Merge pull request '✨ Demolish Mode — Gebäude abreißen (Issue #50)' (#55) from feature/demolish-buildings into master

- New 💥 Demolish button in the action bar
- Red ghost highlights building footprint on hover
- Refund: 100% within 3 min, decays linearly to 0%
- Mine teardown unblocks passability tiles and removes status label
- Nisse inside demolished mine are rescued and reset to idle
- Floor/wall/chest tiles restored to GRASS on demolish
- Build error now shows missing resources instead of generic message
- BuildingState gains builtAt field; old saves default to 0 (no refund)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CHANGELOG.md

@@ -8,6 +8,7 @@ Format follows [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ## [Unreleased]
 
 ### Added
+- **Demolish Mode** (Issue #50): New 💥 Demolish button in the action bar; hover shows a red ghost over any building with a refund percentage; buildings demolished within 3 minutes return 100% of costs (linear decay to 0%); mine footprint tiles are unblocked on teardown; Nisse working inside a demolished building are rescued and resume idle; tile types are restored where applicable (floor/wall/chest → grass)
 - **Mine Building** (Issue #42): 3×2 building placeable only on resource-free ROCK tiles (costs: 200 wood + 50 stone); Nisse with mine priority walk to the entrance, disappear inside for 15 s, then reappear carrying 2 stone; up to 3 Nisse work simultaneously; ⛏ X/3 status label shown directly on the building in world space; surface rock harvesting remains functional alongside the building
 
 ### Fixed

src/StateManager.ts

@@ -233,7 +233,7 @@ class StateManager {
         w.tiles[action.tileY * WORLD_TILES + action.tileX] = action.tile; break
 
       case 'PLACE_BUILDING': {
-        w.buildings[action.building.id] = action.building
+        w.buildings[action.building.id] = { ...action.building, builtAt: w.gameTime }
         for (const [k, v] of Object.entries(action.costs))
           w.stockpile[k as ItemId] = Math.max(0, (w.stockpile[k as ItemId] ?? 0) - (v ?? 0))
         if (action.building.kind === 'forester_hut') {
@@ -415,6 +415,8 @@ class StateManager {
         if (b.kind === 'forester_hut' && !p.world.foresterZones[b.id]) {
           p.world.foresterZones[b.id] = { buildingId: b.id, tiles: [] }
         }
+        // Migrate buildings without builtAt (pre-demolish saves): set to 0 = no refund
+        if (typeof (b as any).builtAt === 'undefined') (b as any).builtAt = 0
       }
       return p
     } catch (_) { return null }

src/config.ts

@@ -61,6 +61,9 @@ export const VILLAGER_NAMES = [
   'Orla','Pike','Quinn','Rook','Sera','Tull','Uma','Vex',
 ]
 
+/** Milliseconds after placement during which demolishing gives a full refund (linearly decays to 0%). */
+export const DEMOLISH_REFUND_MS = 180_000   // 3 minutes
+
 export const SAVE_KEY = 'tg_save_v5'
 export const AUTOSAVE_INTERVAL = 30_000
 

src/scenes/GameScene.ts

@@ -64,6 +64,31 @@ export class GameScene extends Phaser.Scene {
       this.events.emit('toast', msg)
       this.renderPersistentObjects()
     }
+    this.buildingSystem.onDemolishModeChange = (active) => this.events.emit('demolishModeChanged', active)
+    this.buildingSystem.onDemolished = (building, refund) => {
+      // Remove the building sprite
+      this.children.getByName(`bobj_${building.id}`)?.destroy()
+
+      // Mine-specific cleanup: unblock the 5 passability tiles and remove status label
+      if (building.kind === 'mine') {
+        for (let dy = 0; dy < 2; dy++) {
+          for (let dx = 0; dx < 3; dx++) {
+            if (dx === 1 && dy === 1) continue  // entrance tile was never blocked
+            this.worldSystem.removeResourceTile(building.tileX + dx, building.tileY + dy)
+          }
+        }
+        this.mineStatusTexts.get(building.id)?.destroy()
+        this.mineStatusTexts.delete(building.id)
+      }
+
+      // Rescue any Nisse working in or walking to this building
+      this.villagerSystem.rescueNisseFromBuilding(building.id)
+
+      const refundMsg = Object.keys(refund).length
+        ? ` (+${Object.entries(refund).map(([k, v]) => `${v} ${k}`).join(', ')})`
+        : ' (no refund)'
+      this.events.emit('toast', `Demolished ${building.kind}${refundMsg}`)
+    }
 
     this.farmingSystem.create()
     this.farmingSystem.onMessage     = (msg)         => this.events.emit('toast', msg)
@@ -102,7 +127,7 @@ export class GameScene extends Phaser.Scene {
     // Detect left-clicks on forester huts to open the zone panel
     this.input.on('pointerdown', (ptr: Phaser.Input.Pointer) => {
       if (ptr.rightButtonDown() || this.menuOpen) return
-      if (this.buildingSystem.isActive()) return
+      if (this.buildingSystem.isActive() || this.buildingSystem.isDemolishActive()) return
       const tileX = Math.floor(ptr.worldX / TILE_SIZE)
       const tileY = Math.floor(ptr.worldY / TILE_SIZE)
       const state = stateManager.getState()
@@ -116,7 +141,9 @@ export class GameScene extends Phaser.Scene {
 
     this.scene.launch('UI')
 
-    this.events.on('selectBuilding', (kind: BuildingType) => this.buildingSystem.selectBuilding(kind))
+    this.events.on('selectBuilding',    (kind: BuildingType) => this.buildingSystem.selectBuilding(kind))
+    this.events.on('activateDemolish',  () => this.buildingSystem.activateDemolish())
+    this.events.on('deactivateDemolish', () => this.buildingSystem.deactivateDemolish())
     this.events.on('uiMenuOpen',  () => { this.menuOpen = true })
     this.events.on('uiMenuClose', () => { this.menuOpen = false })
     this.events.on('uiRequestBuildMenu', () => {

src/scenes/UIScene.ts

@@ -67,9 +67,11 @@ export class UIScene extends Phaser.Scene {
   private actionBuildLabel!: Phaser.GameObjects.Text
   private actionNisseBtn!: Phaser.GameObjects.Rectangle
   private actionNisseLabel!: Phaser.GameObjects.Text
+  private actionDemolishBtn!: Phaser.GameObjects.Rectangle
+  private actionDemolishLabel!: Phaser.GameObjects.Text
   private actionTrayGroup!: Phaser.GameObjects.Group
   private actionTrayVisible = false
-  private activeCategory: 'build' | 'nisse' | null = null
+  private activeCategory: 'build' | 'nisse' | 'demolish' | null = null
 
   constructor() { super({ key: 'UI' }) }
 
@@ -89,10 +91,16 @@ export class UIScene extends Phaser.Scene {
     this.createActionBar()
 
     const gameScene = this.scene.get('Game')
-    gameScene.events.on('buildModeChanged', (a: boolean, b: BuildingType) => this.onBuildModeChanged(a, b))
-    gameScene.events.on('farmToolChanged',  (t: FarmingTool, l: string) => this.onFarmToolChanged(t, l))
-    gameScene.events.on('toast',            (m: string) => this.showToast(m))
-    gameScene.events.on('openBuildMenu',    () => this.toggleBuildMenu())
+    gameScene.events.on('buildModeChanged',   (a: boolean, b: BuildingType) => this.onBuildModeChanged(a, b))
+    gameScene.events.on('farmToolChanged',    (t: FarmingTool, l: string) => this.onFarmToolChanged(t, l))
+    gameScene.events.on('toast',              (m: string) => this.showToast(m))
+    gameScene.events.on('openBuildMenu',      () => this.toggleBuildMenu())
+    gameScene.events.on('demolishModeChanged', (active: boolean) => {
+      if (!active && this.activeCategory === 'demolish') {
+        this.activeCategory = null
+        this.updateCategoryHighlights()
+      }
+    })
 
     this.input.keyboard!.addKey(Phaser.Input.Keyboard.KeyCodes.B)
       .on('down', () => gameScene.events.emit('uiRequestBuildMenu'))
@@ -563,9 +571,9 @@ export class UIScene extends Phaser.Scene {
     if (this.nisseInfoVisible)     { this.closeNisseInfoPanel();                      return }
     if (this.settingsVisible)      { this.closeSettings();                            return }
     if (this.escMenuVisible)       { this.closeEscMenu();                             return }
-    // Build/farm mode: let BuildingSystem / FarmingSystem handle their own ESC key.
-    // We only skip opening the ESC menu while those modes are active.
+    // Build/farm/demolish mode: let their systems handle ESC. Skip opening the ESC menu.
     if (this.inBuildMode || this.inFarmMode) return
+    if (this.activeCategory === 'demolish') { this.deactivateCategory(); return }
     this.openEscMenu()
   }
 
@@ -1215,14 +1223,28 @@ export class UIScene extends Phaser.Scene {
     this.actionNisseLabel = this.add.text(148, barY + UIScene.BAR_H / 2, '👥 Nisse', {
       fontSize: '12px', color: '#cccccc', fontFamily: 'monospace',
     }).setOrigin(0.5, 0.5).setScrollFactor(0).setDepth(302)
+
+    this.actionDemolishBtn = this.add.rectangle(200, barY + 8, 88, 32, 0x3a1a1a, this.uiOpacity)
+      .setOrigin(0, 0).setScrollFactor(0).setDepth(301).setInteractive()
+    this.actionDemolishBtn.on('pointerover', () => {
+      if (this.activeCategory !== 'demolish') this.actionDemolishBtn.setFillStyle(0x5a2a2a, this.uiOpacity)
+    })
+    this.actionDemolishBtn.on('pointerout', () => {
+      if (this.activeCategory !== 'demolish') this.actionDemolishBtn.setFillStyle(0x3a1a1a, this.uiOpacity)
+    })
+    this.actionDemolishBtn.on('pointerdown', () => this.toggleCategory('demolish'))
+
+    this.actionDemolishLabel = this.add.text(244, barY + UIScene.BAR_H / 2, '💥 Demolish', {
+      fontSize: '12px', color: '#cccccc', fontFamily: 'monospace',
+    }).setOrigin(0.5, 0.5).setScrollFactor(0).setDepth(302)
   }
 
   /**
    * Toggles the given action bar category on or off.
    * Selecting the active category deselects it; selecting a new one closes the previous.
-   * @param cat - The category to toggle ('build' or 'nisse')
+   * @param cat - The category to toggle
    */
-  private toggleCategory(cat: 'build' | 'nisse'): void {
+  private toggleCategory(cat: 'build' | 'nisse' | 'demolish'): void {
     if (this.activeCategory === cat) {
       this.deactivateCategory()
       return
@@ -1230,14 +1252,17 @@ export class UIScene extends Phaser.Scene {
     // Close whatever was open before
     if (this.activeCategory === 'build') this.closeActionTray()
     if (this.activeCategory === 'nisse' && this.villagerPanelVisible) this.closeVillagerPanel()
+    if (this.activeCategory === 'demolish') this.scene.get('Game').events.emit('deactivateDemolish')
 
     this.activeCategory = cat
     this.updateCategoryHighlights()
 
     if (cat === 'build') {
       this.openActionTray()
-    } else {
+    } else if (cat === 'nisse') {
       this.openVillagerPanel()
+    } else {
+      this.scene.get('Game').events.emit('activateDemolish')
     }
   }
 
@@ -1247,17 +1272,19 @@ export class UIScene extends Phaser.Scene {
   private deactivateCategory(): void {
     if (this.activeCategory === 'build') this.closeActionTray()
     if (this.activeCategory === 'nisse' && this.villagerPanelVisible) this.closeVillagerPanel()
+    if (this.activeCategory === 'demolish') this.scene.get('Game').events.emit('deactivateDemolish')
     this.activeCategory = null
     this.updateCategoryHighlights()
   }
 
   /**
-   * Updates the visual highlight of the Build and Nisse buttons
+   * Updates the visual highlight of the Build, Nisse, and Demolish buttons
    * to reflect the current active category.
    */
   private updateCategoryHighlights(): void {
     this.actionBuildBtn.setFillStyle(this.activeCategory === 'build' ? 0x3d7a3d : 0x1a3a1a, this.uiOpacity)
     this.actionNisseBtn.setFillStyle(this.activeCategory === 'nisse' ? 0x3d3d7a : 0x1a1a3a, this.uiOpacity)
+    this.actionDemolishBtn.setFillStyle(this.activeCategory === 'demolish' ? 0x7a3d3d : 0x3a1a1a, this.uiOpacity)
   }
 
   /**
@@ -1352,7 +1379,9 @@ export class UIScene extends Phaser.Scene {
     this.actionBuildBtn.setPosition(8,   height - UIScene.BAR_H + 8)
     this.actionBuildLabel.setPosition(48, height - UIScene.BAR_H + UIScene.BAR_H / 2)
     this.actionNisseBtn.setPosition(104, height - UIScene.BAR_H + 8)
-    this.actionNisseLabel.setPosition(144, height - UIScene.BAR_H + UIScene.BAR_H / 2)
+    this.actionNisseLabel.setPosition(148, height - UIScene.BAR_H + UIScene.BAR_H / 2)
+    this.actionDemolishBtn.setPosition(200, height - UIScene.BAR_H + 8)
+    this.actionDemolishLabel.setPosition(244, height - UIScene.BAR_H + UIScene.BAR_H / 2)
     if (this.actionTrayVisible) this.closeActionTray()
     // Close centered panels — their position is calculated on open, so they
     // would be off-center if left open during a resize

src/systems/BuildingSystem.ts

@@ -1,7 +1,7 @@
 import Phaser from 'phaser'
-import { TILE_SIZE, BUILDING_COSTS } from '../config'
+import { TILE_SIZE, BUILDING_COSTS, DEMOLISH_REFUND_MS } from '../config'
 import { TileType, IMPASSABLE } from '../types'
-import type { BuildingType, BuildingState } from '../types'
+import type { BuildingType, BuildingState, ItemId } from '../types'
 import { stateManager } from '../StateManager'
 import type { LocalAdapter } from '../NetworkAdapter'
 
@@ -12,10 +12,18 @@ const BUILDING_TILE: Partial<Record<BuildingType, TileType>> = {
   // bed and stockpile_zone do NOT change the underlying tile
 }
 
+/** Tile type to restore when a building that changed its tile is demolished. */
+const DEMOLISH_RESTORE_TILE: Partial<Record<BuildingType, TileType>> = {
+  floor: TileType.GRASS,
+  wall:  TileType.GRASS,
+  chest: TileType.GRASS,
+}
+
 export class BuildingSystem {
   private scene: Phaser.Scene
   private adapter: LocalAdapter
   private active = false
+  private demolishActive = false
   private selectedBuilding: BuildingType = 'floor'
   private ghost!: Phaser.GameObjects.Rectangle
   private ghostLabel!: Phaser.GameObjects.Text
@@ -24,12 +32,23 @@ export class BuildingSystem {
 
   onModeChange?: (active: boolean, building: BuildingType) => void
   onPlaced?: (msg: string) => void
+  onDemolishModeChange?: (active: boolean) => void
+  /**
+   * Called after a building is demolished with the removed building data and the refund items.
+   * @param building - The BuildingState that was removed
+   * @param refund   - Items returned to stockpile
+   */
+  onDemolished?: (building: BuildingState, refund: Partial<Record<ItemId, number>>) => void
 
   constructor(scene: Phaser.Scene, adapter: LocalAdapter) {
     this.scene = scene
     this.adapter = adapter
   }
 
+  /**
+   * Initialises ghost sprite, label, and keyboard/pointer handlers for
+   * both build mode and demolish mode.
+   */
   create(): void {
     this.ghost = this.scene.add.rectangle(0, 0, TILE_SIZE, TILE_SIZE, 0x00FF00, 0.35)
     this.ghost.setDepth(1000)
@@ -47,14 +66,15 @@ export class BuildingSystem {
     this.buildKey  = this.scene.input.keyboard!.addKey(Phaser.Input.Keyboard.KeyCodes.B)
     this.cancelKey = this.scene.input.keyboard!.addKey(Phaser.Input.Keyboard.KeyCodes.ESC)
 
-    // Click to place
+    // Click to place (build mode) or demolish (demolish mode)
     this.scene.input.on('pointerdown', (ptr: Phaser.Input.Pointer) => {
-      if (!this.active) return
       if (ptr.rightButtonDown()) {
-        this.deactivate()
+        if (this.active) this.deactivate()
+        if (this.demolishActive) this.deactivateDemolish()
         return
       }
-      this.tryPlace(ptr)
+      if (this.active) this.tryPlace(ptr)
+      else if (this.demolishActive) this.tryDemolish(ptr)
     })
   }
 
@@ -85,8 +105,22 @@ export class BuildingSystem {
     return [{ tileX: b.tileX, tileY: b.tileY }]
   }
 
+  /**
+   * Finds the building whose footprint contains the given tile, if any.
+   * @param tileX - Tile column to check
+   * @param tileY - Tile row to check
+   * @returns The matching BuildingState, or undefined
+   */
+  private findBuildingAtTile(tileX: number, tileY: number): BuildingState | undefined {
+    const buildings = Object.values(stateManager.getState().world.buildings)
+    return buildings.find(b =>
+      this.getBuildingFootprintTiles(b).some(t => t.tileX === tileX && t.tileY === tileY)
+    )
+  }
+
   /** Select a building type and activate build mode */
   selectBuilding(kind: BuildingType): void {
+    if (this.demolishActive) this.deactivateDemolish()
     this.selectedBuilding = kind
     const { w, h } = this.getFootprint(kind)
     this.ghost.setSize(w * TILE_SIZE, h * TILE_SIZE)
@@ -109,6 +143,37 @@ export class BuildingSystem {
 
   isActive(): boolean { return this.active }
 
+  /**
+   * Activates demolish mode. Deactivates build mode if currently active.
+   * In demolish mode the ghost turns red and clicking a building removes it.
+   */
+  activateDemolish(): void {
+    if (this.active) this.deactivate()
+    this.demolishActive = true
+    this.ghost.setSize(TILE_SIZE, TILE_SIZE)
+    this.ghost.setFillStyle(0xFF2222, 0.35)
+    this.ghost.setStrokeStyle(2, 0xFF2222, 0.9)
+    this.ghost.setVisible(true)
+    this.ghostLabel.setVisible(true)
+    this.onDemolishModeChange?.(true)
+  }
+
+  /**
+   * Deactivates demolish mode and hides the ghost.
+   */
+  deactivateDemolish(): void {
+    this.demolishActive = false
+    this.ghost.setVisible(false)
+    this.ghostLabel.setVisible(false)
+    this.onDemolishModeChange?.(false)
+  }
+
+  /** Returns true if demolish mode is currently active. */
+  isDemolishActive(): boolean { return this.demolishActive }
+
+  /**
+   * Updates ghost position and label each frame for both build and demolish modes.
+   */
   update(): void {
     if (Phaser.Input.Keyboard.JustDown(this.buildKey)) {
       if (this.active) this.deactivate()
@@ -116,16 +181,23 @@ export class BuildingSystem {
     }
     if (Phaser.Input.Keyboard.JustDown(this.cancelKey)) {
       this.deactivate()
+      this.deactivateDemolish()
     }
 
-    if (!this.active) return
+    if (this.active) {
+      this.updateBuildGhost()
+    } else if (this.demolishActive) {
+      this.updateDemolishGhost()
+    }
+  }
 
-    // Update ghost to follow mouse (snapped to tile grid)
+  /**
+   * Updates the green/red build-mode ghost to follow the mouse, snapped to the tile grid.
+   */
+  private updateBuildGhost(): void {
     const ptr    = this.scene.input.activePointer
-    const worldX = ptr.worldX
-    const worldY = ptr.worldY
-    const tileX = Math.floor(worldX / TILE_SIZE)
-    const tileY = Math.floor(worldY / TILE_SIZE)
+    const tileX = Math.floor(ptr.worldX / TILE_SIZE)
+    const tileY = Math.floor(ptr.worldY / TILE_SIZE)
     const { w, h } = this.getFootprint(this.selectedBuilding)
     const snapX = tileX * TILE_SIZE + (w * TILE_SIZE) / 2
     const snapY = tileY * TILE_SIZE + (h * TILE_SIZE) / 2
@@ -133,7 +205,6 @@ export class BuildingSystem {
     this.ghost.setPosition(snapX, snapY)
     this.ghostLabel.setPosition(snapX, snapY - (h * TILE_SIZE) / 2 - 2)
 
-    // Color ghost based on can-build
     const canBuild = this.canBuildAt(tileX, tileY)
     const color = canBuild ? 0x00FF00 : 0xFF4444
     this.ghost.setFillStyle(color, 0.35)
@@ -144,6 +215,55 @@ export class BuildingSystem {
     this.ghostLabel.setText(`${this.selectedBuilding} [${costStr}]`)
   }
 
+  /**
+   * Updates the red demolish ghost to follow the mouse. Highlights the hovered building's
+   * footprint and shows the refund percentage in the label.
+   */
+  private updateDemolishGhost(): void {
+    const ptr   = this.scene.input.activePointer
+    const tileX = Math.floor(ptr.worldX / TILE_SIZE)
+    const tileY = Math.floor(ptr.worldY / TILE_SIZE)
+
+    const building = this.findBuildingAtTile(tileX, tileY)
+    if (building) {
+      const { w, h } = this.getFootprint(building.kind)
+      const snapX = building.tileX * TILE_SIZE + (w * TILE_SIZE) / 2
+      const snapY = building.tileY * TILE_SIZE + (h * TILE_SIZE) / 2
+      this.ghost.setSize(w * TILE_SIZE, h * TILE_SIZE)
+      this.ghost.setPosition(snapX, snapY)
+      this.ghostLabel.setPosition(snapX, snapY - (h * TILE_SIZE) / 2 - 2)
+      this.ghost.setFillStyle(0xFF2222, 0.45)
+      this.ghost.setStrokeStyle(2, 0xFF2222, 1)
+
+      const refundPct = this.calcRefundPct(building)
+      const label = refundPct > 0
+        ? `${building.kind} [refund ${Math.round(refundPct * 100)}%]`
+        : `${building.kind} [no refund]`
+      this.ghostLabel.setText(label)
+    } else {
+      // No building under cursor — small neutral ghost
+      const snapX = tileX * TILE_SIZE + TILE_SIZE / 2
+      const snapY = tileY * TILE_SIZE + TILE_SIZE / 2
+      this.ghost.setSize(TILE_SIZE, TILE_SIZE)
+      this.ghost.setPosition(snapX, snapY)
+      this.ghostLabel.setPosition(snapX, snapY - TILE_SIZE / 2 - 2)
+      this.ghost.setFillStyle(0x444444, 0.2)
+      this.ghost.setStrokeStyle(1, 0x666666, 0.5)
+      this.ghostLabel.setText('')
+    }
+  }
+
+  /**
+   * Calculates the refund fraction (0–1) for a building based on how long ago it was built.
+   * Returns 1.0 within the first 3 minutes, decaying linearly to 0.
+   * @param building - The building to evaluate
+   * @returns Refund fraction between 0 and 1
+   */
+  private calcRefundPct(building: BuildingState): number {
+    const elapsed = stateManager.getGameTime() - (building.builtAt ?? 0)
+    return Math.max(0, 1 - elapsed / DEMOLISH_REFUND_MS)
+  }
+
   private canBuildAt(tileX: number, tileY: number): boolean {
     const state = stateManager.getState()
 
@@ -217,17 +337,19 @@ export class BuildingSystem {
     const tileY = Math.floor(worldY / TILE_SIZE)
 
     if (!this.canBuildAt(tileX, tileY)) {
-      this.onPlaced?.('Cannot build here!')
+      const missing = this.getMissingResources(tileX, tileY)
+      this.onPlaced?.(missing.length ? `Need: ${missing}` : 'Cannot build here!')
       return
     }
 
     const costs = BUILDING_COSTS[this.selectedBuilding] ?? {}
-    const building = {
+    const building: BuildingState = {
       id: `building_${tileX}_${tileY}_${Date.now()}`,
       tileX,
       tileY,
       kind: this.selectedBuilding,
       ownerId: stateManager.getState().player.id,
+      builtAt: stateManager.getGameTime(),
     }
 
     this.adapter.send({ type: 'PLACE_BUILDING', building, costs })
@@ -242,6 +364,65 @@ export class BuildingSystem {
     this.onPlaced?.(`Placed ${this.selectedBuilding}!`)
   }
 
+  /**
+   * Returns a human-readable string describing which resources are missing
+   * to build the currently selected building at the given tile.
+   * @param tileX - Tile column
+   * @param tileY - Tile row
+   * @returns Comma-separated missing resource string, or empty string if nothing is missing
+   */
+  private getMissingResources(tileX: number, tileY: number): string {
+    const state = stateManager.getState()
+    const costs = BUILDING_COSTS[this.selectedBuilding] ?? {}
+    const parts: string[] = []
+    for (const [item, qty] of Object.entries(costs)) {
+      const have = state.world.stockpile[item as keyof typeof state.world.stockpile] ?? 0
+      if (have < qty) parts.push(`${qty - have} ${item}`)
+    }
+    return parts.join(', ')
+  }
+
+  /**
+   * Attempts to demolish the building at the clicked tile.
+   * Calculates the time-based refund, removes the building from state,
+   * restores the tile type if applicable, and fires onDemolished.
+   * @param ptr - The pointer that was clicked
+   */
+  private tryDemolish(ptr: Phaser.Input.Pointer): void {
+    const tileX = Math.floor(ptr.worldX / TILE_SIZE)
+    const tileY = Math.floor(ptr.worldY / TILE_SIZE)
+
+    const building = this.findBuildingAtTile(tileX, tileY)
+    if (!building) return
+
+    // Calculate refund
+    const costs = BUILDING_COSTS[building.kind] ?? {}
+    const refundPct = this.calcRefundPct(building)
+    const refund: Partial<Record<ItemId, number>> = {}
+    for (const [item, qty] of Object.entries(costs)) {
+      const amount = Math.floor((qty ?? 0) * refundPct)
+      if (amount > 0) refund[item as ItemId] = amount
+    }
+
+    this.adapter.send({ type: 'REMOVE_BUILDING', buildingId: building.id })
+
+    // Restore tile type for buildings that changed it on placement
+    const restoreTile = DEMOLISH_RESTORE_TILE[building.kind]
+    if (restoreTile !== undefined) {
+      this.adapter.send({ type: 'CHANGE_TILE', tileX: building.tileX, tileY: building.tileY, tile: restoreTile })
+    }
+
+    // Return resources to stockpile
+    if (Object.keys(refund).length > 0) {
+      this.adapter.send({ type: 'ADD_ITEMS', items: refund })
+    }
+
+    this.onDemolished?.(building, refund)
+  }
+
+  /**
+   * Cleans up ghost sprites on scene shutdown.
+   */
   destroy(): void {
     this.ghost.destroy()
     this.ghostLabel.destroy()

src/systems/VillagerSystem.ts

@@ -767,6 +767,33 @@ export class VillagerSystem {
    * Destroys all Nisse sprites and clears the runtime map.
    * Should be called when the scene shuts down.
    */
+  /**
+   * Rescues all Nisse that were working inside a demolished building.
+   * Makes hidden sprites visible again, clears their jobs, and resets AI to idle.
+   * Also releases any mine-capacity claims for that building.
+   * @param buildingId - ID of the building that was demolished
+   */
+  rescueNisseFromBuilding(buildingId: string): void {
+    this.mineClaimsMap.delete(buildingId)
+    const state = stateManager.getState()
+    for (const v of Object.values(state.world.villagers)) {
+      if (v.job?.targetId !== buildingId) continue
+      const rt = this.runtime.get(v.id)
+      if (!rt) continue
+      // Make sprite visible in case the Nisse was hidden inside the mine
+      rt.sprite.setVisible(true)
+      rt.nameLabel.setVisible(true)
+      rt.energyBar.setVisible(true)
+      rt.jobIcon.setVisible(true)
+      rt.workTimer = 0
+      rt.idleScanTimer = 0
+      this.claimed.delete(buildingId)
+      this.adapter.send({ type: 'VILLAGER_SET_JOB', villagerId: v.id, job: null })
+      this.adapter.send({ type: 'VILLAGER_SET_AI', villagerId: v.id, aiState: 'idle' })
+      this.addLog(v.id, '! Building demolished — resuming')
+    }
+  }
+
   /**
    * Destroys all Nisse sprites and clears the runtime map.
    * Should be called when the scene shuts down.

src/types.ts

@@ -81,6 +81,8 @@ export interface BuildingState {
   tileY: number
   kind: BuildingType
   ownerId: string
+  /** In-game time (ms) when the building was placed. Used for demolish refund calculation. */
+  builtAt: number
 }
 
 export interface CropState {