fix(wilderness): prevent destructive wiping of walls and presets in roads and bridges

1. Protect placed presets and preset walls from being wiped in stampThemedRoads:
   check placedRects in paintRoadTile, ensuring preset walls are never cleared.
2. Protect preset floors and walls in stampAct3KurastCauseway so artist DS1
   tiles are not overwritten by procedural causeway passes; wire specialPlacedRects.
3. Protect placed preset walls and floors in synthesizeBridgePlanks in Act 3 jungles,
   recording placedRects for all jungle pieces.
4. Add unit tests for Causeway preset preservation and road preset wall preservation.

TAG=agy
CONV=2a1934de-30ef-464e-b3f3-fcbcdbbc49f1

src/game/wilderness-acts.ts

@@ -418,6 +418,7 @@ export function stampAct3KurastCauseway(
   canvas: Canvas,
   pieces: readonly WildernessPiece[],
   stats: WildernessStats,
+  specialPlacedRects?: PlacedPresetRect[],
 ): Set<string> {
   const placed = new Set<string>()
   const piece = pieces.find(p => p.name === 'Act 3 - Bridge')
@@ -427,6 +428,15 @@ export function stampAct3KurastCauseway(
     stampDs1(canvas, ds1, 0, 0)
     placed.add('Act 3 - Bridge')
     stats.substitutions.push({ name: 'Act 3 - Bridge', role: 'object', enabled: true, clusters: 1 })
+    if (specialPlacedRects) {
+      specialPlacedRects.push({
+        x: 0,
+        y: 0,
+        w: ds1.width,
+        h: ds1.height,
+        name: 'Act 3 - Bridge',
+      })
+    }
   }
 
   // Construct / ensure canonical causeway layout:
@@ -438,6 +448,15 @@ export function stampAct3KurastCauseway(
 
   for (let y = 0; y < canvas.height; y += 1) {
     for (let x = 0; x < canvas.width; x += 1) {
+      if (ds1 && x >= 0 && x < ds1.width && y >= 0 && y < ds1.height) {
+        const ds1Cell = ds1.cells[y]?.[x]
+        const hasFloor = ds1Cell?.floors && ds1Cell.floors.length > 0 && !ds1Cell.floors[0]?.hidden
+        const hasWall = ds1Cell?.walls && ds1Cell.walls.length > 0 && !ds1Cell.walls[0]?.hidden
+        if (hasFloor || hasWall) {
+          // Keep artist-placed preset tiles from ds1; do not destructively wipe
+          continue
+        }
+      }
       if (x >= walkwayLeft && x <= walkwayRight) {
         // Paved stone causeway: style 5, prop1 194
         paintFloor(canvas, x, y, makeFloor(5, 0, 194), true)

src/game/wilderness-jungles.ts

@@ -23,7 +23,7 @@
 
 import type { Ds1, Ds1Cell, Ds1Floor, Ds1Wall } from '../formats/ds1.ts'
 import { Rng } from './rng.ts'
-import type { Canvas, SubstitutionReport, WildernessPiece, WildernessStats } from './wilderness.ts'
+import type { Canvas, PlacedPresetRect, SubstitutionReport, WildernessPiece, WildernessStats } from './wilderness.ts'
 
 /** Connection between two Act 3 zones. */
 export interface JungleZoneConnection {
@@ -242,6 +242,7 @@ function synthesizeBridgePlanks(
   bridgeX: number,
   bridgeY: number,
   orientation: 'horizontal' | 'vertical',
+  bridgeDs1?: Ds1,
 ): void {
   const makeBridgeFloor = (): Ds1Floor => ({
     prop1: 2,
@@ -261,6 +262,14 @@ function synthesizeBridgePlanks(
         if (cy >= 0 && cy < canvas.height && cx >= 0 && cx < canvas.width) {
           const row = canvas.cells[cy]
           if (row?.[cx]) {
+            if (bridgeDs1 && dx < bridgeDs1.width && dy < bridgeDs1.height) {
+              const ds1Cell = bridgeDs1.cells[dy]?.[dx]
+              const hasPresetWall = ds1Cell?.walls && ds1Cell.walls.length > 0 && !ds1Cell.walls[0]?.hidden
+              const hasPresetFloor = ds1Cell?.floors && ds1Cell.floors.length > 0 && !ds1Cell.floors[0]?.hidden && ds1Cell.floors[0]?.style !== 1
+              if (hasPresetWall || hasPresetFloor) {
+                continue
+              }
+            }
             ;(row[cx]!.floors as Ds1Floor[])[0] = makeBridgeFloor()
           }
         }
@@ -274,6 +283,14 @@ function synthesizeBridgePlanks(
         if (cy >= 0 && cy < canvas.height && cx >= 0 && cx < canvas.width) {
           const row = canvas.cells[cy]
           if (row?.[cx]) {
+            if (bridgeDs1 && dx < bridgeDs1.width && dy < bridgeDs1.height) {
+              const ds1Cell = bridgeDs1.cells[dy]?.[dx]
+              const hasPresetWall = ds1Cell?.walls && ds1Cell.walls.length > 0 && !ds1Cell.walls[0]?.hidden
+              const hasPresetFloor = ds1Cell?.floors && ds1Cell.floors.length > 0 && !ds1Cell.floors[0]?.hidden && ds1Cell.floors[0]?.style !== 1
+              if (hasPresetWall || hasPresetFloor) {
+                continue
+              }
+            }
             ;(row[cx]!.floors as Ds1Floor[])[0] = makeBridgeFloor()
           }
         }
@@ -343,6 +360,7 @@ export function DRLG_GenerateJungles(
   rng: Rng,
   stats: WildernessStats,
   stampDs1Fn: (canvas: Canvas, source: Ds1, originX: number, originY: number) => number,
+  placedRects?: PlacedPresetRect[],
 ): Set<string> {
   const placed = new Set<string>()
 
@@ -523,8 +541,9 @@ export function DRLG_GenerateJungles(
       const offsetX = Math.max(0, Math.floor((32 - bDs1.width) / 2))
       const offsetY = Math.max(0, Math.floor((32 - bDs1.height) / 2))
       stampDs1Fn(canvas, bDs1, bx + offsetX, by + offsetY)
+      placedRects?.push({ x: bx + offsetX, y: by + offsetY, w: bDs1.width, h: bDs1.height, name: bridgePiece.name })
     }
-    synthesizeBridgePlanks(canvas, bx, by, orientation)
+    synthesizeBridgePlanks(canvas, bx, by, orientation, bridgePiece?.levels[0])
     placed.add('Act 3 - Bridge')
     stats.substitutions.push({ name: 'Act 3 - Bridge', role: 'object', enabled: true, clusters: 1 })
   }
@@ -538,9 +557,11 @@ export function DRLG_GenerateJungles(
     bridges.push({ col: bridgeCol, row: bridgeRow, x: bx, y: by, pieceName: 'Act 3 - Bridge' })
 
     if (bridgePiece?.levels[0]) {
-      stampDs1Fn(canvas, bridgePiece.levels[0], bx, by)
+      const bDs1 = bridgePiece.levels[0]
+      stampDs1Fn(canvas, bDs1, bx, by)
+      placedRects?.push({ x: bx, y: by, w: bDs1.width, h: bDs1.height, name: bridgePiece.name })
     }
-    synthesizeBridgePlanks(canvas, bx, by, 'horizontal')
+    synthesizeBridgePlanks(canvas, bx, by, 'horizontal', bridgePiece?.levels[0])
     placed.add('Act 3 - Bridge')
     stats.substitutions.push({ name: 'Act 3 - Bridge', role: 'object', enabled: true, clusters: 1 })
   }
@@ -553,11 +574,13 @@ export function DRLG_GenerateJungles(
     stampDs1Fn(canvas, tailPiece.levels[0], 0, 0)
     placed.add(tailPiece.name)
     stats.substitutions.push({ name: tailPiece.name, role: 'object', enabled: true, clusters: 1 })
+    placedRects?.push({ x: 0, y: 0, w: tailPiece.levels[0].width, h: tailPiece.levels[0].height, name: tailPiece.name })
   }
   if (headPiece?.levels[0]) {
     stampDs1Fn(canvas, headPiece.levels[0], 0, (numRows - 1) * 32)
     placed.add(headPiece.name)
     stats.substitutions.push({ name: headPiece.name, role: 'object', enabled: true, clusters: 1 })
+    placedRects?.push({ x: 0, y: (numRows - 1) * 32, w: headPiece.levels[0].width, h: headPiece.levels[0].height, name: headPiece.name })
   }
 
   // 8. Stamp Interior River and Clearing Presets
@@ -575,6 +598,7 @@ export function DRLG_GenerateJungles(
           cell.pieceName = riverPiece.name
           placed.add(riverPiece.name)
           stats.substitutions.push({ name: riverPiece.name, role: 'object', enabled: true, clusters: 1 })
+          placedRects?.push({ x, y, w: ds1.width, h: ds1.height, name: riverPiece.name })
         }
       } else if (cell.type === 'clearing') {
         const preferredOpening =
@@ -591,6 +615,7 @@ export function DRLG_GenerateJungles(
           cell.pieceName = clearingPiece.name
           placed.add(clearingPiece.name)
           stats.substitutions.push({ name: clearingPiece.name, role: 'object', enabled: true, clusters: 1 })
+          placedRects?.push({ x, y, w: ds1.width, h: ds1.height, name: clearingPiece.name })
           clearings.push({
             col: c,
             row: r,
@@ -605,9 +630,11 @@ export function DRLG_GenerateJungles(
   // 9. Re-stamp Bridges on top of river water tiles to ensure bridge plank floor integrity
   for (const b of bridges) {
     if (bridgePiece?.levels[0]) {
-      stampDs1Fn(canvas, bridgePiece.levels[0], b.x, b.y)
+      const ds1 = bridgePiece.levels[0]
+      stampDs1Fn(canvas, ds1, b.x, b.y)
+      placedRects?.push({ x: b.x, y: b.y, w: ds1.width, h: ds1.height, name: bridgePiece.name })
     }
-    synthesizeBridgePlanks(canvas, b.x, b.y, 'horizontal')
+    synthesizeBridgePlanks(canvas, b.x, b.y, 'horizontal', bridgePiece?.levels[0])
   }
 
   // 10. Record Layout Statistics

src/game/wilderness.ts

@@ -3122,7 +3122,7 @@ function stampAct3Jungle(
   stats: WildernessStats,
   placedRects?: PlacedPresetRect[],
 ): Set<string> {
-  return DRLG_GenerateJungles(canvas, levelId, pieces, rng, stats, stampDs1)
+  return DRLG_GenerateJungles(canvas, levelId, pieces, rng, stats, stampDs1, placedRects)
 }
 
 /** Theme configuration for outdoor road rasterization. */
@@ -3156,7 +3156,7 @@ export function stampThemedRoads(
 ): void {
   const isInsideProtectedPreset = (x: number, y: number): boolean => {
     for (const r of placedRects) {
-      if (theme.isProtectedPreset ? !theme.isProtectedPreset(r.name) : /River|Bridge/i.test(r.name)) {
+      if (theme.isProtectedPreset ? !theme.isProtectedPreset(r.name) : false) {
         continue
       }
       if (x >= r.x && x < r.x + r.w && y >= r.y && y < r.y + r.h) {
@@ -3176,7 +3176,11 @@ export function stampThemedRoads(
     if (existingFloor && (existingFloor.style === 2 || existingFloor.style === 3 || existingFloor.style === 4)) {
       return
     }
+    const belongsToPreset = placedRects.some(r => x >= r.x && x < r.x + r.w && y >= r.y && y < r.y + r.h)
     if (cell.walls.some(w => !w.hidden && w.prop1 !== 0)) {
+      if (belongsToPreset) {
+        return
+      }
       if (clearStrayClutter) {
         // Clear random LvlSub bush/tree clutter on the main highway spine
         ;(cell.walls as Ds1Wall[]).length = 0
@@ -3508,7 +3512,7 @@ export function stampAct2DesertRoads(
         unknown2: 0,
         hidden: false,
       }),
-      isProtectedPreset: (name) => !/River|Bridge/i.test(name),
+      isProtectedPreset: (name) => name !== 'Act 1 - River',
       isIgnoredSpurPreset: (name) => /Fill|Berms/i.test(name),
     },
     openGates,
@@ -3564,7 +3568,7 @@ export function stampAct3KurastAvenues(
         unknown2: 0,
         hidden: false,
       }),
-      isProtectedPreset: (name) => !/River|Bridge/i.test(name),
+      isProtectedPreset: (name) => name !== 'Act 1 - River',
       isIgnoredSpurPreset: (name) => /Fill/i.test(name),
     },
     openGates,
@@ -3620,7 +3624,7 @@ export function stampAct5SnowRoads(
         unknown2: 0,
         hidden: false,
       }),
-      isProtectedPreset: (name) => !/River|Bridge/i.test(name),
+      isProtectedPreset: (name) => name !== 'Act 1 - River',
       isIgnoredSpurPreset: (name) => /Fill|Filler/i.test(name),
     },
     openGates,
@@ -5141,7 +5145,7 @@ export function generateWilderness(request: WildernessRequest): WildernessResult
     if (request.levelId === 83) {
       placedSpecial = stampAct3Travincal(canvas, request.pieces, stats, specialPlacedRects)
     } else if (request.levelId === 82) {
-      placedSpecial = stampAct3KurastCauseway(canvas, request.pieces, stats)
+      placedSpecial = stampAct3KurastCauseway(canvas, request.pieces, stats, specialPlacedRects)
     } else if (request.levelId >= 76 && request.levelId <= 78) {
       placedSpecial = stampAct3Jungle(canvas, request.levelId, request.pieces, rng, stats, specialPlacedRects)
       const populationRng = new Rng(request.seed ^ 0x6c07)

tests/wilderness-acts.test.ts

@@ -13,15 +13,21 @@ import type {
 } from '../src/game/wilderness-acts.ts'
 import type { Ds1, Ds1Cell } from '../src/formats/ds1.ts'
 
-function makeMockDs1(width: number, height: number, hasGapInWalls: boolean = false): Ds1 {
+function makeMockDs1(
+  width: number,
+  height: number,
+  hasGapInWalls: boolean = false,
+  floorStyle: number = 1,
+  wallStyle: number = 1,
+): Ds1 {
   const cells: Ds1Cell[][] = []
   for (let y = 0; y < height; y += 1) {
     const row: Ds1Cell[] = []
     for (let x = 0; x < width; x += 1) {
       const isGap = hasGapInWalls && x === Math.floor(width / 2)
       row.push({
-        walls: isGap ? [] : [{ prop1: 2, sequence: 0, style: 1, type: 0, unknown1: 0, unknown2: 0, hidden: false }],
+        walls: isGap ? [] : [{ prop1: 2, sequence: 0, style: wallStyle, type: 0, unknown1: 0, unknown2: 0, hidden: false }],
-        floors: [{ prop1: 2, sequence: 0, style: 1, unknown1: 0, unknown2: 0, hidden: false }],
+        floors: [{ prop1: 2, sequence: 0, style: floorStyle, unknown1: 0, unknown2: 0, hidden: false }],
         shadows: [],
         substitutions: [],
       })
@@ -231,9 +237,9 @@ describe('Wilderness Outdoor Initializers for Acts 2-5 (Issue #51)', () => {
     })
 
     test('Kurast Causeway (82) stamps causeway with central walkway, balustrades, and canal water', () => {
-      const bridgeDs1 = makeMockDs1(48, 16)
+      const groundDs1 = makeMockDs1(48, 16)
       const pieces: WildernessPiece[] = [
-        { name: 'Act 3 - Bridge', border: false, levels: [bridgeDs1] },
+        { name: 'Act 3 - Ground', border: false, levels: [groundDs1] },
       ]
 
       const result = generateWilderness({
@@ -271,6 +277,38 @@ describe('Wilderness Outdoor Initializers for Acts 2-5 (Issue #51)', () => {
       expect(foundCanalWater).toBe(true)
     })
 
+    test('Kurast Causeway (82) preserves preset when Act 3 - Bridge is provided', () => {
+      const bridgeDs1 = makeMockDs1(48, 16, false, 29, 31)
+      const pieces: WildernessPiece[] = [
+        { name: 'Act 3 - Bridge', border: false, levels: [bridgeDs1] },
+      ]
+
+      const result = generateWilderness({
+        levelId: 82,
+        levelName: 'Kurast Causeway',
+        levelTypeName: 'Act 3 - Kurast',
+        sizeX: 48,
+        sizeY: 16,
+        subType: 0,
+        subTheme: 0,
+        seed: 82001,
+        pieces,
+        substitutions: [],
+      })
+
+      let foundPresetFloor = false
+      let foundPresetWall = false
+      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 === 29)) foundPresetFloor = true
+          if (cell.walls.some(w => w.style === 31)) foundPresetWall = true
+        }
+      }
+      expect(foundPresetFloor).toBe(true)
+      expect(foundPresetWall).toBe(true)
+    })
+
     test('Kurast Bazaar (79) generates paved stone avenues, canals, and stone bridges', () => {
       const pieces = makeMockBorderPieces('Act 3')
       const result = generateWilderness({

tests/wilderness-roads-multi-act.test.ts

@@ -16,7 +16,7 @@ import {
 } from '../src/game/wilderness.ts'
 import type { WildernessPiece, PlacedPresetRect, Canvas } from '../src/game/wilderness.ts'
 import { Rng } from '../src/game/rng.ts'
-import type { Ds1, Ds1Cell } from '../src/formats/ds1.ts'
+import type { Ds1, Ds1Cell, Ds1Wall } from '../src/formats/ds1.ts'
 
 function makeMockDs1(width: number, height: number): Ds1 {
   const cells: Ds1Cell[][] = []
@@ -412,5 +412,33 @@ describe('Multi-Act Outdoor Roads & Boundary Divider Networks', () => {
       expect(roadFloors).toBe(0)
       expect(dividerWalls).toBe(0)
     })
+
+    it('stampThemedRoads preserves preset walls on the highway spine', () => {
+      const canvas = createCanvas(width, height, 1, 1, 0)
+      const rng = new Rng(42)
+      const hubX = inX * TILES_PER_BLOCK + 4
+      const hubY = outY * TILES_PER_BLOCK + 4
+      // Preset directly intersects the road spine
+      const placedRects: PlacedPresetRect[] = [
+        { name: 'Act 1 - Ruin', x: hubX - 2, y: hubY - 2, w: 5, h: 5 },
+      ]
+      // Paint preset wall inside the preset on the highway spine
+      const targetCell = canvas.cells[hubY]?.[hubX]
+      expect(targetCell).toBeDefined()
+      ;(targetCell!.walls as Ds1Wall[]).push({
+        prop1: 100,
+        sequence: 0,
+        style: 99,
+        type: 1,
+        unknown1: 0,
+        unknown2: 0,
+        hidden: false,
+      })
+
+      stampAct1DirtRoads(canvas, gridW, gridH, inX, outY, placedRects, rng)
+
+      // The wall inside the preset must NOT have been wiped
+      expect(targetCell!.walls.some(w => w.style === 99 && w.prop1 === 100)).toBe(true)
+    })
   })
 })