fix(maze): use PRNG stream in special passes and fix Act 5 temple NE waypoint generation

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

src/game/maze-special-passes.ts

@@ -15,6 +15,7 @@
  * - `DRLGMAZE_ScanReplaceSpecialAct2SewersPresets`: Lut Gholein Sewers (Radament's Lair & Atma's quest).
  */
 
+import { Rng } from './rng.ts'
 import {
   DIRECTION_WEST,
   DIRECTION_NORTH,
@@ -56,6 +57,11 @@ export interface SpecialPassContext {
   readonly pieces: readonly MazePiece[]
   readonly index: PieceIndex
   readonly stats: MazeStats
+  readonly rng?: Rng
+}
+
+function getPassRng(ctx: SpecialPassContext): Rng {
+  return ctx.rng ?? ctx.level?.rng ?? new Rng(ctx.request.seed)
 }
 
 const DIRS = ['N', 'E', 'S', 'W'] as const
@@ -189,6 +195,7 @@ export function placeNamedPiece(
  * Horadric Cube chest, Leatherarm, and staircases.
  */
 export function placeAct2TombStuff(ctx: SpecialPassContext): void {
+  const rng = getPassRng(ctx)
   const levelId = ctx.request.levelId
   const staffTomb = ctx.request.staffTombLevelId ?? 66
   const bossTomb = ctx.request.bossTombLevelId
@@ -202,9 +209,9 @@ export function placeAct2TombStuff(ctx: SpecialPassContext): void {
     else if (name.includes('NEW')) nDirection = 1
     else if (name.includes('NSE')) nDirection = 2
     else if (name.includes('SEW')) nDirection = 3
-    else nDirection = ctx.request.seed % 4
+    else nDirection = rng.int(0, 3)
   } else {
-    nDirection = ctx.request.seed % 4
+    nDirection = rng.int(0, 3)
   }
 
   const GROW_DIRS = [DIRECTION_SOUTH, DIRECTION_WEST, DIRECTION_NORTH, DIRECTION_EAST]
@@ -279,6 +286,7 @@ export function placeAct2TombStuff(ctx: SpecialPassContext): void {
  * Level 3 places Coldworm the Burrower (Tight Spot S) and the Staff of Kings chest (Treasure W).
  */
 export function placeAct2LairStuff(ctx: SpecialPassContext): void {
+  const rng = getPassRng(ctx)
   const levelId = ctx.request.levelId
 
   if (levelId === 64) {
@@ -309,7 +317,7 @@ export function placeAct2LairStuff(ctx: SpecialPassContext): void {
       preferFurthest: false,
     })
   } else {
-    const nRand = ctx.request.seed % 4
+    const nRand = rng.int(0, 3)
     placeNamedPiece(ctx, {
       kind: 'next',
       namePrefix: 'Act 2 - Lair Next',
@@ -339,8 +347,9 @@ export function placeAct2LairStuff(ctx: SpecialPassContext): void {
  * Temples (levels 94..99) place Lam Esen's Tome altar.
  */
 export function placeAct3DungeonStuff(ctx: SpecialPassContext): void {
+  const rng = getPassRng(ctx)
   const levelId = ctx.request.levelId
-  const nDirection = ctx.request.seed % 4
+  const nDirection = rng.int(0, 3)
 
   if (levelId === 91) {
     // Flayer Dungeon Level 3: Khalim's Brain chest
@@ -404,8 +413,9 @@ export function placeAct3DungeonStuff(ctx: SpecialPassContext): void {
  * Level 1 places the drain descent lever and staircase down to Level 2.
  */
 export function placeAct3SewerStuff(ctx: SpecialPassContext): void {
+  const rng = getPassRng(ctx)
   const levelId = ctx.request.levelId
-  const nDirection = ctx.request.seed % 4
+  const nDirection = rng.int(0, 3)
 
   if (levelId === 92) {
     // Sewer Level 1: Drain lever / stairs down to Sewer 2
@@ -454,8 +464,9 @@ export function placeAct3SewerStuff(ctx: SpecialPassContext): void {
  * Level 2 places Waypoint, Next and Prev.
  */
 export function placeAct3MephistoStuff(ctx: SpecialPassContext): void {
+  const rng = getPassRng(ctx)
   const levelId = ctx.request.levelId
-  const nRand = ctx.request.seed % 4
+  const nRand = rng.int(0, 3)
 
   if (levelId === 102) {
     // Durance of Hate Level 3: Mephisto Complex
@@ -526,6 +537,7 @@ export function placeAct3MephistoStuff(ctx: SpecialPassContext): void {
  * Halls of Pain (level 123) places Waypoint and descent stairs.
  */
 export function placeAct5TempleStuff(ctx: SpecialPassContext): void {
+  const rng = getPassRng(ctx)
   const levelId = ctx.request.levelId
 
   if (levelId === 124) {
@@ -547,7 +559,7 @@ export function placeAct5TempleStuff(ctx: SpecialPassContext): void {
   } else {
     // Levels 122 and 123
     const templeDownDirs = ['NE', 'NW', 'SW']
-    const nDirection = (ctx.request.seed >>> 0) % 3
+    const nDirection = rng.int(0, templeDownDirs.length - 1)
     const downSide = templeDownDirs[nDirection]!
 
     placeNamedPiece(ctx, {
@@ -560,7 +572,7 @@ export function placeAct5TempleStuff(ctx: SpecialPassContext): void {
 
     if (levelId === 123) {
       const templeWaypointDirs = ['NE', 'NW', 'SW', 'SE']
-      const wpSide = templeWaypointDirs[(nDirection + 1) % 4]!
+      const wpSide = templeWaypointDirs[rng.int(0, templeWaypointDirs.length - 1)]!
       placeNamedPiece(ctx, {
         kind: 'waypoint',
         name: `Act 5 - Temple ${wpSide} Waypoint`,
@@ -591,8 +603,9 @@ export function placeAct5TempleStuff(ctx: SpecialPassContext): void {
  * Worldstone Keep 2 places Waypoint and Next stairs.
  */
 export function placeAct5BaalStuff(ctx: SpecialPassContext): void {
+  const rng = getPassRng(ctx)
   const levelId = ctx.request.levelId
-  const nDirection = ctx.request.seed % 4
+  const nDirection = rng.int(0, 3)
 
   if (levelId === 131) {
     // Throne of Destruction
@@ -657,11 +670,12 @@ export function placeAct5BaalStuff(ctx: SpecialPassContext): void {
  * Glacial Trail (115) places Theme and Waypoint.
  */
 export function placeAct5IceStuff(ctx: SpecialPassContext): void {
+  const rng = getPassRng(ctx)
   const levelId = ctx.request.levelId
 
   if (levelId === 114) {
     // Frozen River (Anya platform)
-    const variant = (ctx.request.seed % 2) === 0 ? 'A' : 'B'
+    const variant = rng.int(0, 1) === 0 ? 'A' : 'B'
     if (ctx.level.rooms.length === 1 && ctx.level.first !== null) {
       const riverPiece = ctx.pieces.find(p => p.name === `Act 5 - Ice River ${variant}`)
         ?? ctx.pieces.find(p => p.name.startsWith('Act 5 - Ice River'))
@@ -701,7 +715,7 @@ export function placeAct5IceStuff(ctx: SpecialPassContext): void {
     placeNamedPiece(ctx, { kind: 'quest', name: 'Act 5 - Ice Pool B', preferFurthest: true })
   } else {
     // Levels 113, 115, 118
-    let nDirection = ctx.request.seed % 4
+    let nDirection = rng.int(0, 3)
     placeNamedPiece(ctx, {
       kind: 'prev',
       namePrefix: 'Act 5 - Ice Prev',
@@ -760,6 +774,7 @@ export function placeAct5IceStuff(ctx: SpecialPassContext): void {
  * Places Court Connect, the Smith / Charsi's Malus forge, and stairs to Jail.
  */
 export function placeAct1Barracks(ctx: SpecialPassContext): void {
+  const rng = getPassRng(ctx)
   // Connect towards Outer Cloister
   placeNamedPiece(ctx, {
     kind: 'prev',
@@ -768,8 +783,8 @@ export function placeAct1Barracks(ctx: SpecialPassContext): void {
     preferFurthest: false,
   })
 
-  const nDirection = ctx.request.seed % 4
+  const nDirection = rng.int(0, 3)
-  const roll = (ctx.request.seed >>> 2) % 2
+  const roll = rng.int(0, 1)
 
   if (roll === 1) {
     placeNamedPiece(ctx, {
@@ -815,6 +830,7 @@ export function placeAct1Barracks(ctx: SpecialPassContext): void {
  * Hephasto the Armorer / Hellforge, and fills blanks with Lava X.
  */
 export function placeAct4Lava(ctx: SpecialPassContext): void {
+  const rng = getPassRng(ctx)
   // 1. Warp N (entrance from City of Damned)
   placeNamedPiece(ctx, {
     kind: 'prev',
@@ -840,7 +856,7 @@ export function placeAct4Lava(ctx: SpecialPassContext): void {
   })
 
   // 3. Hellforge (Hephasto the Armorer)
-  const forgeSide = (ctx.request.seed % 2) === 0 ? 'W' : 'E'
+  const forgeSide = rng.int(0, 1) === 0 ? 'W' : 'E'
   placeNamedPiece(ctx, {
     kind: 'quest',
     name: `Act 4 - Lava Forge ${forgeSide}`,
@@ -865,8 +881,9 @@ export function placeAct4Lava(ctx: SpecialPassContext): void {
  * Ancient Tunnels (level 50) places Chest and Prev.
  */
 export function scanReplaceSpecialAct2SewersPresets(ctx: SpecialPassContext): void {
+  const rng = getPassRng(ctx)
   const levelId = ctx.request.levelId
-  let nRand = ctx.request.seed % 4
+  let nRand = rng.int(0, 3)
 
   if (levelId === 49) {
     // Sewers Level 3: Radament's Lair

src/game/maze.ts

@@ -2271,6 +2271,7 @@ export function generateMaze(request: MazeRequest): MazeResult {
         pieces: request.pieces,
         index,
         stats,
+        rng,
       })
     }
   }

tests/maze-special-passes.test.ts

@@ -511,6 +511,33 @@ describe('Diablo II DRLG Maze Special Passes', () => {
       const specials = res.stats.specialsApplied as { room: number; kind: string; sides: string }[]
       expect(specials.some(s => s.kind === 'waypoint')).toBe(true)
     })
+
+    test('Halls of Pain (level 123): generates all 4 waypoint directions including NE across seeds', () => {
+      const pieces = createStandardPieceSet('Act 5 - Temple', templeExtraPieces)
+      const observedDirs = new Set<string>()
+
+      for (let seed = 1; seed <= 50; seed++) {
+        const res = generateMaze({
+          levelId: 123,
+          levelName: 'Halls of Pain',
+          sectionSize: 10,
+          minRooms: 5,
+          merge: 500,
+          seed,
+          pieces,
+        })
+        const specials = res.stats.specialsApplied as { room: number; kind: string; sides: string }[]
+        const wp = specials.find(s => s.kind === 'waypoint')
+        if (wp !== undefined) {
+          observedDirs.add(wp.sides)
+        }
+      }
+
+      expect(observedDirs).toContain('NE')
+      expect(observedDirs).toContain('NW')
+      expect(observedDirs).toContain('SW')
+      expect(observedDirs).toContain('SE')
+    })
   })
 
   /* ----------------------------------------------------------------------- *