Phase 4 — Trees, Rocks, Items, Stockpiles, Hauling

Three gdscript-refactor agents in parallel + Opus integration.

Entities (scenes/entities/, Agent A — 3 scripts + 3 .tscn, ~460 lines):
- item.gd: 16-type StringName registry (matches design.md filter chips);
  Node2D + _draw() colored square + stack-count badge; to_dict/from_dict
- tree.gd: class_name HarvestableTree (Godot 4 ships a built-in 'Tree'
  Control class — renamed to avoid the shadow); CHOP_TICKS=80; on_chop_tick
  advances progress, fells when complete, drops 3 wood items at tile +
  walkable neighbours
- rock.gd: MINE_TICKS=120; angular polygon _draw; mined() drops 1 stone

Toil + provider extensions (scenes/ai/, Agent B — 4 files modified/added,
~250 lines):
- Toil: new KIND_INTERACT (timed entity action), KIND_PICKUP, KIND_DEPOSIT
- JobRunner: _tick_interact resolves NodePath, calls target.<method>()
  each tick, marks done when is_choppable/is_mineable returns false;
  _tick_pickup finds Item at pawn.tile, transfers to pawn.carried_item;
  _tick_deposit places carried_item at pawn.tile + clears the
  items_needing_haul dirty flag
- ChopProvider (priority=5): nearest choppable tree; Job=[walk_to + interact]
- MineProvider (priority=4): same for rocks

Hauling system (scenes/world/ + scenes/ai/, Agent C — 4 files, ~330 lines):
- StorageDestination: abstract Node2D base; Priority enum CRITICAL=0..OFF=4;
  accepted_types (empty=wildcard); _filter_accepts() helper
- StockpileZone: concrete rect-region zone; _draw paints priority-tinted
  overlay (z_index=-1); find_drop_position scans for free cells respecting
  one-stack-per-tile rule
- HaulingProvider (priority=3): nearest dirty item × best destination →
  4-toil job [walk → pickup → walk → deposit]; sweep_for_better_destinations
  enables the priority cascade (items in lower-priority zones re-mark dirty
  when a higher-priority destination opens up)

Opus integration (~200 lines):
- World autoload: trees/rocks/items/items_needing_haul/stockpiles registries
  + register/unregister methods; pathfinder reference exposed for entity
  code (tree.fell needs is_walkable for neighbour drops)
- Pawn: carried_item slot + carry-indicator (small colored rect upper-right
  of body) via queue_redraw in _on_sim_tick
- World scene: registers chop/mine/haul/rest providers; spawns 6 trees
  (cluster east-north), 4 rocks (south-east), 2 stockpile zones (Zone A
  wood-only NORMAL, Zone B wildcard HIGH); periodic
  hauling_provider.sweep_for_better_destinations every 100 sim ticks

Acceptance — MCP-verified end-to-end (the full Phase 4 loop):
- 3 pawns boot, Decision picks chop (highest priority work), all walk to
  nearest tree, chop in parallel (3× speed because all 3 call on_chop_tick
  per tick). Trees fell, drop wood (18 items). Pawns move to rocks, mine,
  drop stone (4 items). Total 22 items spawn.
- HaulingProvider routes wood + stone toward Zone B (wildcard HIGH > Zone
  A's wood-only NORMAL). Pawns carry items one at a time, visual indicator
  shows during transit. Items deposit, items_needing_haul dirty flag
  clears.
- **Priority cascade test:** Zone A promoted from NORMAL to CRITICAL.
  Manually-triggered sweep marks 3 wood items in Zone B for re-haul.
  Within a few thousand ticks: Zone A has 5 wood (cascaded from Zone B),
  Zone B has 4 stone only (wood left, stone stayed because Zone A rejects
  stone). Filter + priority cascade working exactly per design.md spec.

Phase 4 gotchas (logged in implementation.md):
- 'Tree' shadows Godot 4's built-in Tree Control class — class_name had to
  be renamed to HarvestableTree. Scene/file names stayed as 'tree' since
  the game concept is still 'tree'; the rename only affects code-side
  type references.
- draw_colored_polygon(points, color) takes a SINGLE Color, not a
  PackedColorArray. Agent C had to be reminded; draw_polygon(points, colors)
  is the variant that takes per-vertex colors.
- Godot's class-name cache lags behind file changes — a full editor scan
  ('godot --headless --editor --quit') is needed to flush. Even after
  reload_project, type-annotation assignments can fail; duck-typed
  variables ('var x = scene.instantiate()') sidestep the issue.
- JobRunner's _tick_deposit had to explicitly call
  World.clear_item_haul_flag — the dirty set persisted otherwise and
  items appeared 'needing haul' even after deposit.

Delegation report this phase:
- Agent A (Sonnet, gdscript-refactor): Tree + Rock + Item entities + i18n
  keys. ~460 lines.
- Agent B (Sonnet, gdscript-refactor): Toil extensions + JobRunner handlers
  + ChopProvider + MineProvider. ~250 lines.
- Agent C (Sonnet, gdscript-refactor): StorageDestination + StockpileZone
  + HaulingProvider with cascade sweep. ~330 lines.
- Opus: World autoload extensions (entity registries + pathfinder ref),
  Pawn carry slot + visual, world.tscn/gd wiring, the Tree rename, the
  draw_colored_polygon fix, the dirty-set-clear fix, MCP-driven runtime
  verification including the full chop-mine-haul loop and the priority
  cascade demo.

~75% of Phase 4's GDScript was subagent-authored.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scenes/ai/chop_provider.gd

@@ -0,0 +1,49 @@
+class_name ChopProvider extends WorkProvider
+## WorkProvider for the "chop" work category.
+##
+## Scans World.trees for the nearest choppable Tree (Manhattan distance from
+## the requesting pawn) and returns a two-toil Job:
+##   walk_to(tree.tile) → interact(tree.get_path(), "on_chop_tick")
+##
+## The INTERACT toil calls Tree.on_chop_tick() once per sim tick; the Tree
+## internally tracks chop_progress and calls fell() when CHOP_TICKS is
+## reached.  The toil finishes automatically when is_choppable() returns
+## false (felled) or when the node is freed.
+##
+## Phase 4 simplification: trees do not block pathfinding, so walking directly
+## to tree.tile is valid.  No adjacency-offset needed.
+##
+## Duck-typing note: Tree is referenced without class_name (class may not be
+## registered yet when this provider loads).  We rely only on:
+##   tree.tile: Vector2i
+##   tree.is_choppable() -> bool
+##   tree.get_path() -> NodePath
+
+
+func _init() -> void:
+	category = &"chop"
+	priority = 5  # Higher than rest (priority 0); scanned before it by Decision.
+
+
+## Returns a Job targeting the nearest choppable Tree, or null if none exists.
+## `pawn` is duck-typed: must expose .tile (Vector2i).
+func find_best_for(pawn) -> Job:
+	var best = null
+	var best_dist: int = 999999
+
+	for tree in World.trees:
+		if not tree.is_choppable():
+			continue
+		var d: int = abs(tree.tile.x - pawn.tile.x) + abs(tree.tile.y - pawn.tile.y)
+		if d < best_dist:
+			best_dist = d
+			best = tree
+
+	if best == null:
+		return null
+
+	var j := Job.new()
+	j.label = "Chop tree at %s" % best.tile
+	j.toils.append(Toil.walk_to(best.tile))
+	j.toils.append(Toil.interact(best.get_path(), &"on_chop_tick"))
+	return j

scenes/ai/chop_provider.gd.uid

@@ -0,0 +1 @@
+uid://b5wgnawgoqy1v

scenes/ai/hauling_provider.gd

@@ -0,0 +1,148 @@
+class_name HaulingProvider extends WorkProvider
+## WorkProvider for the Hauling work category. Slots into the 5-layer pawn AI
+## (Decision → WorkProvider → Job + JobRunner) as layer 2.
+##
+## Each call to find_best_for(pawn) scans World.items_needing_haul for the
+## item closest to `pawn` that has a valid, reachable destination, then builds
+## a 4-toil haul job: walk → pickup → walk → deposit.
+##
+## sweep_for_better_destinations() is a periodic helper (called by World every
+## ~100 sim ticks) that marks items in lower-priority destinations dirty when a
+## higher-priority destination has space — enabling the "items flow upward"
+## priority cascade described in design.md.
+##
+## Pawn is intentionally duck-typed (no class_name reference) to match the
+## WorkProvider convention and avoid init-order issues.
+##
+## See docs/architecture.md "HaulingProvider".
+
+
+func _init() -> void:
+	category = &"haul"
+	# Priority 3 — below chop (5) and mine (4); above rest (1).
+	# Adjusted once the full 9-category matrix is authored in Phase 17.
+	priority = 3
+
+
+# ── WorkProvider override ─────────────────────────────────────────────────────
+
+## Returns a haul Job for `pawn`, or null if no valid work exists.
+## Picks the item closest to `pawn` (Manhattan distance) that has an open
+## slot in the highest-priority destination accepting its type.
+## Phase 4 simplification: one carry at a time — skip if pawn is already holding something.
+func find_best_for(pawn) -> Job:
+	# One carry at a time — skip if the pawn is already holding an item.
+	if pawn.get("carried_item") != null:
+		return null
+
+	var best_item = null
+	var best_dest = null
+	var best_drop_cell: Vector2i = Vector2i(-1, -1)
+	var best_dist: int = 999999
+
+	for item in World.items_needing_haul.keys():
+		# Skip items another pawn is already carrying.
+		if item.being_carried:
+			continue
+
+		# Find the best destination for this item type + priority.
+		var dest = _find_best_destination_for(item)
+		if dest == null:
+			continue
+
+		var drop: Vector2i = dest.find_drop_position(item)
+		if drop == Vector2i(-1, -1):
+			continue
+
+		# Skip an item that is already sitting in the destination we'd haul it to.
+		# Avoids pointless re-haul of an item that is exactly where it should be.
+		# (Phase 16 refines this once the item→destination link is persisted.)
+		var current_dest = _destination_for_tile(item.tile)
+		if current_dest != null and current_dest == dest:
+			continue
+
+		# Nearest-first heuristic (pawn → item only).
+		var d: int = abs(item.tile.x - pawn.tile.x) + abs(item.tile.y - pawn.tile.y)
+		if d < best_dist:
+			best_dist = d
+			best_item = item
+			best_dest = dest
+			best_drop_cell = drop
+
+	if best_item == null:
+		return null
+
+	var j := Job.new()
+	j.label = "Haul %s x%d -> (%d,%d)" % [
+		best_item.item_type,
+		best_item.stack_size,
+		best_drop_cell.x,
+		best_drop_cell.y,
+	]
+	j.toils.append(Toil.walk_to(best_item.tile))
+	j.toils.append(Toil.pickup())
+	j.toils.append(Toil.walk_to(best_drop_cell))
+	j.toils.append(Toil.deposit())
+	return j
+
+
+# ── priority cascade ──────────────────────────────────────────────────────────
+
+## Periodic sweep (called by World every ~100 sim ticks).
+## Walks all items NOT already in the dirty set and marks them dirty when:
+##   (a) they are loose on the floor with no destination covering their tile, OR
+##   (b) they are in a stockpile but a higher-priority destination now has room.
+## Returns the count of newly marked items (logged when > 0).
+## This is the mechanism that makes "items flow up" to Critical stockpiles.
+func sweep_for_better_destinations() -> int:
+	var count: int = 0
+	for item in World.items:
+		if item.being_carried:
+			continue
+		# Already flagged — HaulingProvider will handle it.
+		if World.items_needing_haul.has(item):
+			continue
+
+		var current = _destination_for_tile(item.tile)
+		var best = _find_best_destination_for(item)
+
+		if current == null and best != null:
+			# Loose item with a valid destination — mark it.
+			World.items_needing_haul[item] = true
+			count += 1
+		elif current != null and best != null:
+			# Item is stored, but a better destination exists.
+			if int(best.priority) < int(current.priority):
+				World.items_needing_haul[item] = true
+				count += 1
+
+	if count > 0:
+		Audit.log("hauling", "sweep marked %d items for re-haul" % count)
+	return count
+
+
+# ── private helpers ───────────────────────────────────────────────────────────
+
+## Returns the highest-priority StorageDestination that accepts `item` and has
+## at least one open slot. Among equal-priority destinations, first found wins.
+## Returns null when no destination qualifies.
+func _find_best_destination_for(item):
+	var best = null
+	for dest in World.stockpiles:
+		if not dest.accepts(item):
+			continue
+		if dest.find_drop_position(item) == Vector2i(-1, -1):
+			continue
+		# Lower enum int = higher priority (CRITICAL=0 beats HIGH=1).
+		if best == null or int(dest.priority) < int(best.priority):
+			best = dest
+	return best
+
+
+## Returns the StorageDestination whose region contains `tile`, or null if the
+## tile is not inside any registered destination.
+func _destination_for_tile(tile: Vector2i):
+	for dest in World.stockpiles:
+		if dest.covers_tile(tile):
+			return dest
+	return null

scenes/ai/hauling_provider.gd.uid

@@ -0,0 +1 @@
+uid://6mkqd2t286tn

scenes/ai/job_runner.gd

@@ -91,6 +91,12 @@ func tick() -> void:
 			_tick_wait(t)
 		Toil.KIND_IDLE:
 			pass  # Never completes on its own — Decision or player overrides.
+		Toil.KIND_INTERACT:
+			_tick_interact(t)
+		Toil.KIND_PICKUP:
+			_tick_pickup(t)
+		Toil.KIND_DEPOSIT:
+			_tick_deposit(t)
 
 	if t.done:
 		job.advance()
@@ -173,6 +179,109 @@ func _tick_wait(t) -> void:
 		t.done = true
 
 
+## Execute one tick of an INTERACT toil.
+##
+## First tick: resolve the target node from the stored NodePath string.
+## If the target is gone or freed, log and skip immediately (done=true).
+## Otherwise mark started and log the action start.
+##
+## Every subsequent tick: call tick_method on the target.  After the call,
+## check whether the target has been consumed (is_choppable/is_mineable
+## returns false, or the node was freed).  If so, mark done.
+func _tick_interact(t) -> void:
+	var target_path := NodePath(t.data.get("target", ""))
+	var target = get_tree().get_root().get_node_or_null(target_path)
+
+	if not t.data.get("started", false):
+		if target == null or not is_instance_valid(target):
+			Audit.log(
+				"job_runner",
+				"%s interact target gone — skipping" % pawn.pawn_name
+			)
+			t.done = true
+			return
+		t.data["started"] = true
+		Audit.log(
+			"job_runner",
+			"%s interact start: %s.%s" % [pawn.pawn_name, target.name, t.data.get("tick_method", "")]
+		)
+
+	# Re-resolve each tick in case the node was freed between ticks.
+	target = get_tree().get_root().get_node_or_null(target_path)
+	if target == null or not is_instance_valid(target):
+		t.done = true
+		return
+
+	target.call(StringName(t.data.get("tick_method", "")))
+
+	# Re-check validity after the call (the call may have freed the node).
+	if target == null or not is_instance_valid(target):
+		t.done = true
+		return
+	if target.has_method("is_choppable") and not target.is_choppable():
+		Audit.log("job_runner", "%s interact done: %s chopped" % [pawn.pawn_name, target.name])
+		t.done = true
+		return
+	if target.has_method("is_mineable") and not target.is_mineable():
+		Audit.log("job_runner", "%s interact done: %s mined" % [pawn.pawn_name, target.name])
+		t.done = true
+
+
+## Execute one tick of a PICKUP toil.
+##
+## Finds the first unheld Item at pawn.tile in World.items.
+## Transfers it into pawn.carried_item via set_being_carried(true).
+## Completes in a single tick.
+func _tick_pickup(t) -> void:
+	var item = null
+	for it in World.items:
+		if it.tile == pawn.tile and not it.being_carried:
+			item = it
+			break
+	if item == null:
+		Audit.log(
+			"job_runner",
+			"%s pickup: no item at %s" % [pawn.pawn_name, pawn.tile]
+		)
+		t.done = true
+		return
+	pawn.carried_item = item
+	item.set_being_carried(true)
+	Audit.log(
+		"job_runner",
+		"%s pickup: %s ×%d" % [pawn.pawn_name, item.item_type, item.stack_size]
+	)
+	t.done = true
+
+
+## Execute one tick of a DEPOSIT toil.
+##
+## Places pawn.carried_item at pawn.tile (pixel-centred in the 16 px grid).
+## Clears pawn.carried_item. Completes in a single tick.
+func _tick_deposit(t) -> void:
+	if pawn.carried_item == null:
+		Audit.log(
+			"job_runner",
+			"%s deposit: nothing to deposit" % pawn.pawn_name
+		)
+		t.done = true
+		return
+	var item = pawn.carried_item
+	item.tile = pawn.tile
+	item.position = Vector2(pawn.tile.x * 16 + 8, pawn.tile.y * 16 + 8)
+	item.set_being_carried(false)
+	pawn.carried_item = null
+	# Phase 4: clear the haul-dirty flag — item has landed at its destination.
+	# The periodic sweep_for_better_destinations will re-mark it if a higher-
+	# priority destination opens up later.
+	World.clear_item_haul_flag(item)
+	Audit.log(
+		"job_runner",
+		"%s deposit: %s ×%d at %s" % [pawn.pawn_name, item.item_type, item.stack_size, pawn.tile]
+	)
+	t.done = true
+
+
 # ── helpers ──────────────────────────────────────────────────────────────────
 
 ## Emit job_completed, log, and clear the job reference.

scenes/ai/mine_provider.gd

@@ -0,0 +1,50 @@
+class_name MineProvider extends WorkProvider
+## WorkProvider for the "mine" work category.
+##
+## Scans World.rocks for the nearest mineable Rock (Manhattan distance from
+## the requesting pawn) and returns a two-toil Job:
+##   walk_to(rock.tile) → interact(rock.get_path(), "on_mine_tick")
+##
+## The INTERACT toil calls Rock.on_mine_tick() once per sim tick; the Rock
+## internally tracks mine_progress and handles removal when MINE_TICKS is
+## reached.  The toil finishes automatically when is_mineable() returns
+## false (exhausted) or when the node is freed.
+##
+## Phase 4 simplification: rocks are assumed walkable during mining approach
+## (they may block movement in a later phase once obstruction is added to the
+## pathfinder).
+##
+## Duck-typing note: Rock is referenced without class_name (class may not be
+## registered yet when this provider loads).  We rely only on:
+##   rock.tile: Vector2i
+##   rock.is_mineable() -> bool
+##   rock.get_path() -> NodePath
+
+
+func _init() -> void:
+	category = &"mine"
+	priority = 4  # Slightly lower than chop (5); both higher than rest (0).
+
+
+## Returns a Job targeting the nearest mineable Rock, or null if none exists.
+## `pawn` is duck-typed: must expose .tile (Vector2i).
+func find_best_for(pawn) -> Job:
+	var best = null
+	var best_dist: int = 999999
+
+	for rock in World.rocks:
+		if not rock.is_mineable():
+			continue
+		var d: int = abs(rock.tile.x - pawn.tile.x) + abs(rock.tile.y - pawn.tile.y)
+		if d < best_dist:
+			best_dist = d
+			best = rock
+
+	if best == null:
+		return null
+
+	var j := Job.new()
+	j.label = "Mine rock at %s" % best.tile
+	j.toils.append(Toil.walk_to(best.tile))
+	j.toils.append(Toil.interact(best.get_path(), &"on_mine_tick"))
+	return j

scenes/ai/mine_provider.gd.uid

@@ -0,0 +1 @@
+uid://dgnufybspp1ja

scenes/ai/toil.gd

@@ -13,6 +13,9 @@ class_name Toil extends RefCounted
 const KIND_WALK: StringName = &"walk"
 const KIND_WAIT: StringName = &"wait"
 const KIND_IDLE: StringName = &"idle"
+const KIND_INTERACT: StringName = &"interact"  # Timed action on a target entity (Tree, Rock, …)
+const KIND_PICKUP: StringName = &"pickup"       # Transfer Item at pawn.tile into pawn.carried_item
+const KIND_DEPOSIT: StringName = &"deposit"     # Place pawn.carried_item at pawn.tile
 
 var kind: StringName = KIND_IDLE
 ## Toil-specific params — all values must be int, float, bool, String, Dict, or Array.
@@ -51,6 +54,41 @@ static func idle() -> Toil:
 	return t
 
 
+## Timed action on a scene-node target (Tree, Rock, …).
+## `target_node_path` is the NodePath of the entity; stored as String for JSON safety.
+## `tick_method` is the method to call each sim tick (e.g. "on_chop_tick").
+## JobRunner resolves the node at first-tick and calls tick_method every sim tick
+## until the target is no longer choppable/mineable (method source sets done via
+## is_choppable() / is_mineable() returning false).
+static func interact(target_node_path: NodePath, tick_method: StringName) -> Toil:
+	var t := Toil.new()
+	t.kind = KIND_INTERACT
+	t.data = {
+		"target": String(target_node_path),
+		"tick_method": String(tick_method),
+		"started": false,
+	}
+	return t
+
+
+## Pick up an Item at pawn.tile into pawn.carried_item. Single-tick action.
+## data is empty — the item is located at pawn.tile at execution time.
+static func pickup() -> Toil:
+	var t := Toil.new()
+	t.kind = KIND_PICKUP
+	t.data = {}
+	return t
+
+
+## Place pawn.carried_item at pawn.tile. Single-tick action.
+## data is empty — the item comes from pawn.carried_item at execution time.
+static func deposit() -> Toil:
+	var t := Toil.new()
+	t.kind = KIND_DEPOSIT
+	t.data = {}
+	return t
+
+
 # ── save / load ──────────────────────────────────────────────────────────────
 
 func to_dict() -> Dictionary:

scenes/entities/item.gd

@@ -0,0 +1,151 @@
+## Dropped item entity — a single stack of one item type lying on the world floor.
+##
+## Visuals are drawn procedurally via _draw() (Phase 4 placeholder). Real
+## ElvGames item icons land in Phase 5+.
+##
+## Item type constants mirror the 16 filter chips in docs/design.md. They are
+## used by StockpileZone filter bitmasks and pawn-carry typing.
+##
+## World registration (World.register_item / World.unregister_item) is called
+## here but the methods land in World during Opus integration. The script will
+## parse cleanly; the call will fail at runtime until then.
+
+class_name Item extends Node2D
+
+const TILE_SIZE_PX: int = 16
+
+# ── canonical type registry — matches docs/design.md "16 filter chips" ───────
+
+const TYPE_WOOD: StringName       = &"wood"         # Wd
+const TYPE_STONE: StringName      = &"stone"        # St
+const TYPE_IRON_ORE: StringName   = &"iron_ore"     # Ir
+const TYPE_COPPER_ORE: StringName = &"copper_ore"   # Cu
+const TYPE_SILVER: StringName     = &"silver"       # Ag
+const TYPE_GOLD: StringName       = &"gold"         # Au
+const TYPE_CLOTH: StringName      = &"cloth"        # Cl
+const TYPE_VEGETABLE: StringName  = &"vegetable"    # Veg
+const TYPE_MEAT: StringName       = &"meat"         # Mt
+const TYPE_GRAIN: StringName      = &"grain"        # Gr
+const TYPE_MEAL: StringName       = &"meal"         # Ck (cooked)
+const TYPE_MEDICINE: StringName   = &"medicine"     # Md
+const TYPE_TOOL: StringName       = &"tool"         # Tl
+const TYPE_WEAPON: StringName     = &"weapon"       # Wp
+const TYPE_ARMOR: StringName      = &"armor"        # Ar
+const TYPE_CORPSE: StringName     = &"corpse"       # Co
+
+const ALL_TYPES: Array[StringName] = [
+	TYPE_WOOD, TYPE_STONE, TYPE_IRON_ORE, TYPE_COPPER_ORE,
+	TYPE_SILVER, TYPE_GOLD, TYPE_CLOTH, TYPE_VEGETABLE,
+	TYPE_MEAT, TYPE_GRAIN, TYPE_MEAL, TYPE_MEDICINE,
+	TYPE_TOOL, TYPE_WEAPON, TYPE_ARMOR, TYPE_CORPSE,
+]
+
+# ── state ────────────────────────────────────────────────────────────────────
+
+@export var item_type: StringName = TYPE_WOOD
+@export var stack_size: int = 1
+
+var tile: Vector2i = Vector2i.ZERO
+
+## When true the on-floor visual is suppressed; the carrying pawn renders the
+## carry indicator instead.
+var being_carried: bool = false
+
+
+# ── lifecycle ─────────────────────────────────────────────────────────────────
+
+func _ready() -> void:
+	position = _tile_to_world(tile)
+	visible = not being_carried
+
+
+func _exit_tree() -> void:
+	World.unregister_item(self)
+
+
+# ── public API ────────────────────────────────────────────────────────────────
+
+## One-shot initialiser called by the spawning code (Tree.fell, Rock.mined, etc.)
+## Sets all fields, syncs position, and registers with World.
+func setup(p_type: StringName, p_stack: int, p_tile: Vector2i) -> void:
+	item_type = p_type
+	stack_size = p_stack
+	tile = p_tile
+	position = _tile_to_world(tile)
+	visible = not being_carried
+	queue_redraw()
+	World.register_item(self)
+	Audit.log("item", "spawned %s×%d at %s" % [item_type, stack_size, tile])
+
+
+## Hide/show the on-floor sprite when the pawn picks up or drops this item.
+func set_being_carried(value: bool) -> void:
+	being_carried = value
+	visible = not being_carried
+
+
+# ── save / load ───────────────────────────────────────────────────────────────
+
+func to_dict() -> Dictionary:
+	return {
+		"type": String(item_type),
+		"stack_size": stack_size,
+		"tile_x": tile.x,
+		"tile_y": tile.y,
+	}
+
+
+## Returns a plain Dictionary spec for World.load_items() to instantiate from.
+## Items cannot reconstruct themselves standalone — they need a parent in the
+## scene tree. World adds the node, then calls setup() from the returned dict.
+static func from_dict(d: Dictionary) -> Dictionary:
+	return {
+		"type": StringName(d.get("type", "wood")),
+		"stack_size": int(d.get("stack_size", 1)),
+		"tile_x": int(d.get("tile_x", 0)),
+		"tile_y": int(d.get("tile_y", 0)),
+	}
+
+
+# ── render ────────────────────────────────────────────────────────────────────
+
+func _draw() -> void:
+	# 12×12 coloured square centered on the tile; colour hashed from item_type.
+	var hue := float(item_type.hash() % 360) / 360.0
+	var fill := Color.from_hsv(hue, 0.6, 0.85)
+	var half: int = 6
+	var square := Rect2(Vector2(-half, -half), Vector2(half * 2, half * 2))
+
+	draw_rect(square, fill)
+	draw_rect(square, Color(0.0, 0.0, 0.0, 0.75), false, 1.0)
+
+	# Stack count badge — bottom-right corner of the square, font_size 7.
+	if stack_size > 1:
+		var label := Strings.t(&"item.stack_count").format({"n": stack_size})
+		draw_string(
+			ThemeDB.fallback_font,
+			Vector2(half - 1, half - 1),
+			label,
+			HORIZONTAL_ALIGNMENT_RIGHT,
+			-1,
+			7,
+			Color(0.0, 0.0, 0.0, 0.6)  # drop-shadow offset below
+		)
+		draw_string(
+			ThemeDB.fallback_font,
+			Vector2(half - 2, half - 2),
+			label,
+			HORIZONTAL_ALIGNMENT_RIGHT,
+			-1,
+			7,
+			Color(1.0, 1.0, 1.0, 1.0)
+		)
+
+
+# ── helpers ───────────────────────────────────────────────────────────────────
+
+func _tile_to_world(t: Vector2i) -> Vector2:
+	return Vector2(
+		t.x * TILE_SIZE_PX + TILE_SIZE_PX / 2.0,
+		t.y * TILE_SIZE_PX + TILE_SIZE_PX / 2.0
+	)

scenes/entities/item.gd.uid

@@ -0,0 +1 @@
+uid://576k8p7pk4xx

scenes/entities/item.tscn

@@ -0,0 +1,6 @@
+[gd_scene load_steps=2 format=3 uid="uid://item_entity"]
+
+[ext_resource type="Script" path="res://scenes/entities/item.gd" id="1_item"]
+
+[node name="Item" type="Node2D"]
+script = ExtResource("1_item")

scenes/entities/rock.gd

@@ -0,0 +1,147 @@
+## Rock entity — mineable by a pawn with a Mine job. Drops a stone Item node
+## when mined out.
+##
+## Mirrors Tree's chopping model; stone is harder so MINE_TICKS is longer.
+## A MineProvider (Opus, Phase 4) creates a Job whose INTERACT toil calls
+## on_mine_tick() once per sim tick via JobRunner.
+##
+## World registration (World.register_rock / World.unregister_rock) is called
+## here but the methods land in World during Opus integration.
+
+class_name Rock extends Node2D
+
+const TILE_SIZE_PX: int = 16
+
+## Sim ticks to mine a rock at 1× speed (120 ticks = 6 sim seconds at 20 Hz).
+## Stone is harder than wood — MINE_TICKS > Tree.CHOP_TICKS.
+const MINE_TICKS: int = 120
+## Stone Items dropped on a successful mine.
+const STONE_DROPS_ON_MINE: int = 1
+
+# ── state ─────────────────────────────────────────────────────────────────────
+
+var tile: Vector2i = Vector2i.ZERO
+## 0..MINE_TICKS. Advanced by on_mine_tick(); rock is mined when equal to MINE_TICKS.
+var mine_progress: int = 0
+
+# Preloaded scene for spawned stone items.
+const ITEM_SCENE: PackedScene = preload("res://scenes/entities/item.tscn")
+
+
+# ── lifecycle ─────────────────────────────────────────────────────────────────
+
+func _ready() -> void:
+	position = _tile_to_world(tile)
+	World.register_rock(self)
+
+
+func _exit_tree() -> void:
+	World.unregister_rock(self)
+
+
+# ── public API ────────────────────────────────────────────────────────────────
+
+## One-shot initialiser. Call after add_child() so _ready() already fired.
+func setup(start_tile: Vector2i) -> void:
+	tile = start_tile
+	mine_progress = 0
+	position = _tile_to_world(tile)
+	queue_redraw()
+	Audit.log("rock", "spawned at %s" % tile)
+
+
+## True when the rock hasn't been fully mined yet.
+func is_mineable() -> bool:
+	return mine_progress < MINE_TICKS
+
+
+## Called by the INTERACT toil in JobRunner once per sim tick while the pawn
+## works this rock. Advances mine_progress and triggers mined() when complete.
+func on_mine_tick() -> void:
+	if not is_mineable():
+		return
+	mine_progress += 1
+	queue_redraw()
+	if mine_progress >= MINE_TICKS:
+		mined()
+
+
+## Drop stone Item(s) and free this node. Called automatically by on_mine_tick()
+## but also accessible for scripted removal (debug, storyteller events).
+func mined() -> void:
+	# Single drop lands on the rock's own tile.
+	var item: Item = ITEM_SCENE.instantiate()
+	get_parent().add_child(item)
+	item.setup(Item.TYPE_STONE, 1, tile)
+	Audit.log("rock", "mined at %s; %d stone drop" % [tile, STONE_DROPS_ON_MINE])
+	queue_free()
+
+
+# ── save / load ───────────────────────────────────────────────────────────────
+
+func to_dict() -> Dictionary:
+	return {
+		"tile_x": tile.x,
+		"tile_y": tile.y,
+		"mine_progress": mine_progress,
+	}
+
+
+static func from_dict(d: Dictionary) -> Dictionary:
+	return {
+		"tile_x": int(d.get("tile_x", 0)),
+		"tile_y": int(d.get("tile_y", 0)),
+		"mine_progress": int(d.get("mine_progress", 0)),
+	}
+
+
+# ── render ────────────────────────────────────────────────────────────────────
+
+func _draw() -> void:
+	# Angular cluster of 3–4 triangles in a dark-grey / light-grey palette.
+	var c1 := Color(0.55, 0.55, 0.50)   # light face
+	var c2 := Color(0.38, 0.38, 0.36)   # shadow face
+
+	# Main body polygon (roughly an irregular hex).
+	var body := PackedVector2Array([
+		Vector2(-5.0, 3.0),
+		Vector2(-6.0, -1.0),
+		Vector2(-2.0, -6.0),
+		Vector2(3.0, -5.0),
+		Vector2(6.0, 0.0),
+		Vector2(4.0, 4.0),
+	])
+	draw_colored_polygon(body, c1)
+
+	# Shadow face on the bottom-right triangle to give depth.
+	var shadow := PackedVector2Array([
+		Vector2(3.0, -5.0),
+		Vector2(6.0, 0.0),
+		Vector2(4.0, 4.0),
+		Vector2(-5.0, 3.0),
+	])
+	draw_colored_polygon(shadow, c2)
+
+	# Outline.
+	draw_polyline(body, Color(0.0, 0.0, 0.0, 0.5), 1.0)
+	draw_line(body[5], body[0], Color(0.0, 0.0, 0.0, 0.5), 1.0)
+
+	# Mine-progress crack: a dark jagged line on the face when partially mined.
+	if mine_progress > 0:
+		var ratio := float(mine_progress) / float(MINE_TICKS)
+		var crack_len := ratio * 5.0
+		draw_line(
+			Vector2(-1.0, -2.0),
+			Vector2(-1.0 + crack_len, 1.0),
+			Color(0.15, 0.12, 0.10, 0.85),
+			1.5
+		)
+
+
+# ── helpers ───────────────────────────────────────────────────────────────────
+
+func _tile_to_world(t: Vector2i) -> Vector2:
+	return Vector2(
+		t.x * TILE_SIZE_PX + TILE_SIZE_PX / 2.0,
+		t.y * TILE_SIZE_PX + TILE_SIZE_PX / 2.0
+	)

scenes/entities/rock.gd.uid

@@ -0,0 +1 @@
+uid://dpy14o4grgsgt

scenes/entities/rock.tscn

@@ -0,0 +1,6 @@
+[gd_scene load_steps=2 format=3 uid="uid://rock_entity"]
+
+[ext_resource type="Script" path="res://scenes/entities/rock.gd" id="1_rock"]
+
+[node name="Rock" type="Node2D"]
+script = ExtResource("1_rock")

scenes/entities/tree.gd

@@ -0,0 +1,162 @@
+## Tree entity — choppable by a pawn with a Chop job. Drops wood Item nodes
+## when felled.
+##
+## Chopping model (docs/implementation.md Phase 4):
+##   A ChopProvider creates a Job whose INTERACT toil calls on_chop_tick() once
+##   per sim tick via JobRunner. After CHOP_TICKS ticks the tree is felled.
+##
+## World registration (World.register_tree / World.unregister_tree) is called
+## here but the methods land in World during Opus integration.
+
+class_name HarvestableTree extends Node2D
+## NOTE: class_name is HarvestableTree because Godot 4 ships a built-in `Tree`
+## Control node — using "Tree" would shadow that. Filename / scene name stay
+## as `tree` because the game-side concept is still just "tree".
+
+const TILE_SIZE_PX: int = 16
+
+## Sim ticks to fell a tree at 1× speed (80 ticks = ~4 sim seconds at 20 Hz).
+const CHOP_TICKS: int = 80
+## Number of separate wood Item nodes dropped on fell.
+const WOOD_DROPS_ON_FELL: int = 3
+## Stack size per dropped Item (Phase 4 simplicity: 3 items of stack 1 each).
+const STACK_SIZE_PER_DROP: int = 1
+
+# ── state ─────────────────────────────────────────────────────────────────────
+
+var tile: Vector2i = Vector2i.ZERO
+## 0..CHOP_TICKS. Advanced by on_chop_tick(); tree is felled when equal to CHOP_TICKS.
+var chop_progress: int = 0
+
+# Preloaded scene for spawned wood items.
+const ITEM_SCENE: PackedScene = preload("res://scenes/entities/item.tscn")
+
+
+# ── lifecycle ─────────────────────────────────────────────────────────────────
+
+func _ready() -> void:
+	position = _tile_to_world(tile)
+	World.register_tree(self)
+
+
+func _exit_tree() -> void:
+	World.unregister_tree(self)
+
+
+# ── public API ────────────────────────────────────────────────────────────────
+
+## One-shot initialiser. Call after add_child() so _ready() already fired.
+func setup(start_tile: Vector2i) -> void:
+	tile = start_tile
+	chop_progress = 0
+	position = _tile_to_world(tile)
+	queue_redraw()
+	Audit.log("tree", "spawned at %s" % tile)
+
+
+## True when the tree hasn't been fully chopped yet.
+func is_choppable() -> bool:
+	return chop_progress < CHOP_TICKS
+
+
+## Called by the INTERACT toil in JobRunner once per sim tick while the pawn
+## works this tree. Advances chop_progress and fells the tree when complete.
+func on_chop_tick() -> void:
+	if not is_choppable():
+		return
+	chop_progress += 1
+	queue_redraw()
+	if chop_progress >= CHOP_TICKS:
+		fell()
+
+
+## Drop wood Items and free this node. Called by on_chop_tick() automatically,
+## but also accessible for scripted felling (debug, storyteller events).
+func fell() -> void:
+	var drop_tiles := _pick_drop_tiles()
+	var drops_count := 0
+	for drop_tile in drop_tiles:
+		var item: Item = ITEM_SCENE.instantiate()
+		get_parent().add_child(item)
+		item.setup(Item.TYPE_WOOD, STACK_SIZE_PER_DROP, drop_tile)
+		drops_count += 1
+	Audit.log("tree", "felled at %s; %d wood drops" % [tile, drops_count])
+	queue_free()
+
+
+# ── save / load ───────────────────────────────────────────────────────────────
+
+func to_dict() -> Dictionary:
+	return {
+		"tile_x": tile.x,
+		"tile_y": tile.y,
+		"chop_progress": chop_progress,
+	}
+
+
+static func from_dict(d: Dictionary) -> Dictionary:
+	return {
+		"tile_x": int(d.get("tile_x", 0)),
+		"tile_y": int(d.get("tile_y", 0)),
+		"chop_progress": int(d.get("chop_progress", 0)),
+	}
+
+
+# ── render ────────────────────────────────────────────────────────────────────
+
+func _draw() -> void:
+	# Brown trunk: small filled rect at centre-bottom (~4 wide × 6 tall).
+	var trunk_color := Color(0.45, 0.28, 0.12)
+	draw_rect(Rect2(Vector2(-2.0, 1.0), Vector2(4.0, 6.0)), trunk_color)
+
+	# Green canopy: large filled circle centered near the top.
+	var canopy_color := Color(0.22, 0.60, 0.18)
+	draw_circle(Vector2(0.0, -3.0), 7.0, canopy_color)
+
+	# Canopy outline.
+	draw_arc(Vector2(0.0, -3.0), 7.0, 0.0, TAU, 24, Color(0.0, 0.0, 0.0, 0.4), 1.0)
+
+	# Chop-progress wedge: a dark angled line on the trunk when partially chopped.
+	if chop_progress > 0:
+		var ratio := float(chop_progress) / float(CHOP_TICKS)
+		var notch_depth := ratio * 3.0
+		draw_line(
+			Vector2(-2.0, 2.0 + notch_depth),
+			Vector2(2.0, 2.0),
+			Color(0.15, 0.08, 0.02, 0.9),
+			1.5
+		)
+
+
+# ── helpers ───────────────────────────────────────────────────────────────────
+
+## Returns up to WOOD_DROPS_ON_FELL tile positions for wood drops.
+## Prefers the tree's own tile then walkable 4-neighbours; falls back to the
+## tree tile for any remaining drops when neighbours are scarce.
+func _pick_drop_tiles() -> Array[Vector2i]:
+	var chosen: Array[Vector2i] = []
+
+	# First drop always goes on the tree's tile itself.
+	chosen.append(tile)
+
+	# Remaining drops prefer walkable neighbours.
+	var offsets: Array[Vector2i] = [Vector2i(1, 0), Vector2i(-1, 0), Vector2i(0, 1), Vector2i(0, -1)]
+	for offset in offsets:
+		if chosen.size() >= WOOD_DROPS_ON_FELL:
+			break
+		var candidate: Vector2i = tile + offset
+		if World.pathfinder != null and World.pathfinder.is_walkable(candidate):
+			chosen.append(candidate)
+
+	# Fill any remaining slots with the tree tile (all 3 land there if boxed in).
+	while chosen.size() < WOOD_DROPS_ON_FELL:
+		chosen.append(tile)
+
+	return chosen
+
+
+func _tile_to_world(t: Vector2i) -> Vector2:
+	return Vector2(
+		t.x * TILE_SIZE_PX + TILE_SIZE_PX / 2.0,
+		t.y * TILE_SIZE_PX + TILE_SIZE_PX / 2.0
+	)

scenes/entities/tree.gd.uid

@@ -0,0 +1 @@
+uid://cpg0v8f6hajgi

scenes/entities/tree.tscn

@@ -0,0 +1,6 @@
+[gd_scene load_steps=2 format=3 uid="uid://tree_entity"]
+
+[ext_resource type="Script" path="res://scenes/entities/tree.gd" id="1_tree"]
+
+[node name="Tree" type="Node2D"]
+script = ExtResource("1_tree")

scenes/pawn/pawn.gd

@@ -42,6 +42,11 @@ var forced_job = null
 # can be paired with the pathfinder). May be null in tests / pre-Phase-3 scenes.
 var job_runner = null
 
+# Phase 4 — carry slot for hauling. Holds an Item node while carrying; null
+# when empty-handed. PICKUP toil sets this; DEPOSIT clears it. One stack /
+# one type at a time per design.md.
+var carried_item = null
+
 var _path: Array[Vector2i] = []
 var _step_progress: float = 0.0
 var _selected: bool = false
@@ -142,6 +147,9 @@ func from_dict(d: Dictionary) -> void:
 func _on_sim_tick(_tick_number: int) -> void:
 	_orchestrate_ai()
 	_advance_walk()
+	# Phase 4 — the carry indicator changes when PICKUP/DEPOSIT toils mutate
+	# carried_item directly. Cheapest reliable redraw hook is here.
+	queue_redraw()
 
 
 func _orchestrate_ai() -> void:
@@ -201,6 +209,13 @@ func _draw() -> void:
 	if _selected:
 		draw_arc(Vector2.ZERO, 10.0, 0.0, TAU, 32, Color(1.0, 0.9, 0.2, 0.85), 2.0)
 
+	# Phase 4 — carry indicator: small coloured square at upper-right of body.
+	if carried_item != null:
+		var ci_hue := float(carried_item.item_type.hash() % 360) / 360.0
+		var ci_color := Color.from_hsv(ci_hue, 0.6, 0.85)
+		draw_rect(Rect2(6, -10, 7, 7), ci_color)
+		draw_rect(Rect2(6, -10, 7, 7), Color(0, 0, 0, 0.7), false, 1.0)
+
 
 # ── helpers ─────────────────────────────────────────────────────────────────
 

scenes/world/stockpile_zone.gd

@@ -0,0 +1,96 @@
+class_name StockpileZone extends StorageDestination
+## Concrete floor stockpile zone. A rectangular region (in tile coords) that
+## accepts items matching the filter and deposits them one-per-tile.
+##
+## Rendered as a translucent priority-tinted overlay via _draw(). The overlay
+## is always visible — Phase 17 will toggle it when the Zones panel is open.
+## z_index = -1 keeps the tint below items (z_index 0) and pawns.
+##
+## Register/unregister with World.stockpiles happen automatically in
+## _ready / _exit_tree — no external wiring needed.
+##
+## One-stack-per-tile, one-type-per-tile rule (design.md).
+##
+## See docs/architecture.md "StockpileZone".
+
+## Region in tile coordinates. (0,0) relative to this node's map position;
+## in practice this node lives at world origin so region is in world-tile space.
+@export var region: Rect2i = Rect2i(0, 0, 4, 4)
+
+## Player-visible label shown in zone inspect UI (Phase 17).
+@export var label: String = "Stockpile"
+
+## Pixel size of one tile — must match World.TILE_SIZE_PX.
+const _TILE_PX: int = 16
+
+## Priority-keyed fill colors for the overlay (Color(r, g, b, a)).
+const _PRIORITY_COLORS: Dictionary = {
+	StorageDestination.Priority.CRITICAL: Color(0.9, 0.3, 0.3, 0.15),
+	StorageDestination.Priority.HIGH:     Color(0.9, 0.6, 0.3, 0.15),
+	StorageDestination.Priority.NORMAL:   Color(0.9, 0.9, 0.3, 0.12),
+	StorageDestination.Priority.LOW:      Color(0.3, 0.9, 0.3, 0.10),
+	StorageDestination.Priority.OFF:      Color(0.3, 0.3, 0.3, 0.10),
+}
+
+
+func _ready() -> void:
+	z_index = -1
+	World.register_stockpile(self)
+	queue_redraw()
+
+
+func _exit_tree() -> void:
+	World.unregister_stockpile(self)
+
+
+# ── StorageDestination overrides ─────────────────────────────────────────────
+
+func accepts(item) -> bool:
+	return _filter_accepts(item)
+
+
+func covers_tile(tile: Vector2i) -> bool:
+	return region.has_point(tile)
+
+
+## Scan region cells in row-major order; return the first tile not occupied by
+## an item that is not being carried. Returns Vector2i(-1, -1) if the zone is
+## full or the item fails the filter.
+func find_drop_position(item) -> Vector2i:
+	if not accepts(item):
+		return Vector2i(-1, -1)
+	for x in range(region.position.x, region.position.x + region.size.x):
+		for y in range(region.position.y, region.position.y + region.size.y):
+			var cell := Vector2i(x, y)
+			if _is_cell_free(cell):
+				return cell
+	return Vector2i(-1, -1)
+
+
+# ── drawing ───────────────────────────────────────────────────────────────────
+
+func _draw() -> void:
+	var fill_color: Color = _PRIORITY_COLORS.get(priority, Color(0.5, 0.5, 0.5, 0.12))
+	var border_color := Color(fill_color.r, fill_color.g, fill_color.b, 0.6)
+	var tile_px := float(_TILE_PX)
+
+	# Filled rectangle covering the entire region.
+	var rect_px := Rect2(
+		Vector2(region.position) * tile_px,
+		Vector2(region.size) * tile_px
+	)
+	draw_rect(rect_px, fill_color, true)
+
+	# 1-px border outline.
+	draw_rect(rect_px, border_color, false, 1.0)
+
+
+# ── internal helpers ──────────────────────────────────────────────────────────
+
+## Returns true when no un-carried item is sitting on `cell`.
+## One-stack-per-tile rule: the first occupied, non-carried item blocks the cell.
+func _is_cell_free(cell: Vector2i) -> bool:
+	for it in World.items:
+		if it.tile == cell and not it.being_carried:
+			return false
+	return true

scenes/world/stockpile_zone.gd.uid

@@ -0,0 +1 @@
+uid://cws7im713niq4

scenes/world/stockpile_zone.tscn

@@ -0,0 +1,7 @@
+[gd_scene load_steps=2 format=3 uid="uid://stockpile_zone"]
+
+[ext_resource type="Script" path="res://scenes/world/stockpile_zone.gd" id="1_stockpile"]
+
+[node name="StockpileZone" type="Node2D"]
+script = ExtResource("1_stockpile")
+z_index = -1

scenes/world/storage_destination.gd

@@ -0,0 +1,73 @@
+class_name StorageDestination extends Node2D
+## Abstract base for all item-storage destinations (floor stockpile zones,
+## containers, etc.). Hauling AI treats all subclasses as a unified candidate
+## pool via this interface.
+##
+## StorageDestination extends Node2D (not Node) so subclasses can implement
+## _draw() for priority-tinted overlays without a separate CanvasItem child.
+##
+## Subclasses MUST override: accepts(), find_drop_position(), covers_tile().
+## Subclasses SHOULD call World.register_stockpile(self) in _ready() and
+## World.unregister_stockpile(self) in _exit_tree().
+##
+## See docs/architecture.md "Storage destinations: a unified concept".
+
+## Five priority levels matching Rimworld semantics (design.md Priorities).
+## Lower enum int = higher priority (CRITICAL = 0 pulls before LOW = 4).
+## Priority.OFF = no hauling in or out; invisible to HaulingProvider.
+enum Priority {
+	CRITICAL = 0,
+	HIGH     = 1,
+	NORMAL   = 2,
+	LOW      = 3,
+	OFF      = 4,
+}
+
+## Priority determines whether haulers will fill this destination and whether
+## items here will be re-hauled upward to a higher-priority destination.
+@export var priority: Priority = Priority.NORMAL
+
+## Item types this destination accepts. Empty array = wildcard (accepts all).
+## Each entry is a StringName matching Item.TYPE_* constants (e.g. &"wood").
+@export var accepted_types: Array[StringName] = []
+
+## Emitted when items are registered or unregistered with this destination,
+## so interested parties (UI, re-scan logic) can react without polling.
+signal contents_changed
+
+
+# ── abstract interface — subclasses must override ────────────────────────────
+
+## Returns true if this destination currently accepts `item` (filter + priority
+## check + any capacity logic owned by the subclass).
+func accepts(item) -> bool:
+	push_error("StorageDestination.accepts: '%s' must override this method" % name)
+	return false
+
+
+## Returns a tile coordinate inside this destination where `item` can be
+## placed (filter-pass AND the tile is not already occupied by another item).
+## Returns Vector2i(-1, -1) when no slot is available.
+func find_drop_position(item) -> Vector2i:
+	push_error("StorageDestination.find_drop_position: '%s' must override this method" % name)
+	return Vector2i(-1, -1)
+
+
+## Returns true if `tile` falls inside this destination's region.
+## Used by HaulingProvider to find which destination currently holds an item.
+func covers_tile(tile: Vector2i) -> bool:
+	push_error("StorageDestination.covers_tile: '%s' must override this method" % name)
+	return false
+
+
+# ── shared helper ────────────────────────────────────────────────────────────
+
+## Priority-and-filter gate, shared by all subclasses.
+## Returns false when OFF or when the item's type is not in accepted_types.
+## accepted_types.is_empty() is the wildcard "accept any type" case.
+func _filter_accepts(item) -> bool:
+	if priority == Priority.OFF:
+		return false
+	if accepted_types.is_empty():
+		return true
+	return item.item_type in accepted_types

scenes/world/storage_destination.gd.uid

@@ -0,0 +1 @@
+uid://f7rilcintvg2

scenes/world/world.gd

@@ -1,11 +1,8 @@
 extends Node2D
-## Phase 2 world view. 80×80 TileMap with 6 layers, 3 sample pawns, pathfinder,
-## click-to-select / click-to-move selection.
-##
-## Real ElvGames art lands in Phase 5+ (wood walls custom-authored on
-## FG_Houses, stone walls autotiled from FG_Fortress per the 2026-05-10
-## audit lock). The procedural placeholder tileset is enough to prove the
-## TileMap pipeline + pawn movement + camera + pathfinding end-to-end.
+## Phase 4 world view. 80×80 TileMap, 6 layers, 3 pawns, full AI pipeline:
+##   RestProvider → ChopProvider → MineProvider → HaulingProvider → idle
+## plus sample trees, rocks, and two stockpile zones with different priorities
+## for the haul-cascade demo.
 ##
 ## TileMap layer indices follow docs/architecture.md:
 ##   0 Terrain · 1 Floor · 2 Wall · 3 Designation · 4 Roof · 5 Fog
@@ -13,8 +10,6 @@ extends Node2D
 const MAP_SIZE_TILES: Vector2i = Vector2i(80, 80)
 const TILE_SIZE_PX: int = 16
 
-# Atlas coords inside the placeholder tileset (one source, source_id = 0).
-# Real assets in Phase 5 will use multiple atlas sources.
 const TILE_GRASS: Vector2i = Vector2i(0, 0)
 const TILE_DIRT: Vector2i = Vector2i(1, 0)
 const TILE_STONE: Vector2i = Vector2i(2, 0)
@@ -23,6 +18,9 @@ const TILE_STONE_DARK: Vector2i = Vector2i(3, 0)
 const PLACEHOLDER_SOURCE_ID: int = 0
 
 const PAWN_SCENE: PackedScene = preload("res://scenes/pawn/pawn.tscn")
+const TREE_SCENE: PackedScene = preload("res://scenes/entities/tree.tscn")
+const ROCK_SCENE: PackedScene = preload("res://scenes/entities/rock.tscn")
+const STOCKPILE_SCENE: PackedScene = preload("res://scenes/world/stockpile_zone.tscn")
 
 # 3 starting pawns — Phase 2 demo. Phase 7+ replaces this with map-gen + name table.
 const SAMPLE_PAWNS: Array[Dictionary] = [
@@ -31,6 +29,18 @@ const SAMPLE_PAWNS: Array[Dictionary] = [
 	{"name": "Edda", "tile": Vector2i(30, 40)},
 ]
 
+# Phase 4 — sample harvestables. Trees clustered east, rocks south-east.
+const SAMPLE_TREES: Array[Vector2i] = [
+	Vector2i(58, 30), Vector2i(60, 31), Vector2i(62, 30),
+	Vector2i(61, 33), Vector2i(63, 34), Vector2i(59, 35),
+]
+const SAMPLE_ROCKS: Array[Vector2i] = [
+	Vector2i(60, 60), Vector2i(62, 60), Vector2i(63, 62), Vector2i(58, 62),
+]
+
+# HaulingProvider re-flow cadence — every 5 sim seconds at 1× (100 ticks).
+const HAUL_SWEEP_INTERVAL_TICKS: int = 100
+
 @onready var terrain_layer: TileMapLayer = $Terrain
 @onready var floor_layer: TileMapLayer = $Floor
 @onready var wall_layer: TileMapLayer = $Wall
@@ -40,10 +50,13 @@ const SAMPLE_PAWNS: Array[Dictionary] = [
 @onready var pathfinder: Pathfinder = $Pathfinder
 @onready var selection: Selection = $Selection
 @onready var rest_provider: RestProvider = $RestProvider
+@onready var chop_provider: ChopProvider = $ChopProvider
+@onready var mine_provider: MineProvider = $MineProvider
+@onready var hauling_provider: HaulingProvider = $HaulingProvider
 
 
 func _ready() -> void:
-	Audit.log("world", "Phase 3 — building %d×%d world + pawns + AI." % [MAP_SIZE_TILES.x, MAP_SIZE_TILES.y])
+	Audit.log("world", "Phase 4 — building %d×%d world + harvestables + AI." % [MAP_SIZE_TILES.x, MAP_SIZE_TILES.y])
 	var tileset := _build_placeholder_tileset()
 	for layer in [terrain_layer, floor_layer, wall_layer, designation_layer, roof_layer, fog_layer]:
 		layer.tile_set = tileset
@@ -54,12 +67,24 @@ func _ready() -> void:
 	pathfinder.setup(MAP_SIZE_TILES)
 	_wire_walls_to_pathfinder()
 	selection.bind(pathfinder)
+	World.pathfinder = pathfinder  # expose to entities (Tree.fell() walkability checks, etc.)
 
+	# Register all 4 providers — Decision iterates by .priority desc.
+	# chop=5 > mine=4 > haul=3 > rest=0.
+	World.register_work_provider(chop_provider)
+	World.register_work_provider(mine_provider)
+	World.register_work_provider(hauling_provider)
 	World.register_work_provider(rest_provider)
 
 	_spawn_sample_pawns()
+	_spawn_sample_harvestables()
+	_spawn_sample_stockpiles()
 	_run_pathfinder_spike()
 
+	# Phase 4: every 5 in-game seconds (100 ticks), re-evaluate items in
+	# stockpiles in case a higher-priority destination opened up.
+	EventBus.sim_tick.connect(_on_sim_tick_world_sweep)
+
 
 func world_bounds_px() -> Rect2:
 	return Rect2(Vector2.ZERO, Vector2(MAP_SIZE_TILES * TILE_SIZE_PX))
@@ -68,9 +93,8 @@ func world_bounds_px() -> Rect2:
 # ── tileset & map painting ──────────────────────────────────────────────────
 
 func _build_placeholder_tileset() -> TileSet:
-	# Four 16×16 placeholder tiles laid out as a 4×1 atlas. No PNG dependency
-	# — atlas built at runtime from a programmatic Image. Real ElvGames art
-	# replaces this when wood/stone wall variants are imported in Phase 5.
+	# Four 16×16 placeholder tiles laid out as a 4×1 atlas. Real ElvGames
+	# art replaces this in Phase 5 (wood walls + stone walls).
 	var ts := TileSet.new()
 	ts.tile_size = Vector2i(TILE_SIZE_PX, TILE_SIZE_PX)
 
@@ -110,8 +134,6 @@ func _paint_terrain() -> void:
 
 
 func _paint_sample_walls() -> void:
-	# An 8×8 stone ring near the map centre as a visual landmark + pathfinding
-	# obstacle so the demo proves pawns route around walls.
 	var origin := Vector2i(36, 36)
 	var size: int = 8
 	for i in size:
@@ -124,7 +146,6 @@ func _paint_sample_walls() -> void:
 # ── pathfinder + pawns ──────────────────────────────────────────────────────
 
 func _wire_walls_to_pathfinder() -> void:
-	# Wall cells block pathing. Re-runs on Phase 5 build/destroy events later.
 	var wall_cells := wall_layer.get_used_cells()
 	for cell in wall_cells:
 		pathfinder.set_cell_walkable(cell, false)
@@ -147,12 +168,59 @@ func _spawn_sample_pawns() -> void:
 		World.register_pawn(p)
 
 
+# ── Phase 4: harvestables + stockpile zones ─────────────────────────────────
+
+func _spawn_sample_harvestables() -> void:
+	# Untyped vars — Godot's class-name cache for class_name'd classes is
+	# scan-time and intermittently lags behind file changes. Duck typing is
+	# safer here and the calls below are all spec'd on the entity types.
+	for t_tile in SAMPLE_TREES:
+		var tree = TREE_SCENE.instantiate()
+		add_child(tree)
+		tree.setup(t_tile)
+	for r_tile in SAMPLE_ROCKS:
+		var rock = ROCK_SCENE.instantiate()
+		add_child(rock)
+		rock.setup(r_tile)
+	Audit.log("world", "spawned %d trees + %d rocks" % [SAMPLE_TREES.size(), SAMPLE_ROCKS.size()])
+
+
+func _spawn_sample_stockpiles() -> void:
+	# Two zones for the Phase 4 acceptance demo:
+	#   - Zone A (north): wood-only filter, NORMAL priority (just a wood drop)
+	#   - Zone B (south): wildcard, HIGH priority (the "watch wood flow upward" target)
+	# When the sweep runs, wood items in Zone A get re-marked for haul and
+	# eventually migrate to Zone B.
+	var zone_a: StockpileZone = STOCKPILE_SCENE.instantiate()
+	add_child(zone_a)
+	zone_a.region = Rect2i(15, 55, 4, 4)
+	zone_a.label = "Wood (Normal)"
+	zone_a.priority = StorageDestination.Priority.NORMAL
+	zone_a.accepted_types = [Item.TYPE_WOOD] as Array[StringName]
+	zone_a.queue_redraw()
+
+	var zone_b: StockpileZone = STOCKPILE_SCENE.instantiate()
+	add_child(zone_b)
+	zone_b.region = Rect2i(15, 62, 4, 4)
+	zone_b.label = "Anything (High)"
+	zone_b.priority = StorageDestination.Priority.HIGH
+	zone_b.accepted_types = [] as Array[StringName]  # wildcard
+	zone_b.queue_redraw()
+
+	Audit.log("world", "spawned 2 stockpiles: %s + %s" % [zone_a.label, zone_b.label])
+
+
+# ── periodic re-flow (the "wood floats up" cascade) ─────────────────────────
+
+func _on_sim_tick_world_sweep(tick_n: int) -> void:
+	if tick_n % HAUL_SWEEP_INTERVAL_TICKS != 0:
+		return
+	hauling_provider.sweep_for_better_destinations()
+
+
 # ── spike: AStarGrid2D query timing at 80² ──────────────────────────────────
 
 func _run_pathfinder_spike() -> void:
-	# Phase 2 acceptance spike (~30 min): "AStarGrid2D path-query timing at 80²
-	# with 6 pawns simultaneously requesting paths. Confirm sub-millisecond."
-	# We benchmark all 4-corner pairs × 3 iterations = 36 path queries.
 	var corners := [
 		Vector2i(2, 2),
 		Vector2i(MAP_SIZE_TILES.x - 3, 2),

scenes/world/world.tscn

@@ -1,10 +1,13 @@
-[gd_scene load_steps=6 format=3 uid="uid://rimlike_world"]
+[gd_scene load_steps=9 format=3 uid="uid://rimlike_world"]
 
 [ext_resource type="Script" path="res://scenes/world/world.gd" id="1_world"]
 [ext_resource type="PackedScene" uid="uid://rimlike_camera_rig" path="res://scenes/world/camera_rig.tscn" id="2_camera"]
 [ext_resource type="Script" path="res://scenes/world/pathfinder.gd" id="3_pathfinder"]
 [ext_resource type="Script" path="res://scenes/world/selection.gd" id="4_selection"]
 [ext_resource type="Script" path="res://scenes/ai/rest_provider.gd" id="5_rest_provider"]
+[ext_resource type="Script" path="res://scenes/ai/chop_provider.gd" id="6_chop_provider"]
+[ext_resource type="Script" path="res://scenes/ai/mine_provider.gd" id="7_mine_provider"]
+[ext_resource type="Script" path="res://scenes/ai/hauling_provider.gd" id="8_hauling_provider"]
 
 [node name="World" type="Node2D"]
 script = ExtResource("1_world")
@@ -39,5 +42,14 @@ script = ExtResource("4_selection")
 script = ExtResource("5_rest_provider")
 rest_tile = Vector2i(50, 50)
 
+[node name="ChopProvider" type="Node" parent="."]
+script = ExtResource("6_chop_provider")
+
+[node name="MineProvider" type="Node" parent="."]
+script = ExtResource("7_mine_provider")
+
+[node name="HaulingProvider" type="Node" parent="."]
+script = ExtResource("8_hauling_provider")
+
 [node name="CameraRig" parent="." instance=ExtResource("2_camera")]
 position = Vector2(640, 640)