diff --git a/CHANGELOG.md b/CHANGELOG.md
index e26536e..21bfe94 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,9 @@ Format follows [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## [Unreleased]
 
+### Added
+- **F3 Debug View**: toggleable overlay showing FPS, tile type and contents under the cursor, Nisse count by AI state, active jobs by type, and pathfinding visualization (cyan lines in world space)
+
 ### Fixed
 - Nisse now clear the FOREST/ROCK tile after harvesting, opening paths to deeper resources
 - Nisse no longer get stuck idle after depositing items at the stockpile
diff --git a/CLAUDE.md b/CLAUDE.md
index e09a9e8..a2c24cc 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -1,5 +1,16 @@
 # CLAUDE.md — Game Project
 
+## ⚠️ Important: Session Start Location
+
+**Claude Code must be started from `~` (home directory), NOT from `~/game`.**
+
+If you are reading this and the working directory is `/home/tekki/game`, please let the user know:
+> "Heads up: you've started me from inside `~/game`. Please exit and restart from your home directory (`~`) so that `.claude/` settings and memory stay outside the repo."
+
+`.claude/` directories inside `~/game` are gitignored and must stay that way — no settings, tokens, or memory files belong in the project repo.
+
+---
+
 ## Project Overview
 
 A browser-based top-down game built with **Phaser 3** and **TypeScript**, bundled via **Vite**.
diff --git a/src/scenes/GameScene.ts b/src/scenes/GameScene.ts
index c9a221d..fb8b074 100644
--- a/src/scenes/GameScene.ts
+++ b/src/scenes/GameScene.ts
@@ -9,6 +9,7 @@ import { ResourceSystem } from '../systems/ResourceSystem'
 import { BuildingSystem } from '../systems/BuildingSystem'
 import { FarmingSystem } from '../systems/FarmingSystem'
 import { VillagerSystem } from '../systems/VillagerSystem'
+import { DebugSystem } from '../systems/DebugSystem'
 
 export class GameScene extends Phaser.Scene {
   private adapter!: LocalAdapter
@@ -18,11 +19,16 @@ export class GameScene extends Phaser.Scene {
   private buildingSystem!: BuildingSystem
   private farmingSystem!: FarmingSystem
   villagerSystem!: VillagerSystem
+  debugSystem!: DebugSystem
   private autosaveTimer = 0
   private menuOpen = false
 
   constructor() { super({ key: 'Game' }) }
 
+  /**
+   * Initialises all game systems, wires up inter-system events,
+   * launches the UI scene overlay, and starts the autosave timer.
+   */
   create(): void {
     this.adapter = new LocalAdapter()
 
@@ -33,6 +39,7 @@ export class GameScene extends Phaser.Scene {
     this.farmingSystem  = new FarmingSystem(this, this.adapter)
     this.villagerSystem = new VillagerSystem(this, this.adapter, this.worldSystem)
     this.villagerSystem.init(this.resourceSystem, this.farmingSystem)
+    this.debugSystem    = new DebugSystem(this, this.villagerSystem, this.worldSystem)
 
     this.worldSystem.create()
     this.renderPersistentObjects()
@@ -56,6 +63,8 @@ export class GameScene extends Phaser.Scene {
     this.villagerSystem.create()
     this.villagerSystem.onMessage = (msg) => this.events.emit('toast', msg)
 
+    this.debugSystem.create()
+
     // Sync tile changes and building visuals through adapter
     this.adapter.onAction = (action) => {
       if (action.type === 'CHANGE_TILE') {
@@ -74,10 +83,17 @@ export class GameScene extends Phaser.Scene {
     this.events.on('updatePriorities', (villagerId: string, priorities: { chop: number; mine: number; farm: number }) => {
       this.adapter.send({ type: 'UPDATE_PRIORITIES', villagerId, priorities })
     })
+    this.events.on('debugToggle', () => this.debugSystem.toggle())
 
     this.autosaveTimer = AUTOSAVE_INTERVAL
   }
 
+  /**
+   * Main game loop: updates all systems and emits the cameraMoved event for the UI.
+   * Skips system updates while a menu is open.
+   * @param _time  - Total elapsed time (unused)
+   * @param delta  - Frame delta in milliseconds
+   */
   update(_time: number, delta: number): void {
     if (this.menuOpen) return
 
@@ -86,6 +102,7 @@ export class GameScene extends Phaser.Scene {
     this.resourceSystem.update(delta)
     this.farmingSystem.update(delta)
     this.villagerSystem.update(delta)
+    this.debugSystem.update()
 
     this.events.emit('cameraMoved', this.cameraSystem.getCenterTile())
     this.buildingSystem.update()
@@ -119,6 +136,7 @@ export class GameScene extends Phaser.Scene {
     }
   }
 
+  /** Saves game state and destroys all systems cleanly on scene shutdown. */
   shutdown(): void {
     stateManager.save()
     this.worldSystem.destroy()
diff --git a/src/scenes/UIScene.ts b/src/scenes/UIScene.ts
index fa94dd0..9b186d9 100644
--- a/src/scenes/UIScene.ts
+++ b/src/scenes/UIScene.ts
@@ -1,6 +1,7 @@
 import Phaser from 'phaser'
 import type { BuildingType, JobPriorities } from '../types'
 import type { FarmingTool } from '../systems/FarmingSystem'
+import type { DebugData } from '../systems/DebugSystem'
 import { stateManager } from '../StateManager'
 
 const ITEM_ICONS: Record<string, string> = {
@@ -28,9 +29,15 @@ export class UIScene extends Phaser.Scene {
   private contextMenuVisible = false
   private inBuildMode = false
   private inFarmMode = false
+  private debugPanelText!: Phaser.GameObjects.Text
+  private debugActive = false
 
   constructor() { super({ key: 'UI' }) }
 
+  /**
+   * Creates all HUD elements, wires up game scene events, and registers
+   * keyboard shortcuts (B, V, F3, ESC).
+   */
   create(): void {
     this.createStockpilePanel()
     this.createHintText()
@@ -39,6 +46,7 @@ export class UIScene extends Phaser.Scene {
     this.createBuildModeIndicator()
     this.createFarmToolIndicator()
     this.createCoordsDisplay()
+    this.createDebugPanel()
 
     const gameScene = this.scene.get('Game')
     gameScene.events.on('buildModeChanged', (a: boolean, b: BuildingType) => this.onBuildModeChanged(a, b))
@@ -51,6 +59,8 @@ export class UIScene extends Phaser.Scene {
       .on('down', () => gameScene.events.emit('uiRequestBuildMenu'))
     this.input.keyboard!.addKey(Phaser.Input.Keyboard.KeyCodes.V)
       .on('down', () => this.toggleVillagerPanel())
+    this.input.keyboard!.addKey(Phaser.Input.Keyboard.KeyCodes.F3)
+      .on('down', () => this.toggleDebugPanel())
 
     this.scale.on('resize', () => this.repositionUI())
 
@@ -71,14 +81,22 @@ export class UIScene extends Phaser.Scene {
       .on('down', () => this.hideContextMenu())
   }
 
+  /**
+   * Updates the stockpile display, toast fade timer, population count,
+   * and the debug panel each frame.
+   * @param _t    - Total elapsed time (unused)
+   * @param delta - Frame delta in milliseconds
+   */
   update(_t: number, delta: number): void {
     this.updateStockpile()
     this.updateToast(delta)
     this.updatePopText()
+    if (this.debugActive) this.updateDebugPanel()
   }
 
   // ─── Stockpile ────────────────────────────────────────────────────────────
 
+  /** Creates the stockpile panel in the top-right corner with item rows and population count. */
   private createStockpilePanel(): void {
     const x = this.scale.width - 178, y = 10
     this.stockpilePanel = this.add.rectangle(x, y, 168, 165, 0x000000, 0.72).setOrigin(0, 0).setScrollFactor(0).setDepth(100)
@@ -91,6 +109,7 @@ export class UIScene extends Phaser.Scene {
     this.popText = this.add.text(x + 10, y + 145, '👥 Nisse: 0 / 0', { fontSize: '11px', color: '#aaaaaa', fontFamily: 'monospace' }).setScrollFactor(0).setDepth(101)
   }
 
+  /** Refreshes all item quantities and colors in the stockpile panel. */
   private updateStockpile(): void {
     const sp = stateManager.getState().world.stockpile
     for (const [item, t] of this.stockpileTexts) {
@@ -100,6 +119,7 @@ export class UIScene extends Phaser.Scene {
     }
   }
 
+  /** Updates the Nisse population / bed capacity counter. */
   private updatePopText(): void {
     const state = stateManager.getState()
     const beds    = Object.values(state.world.buildings).filter(b => b.kind === 'bed').length
@@ -109,6 +129,7 @@ export class UIScene extends Phaser.Scene {
 
   // ─── Hint ─────────────────────────────────────────────────────────────────
 
+  /** Creates the centered hint text element near the bottom of the screen. */
   private createHintText(): void {
     this.hintText = this.add.text(this.scale.width / 2, this.scale.height - 40, '', {
       fontSize: '14px', color: '#ffff88', fontFamily: 'monospace',
@@ -118,6 +139,7 @@ export class UIScene extends Phaser.Scene {
 
   // ─── Toast ────────────────────────────────────────────────────────────────
 
+  /** Creates the toast notification text element (top center, initially hidden). */
   private createToast(): void {
     this.toastText = this.add.text(this.scale.width / 2, 60, '', {
       fontSize: '15px', color: '#88ff88', fontFamily: 'monospace',
@@ -125,8 +147,16 @@ export class UIScene extends Phaser.Scene {
     }).setOrigin(0.5, 0).setScrollFactor(0).setDepth(102).setAlpha(0)
   }
 
+  /**
+   * Displays a toast message for 2.2 seconds then fades it out.
+   * @param msg - Message to display
+   */
   showToast(msg: string): void { this.toastText.setText(msg).setAlpha(1); this.toastTimer = 2200 }
 
+  /**
+   * Counts down the toast timer and triggers the fade-out tween when it expires.
+   * @param delta - Frame delta in milliseconds
+   */
   private updateToast(delta: number): void {
     if (this.toastTimer <= 0) return
     this.toastTimer -= delta
@@ -135,6 +165,7 @@ export class UIScene extends Phaser.Scene {
 
   // ─── Build Menu ───────────────────────────────────────────────────────────
 
+  /** Creates and hides the build menu with buttons for each available building type. */
   private createBuildMenu(): void {
     this.buildMenuGroup = this.add.group()
     const buildings: { kind: BuildingType; label: string; cost: string }[] = [
@@ -162,12 +193,18 @@ export class UIScene extends Phaser.Scene {
     this.buildMenuGroup.setVisible(false)
   }
 
+  /** Toggles the build menu open or closed. */
   private toggleBuildMenu(): void { this.buildMenuVisible ? this.closeBuildMenu() : this.openBuildMenu() }
+
+  /** Opens the build menu and notifies GameScene that a menu is active. */
   private openBuildMenu():  void { this.buildMenuVisible = true;  this.buildMenuGroup.setVisible(true);  this.scene.get('Game').events.emit('uiMenuOpen') }
+
+  /** Closes the build menu and notifies GameScene that no menu is active. */
   private closeBuildMenu(): void { this.buildMenuVisible = false; this.buildMenuGroup.setVisible(false); this.scene.get('Game').events.emit('uiMenuClose') }
 
   // ─── Villager Panel (V key) ───────────────────────────────────────────────
 
+  /** Toggles the Nisse management panel open or closed. */
   private toggleVillagerPanel(): void {
     if (this.villagerPanelVisible) {
       this.closeVillagerPanel()
@@ -176,18 +213,24 @@ export class UIScene extends Phaser.Scene {
     }
   }
 
+  /** Opens the Nisse panel, builds its contents, and notifies GameScene. */
   private openVillagerPanel(): void {
     this.villagerPanelVisible = true
     this.buildVillagerPanel()
     this.scene.get('Game').events.emit('uiMenuOpen')
   }
 
+  /** Closes and destroys the Nisse panel and notifies GameScene. */
   private closeVillagerPanel(): void {
     this.villagerPanelVisible = false
     this.villagerPanelGroup?.destroy(true)
     this.scene.get('Game').events.emit('uiMenuClose')
   }
 
+  /**
+   * Destroys and rebuilds the Nisse panel from current state.
+   * Shows name, status, energy bar, and job priority buttons per Nisse.
+   */
   private buildVillagerPanel(): void {
     if (this.villagerPanelGroup) this.villagerPanelGroup.destroy(true)
     this.villagerPanelGroup = this.add.group()
@@ -266,9 +309,16 @@ export class UIScene extends Phaser.Scene {
 
   // ─── Build mode indicator ─────────────────────────────────────────────────
 
+  /** Creates the build-mode indicator text in the top-left corner (initially hidden). */
   private createBuildModeIndicator(): void {
     this.buildModeText = this.add.text(10, 10, '', { fontSize: '13px', color: '#ffff00', fontFamily: 'monospace', backgroundColor: '#00000099', padding: { x: 8, y: 4 } }).setScrollFactor(0).setDepth(100).setVisible(false)
   }
+
+  /**
+   * Shows or hides the build-mode indicator based on whether build mode is active.
+   * @param active   - Whether build mode is currently active
+   * @param building - The selected building type
+   */
   private onBuildModeChanged(active: boolean, building: BuildingType): void {
     this.inBuildMode = active
     this.buildModeText.setText(active ? `🏗  BUILD: ${building.toUpperCase()}  [RMB/ESC cancel]` : '').setVisible(active)
@@ -276,9 +326,16 @@ export class UIScene extends Phaser.Scene {
 
   // ─── Farm tool indicator ──────────────────────────────────────────────────
 
+  /** Creates the farm-tool indicator text below the build-mode indicator (initially hidden). */
   private createFarmToolIndicator(): void {
     this.farmToolText = this.add.text(10, 44, '', { fontSize: '13px', color: '#aaffaa', fontFamily: 'monospace', backgroundColor: '#00000099', padding: { x: 8, y: 4 } }).setScrollFactor(0).setDepth(100).setVisible(false)
   }
+
+  /**
+   * Shows or hides the farm-tool indicator and updates the active tool label.
+   * @param tool  - Currently selected farm tool
+   * @param label - Human-readable label for the tool
+   */
   private onFarmToolChanged(tool: FarmingTool, label: string): void {
     this.inFarmMode = tool !== 'none'
     this.farmToolText.setText(tool === 'none' ? '' : `[F] Farm: ${label}  [RMB cancel]`).setVisible(tool !== 'none')
@@ -286,16 +343,88 @@ export class UIScene extends Phaser.Scene {
 
   // ─── Coords + controls ────────────────────────────────────────────────────
 
+  /** Creates the tile-coordinate display and controls hint at the bottom-left. */
   private createCoordsDisplay(): void {
     this.coordsText = this.add.text(10, this.scale.height - 24, '', { fontSize: '11px', color: '#666666', fontFamily: 'monospace' }).setScrollFactor(0).setDepth(100)
-    this.controlsHintText = this.add.text(10, this.scale.height - 42, '[WASD] Pan  [Scroll] Zoom  [F] Farm  [B] Build  [V] Nisse', {
+    this.controlsHintText = this.add.text(10, this.scale.height - 42, '[WASD] Pan  [Scroll] Zoom  [F] Farm  [B] Build  [V] Nisse  [F3] Debug', {
       fontSize: '10px', color: '#444444', fontFamily: 'monospace', backgroundColor: '#00000066', padding: { x: 4, y: 2 }
     }).setScrollFactor(0).setDepth(100)
   }
+
+  /**
+   * Updates the tile-coordinate display when the camera moves.
+   * @param pos - Tile position of the camera center
+   */
   private onCameraMoved(pos: { tileX: number; tileY: number }): void {
     this.coordsText.setText(`Tile: ${pos.tileX}, ${pos.tileY}`)
   }
 
+  // ─── Debug Panel (F3) ─────────────────────────────────────────────────────
+
+  /** Creates the debug panel text object (initially hidden). */
+  private createDebugPanel(): void {
+    this.debugPanelText = this.add.text(10, 80, '', {
+      fontSize: '12px',
+      color: '#cccccc',
+      backgroundColor: '#000000cc',
+      padding: { x: 8, y: 6 },
+      lineSpacing: 2,
+      fontFamily: 'monospace',
+    }).setScrollFactor(0).setDepth(150).setVisible(false)
+  }
+
+  /** Toggles the debug panel and notifies GameScene to toggle the pathfinding overlay. */
+  private toggleDebugPanel(): void {
+    this.debugActive = !this.debugActive
+    this.debugPanelText.setVisible(this.debugActive)
+    this.scene.get('Game').events.emit('debugToggle')
+  }
+
+  /**
+   * Reads current debug data from DebugSystem and updates the panel text.
+   * Called every frame while debug mode is active.
+   */
+  private updateDebugPanel(): void {
+    const gameScene = this.scene.get('Game') as any
+    const debugSystem = gameScene.debugSystem
+    if (!debugSystem?.isActive()) return
+
+    const ptr  = this.input.activePointer
+    const data = debugSystem.getDebugData(ptr) as DebugData
+
+    const resLine   = data.resourcesOnTile.length > 0
+      ? data.resourcesOnTile.map(r => `${r.kind} (hp:${r.hp})`).join(', ')
+      : '—'
+    const bldLine   = data.buildingsOnTile.length > 0 ? data.buildingsOnTile.join(', ') : '—'
+    const cropLine  = data.cropsOnTile.length > 0
+      ? data.cropsOnTile.map(c => `${c.kind} (${c.stage}/${c.maxStage})`).join(', ')
+      : '—'
+    const { idle, walking, working, sleeping } = data.nisseByState
+    const { chop, mine, farm } = data.jobsByType
+
+    this.debugPanelText.setText([
+      '── F3 DEBUG ──────────────────',
+      `FPS:         ${data.fps}`,
+      '',
+      `Mouse world: ${data.mouseWorld.x.toFixed(1)}, ${data.mouseWorld.y.toFixed(1)}`,
+      `Mouse tile:  ${data.mouseTile.tileX}, ${data.mouseTile.tileY}`,
+      `Tile type:   ${data.tileType}`,
+      `Resources:   ${resLine}`,
+      `Buildings:   ${bldLine}`,
+      `Crops:       ${cropLine}`,
+      '',
+      `Nisse: ${data.nisseTotal} total`,
+      `  idle: ${idle}  walking: ${walking}  working: ${working}  sleeping: ${sleeping}`,
+      '',
+      `Jobs active:`,
+      `  chop: ${chop}  mine: ${mine}  farm: ${farm}`,
+      '',
+      `Paths: ${data.activePaths} (cyan lines in world)`,
+      '',
+      '[F3] close',
+    ])
+  }
+
   // ─── Context Menu ─────────────────────────────────────────────────────────
 
   /**
diff --git a/src/systems/DebugSystem.ts b/src/systems/DebugSystem.ts
new file mode 100644
index 0000000..9db6e7a
--- /dev/null
+++ b/src/systems/DebugSystem.ts
@@ -0,0 +1,164 @@
+import Phaser from 'phaser'
+import { TILE_SIZE } from '../config'
+import { TileType } from '../types'
+import { stateManager } from '../StateManager'
+import type { VillagerSystem } from './VillagerSystem'
+import type { WorldSystem } from './WorldSystem'
+
+/** All data collected each frame for the debug panel. */
+export interface DebugData {
+  fps: number
+  mouseWorld: { x: number; y: number }
+  mouseTile:  { tileX: number; tileY: number }
+  tileType:   string
+  resourcesOnTile: Array<{ kind: string; hp: number }>
+  buildingsOnTile: string[]
+  cropsOnTile: Array<{ kind: string; stage: number; maxStage: number }>
+  nisseTotal: number
+  nisseByState: { idle: number; walking: number; working: number; sleeping: number }
+  jobsByType:   { chop: number; mine: number; farm: number }
+  activePaths:  number
+}
+
+/** Human-readable names for TileType enum values. */
+const TILE_NAMES: Record<number, string> = {
+  [TileType.DEEP_WATER]:    'DEEP_WATER',
+  [TileType.SHALLOW_WATER]: 'SHALLOW_WATER',
+  [TileType.SAND]:          'SAND',
+  [TileType.GRASS]:         'GRASS',
+  [TileType.DARK_GRASS]:    'DARK_GRASS',
+  [TileType.FOREST]:        'FOREST',
+  [TileType.ROCK]:          'ROCK',
+  [TileType.FLOOR]:         'FLOOR',
+  [TileType.WALL]:          'WALL',
+  [TileType.TILLED_SOIL]:   'TILLED_SOIL',
+  [TileType.WATERED_SOIL]:  'WATERED_SOIL',
+}
+
+export class DebugSystem {
+  private scene:          Phaser.Scene
+  private villagerSystem: VillagerSystem
+  private worldSystem:    WorldSystem
+  private pathGraphics!:  Phaser.GameObjects.Graphics
+  private active = false
+
+  /**
+   * @param scene          - The Phaser scene this system belongs to
+   * @param villagerSystem - Used to read active paths for visualization
+   * @param worldSystem    - Used to read tile types under the mouse
+   */
+  constructor(scene: Phaser.Scene, villagerSystem: VillagerSystem, worldSystem: WorldSystem) {
+    this.scene          = scene
+    this.villagerSystem = villagerSystem
+    this.worldSystem    = worldSystem
+  }
+
+  /**
+   * Creates the world-space Graphics object used for pathfinding visualization.
+   * Starts hidden until toggled on.
+   */
+  create(): void {
+    this.pathGraphics = this.scene.add.graphics().setDepth(50)
+    this.pathGraphics.setVisible(false)
+  }
+
+  /**
+   * Toggles debug mode on or off.
+   * Shows or hides the pathfinding overlay graphics accordingly.
+   */
+  toggle(): void {
+    this.active = !this.active
+    this.pathGraphics.setVisible(this.active)
+    if (!this.active) this.pathGraphics.clear()
+  }
+
+  /** Returns whether debug mode is currently active. */
+  isActive(): boolean {
+    return this.active
+  }
+
+  /**
+   * Redraws pathfinding lines for all currently walking Nisse.
+   * Should be called every frame while debug mode is active.
+   */
+  update(): void {
+    if (!this.active) return
+    this.pathGraphics.clear()
+
+    const paths = this.villagerSystem.getActivePaths()
+    this.pathGraphics.lineStyle(1, 0x00ffff, 0.65)
+
+    for (const entry of paths) {
+      if (entry.path.length === 0) continue
+      this.pathGraphics.beginPath()
+      this.pathGraphics.moveTo(entry.x, entry.y)
+      for (const step of entry.path) {
+        this.pathGraphics.lineTo(
+          (step.tileX + 0.5) * TILE_SIZE,
+          (step.tileY + 0.5) * TILE_SIZE,
+        )
+      }
+      this.pathGraphics.strokePath()
+
+      // Mark the destination tile
+      const last = entry.path[entry.path.length - 1]
+      this.pathGraphics.fillStyle(0x00ffff, 0.4)
+      this.pathGraphics.fillRect(
+        last.tileX * TILE_SIZE,
+        last.tileY * TILE_SIZE,
+        TILE_SIZE,
+        TILE_SIZE,
+      )
+    }
+  }
+
+  /**
+   * Collects and returns all debug data for the current frame.
+   * Called by UIScene to populate the debug panel.
+   * @param ptr - The active pointer, used to resolve world position
+   * @returns Snapshot of game state for display
+   */
+  getDebugData(ptr: Phaser.Input.Pointer): DebugData {
+    const state   = stateManager.getState()
+    const villagers = Object.values(state.world.villagers)
+    const tileX   = Math.floor(ptr.worldX / TILE_SIZE)
+    const tileY   = Math.floor(ptr.worldY / TILE_SIZE)
+    const tileType = this.worldSystem.getTileType(tileX, tileY)
+
+    const nisseByState = { idle: 0, walking: 0, working: 0, sleeping: 0 }
+    const jobsByType   = { chop: 0, mine: 0, farm: 0 }
+
+    for (const v of villagers) {
+      nisseByState[v.aiState as keyof typeof nisseByState]++
+      if (v.job && (v.aiState === 'working' || v.aiState === 'walking')) {
+        jobsByType[v.job.type as keyof typeof jobsByType]++
+      }
+    }
+
+    const resourcesOnTile = Object.values(state.world.resources)
+      .filter(r => r.tileX === tileX && r.tileY === tileY)
+      .map(r => ({ kind: r.kind, hp: r.hp }))
+
+    const buildingsOnTile = Object.values(state.world.buildings)
+      .filter(b => b.tileX === tileX && b.tileY === tileY)
+      .map(b => b.kind)
+
+    const cropsOnTile = Object.values(state.world.crops)
+      .filter(c => c.tileX === tileX && c.tileY === tileY)
+      .map(c => ({ kind: c.kind, stage: c.stage, maxStage: c.maxStage }))
+
+    return {
+      fps:            Math.round(this.scene.game.loop.actualFps),
+      mouseWorld:     { x: ptr.worldX, y: ptr.worldY },
+      mouseTile:      { tileX, tileY },
+      tileType:       TILE_NAMES[tileType] ?? `UNKNOWN(${tileType})`,
+      resourcesOnTile,
+      buildingsOnTile,
+      cropsOnTile,
+      nisseTotal:     villagers.length,
+      nisseByState,
+      jobsByType,
+      activePaths:    this.villagerSystem.getActivePaths().length,
+    }
+  }
+}
diff --git a/src/systems/VillagerSystem.ts b/src/systems/VillagerSystem.ts
index 68efa98..45f82c2 100644
--- a/src/systems/VillagerSystem.ts
+++ b/src/systems/VillagerSystem.ts
@@ -36,18 +36,32 @@ export class VillagerSystem {
 
   onMessage?: (msg: string) => void
 
+  /**
+   * @param scene        - The Phaser scene this system belongs to
+   * @param adapter      - Network adapter for dispatching state actions
+   * @param worldSystem  - Used for passability checks during pathfinding
+   */
   constructor(scene: Phaser.Scene, adapter: LocalAdapter, worldSystem: WorldSystem) {
     this.scene = scene
     this.adapter = adapter
     this.worldSystem = worldSystem
   }
 
-  /** Wire in sibling systems after construction */
+  /**
+   * Wires in sibling systems that are not available at construction time.
+   * Must be called before create().
+   * @param resourceSystem - Used to remove harvested resource sprites
+   * @param farmingSystem  - Used to remove harvested crop sprites
+   */
   init(resourceSystem: ResourceSystem, farmingSystem: FarmingSystem): void {
     this.resourceSystem = resourceSystem
     this.farmingSystem  = farmingSystem
   }
 
+  /**
+   * Spawns sprites for all Nisse that exist in the saved state
+   * and re-claims any active job targets.
+   */
   create(): void {
     const state = stateManager.getState()
     for (const v of Object.values(state.world.villagers)) {
@@ -57,6 +71,10 @@ export class VillagerSystem {
     }
   }
 
+  /**
+   * Advances the spawn timer and ticks every Nisse's AI.
+   * @param delta - Frame delta in milliseconds
+   */
   update(delta: number): void {
     this.spawnTimer += delta
     if (this.spawnTimer >= VILLAGER_SPAWN_INTERVAL) {
@@ -72,6 +90,12 @@ export class VillagerSystem {
 
   // ─── Per-villager tick ────────────────────────────────────────────────────
 
+  /**
+   * Dispatches the correct AI tick method based on the villager's current state,
+   * then syncs the sprite, name label, energy bar, and job icon to the state.
+   * @param v     - Villager state from the store
+   * @param delta - Frame delta in milliseconds
+   */
   private tickVillager(v: VillagerState, delta: number): void {
     const rt = this.runtime.get(v.id)
     if (!rt) return
@@ -97,6 +121,14 @@ export class VillagerSystem {
 
   // ─── IDLE ─────────────────────────────────────────────────────────────────
 
+  /**
+   * Handles the idle AI state: hauls items to stockpile if carrying any,
+   * seeks a bed if energy is low, otherwise picks the next job and begins walking.
+   * Applies a cooldown before scanning again if no job is found.
+   * @param v     - Villager state
+   * @param rt    - Villager runtime (sprites, path, timers)
+   * @param delta - Frame delta in milliseconds
+   */
   private tickIdle(v: VillagerState, rt: VillagerRuntime, delta: number): void {
     // Decrement scan timer if cooling down
     if (rt.idleScanTimer > 0) {
@@ -133,6 +165,14 @@ export class VillagerSystem {
 
   // ─── WALKING ──────────────────────────────────────────────────────────────
 
+  /**
+   * Advances the Nisse along its path toward the current destination.
+   * Calls onArrived when the path is exhausted.
+   * Drains energy slowly while walking.
+   * @param v     - Villager state
+   * @param rt    - Villager runtime
+   * @param delta - Frame delta in milliseconds
+   */
   private tickWalking(v: VillagerState, rt: VillagerRuntime, delta: number): void {
     if (rt.path.length === 0) {
       this.onArrived(v, rt)
@@ -161,6 +201,12 @@ export class VillagerSystem {
     ;(v as { energy: number }).energy = Math.max(0, v.energy - delta * 0.0015)
   }
 
+  /**
+   * Called when a Nisse reaches its destination tile.
+   * Transitions to the appropriate next AI state based on destination type.
+   * @param v  - Villager state
+   * @param rt - Villager runtime
+   */
   private onArrived(v: VillagerState, rt: VillagerRuntime): void {
     switch (rt.destination) {
       case 'job':
@@ -186,6 +232,14 @@ export class VillagerSystem {
 
   // ─── WORKING ──────────────────────────────────────────────────────────────
 
+  /**
+   * Counts down the work timer and performs the harvest action on completion.
+   * Handles chop, mine, and farm job types.
+   * Returns the Nisse to idle when done.
+   * @param v     - Villager state
+   * @param rt    - Villager runtime
+   * @param delta - Frame delta in milliseconds
+   */
   private tickWorking(v: VillagerState, rt: VillagerRuntime, delta: number): void {
     rt.workTimer -= delta
     // Wobble while working
@@ -237,6 +291,12 @@ export class VillagerSystem {
 
   // ─── SLEEPING ─────────────────────────────────────────────────────────────
 
+  /**
+   * Restores energy while sleeping. Returns to idle once energy is full.
+   * @param v     - Villager state
+   * @param rt    - Villager runtime
+   * @param delta - Frame delta in milliseconds
+   */
   private tickSleeping(v: VillagerState, rt: VillagerRuntime, delta: number): void {
     ;(v as { energy: number }).energy = Math.min(100, v.energy + delta * 0.04)
     // Gentle bob while sleeping
@@ -249,6 +309,13 @@ export class VillagerSystem {
 
   // ─── Job picking (RimWorld-style priority) ────────────────────────────────
 
+  /**
+   * Selects the best available job for a Nisse based on their priority settings.
+   * Among jobs at the same priority level, the closest one wins.
+   * Returns null if no unclaimed job is available.
+   * @param v - Villager state (used for position and priorities)
+   * @returns The chosen job candidate, or null
+   */
   private pickJob(v: VillagerState): { type: JobType; targetId: string; tileX: number; tileY: number } | null {
     const state = stateManager.getState()
     const p     = v.priorities
@@ -289,6 +356,15 @@ export class VillagerSystem {
 
   // ─── Pathfinding ──────────────────────────────────────────────────────────
 
+  /**
+   * Computes a path from the Nisse's current tile to the target tile and
+   * begins walking. If no path is found, the job is cleared and a cooldown applied.
+   * @param v     - Villager state
+   * @param rt    - Villager runtime
+   * @param tileX - Target tile X
+   * @param tileY - Target tile Y
+   * @param dest  - Semantic destination type (used by onArrived)
+   */
   private beginWalk(v: VillagerState, rt: VillagerRuntime, tileX: number, tileY: number, dest: VillagerRuntime['destination']): void {
     const sx = Math.floor(v.x / TILE_SIZE)
     const sy = Math.floor(v.y / TILE_SIZE)
@@ -310,6 +386,11 @@ export class VillagerSystem {
 
   // ─── Building finders ─────────────────────────────────────────────────────
 
+  /**
+   * Returns the nearest building of the given kind to the Nisse, or null if none exist.
+   * @param v    - Villager state (used as reference position)
+   * @param kind - Building kind to search for
+   */
   private nearestBuilding(v: VillagerState, kind: string): { tileX: number; tileY: number } | null {
     const state = stateManager.getState()
     const hits = Object.values(state.world.buildings).filter(b => b.kind === kind)
@@ -319,6 +400,11 @@ export class VillagerSystem {
     return hits.sort((a, b) => Math.hypot(a.tileX - vx, a.tileY - vy) - Math.hypot(b.tileX - vx, b.tileY - vy))[0]
   }
 
+  /**
+   * Returns the Nisse's assigned bed if it still exists, otherwise the nearest bed.
+   * Returns null if no beds are placed.
+   * @param v - Villager state
+   */
   private findBed(v: VillagerState): { id: string; tileX: number; tileY: number } | null {
     const state = stateManager.getState()
     // Prefer assigned bed
@@ -328,6 +414,10 @@ export class VillagerSystem {
 
   // ─── Spawning ─────────────────────────────────────────────────────────────
 
+  /**
+   * Attempts to spawn a new Nisse if a free bed is available and the
+   * current population is below the bed count.
+   */
   private trySpawn(): void {
     const state   = stateManager.getState()
     const beds    = Object.values(state.world.buildings).filter(b => b.kind === 'bed')
@@ -361,6 +451,11 @@ export class VillagerSystem {
 
   // ─── Sprite management ────────────────────────────────────────────────────
 
+  /**
+   * Creates and registers all runtime objects (sprite, label, energy bar, icon)
+   * for a newly added Nisse.
+   * @param v - Villager state to create sprites for
+   */
   private spawnSprite(v: VillagerState): void {
     const sprite = this.scene.add.image(v.x, v.y, 'villager').setDepth(11)
 
@@ -375,6 +470,14 @@ export class VillagerSystem {
     this.runtime.set(v.id, { sprite, nameLabel, energyBar, jobIcon, path: [], destination: null, workTimer: 0, idleScanTimer: 0 })
   }
 
+  /**
+   * Redraws the energy bar graphic for a Nisse at the given world position.
+   * Color transitions green → orange → red as energy decreases.
+   * @param g      - Graphics object to draw into
+   * @param x      - World X center of the Nisse
+   * @param y      - World Y center of the Nisse
+   * @param energy - Current energy value (0–100)
+   */
   private drawEnergyBar(g: Phaser.GameObjects.Graphics, x: number, y: number, energy: number): void {
     const W = 20, H = 3
     g.clear()
@@ -385,6 +488,12 @@ export class VillagerSystem {
 
   // ─── Public API ───────────────────────────────────────────────────────────
 
+  /**
+   * Returns a short human-readable status string for the given Nisse,
+   * suitable for display in UI panels.
+   * @param villagerId - The Nisse's ID
+   * @returns Status string, or '—' if the Nisse is not found
+   */
   getStatusText(villagerId: string): string {
     const v = stateManager.getState().world.villagers[villagerId]
     if (!v) return '—'
@@ -397,6 +506,28 @@ export class VillagerSystem {
     return '💭 Idle'
   }
 
+  /**
+   * Returns the current world position and remaining path for every Nisse
+   * that is currently in the 'walking' state. Used by DebugSystem for
+   * pathfinding visualization.
+   * @returns Array of path entries, one per walking Nisse
+   */
+  getActivePaths(): Array<{ x: number; y: number; path: Array<{ tileX: number; tileY: number }> }> {
+    const state = stateManager.getState()
+    const result: Array<{ x: number; y: number; path: Array<{ tileX: number; tileY: number }> }> = []
+    for (const v of Object.values(state.world.villagers)) {
+      if (v.aiState !== 'walking') continue
+      const rt = this.runtime.get(v.id)
+      if (!rt) continue
+      result.push({ x: v.x, y: v.y, path: [...rt.path] })
+    }
+    return result
+  }
+
+  /**
+   * Destroys all Nisse sprites and clears the runtime map.
+   * Should be called when the scene shuts down.
+   */
   destroy(): void {
     for (const rt of this.runtime.values()) {
       rt.sprite.destroy(); rt.nameLabel.destroy()
diff --git a/src/systems/WorldSystem.ts b/src/systems/WorldSystem.ts
index 26ea7b7..faff74f 100644
--- a/src/systems/WorldSystem.ts
+++ b/src/systems/WorldSystem.ts
@@ -22,10 +22,15 @@ export class WorldSystem {
   private bgImage!: Phaser.GameObjects.Image
   private builtLayer!: Phaser.Tilemaps.TilemapLayer
 
+  /** @param scene - The Phaser scene this system belongs to */
   constructor(scene: Phaser.Scene) {
     this.scene = scene
   }
 
+  /**
+   * Generates the terrain background canvas from saved tile data,
+   * creates the built-tile tilemap layer, and sets camera bounds.
+   */
   create(): void {
     const state = stateManager.getState()
 
@@ -81,10 +86,18 @@ export class WorldSystem {
     this.scene.cameras.main.setBounds(0, 0, WORLD_TILES * TILE_SIZE, WORLD_TILES * TILE_SIZE)
   }
 
+  /** Returns the built-tile tilemap layer (floor, wall, soil). */
   getLayer(): Phaser.Tilemaps.TilemapLayer {
     return this.builtLayer
   }
 
+  /**
+   * Places or removes a tile on the built layer.
+   * Built tile types are added; natural types remove the built-layer entry.
+   * @param tileX - Tile column
+   * @param tileY - Tile row
+   * @param type  - New tile type to apply
+   */
   setTile(tileX: number, tileY: number, type: TileType): void {
     const BUILT_TILES = new Set([TileType.FLOOR, TileType.WALL, TileType.TILLED_SOIL, TileType.WATERED_SOIL])
     if (BUILT_TILES.has(type)) {
@@ -95,6 +108,12 @@ export class WorldSystem {
     }
   }
 
+  /**
+   * Returns whether the tile at the given coordinates can be walked on.
+   * Out-of-bounds tiles are treated as impassable.
+   * @param tileX - Tile column
+   * @param tileY - Tile row
+   */
   isPassable(tileX: number, tileY: number): boolean {
     if (tileX < 0 || tileY < 0 || tileX >= WORLD_TILES || tileY >= WORLD_TILES) return false
     const state = stateManager.getState()
@@ -102,6 +121,12 @@ export class WorldSystem {
     return !IMPASSABLE.has(tile)
   }
 
+  /**
+   * Converts world pixel coordinates to tile coordinates.
+   * @param worldX - World X in pixels
+   * @param worldY - World Y in pixels
+   * @returns Integer tile position
+   */
   worldToTile(worldX: number, worldY: number): { tileX: number; tileY: number } {
     return {
       tileX: Math.floor(worldX / TILE_SIZE),
@@ -109,6 +134,12 @@ export class WorldSystem {
     }
   }
 
+  /**
+   * Converts tile coordinates to the world pixel center of that tile.
+   * @param tileX - Tile column
+   * @param tileY - Tile row
+   * @returns World pixel center position
+   */
   tileToWorld(tileX: number, tileY: number): { x: number; y: number } {
     return {
       x: tileX * TILE_SIZE + TILE_SIZE / 2,
@@ -116,11 +147,17 @@ export class WorldSystem {
     }
   }
 
+  /**
+   * Returns the tile type at the given tile coordinates from saved state.
+   * @param tileX - Tile column
+   * @param tileY - Tile row
+   */
   getTileType(tileX: number, tileY: number): TileType {
     const state = stateManager.getState()
     return state.world.tiles[tileY * WORLD_TILES + tileX] as TileType
   }
 
+  /** Destroys the tilemap and background image. */
   destroy(): void {
     this.map.destroy()
     this.bgImage.destroy()