fix(game): import canonical SUB_TILES_PER_TILE and use dynamic bounds/stride in siege

- Import canonical SUB_TILES_PER_TILE from map.ts in maze-objects.ts and level-links.ts
- Replace hardcoded y < 6 || y > 42 bounds with dynamic canvas.height - 6 bounds in wilderness-siege.ts
- Replace static i * 16 stride assumption with dynamic ds1.width and canvas.width stride

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

src/game/level-links.ts

@@ -34,9 +34,7 @@
  */
 
 import type { Side } from './world-graph.ts'
-
-/** Sub-tiles per cell, matching `SUB_TILES_PER_TILE` in `map.ts`. */
-const SUB_TILES_PER_TILE = 5
+import { SUB_TILES_PER_TILE } from './map.ts'
 
 /**
  * How close the player must be to a border seam for it to fire, in sub-tiles.

src/game/maze-objects.ts

@@ -20,8 +20,10 @@
 import type { Ds1, Ds1Cell, Ds1Object } from '../formats/ds1.ts'
 import { Rng } from './rng.ts'
 
+import { SUB_TILES_PER_TILE } from './map.ts'
+
 /** Subtiles per DS1 cell. */
-export const SUB_TILES_PER_TILE = 5
+export { SUB_TILES_PER_TILE }
 
 /** Dynamic dungeon object categories. */
 export type MazeObjectCategory = 'shrine' | 'chest' | 'rack' | 'container'

src/game/wilderness-siege.ts

@@ -111,7 +111,7 @@ function stampTrench(
   if (orientation === 'vertical') {
     for (let dy = 0; dy < length; dy += 1) {
       const y = startY + dy
-      if (y < 6 || y > 42) continue
+      if (y < 6 || y > canvas.height - 6) continue
       for (let dx = 0; dx < width; dx += 1) {
         const x = startX + dx
         if (x < 4 || x >= canvas.width - 4) continue
@@ -133,7 +133,7 @@ function stampTrench(
       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
+        if (y < 6 || y > canvas.height - 6) continue
         setFloor(canvas, x, y, {
           style: 5,
           sequence: rng.int(0, 5),
@@ -169,7 +169,7 @@ function stampBreachedBarricade(
 
   for (let dy = 0; dy < length; dy += 1) {
     const y = startY + dy
-    if (y < 6 || y > 42) continue
+    if (y < 6 || y > canvas.height - 6) continue
 
     if (y >= breachY && y < breachY + breachHeight) {
       // Traversable breach gap: clear walls and trample floor
@@ -226,7 +226,7 @@ function stampCatapultPlatform(
 ): void {
   for (let dy = 0; dy < height; dy += 1) {
     const y = originY + dy
-    if (y < 6 || y > 42) continue
+    if (y < 6 || y > canvas.height - 6) continue
     for (let dx = 0; dx < width; dx += 1) {
       const x = originX + dx
       if (x < 4 || x >= canvas.width - 4) continue
@@ -273,7 +273,7 @@ function stampFortRuin(
 ): void {
   for (let dy = 0; dy < size; dy += 1) {
     const y = originY + dy
-    if (y < 6 || y > 42) continue
+    if (y < 6 || y > canvas.height - 6) continue
     for (let dx = 0; dx < size; dx += 1) {
       const x = originX + dx
       if (x < 4 || x >= canvas.width - 4) continue
@@ -371,12 +371,25 @@ export function stampAct5SiegeStrips(
   const placed = new Set<string>()
 
   // 1. Assemble 15 strips West (x=0) to East (x=224)
+  const dynamicStripStride = canvas.width > 0
+    ? Math.floor(canvas.width / ACT5_SIEGE_STRIP_NAMES.length)
+    : 16
+  let currentX = 0
   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
+    if (!selection) {
+      currentX += dynamicStripStride
+      continue
+    }
 
-    stampDs1(canvas, selection.ds1, i * 16, 0)
+    // DS1 tiles often include a +1 border overlap column (e.g. 17 width for 16 stride)
+    const ds1Width = selection.ds1.width
+    const stripStride = ds1Width > 0
+      ? (ds1Width % 16 === 1 ? ds1Width - 1 : ds1Width)
+      : dynamicStripStride
+    stampDs1(canvas, selection.ds1, currentX, 0)
+    currentX += stripStride
     placed.add(selection.piece.name)
     stats.substitutions.push({
       name: selection.piece.name,