Save Systems

What it does

When your agent uses it

• The user mentions save system
• Game state persistence
• Save file corruption
• Migrating old saves to a new version

Example prompts

• “/save-systems”

Requirements

• Python 3
• Compatibility (from SKILL.md): Engine-agnostic. Snippets in GDScript-like / Python pseudocode; pairs with Godot FileAccess/ResourceSaver, Unity serialization, or roblox-datastores.

Workflow steps

4 steps, taken from the step headings in SKILL.md.

1. 1Serialize state as plain data (not engine objects)
2. 2Atomic, crash-safe write (temp + rename)
3. 3Versioned load with migration
4. 4Save slots + throttled autosave

What it can do on your machine

Read from SKILL.md and the folder at commit fc215d4. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  No scripts in the folder and no shell commands in SKILL.md (its code samples are gdscript and python).

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md.

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

• Compatibility

  Engine-agnostic. Snippets in GDScript-like / Python pseudocode; pairs with Godot FileAccess/ResourceSaver, Unity serialization, or roblox-datastores.

  From compatibility in the SKILL.md frontmatter.

Context cost

Save Systems loads about 1.9k tokens when it runs, and up to ~2.9k if it reads all its reference files. Until then it costs about 87 tokens; SKILL.md has 581 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~87

When it runs · the whole SKILL.md, loaded when a task matches

~1.9k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~2.9k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from ukanwat/overtime at commit fc215d4, republished under its Apache-2.0 licence (© ukanwat). 581 words, ~1,891 tokens.

name

save-systems

description

Design save/load for game state — choosing what to serialize, file formats, save slots, atomic crash-safe writes, schema versioning and migration, and autosave. Engine-neutral. Use when the user mentions save system, save/load, game state persistence, save slots, autosave, save file corruption, or migrating old saves to a new version.

compatibility

Engine-agnostic. Snippets in GDScript-like / Python pseudocode; pairs with Godot FileAccess/ResourceSaver, Unity serialization, or roblox-datastores.

license

Apache-2.0

metadata.engine

none

metadata.category

disciplines

metadata.difficulty

intermediate

# Build a dictionary of pure data. Each savable object reports its own state.
func capture_state() -> Dictionary:
    return {
        "version": SAVE_VERSION,                 # ALWAYS stamp the schema version
        "player": { "hp": player.hp, "pos": [player.position.x, player.position.y] },
        "inventory": player.inventory.to_array(),  # ids + counts, not Item nodes
        "flags": world.flags,                    # e.g. {"met_guard": true}
        "seed": world.seed,                      # regenerate procedural content
    }

# On load, RECONSTRUCT objects from the data — do not expect live references back.
func apply_state(data: Dictionary) -> void:
    player.hp = data["player"]["hp"]
    player.position = Vector2(data["player"]["pos"][0], data["player"]["pos"][1])
    player.inventory.from_array(data["inventory"])
    world.flags = data["flags"]

# RIGHT: write to a temp file, then atomically rename over the target.
func save_atomic(path: String, data: Dictionary) -> void:
    var tmp := path + ".tmp"
    var f := FileAccess.open(tmp, FileAccess.WRITE)
    f.store_string(JSON.stringify(data))
    f.flush()                                    # ensure bytes hit disk
    f.close()
    DirAccess.rename_absolute(tmp, path)         # replaces the target; atomic on POSIX
# WRONG: opening `path` directly and writing in place — a crash mid-write leaves a
# truncated, unloadable save and destroys the player's progress.

SAVE_VERSION = 3

def load_save(raw_bytes):
    data = parse(raw_bytes)                  # JSON/binary -> dict
    v = data.get("version", 0)
    if v > SAVE_VERSION:
        raise NewerSaveError(v)              # save is from a newer build; refuse
    while v < SAVE_VERSION:                   # apply migrations in order, v -> v+1
        data = MIGRATIONS[v](data)
        v += 1
        data["version"] = v
    validate(data)                            # check required keys / ranges
    return data

# Each migration is a pure function from one version's shape to the next.
def migrate_1_to_2(d):
    d["flags"] = {k: True for k in d.pop("completed_quests", [])}  # list -> set-map
    return d
MIGRATIONS = {1: migrate_1_to_2, 2: migrate_2_to_3}

const SLOT_PATH := "user://save_%d.json"      # manual slots 0..N
const AUTOSAVE_PATH := "user://autosave.json"  # separate file: never clobbers a slot
var _autosave_cooldown := 0.0

func autosave_if_due(dt: float) -> void:
    _autosave_cooldown -= dt
    if _autosave_cooldown <= 0.0:
        save_atomic(AUTOSAVE_PATH, capture_state())
        _autosave_cooldown = 60.0             # throttle: at most once a minute
# Trigger an immediate autosave on checkpoints/level transitions, not mid-combat.

© ukanwat, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 1 other file (references) in .claude/skills/save-systems of ukanwat/overtime.

• SKILL.md
• references/versioning-and-migration.md

Open the folder on GitHubat commit fc215d4

Used in 1 other repository

We found 1 copy of this SKILL.md (exact, near-identical or edited) in other folders, from 1 other GitHub owner. This page covers the copy in ukanwat/overtime, which our catalogue first saw on October 7, 2026.

• gamedev-skills/awesome-gamedev-agent-skillsskills/disciplines/save-systems