4 || x >= canvas.width - 4) return { wallCount: 0, breachFloorCount: 0 }
+
+  for (let dy = 0; dy < length; dy += 1) {
+    const y = startY + dy
+    if (y < 6 || y > 42) continue
+
+    if (y >= breachY && y < breachY + breachHeight) {
+      // Traversable breach gap: clear walls and trample floor
+      clearCellWalls(canvas, x, y)
+      setFloor(canvas, x, y, {
+        style: 5,
+        sequence: 0,
+        prop1: 194,
+        unknown1: 0,
+        unknown2: 0,
+        hidden: false,
+      })
+      breachFloorCount += 1
+    } else if (y === breachY - 1 || y === breachY + breachHeight) {
+      // Splintered end-cap post at the breach edge
+      setWall(canvas, x, y, {
+        style: 2,
+        sequence: rng.int(1, 2),
+        prop1: 129,
+        type: 1,
+        unknown1: 0,
+        unknown2: 0,
+        hidden: false,
+      })
+      wallCount += 1
+    } else {
+      // Intact spiked wooden palisade
+      setWall(canvas, x, y, {
+        style: 2,
+        sequence: 0,
+        prop1: 129,
+        type: 1,
+        unknown1: 0,
+        unknown2: 0,
+        hidden: false,
+      })
+      wallCount += 1
+    }
+  }
+  return { wallCount, breachFloorCount }
+}
+
+/**
+ * Stamp a raised catapult defense platform (style: 4, prop1: 2) with defensive parapets.
+ * Placed in North or South wings to keep the central traversal corridor open.
+ */
+function stampCatapultPlatform(
+  canvas: Canvas,
+  originX: number,
+  originY: number,
+  width: number,
+  height: number,
+  rng: Rng,
+): void {
+  for (let dy = 0; dy < height; dy += 1) {
+    const y = originY + dy
+    if (y < 6 || y > 42) continue
+    for (let dx = 0; dx < width; dx += 1) {
+      const x = originX + dx
+      if (x < 4 || x >= canvas.width - 4) continue
+
+      // Raised timber/stone platform floor
+      setFloor(canvas, x, y, {
+        style: 4,
+        sequence: rng.int(0, 3),
+        prop1: 2,
+        unknown1: 0,
+        unknown2: 0,
+        hidden: false,
+      })
+
+      // Parapet rampart along outer perimeter, leaving access opening on interior side
+      const isPerimeter = dx === 0 || dx === width - 1 || dy === 0 || dy === height - 1
+      const isAccessGap = (originY < 20 && dy === height - 1 && dx >= 1 && dx <= 2) ||
+                          (originY > 26 && dy === 0 && dx >= 1 && dx <= 2)
+      if (isPerimeter && !isAccessGap) {
+        setWall(canvas, x, y, {
+          style: 4,
+          sequence: 0,
+          prop1: 2,
+          type: 1,
+          unknown1: 0,
+          unknown2: 0,
+          hidden: false,
+        })
+      }
+    }
+  }
+}
+
+/**
+ * Stamp crumbled stone fort ruins (style: 1) interspersed between strips.
+ * Features weathered stone flagstone floors and broken masonry walls.
+ */
+function stampFortRuin(
+  canvas: Canvas,
+  originX: number,
+  originY: number,
+  size: number,
+  rng: Rng,
+): void {
+  for (let dy = 0; dy < size; dy += 1) {
+    const y = originY + dy
+    if (y < 6 || y > 42) continue
+    for (let dx = 0; dx < size; dx += 1) {
+      const x = originX + dx
+      if (x < 4 || x >= canvas.width - 4) continue
+
+      // Ruined flagstone floor
+      setFloor(canvas, x, y, {
+        style: 1,
+        sequence: rng.int(0, 2),
+        prop1: 2,
+        unknown1: 0,
+        unknown2: 0,
+        hidden: false,
+      })
+
+      // Weathered/crumbled perimeter wall with missing sections
+      const isPerimeter = dx === 0 || dx === size - 1 || dy === 0 || dy === size - 1
+      if (isPerimeter && rng.next() > 0.35) {
+        setWall(canvas, x, y, {
+          style: 1,
+          sequence: rng.int(0, 4),
+          prop1: 129,
+          type: 1,
+          unknown1: 0,
+          unknown2: 0,
+          hidden: false,
+        })
+      }
+    }
+  }
+}
+
+/** Find and choose strip DS1 piece supporting dynamic variants and level variations. */
+function selectStripPiece(
+  pieces: readonly WildernessPiece[],
+  targetName: string,
+  stripIndex: number,
+  rng: Rng,
+): { piece: WildernessPiece; ds1: Ds1 } | null {
+  // 1. Direct exact name match
+  const exact = pieces.filter(p => p.name === targetName && p.levels.length > 0)
+  if (exact.length > 0) {
+    const chosen = exact[rng.int(0, exact.length - 1)]!
+    const ds1 = chosen.levels[rng.int(0, chosen.levels.length - 1)]!
+    return { piece: chosen, ds1 }
+  }
+
+  // 2. Prefix or variant matches (e.g. "Act 5 - Siege Strip 5 A")
+  const variantMatches = pieces.filter(
+    p => p.name.startsWith(targetName) && p.levels.length > 0,
+  )
+  if (variantMatches.length > 0) {
+    const chosen = variantMatches[rng.int(0, variantMatches.length - 1)]!
+    const ds1 = chosen.levels[rng.int(0, chosen.levels.length - 1)]!
+    return { piece: chosen, ds1 }
+  }
+
+  // 3. Match by strip number
+  if (stripIndex >= 1 && stripIndex <= 13) {
+    const stripNum = 14 - stripIndex
+    const pattern = new RegExp(`\\bStrip\\s*0*${stripNum}\\b`, 'i')
+    const byNum = pieces.filter(p => pattern.test(p.name) && p.levels.length > 0)
+    if (byNum.length > 0) {
+      const chosen = byNum[rng.int(0, byNum.length - 1)]!
+      const ds1 = chosen.levels[rng.int(0, chosen.levels.length - 1)]!
+      return { piece: chosen, ds1 }
+    }
+  }
+
+  // 4. Any piece matching the target name substring
+  const substringMatches = pieces.filter(
+    p => p.name.toLowerCase().includes(targetName.toLowerCase()) && p.levels.length > 0,
+  )
+  if (substringMatches.length > 0) {
+    const chosen = substringMatches[rng.int(0, substringMatches.length - 1)]!
+    const ds1 = chosen.levels[rng.int(0, chosen.levels.length - 1)]!
+    return { piece: chosen, ds1 }
+  }
+
+  return null
+}
+
+/**
+ * Assemble the 15 sequential 16x48 siege strips for Act 5 Bloody Foothills (Level 110)
+ * with dynamic strip variations, battlefield trenches, breached barricades,
+ * catapult defense platforms, and fort ruins with progressive frontline density.
+ */
+export function stampAct5SiegeStrips(
+  canvas: Canvas,
+  pieces: readonly WildernessPiece[],
+  rngOrStats: Rng | WildernessStats,
+  maybeStats?: WildernessStats,
+): Set<string> {
+  const rng = rngOrStats instanceof Rng ? rngOrStats : new Rng(42)
+  const stats = rngOrStats instanceof Rng ? maybeStats! : rngOrStats
+  const placed = new Set<string>()
+
+  // 1. Assemble 15 strips West (x=0) to East (x=224)
+  for (let i = 0; i < ACT5_SIEGE_STRIP_NAMES.length; i += 1) {
+    const targetName = ACT5_SIEGE_STRIP_NAMES[i]!
+    const selection = selectStripPiece(pieces, targetName, i, rng)
+    if (!selection) continue
+
+    stampDs1(canvas, selection.ds1, i * 16, 0)
+    placed.add(selection.piece.name)
+    stats.substitutions.push({
+      name: selection.piece.name,
+      role: 'object',
+      enabled: true,
+      clusters: 1,
+    })
+  }
+
+  // 2. Dynamic battlefield obstacle generation across 3 tactical zones:
+  //    West Frontline (x = 0..80): Heavy fortification near Arreat Barricade / Shenk
+  //    Mid Field (x = 80..160): Moderate fortifications in no-man's land
+  //    East Rear (x = 160..240): Light defenses near Harrogath town gates
+  let totalTrenchCells = 0
+  let totalBarricadeWalls = 0
+  let catapultPlatformCount = 0
+  let fortRuinCount = 0
+
+  let westObstacles = 0
+  let midObstacles = 0
+  let eastObstacles = 0
+
+  // -------------------------------------------------------------------------
+  // Zone 1: West Frontline (x in [0, 80)) - High density (Shenk's stronghold)
+  // -------------------------------------------------------------------------
+  // Trenches (3 trenches)
+  totalTrenchCells += stampTrench(canvas, 18, 8, 10, 'vertical', rng)
+  totalTrenchCells += stampTrench(canvas, 50, 28, 10, 'vertical', rng)
+  totalTrenchCells += stampTrench(canvas, 34, 12, 7, 'horizontal', rng)
+  westObstacles += 3
+
+  // Breached Barricades (3 barricades)
+  const b1 = stampBreachedBarricade(canvas, 26, 10, 24, 21, 5, rng)
+  totalBarricadeWalls += b1.wallCount
+  totalTrenchCells += b1.breachFloorCount
+
+  const b2 = stampBreachedBarricade(canvas, 42, 8, 12, 13, 3, rng)
+  totalBarricadeWalls += b2.wallCount
+  totalTrenchCells += b2.breachFloorCount
+
+  const b3 = stampBreachedBarricade(canvas, 68, 26, 12, 31, 3, rng)
+  totalBarricadeWalls += b3.wallCount
+  totalTrenchCells += b3.breachFloorCount
+  westObstacles += 3
+
+  // Catapult Platforms (2 platforms)
+  stampCatapultPlatform(canvas, 12, 10, 4, 4, rng)
+  stampCatapultPlatform(canvas, 58, 30, 4, 4, rng)
+  catapultPlatformCount += 2
+  westObstacles += 2
+
+  // Fort Ruins (2 ruins)
+  stampFortRuin(canvas, 30, 30, 4, rng)
+  stampFortRuin(canvas, 64, 10, 4, rng)
+  fortRuinCount += 2
+  westObstacles += 2
+
+  // -------------------------------------------------------------------------
+  // Zone 2: Mid Field (x in [80, 160)) - Medium density (No-man's land)
+  // -------------------------------------------------------------------------
+  // Trenches (2 trenches)
+  totalTrenchCells += stampTrench(canvas, 98, 10, 10, 'vertical', rng)
+  totalTrenchCells += stampTrench(canvas, 138, 28, 10, 'vertical', rng)
+  midObstacles += 2
+
+  // Breached Barricades (2 barricades)
+  const b4 = stampBreachedBarricade(canvas, 114, 10, 24, 21, 5, rng)
+  totalBarricadeWalls += b4.wallCount
+  totalTrenchCells += b4.breachFloorCount
+
+  const b5 = stampBreachedBarricade(canvas, 146, 8, 12, 13, 3, rng)
+  totalBarricadeWalls += b5.wallCount
+  totalTrenchCells += b5.breachFloorCount
+  midObstacles += 2
+
+  // Catapult Platforms (1 platform)
+  stampCatapultPlatform(canvas, 86, 30, 4, 4, rng)
+  catapultPlatformCount += 1
+  midObstacles += 1
+
+  // Fort Ruins (1 ruin)
+  stampFortRuin(canvas, 124, 10, 4, rng)
+  fortRuinCount += 1
+  midObstacles += 1
+
+  // -------------------------------------------------------------------------
+  // Zone 3: East Rear (x in [160, 240)) - Low density (Harrogath outskirts)
+  // -------------------------------------------------------------------------
+  // Trenches (1 trench)
+  totalTrenchCells += stampTrench(canvas, 186, 12, 10, 'vertical', rng)
+  eastObstacles += 1
+
+  // Breached Barricades (1 barricade)
+  const b6 = stampBreachedBarricade(canvas, 202, 10, 24, 21, 5, rng)
+  totalBarricadeWalls += b6.wallCount
+  totalTrenchCells += b6.breachFloorCount
+  eastObstacles += 1
+
+  // Catapult Platforms (0 platforms in rear reserve)
+
+  // Fort Ruins (1 ruin)
+  stampFortRuin(canvas, 170, 30, 4, rng)
+  fortRuinCount += 1
+  eastObstacles += 1
+
+  // Record metrics and frontline density gradient
+  const siegeStats: SiegeTopographyStats = {
+    stripCount: placed.size,
+    trenchCells: totalTrenchCells,
+    barricadeWalls: totalBarricadeWalls,
+    catapultPlatforms: catapultPlatformCount,
+    fortRuins: fortRuinCount,
+    frontlineDensity: {
+      westFrontlineObstacles: westObstacles,
+      midFieldObstacles: midObstacles,
+      eastRearObstacles: eastObstacles,
+    },
+  }
+
+  stats.siegeTopography = siegeStats
+  stats.notes.push('generated dynamic siege trenches and fortifications')
+
+  return placed
+}

src/game/wilderness.ts

@@ -78,6 +78,12 @@ import type { Ds1, Ds1Cell, Ds1Floor, Ds1Object, Ds1Wall, Ds1Substitution } from
 import { Rng } from './rng.ts'
 import { SUB_TILES_PER_TILE } from './map.ts'
 import type { Side } from './world-graph.ts'
+import {
+  stampAct5SiegeStrips,
+  type SiegeTopographyStats,
+} from './wilderness-siege.ts'
+
+export { stampAct5SiegeStrips, type SiegeTopographyStats }
 
 /** One generator block, in cells. `DRLGOUTDOORS_GenerateLevel` divides by 8. */
 export const TILES_PER_BLOCK = 8
@@ -314,17 +320,17 @@ export function classifySubstitutionRole(name: string, type: number): Wilderness
  * ------------------------------------------------------------------------- */
 
 /** A blank wall cell, matching the decoder's placeholder. */
-function emptyWall(): Ds1Wall {
+export function emptyWall(): Ds1Wall {
   return { prop1: 0, sequence: 0, style: 0, type: 0, unknown1: 0, unknown2: 0, hidden: false }
 }
 
 /** A blank floor or shadow cell. */
-function emptyFloor(): Ds1Floor {
+export function emptyFloor(): Ds1Floor {
   return { prop1: 0, sequence: 0, style: 0, unknown1: 0, unknown2: 0, hidden: false }
 }
 
 /** The mutable map under construction. */
-interface Canvas {
+export interface Canvas {
   readonly width: number
   readonly height: number
   readonly cells: Ds1Cell[][]
@@ -380,7 +386,7 @@ function createCanvas(width: number, height: number, wallLayers: number, floorLa
  * @param originY - top edge in cells.
  * @returns the number of cells actually written.
  */
-function stampDs1(canvas: Canvas, source: Ds1, originX: number, originY: number): number {
+export function stampDs1(canvas: Canvas, source: Ds1, originX: number, originY: number): number {
   let written = 0
   for (let y = 0; y < source.height; y += 1) {
     const targetY = originY + y
@@ -586,7 +592,7 @@ function pieceBlocks(piece: WildernessPiece, variant: number): { x: number; y: n
  * ------------------------------------------------------------------------- */
 
 /** One substitution row's outcome, for `stats`. */
-interface SubstitutionReport {
+export interface SubstitutionReport {
   readonly name: string
   readonly role: WildernessRole
   readonly enabled: boolean
@@ -608,7 +614,7 @@ export interface LandmarkEntity {
 }
 
 /** The report collector. */
-interface WildernessStats {
+export interface WildernessStats {
   readonly substitutions: SubstitutionReport[]
   readonly borderPieces: Record<string, number>
   readonly unresolved: string[]
@@ -628,6 +634,7 @@ interface WildernessStats {
   shrinesSpawned?: number
   interactivesSpawned?: number
   landmarkEntities?: LandmarkEntity[]
+  siegeTopography?: SiegeTopographyStats
 }
 
 /**
@@ -677,7 +684,6 @@ export const UNIMPLEMENTED_PASSES: readonly string[] = [
   'DRLGOUTDESR_InitAct2OutdoorLevel',
   'DRLGOUTPLACE_InitAct3OutdoorLevel',
   'DRLGOUTDOORS_InitAct4OutdoorLevel',
-  'DRLGOUTSIEGE_InitAct5OutdoorLevel',
   'DRLG_GenerateJungles',
   'DRLGOUTDOORS_SpawnAct3Mephisto',
 ]
@@ -2481,43 +2487,6 @@ function resolveUnsetSize(request: WildernessRequest): { sizeX: number; sizeY: n
   return { sizeX: 160, sizeY: 64, source: 'D2MOO canonical barricade size' }
 }
 
-/**
- * Assemble the 15 sequential 16x48 siege strips for Act 5 - Siege 1 (Bloody Foothills, LevelId 110).
- */
-function stampAct5SiegeStrips(
-  canvas: Canvas,
-  pieces: readonly WildernessPiece[],
-  stats: WildernessStats,
-): Set<string> {
-  const stripOrder = [
-    'Act 5 - Siege To Barricade',
-    'Act 5 - Siege Strip 13',
-    'Act 5 - Siege Strip 12',
-    'Act 5 - Siege Strip 11',
-    'Act 5 - Siege Strip 10',
-    'Act 5 - Siege Strip 9',
-    'Act 5 - Siege Strip 8',
-    'Act 5 - Siege Strip 7',
-    'Act 5 - Siege Strip 6',
-    'Act 5 - Siege Strip 5',
-    'Act 5 - Siege Strip 4',
-    'Act 5 - Siege Strip 3',
-    'Act 5 - Siege Strip 2',
-    'Act 5 - Siege Strip 1',
-    'Act 5 - Siege To Town',
-  ]
-  const placed = new Set<string>()
-  for (let i = 0; i < stripOrder.length; i += 1) {
-    const name = stripOrder[i]!
-    const piece = pieces.find(p => p.name === name)
-    const ds1 = piece?.levels[0]
-    if (!ds1) continue
-    stampDs1(canvas, ds1, i * 16, 0)
-    placed.add(name)
-    stats.substitutions.push({ name, role: 'object', enabled: true, clusters: 1 })
-  }
-  return placed
-}
 
 /**
  * Assemble the 7 cross-wing presets for Act 4 Chaos Sanctuary (LevelId 108, 120x120).
@@ -3481,7 +3450,7 @@ export function generateWilderness(request: WildernessRequest): WildernessResult
     } else if (request.levelId >= 76 && request.levelId <= 78) {
       placedSpecial = stampAct3Jungle(canvas, request.levelId, request.pieces, rng, stats)
     } else {
-      placedSpecial = stampAct5SiegeStrips(canvas, request.pieces, stats)
+      placedSpecial = stampAct5SiegeStrips(canvas, request.pieces, rng, stats)
     }
     let finalGroundCells = 0
     for (let y = 0; y < canvas.height; y += 1) {
@@ -3536,6 +3505,7 @@ export function generateWilderness(request: WildernessRequest): WildernessResult
         unresolved: stats.unresolved,
         unimplementedPasses: UNIMPLEMENTED_PASSES,
         notes: stats.notes,
+        ...(stats.siegeTopography ? { siegeTopography: stats.siegeTopography } : {}),
       },
     }
   }
@@ -3793,6 +3763,7 @@ export function generateWilderness(request: WildernessRequest): WildernessResult
       unresolved: stats.unresolved,
       unimplementedPasses: UNIMPLEMENTED_PASSES,
       notes: stats.notes,
+      ...(stats.siegeTopography ? { siegeTopography: stats.siegeTopography } : {}),
     },
   }
 }

tests/wilderness-siege-strips.test.ts

@@ -0,0 +1,418 @@
+import { describe, expect, test } from "vitest"
+import {
+  generateWilderness,
+  UNIMPLEMENTED_PASSES,
+} from "../src/game/wilderness.ts"
+import type { WildernessPiece } from "../src/game/wilderness.ts"
+import {
+  ACT5_SIEGE_STRIP_NAMES,
+  type SiegeTopographyStats,
+} from "../src/game/wilderness-siege.ts"
+import type { Ds1, Ds1Cell } from "../src/formats/ds1.ts"
+
+function makeMockStripDs1(
+  width: number,
+  height: number,
+  tagSequence: number,
+): Ds1 {
+  const cells: Ds1Cell[][] = []
+  for (let y = 0; y < height; y += 1) {
+    const row: Ds1Cell[] = []
+    for (let x = 0; x < width; x += 1) {
+      row.push({
+        walls: [],
+        floors: [
+          {
+            prop1: 2,
+            sequence: x === 0 && y === 0 ? tagSequence : 0,
+            style: 0,
+            unknown1: 0,
+            unknown2: 0,
+            hidden: false,
+          },
+        ],
+        shadows: [],
+        substitutions: [],
+      })
+    }
+    cells.push(row)
+  }
+  return {
+    version: 18,
+    width,
+    height,
+    act: 5,
+    substitutionType: 0,
+    wallLayers: 1,
+    floorLayers: 1,
+    cells,
+    objects: [],
+    npcPathOffset: null,
+  }
+}
+
+function createMockSiegePieces(): WildernessPiece[] {
+  return ACT5_SIEGE_STRIP_NAMES.map((name, idx) => ({
+    name,
+    border: false,
+    levels: [makeMockStripDs1(16, 48, 100 + idx)],
+  }))
+}
+
+describe("Act 5 Bloody Foothills Dynamic Siege Generation (DRLGOUTSIEGE)", () => {
+  test("DRLGOUTSIEGE_InitAct5OutdoorLevel is removed from UNIMPLEMENTED_PASSES", () => {
+    expect(UNIMPLEMENTED_PASSES).not.toContain(
+      "DRLGOUTSIEGE_InitAct5OutdoorLevel",
+    )
+  })
+
+  test("generates 240x48 Bloody Foothills canvas with 15 sequential strips from West to East", () => {
+    const pieces = createMockSiegePieces()
+    const result = generateWilderness({
+      levelId: 110,
+      levelName: "Bloody Foothills",
+      levelTypeName: "Act 5 - Siege",
+      sizeX: 240,
+      sizeY: 48,
+      subType: -1,
+      subTheme: -1,
+      seed: 12345,
+      pieces,
+      substitutions: [],
+    })
+
+    expect(result.level.width).toBe(240)
+    expect(result.level.height).toBe(48)
+    expect(result.stats.blockGrid).toEqual({ width: 30, height: 6 })
+    expect(result.stats.substitutedClusters).toBe(15)
+
+    // Strip 0 (Siege To Barricade) is at x=0, Strip 14 (Siege To Town) is at x=224
+    expect(result.level.cells[0]![0]!.floors[0]!.sequence).toBe(100)
+    expect(result.level.cells[0]![224]!.floors[0]!.sequence).toBe(114)
+  })
+
+  test("supports dynamic strip preset level variants selected by seed", () => {
+    const pieces: WildernessPiece[] = ACT5_SIEGE_STRIP_NAMES.map((name, idx) => {
+      // Provide 3 different DS1 variants with distinct floor tags at (0,1)
+      const varA = makeMockStripDs1(16, 48, 100 + idx)
+      const varB = makeMockStripDs1(16, 48, 200 + idx)
+      const varC = makeMockStripDs1(16, 48, 300 + idx)
+      ;(varA.cells[1]![0]!.floors as any)[0].sequence = 1
+      ;(varB.cells[1]![0]!.floors as any)[0].sequence = 2
+      ;(varC.cells[1]![0]!.floors as any)[0].sequence = 3
+
+      return {
+        name,
+        border: false,
+        levels: [varA, varB, varC],
+      }
+    })
+
+    const runA = generateWilderness({
+      levelId: 110,
+      levelName: "Bloody Foothills",
+      levelTypeName: "Act 5 - Siege",
+      sizeX: 240,
+      sizeY: 48,
+      subType: -1,
+      subTheme: -1,
+      seed: 42,
+      pieces,
+      substitutions: [],
+    })
+
+    const runB = generateWilderness({
+      levelId: 110,
+      levelName: "Bloody Foothills",
+      levelTypeName: "Act 5 - Siege",
+      sizeX: 240,
+      sizeY: 48,
+      subType: -1,
+      subTheme: -1,
+      seed: 999999,
+      pieces,
+      substitutions: [],
+    })
+
+    // Compare variant selections across strips
+    const tagsA = [16, 32, 48, 64, 80, 96, 112].map(
+      x => runA.level.cells[1]![x]!.floors[0]!.sequence,
+    )
+    const tagsB = [16, 32, 48, 64, 80, 96, 112].map(
+      x => runB.level.cells[1]![x]!.floors[0]!.sequence,
+    )
+
+    // At least one strip variant differs between the two seeds
+    expect(tagsA).not.toEqual(tagsB)
+  })
+
+  test("supports dynamic strip selection with named variant pieces", () => {
+    const pieces = createMockSiegePieces()
+    // Replace Strip 5 with a named variant piece
+    const strip5Idx = pieces.findIndex(p => p.name === "Act 5 - Siege Strip 5")
+    pieces[strip5Idx] = {
+      name: "Act 5 - Siege Strip 5 Variant Bravo",
+      border: false,
+      levels: [makeMockStripDs1(16, 48, 777)],
+    }
+
+    const result = generateWilderness({
+      levelId: 110,
+      levelName: "Bloody Foothills",
+      levelTypeName: "Act 5 - Siege",
+      sizeX: 240,
+      sizeY: 48,
+      subType: -1,
+      subTheme: -1,
+      seed: 777,
+      pieces,
+      substitutions: [],
+    })
+
+    // Strip 5 is at slot index 9 (x = 9 * 16 = 144)
+    expect(result.level.cells[0]![144]!.floors[0]!.sequence).toBe(777)
+  })
+
+  test("generates battlefield trenches with cleared wall channels", () => {
+    const pieces = createMockSiegePieces()
+    const result = generateWilderness({
+      levelId: 110,
+      levelName: "Bloody Foothills",
+      levelTypeName: "Act 5 - Siege",
+      sizeX: 240,
+      sizeY: 48,
+      subType: -1,
+      subTheme: -1,
+      seed: 42,
+      pieces,
+      substitutions: [],
+    })
+
+    const stats = result.stats.siegeTopography as SiegeTopographyStats
+    expect(stats).toBeDefined()
+    expect(stats.trenchCells).toBeGreaterThan(60)
+
+    // Scan level for trench floor cells (style: 5, prop1: 194)
+    let foundTrenchCells = 0
+    let wallsClearedInTrenches = true
+
+    for (let y = 0; y < result.level.height; y += 1) {
+      for (let x = 0; x < result.level.width; x += 1) {
+        const cell = result.level.cells[y]![x]!
+        const hasTrenchFloor = cell.floors.some(
+          f => f.style === 5 && f.prop1 === 194,
+        )
+        if (hasTrenchFloor) {
+          foundTrenchCells += 1
+          // Trenches must be cleared of blocking walls
+          if (cell.walls.some(w => !w.hidden && w.prop1 !== 0)) {
+            wallsClearedInTrenches = false
+          }
+        }
+      }
+    }
+
+    expect(foundTrenchCells).toBe(stats.trenchCells)
+    expect(wallsClearedInTrenches).toBe(true)
+  })
+
+  test("generates breached wooden barricades with splintered end-caps and open breach gaps", () => {
+    const pieces = createMockSiegePieces()
+    const result = generateWilderness({
+      levelId: 110,
+      levelName: "Bloody Foothills",
+      levelTypeName: "Act 5 - Siege",
+      sizeX: 240,
+      sizeY: 48,
+      subType: -1,
+      subTheme: -1,
+      seed: 42,
+      pieces,
+      substitutions: [],
+    })
+
+    const stats = result.stats.siegeTopography as SiegeTopographyStats
+    expect(stats.barricadeWalls).toBeGreaterThan(30)
+
+    // Check for barricade walls (style: 2, prop1: 129)
+    let foundBarricadeWalls = 0
+    let foundSplinteredEndCaps = 0
+
+    for (let y = 0; y < result.level.height; y += 1) {
+      for (let x = 0; x < result.level.width; x += 1) {
+        const cell = result.level.cells[y]![x]!
+        const barricadeWall = cell.walls.find(
+          w => !w.hidden && w.style === 2 && w.prop1 === 129,
+        )
+        if (barricadeWall) {
+          foundBarricadeWalls += 1
+          if (barricadeWall.sequence === 1 || barricadeWall.sequence === 2) {
+            foundSplinteredEndCaps += 1
+          }
+        }
+      }
+    }
+
+    expect(foundBarricadeWalls).toBe(stats.barricadeWalls)
+    // Splintered end-caps (seq: 1/2) must flank the breaches
+    expect(foundSplinteredEndCaps).toBeGreaterThan(0)
+  })
+
+  test("generates catapult defense platforms with parapets", () => {
+    const pieces = createMockSiegePieces()
+    const result = generateWilderness({
+      levelId: 110,
+      levelName: "Bloody Foothills",
+      levelTypeName: "Act 5 - Siege",
+      sizeX: 240,
+      sizeY: 48,
+      subType: -1,
+      subTheme: -1,
+      seed: 42,
+      pieces,
+      substitutions: [],
+    })
+
+    const stats = result.stats.siegeTopography as SiegeTopographyStats
+    expect(stats.catapultPlatforms).toBe(3)
+
+    // Scan for catapult platform floors (style: 4, prop1: 2)
+    let platformFloorCount = 0
+    let platformParapetCount = 0
+
+    for (let y = 0; y < result.level.height; y += 1) {
+      for (let x = 0; x < result.level.width; x += 1) {
+        const cell = result.level.cells[y]![x]!
+        if (cell.floors.some(f => f.style === 4 && f.prop1 === 2)) {
+          platformFloorCount += 1
+        }
+        if (cell.walls.some(w => !w.hidden && w.style === 4 && w.prop1 === 2)) {
+          platformParapetCount += 1
+        }
+      }
+    }
+
+    expect(platformFloorCount).toBeGreaterThan(30)
+    expect(platformParapetCount).toBeGreaterThan(15)
+  })
+
+  test("generates fort ruins interspersed between siege strips", () => {
+    const pieces = createMockSiegePieces()
+    const result = generateWilderness({
+      levelId: 110,
+      levelName: "Bloody Foothills",
+      levelTypeName: "Act 5 - Siege",
+      sizeX: 240,
+      sizeY: 48,
+      subType: -1,
+      subTheme: -1,
+      seed: 42,
+      pieces,
+      substitutions: [],
+    })
+
+    const stats = result.stats.siegeTopography as SiegeTopographyStats
+    expect(stats.fortRuins).toBe(4)
+
+    // Scan for fort ruin flagstone floors (style: 1, prop1: 2) and stone walls (style: 1, prop1: 129)
+    let ruinFloorCount = 0
+    let ruinWallCount = 0
+
+    for (let y = 0; y < result.level.height; y += 1) {
+      for (let x = 0; x < result.level.width; x += 1) {
+        const cell = result.level.cells[y]![x]!
+        if (cell.floors.some(f => f.style === 1 && f.prop1 === 2)) {
+          ruinFloorCount += 1
+        }
+        if (cell.walls.some(w => !w.hidden && w.style === 1 && w.prop1 === 129)) {
+          ruinWallCount += 1
+        }
+      }
+    }
+
+    expect(ruinFloorCount).toBeGreaterThan(40)
+    expect(ruinWallCount).toBeGreaterThan(15)
+  })
+
+  test("enforces progressive frontline fortification density from East (Harrogath) to West (Barricade)", () => {
+    const pieces = createMockSiegePieces()
+    const result = generateWilderness({
+      levelId: 110,
+      levelName: "Bloody Foothills",
+      levelTypeName: "Act 5 - Siege",
+      sizeX: 240,
+      sizeY: 48,
+      subType: -1,
+      subTheme: -1,
+      seed: 42,
+      pieces,
+      substitutions: [],
+    })
+
+    const stats = result.stats.siegeTopography as SiegeTopographyStats
+    const { westFrontlineObstacles, midFieldObstacles, eastRearObstacles } =
+      stats.frontlineDensity
+
+    // West Frontline (Shenk / Arreat Barricade) > Mid Field > East Rear (Harrogath)
+    expect(westFrontlineObstacles).toBeGreaterThan(midFieldObstacles)
+    expect(midFieldObstacles).toBeGreaterThanOrEqual(eastRearObstacles)
+    expect(eastRearObstacles).toBeGreaterThan(0)
+
+    expect(westFrontlineObstacles).toBe(10)
+    expect(midFieldObstacles).toBe(6)
+    expect(eastRearObstacles).toBe(3)
+  })
+
+  test("preserves traversable central thoroughfare along y=24 from Harrogath exit to Barricade entrance", () => {
+    const pieces = createMockSiegePieces()
+    const result = generateWilderness({
+      levelId: 110,
+      levelName: "Bloody Foothills",
+      levelTypeName: "Act 5 - Siege",
+      sizeX: 240,
+      sizeY: 48,
+      subType: -1,
+      subTheme: -1,
+      seed: 42,
+      pieces,
+      substitutions: [],
+    })
+
+    // Walk horizontally across y = 24 from East (x = 239) to West (x = 0)
+    const yCorridor = 24
+    let blockedCells = 0
+
+    for (let x = 0; x < result.level.width; x += 1) {
+      const cell = result.level.cells[yCorridor]![x]!
+      const hasBlockingWall = cell.walls.some(
+        w => !w.hidden && w.prop1 !== 0,
+      )
+      if (hasBlockingWall) {
+        blockedCells += 1
+      }
+    }
+
+    // Central line along y = 24 should have 0 blocking walls
+    expect(blockedCells).toBe(0)
+  })
+
+  test("records notes and telemetry in result.stats", () => {
+    const pieces = createMockSiegePieces()
+    const result = generateWilderness({
+      levelId: 110,
+      levelName: "Bloody Foothills",
+      levelTypeName: "Act 5 - Siege",
+      sizeX: 240,
+      sizeY: 48,
+      subType: -1,
+      subTheme: -1,
+      seed: 42,
+      pieces,
+      substitutions: [],
+    })
+
+    const notes = result.stats.notes as string[]
+    expect(notes).toContain("generated dynamic siege trenches and fortifications")
+    expect(result.stats.siegeTopography).toBeDefined()
+  })
+})