Restore a safe checkpoint and inventory

Worked example

A validated save contains known scalar fields and a version. An array instead of a dictionary is syntactically valid JSON but should still be rejected by the schema. Scaffold C-WORLD-DATA — Consistent pickup/bed persistence with derived inventory Setup: Attach to a separate Node named WorldData. This is the default integrated Seed Station model after the scalar-save lab. Fixed pickup IDs are s1,s2,s3,w1,w2; fixed bed IDs are b1,b2. Manager records picked IDs only after a successful pickup and planted IDs only after validating both resource costs. Inventory is derived from these IDs, so reloading cannot keep quantities while respawning already-picked rewards. On load, hide/free picked objects, mark planted beds, set the known start/greenhouse marker, then refresh HUD. Version 1 scalar labs are intentionally not migrated: report a new-game fallback. ```gdscript extends Node const PATH: String = "user://seed_station_world_v2.json" func defaults() -> Dictionary: return {"version": 2, "picked": [], "planted": [], "seed": 0, "water": 0, "checkpoint": "start"} func _ids(raw: Variant, allowed: Array) -> Array[String]: var clean: Array[String] = [] if raw is Array: for value in raw: if value is String and value in allowed and value not in clean: clean.append(value) return clean func validate(raw: Variant) -> Dictionary: var result := defaults() if not raw is Dictionary: return result var data: Dictionary = raw if data.get("version", 0) != 2: return result var picked := _ids(data.get("picked", []), ["s1", "s2", "s3", "w1", "w2"]) var planted := _ids(data.get("planted", []), ["b1", "b2"]) var seed_total: int = 0 var water_total: int = 0 for id in picked: if id.begins_with("s"): seed_total += 1 else: water_total += 1 while planted.size() > mini(seed_total, water_total): planted.pop_back() result["picked"] = picked result["planted"] = planted result["seed"] = seed_total - planted.size() result["water"] = water_total - planted.size() result["checkpoint"] = "greenhouse" if "b1" in planted else "start" return result func save_data(raw: Dictionary) -> bool: var file := FileAccess.open(PATH, FileAccess.WRITE) if file == null: return false file.store_string(JSON.stringify(validate(raw))) file.close() return true func load_data() -> Dictionary: if not FileAccess.file_exists(PATH): return defaults() var file := FileAccess.open(PATH, FileAccess.READ) if file == null: return defaults() var text: String = file.get_as_text() file.close() var parser := JSON.new() if parser.parse(text) != OK: return defaults() return validate(parser.data) ``` Scaffold C-CHECKPOINT — A safe checkpoint respawn Setup: Add this pattern to a separate Node2D level root with child Player using C-PLATFORM. Call set_checkpoint with a safe global position when a player reaches a checkpoint Area2D; call respawn when entering a fall zone. This code does not connect Area2D automatically; select the area body_entered signal in editor and call these methods from its handler after checking the player group. Respawn is deferred because a physics callback may be active. ```gdscript extends Node2D @onready var player: CharacterBody2D = $Player var checkpoint: Vector2 func _ready() -> void: checkpoint = player.global_position func set_checkpoint(safe_position: Vector2) -> void: checkpoint = safe_position func respawn() -> void: _apply_respawn.call_deferred() func _apply_respawn() -> void: player.global_position = checkpoint player.velocity = Vector2.ZERO ``` Scaffold C-INVENTORY — Dictionary inventory with guarded spending Setup: Attach to Node InventoryLab for standalone testing. In a real level put the same functions on its inventory node and update UI after successful calls. Item IDs are short fixed strings, never a player’s name. A key represents one item type and its integer value is the quantity. ```gdscript extends Node var items: Dictionary = {"seed": 0, "water": 0} func add_item(id: String, amount: int = 1) -> bool: if not items.has(id) or amount <= 0: return false items[id] = int(items[id]) + amount return true func spend(id: String, amount: int = 1) -> bool: if not items.has(id) or amount <= 0 or int(items[id]) < amount: return false items[id] = int(items[id]) - amount return true func _ready() -> void: assert(add_item("seed", 2)) assert(spend("seed", 1)) assert(not spend("seed", 2)) assert(items["seed"] == 1) ```

Consistent pickup/bed persistence with derived inventory

GDScript (Godot 4, not Scratch, Python, JavaScript or C#). Scaffold C-WORLD-DATA. Copy starts from this text. The desk does not run it.

Scene and node setup

Attach to a separate Node named WorldData. This is the default integrated Seed Station model after the scalar-save lab. Fixed pickup IDs are s1,s2,s3,w1,w2; fixed bed IDs are b1,b2. Manager records picked IDs only after a successful pickup and planted IDs only after validating both resource costs. Inventory is derived from these IDs, so reloading cannot keep quantities while respawning already-picked rewards. On load, hide/free picked objects, mark planted beds, set the known start/greenhouse marker, then refresh HUD. Version 1 scalar labs are intentionally not migrated: report a new-game fallback.

extends Node
const PATH: String = "user://seed_station_world_v2.json"
func defaults() -> Dictionary:
    return {"version": 2, "picked": [], "planted": [], "seed": 0, "water": 0, "checkpoint": "start"}
func _ids(raw: Variant, allowed: Array) -> Array[String]:
    var clean: Array[String] = []
    if raw is Array:
        for value in raw:
            if value is String and value in allowed and value not in clean:
                clean.append(value)
    return clean
func validate(raw: Variant) -> Dictionary:
    var result := defaults()
    if not raw is Dictionary:
        return result
    var data: Dictionary = raw
    if data.get("version", 0) != 2:
        return result
    var picked := _ids(data.get("picked", []), ["s1", "s2", "s3", "w1", "w2"])
    var planted := _ids(data.get("planted", []), ["b1", "b2"])
    var seed_total: int = 0
    var water_total: int = 0
    for id in picked:
        if id.begins_with("s"):
            seed_total += 1
        else:
            water_total += 1
    while planted.size() > mini(seed_total, water_total):
        planted.pop_back()
    result["picked"] = picked
    result["planted"] = planted
    result["seed"] = seed_total - planted.size()
    result["water"] = water_total - planted.size()
    result["checkpoint"] = "greenhouse" if "b1" in planted else "start"
    return result
func save_data(raw: Dictionary) -> bool:
    var file := FileAccess.open(PATH, FileAccess.WRITE)
    if file == null:
        return false
    file.store_string(JSON.stringify(validate(raw)))
    file.close()
    return true
func load_data() -> Dictionary:
    if not FileAccess.file_exists(PATH):
        return defaults()
    var file := FileAccess.open(PATH, FileAccess.READ)
    if file == null:
        return defaults()
    var text: String = file.get_as_text()
    file.close()
    var parser := JSON.new()
    if parser.parse(text) != OK:
        return defaults()
    return validate(parser.data)

Checks to run in the editor

• Picked s1,s2,w1 and planted b1 yields seed1,water0,greenhouse.
• Duplicate s1 entries do not add extra inventory.
• No collected IDs plus two planted IDs cleans to no planted beds.
• Reload removes collected pickups and restores planted-bed state through the manager.

Native Godot 4.7.2.stable.official.ed1daf0bf headless compile and representative node-tree/runtime tests passed; see native-qa-results.json. Visual UI, audible output, exports and website submission still need separate checks.

A safe checkpoint respawn

GDScript (Godot 4, not Scratch, Python, JavaScript or C#). Scaffold C-CHECKPOINT. Copy starts from this text. The desk does not run it.

Scene and node setup

Add this pattern to a separate Node2D level root with child Player using C-PLATFORM. Call set_checkpoint with a safe global position when a player reaches a checkpoint Area2D; call respawn when entering a fall zone. This code does not connect Area2D automatically; select the area body_entered signal in editor and call these methods from its handler after checking the player group. Respawn is deferred because a physics callback may be active.

extends Node2D
@onready var player: CharacterBody2D = $Player
var checkpoint: Vector2
func _ready() -> void:
    checkpoint = player.global_position
func set_checkpoint(safe_position: Vector2) -> void:
    checkpoint = safe_position
func respawn() -> void:
    _apply_respawn.call_deferred()
func _apply_respawn() -> void:
    player.global_position = checkpoint
    player.velocity = Vector2.ZERO

Checks to run in the editor

• A fall returns to last safe point, not origin.
• Player has no leftover falling velocity on return.

Native Godot 4.7.2.stable.official.ed1daf0bf headless compile and representative node-tree/runtime tests passed; see native-qa-results.json. Visual UI, audible output, exports and website submission still need separate checks.

Dictionary inventory with guarded spending

GDScript (Godot 4, not Scratch, Python, JavaScript or C#). Scaffold C-INVENTORY. Copy starts from this text. The desk does not run it.

Scene and node setup

Attach to Node InventoryLab for standalone testing. In a real level put the same functions on its inventory node and update UI after successful calls. Item IDs are short fixed strings, never a player’s name. A key represents one item type and its integer value is the quantity.

extends Node
var items: Dictionary = {"seed": 0, "water": 0}
func add_item(id: String, amount: int = 1) -> bool:
    if not items.has(id) or amount <= 0:
        return false
    items[id] = int(items[id]) + amount
    return true
func spend(id: String, amount: int = 1) -> bool:
    if not items.has(id) or amount <= 0 or int(items[id]) < amount:
        return false
    items[id] = int(items[id]) - amount
    return true
func _ready() -> void:
    assert(add_item("seed", 2))
    assert(spend("seed", 1))
    assert(not spend("seed", 2))
    assert(items["seed"] == 1)

Checks to run in the editor

• Spending more than owned returns false and does not change inventory.
• Unknown IDs and nonpositive amounts are rejected.

Native Godot 4.7.2.stable.official.ed1daf0bf headless compile and representative node-tree/runtime tests passed; see native-qa-results.json. Visual UI, audible output, exports and website submission still need separate checks.

Restore a safe checkpoint and inventory — evidence task

1. 1. Integrate C-WORLD-DATA and restore collected pickup IDs, planted bed IDs, derived inventory and the approved checkpoint marker.
2. 2. Collect s1,s2,w1, plant b1, save, stop and relaunch. Verify seed1/water0, b1 planted, and the three collected pickups absent.

Deliverable. Integrated save checkpoint, schema amendment if needed, and relaunch test.

Acceptance checks

• VGC-L114-T1. After the specified relaunch: seed1, water0, b1 planted, and s1/s2/w1 absent.
• VGC-L114-T2. A remaining pickup awards once; reloading cannot award an already-picked ID again.

Understanding question. Why can restoring inventory alone duplicate resources?

Include a downloadable project ZIP with project.godot, .tscn, .gd and original asset files when code changes. A private, teacher-accessible download link to that ZIP is equivalent. Screenshots or a playthrough do not replace editable source.

If this is still shaky. Use the course-specific save filenames in C-SAVE and C-STATE-SAVE. Never edit unrelated game saves or load scripts from save data. Start with the first assigned task and re-run its acceptance test before adding the remaining feature.

Optional extra. Add a new fixed scalar field with a safe default and explicit validation. Document one changed parameter, your prediction, and the observed effect; optional, not required for completion.

• Godot step by step: nodes, scenes, GDScript, input, signals

  Free public documentation, no account. Same class help is available within the desktop editor.

  · Opening this link does not submit the lesson.
• Saving games: FileAccess and JSON

  Free public documentation, no account.

  · Opening this link does not submit the lesson.