Marker Command Engine - Macro-free Command Framework

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A trusted command runtime/dependency framework for datapacks. Not designed as a sandbox. Use only with trusted packs and operators.

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Marker Command Engine is a lightweight command execution engine for Minecraft datapacks. It runs commands stored in NBT storage using a marker entity + command block technique, with full LanternLoad integration for reliable load ordering.

Features

• Execute commands stored in storage mce:cmd
• No macros required — compatible with Minecraft 1.19.3+
• Low performance impact
• Clean public API (mce:api/*) — internal functions are private
• Batch & Queue system
• MCE-managed scheduler (replaces /schedule, preserves entity context)
• Per-player cooldown system — macro-free, scoreboard-based
• Run at fixed world coordinates — execute commands from any integer coordinate
• Announce system — title, subtitle, and actionbar in a single call
• Structured log system — write/show/clear with severity levels
• Version query API — check MCE version from storage at runtime
• LanternLoad integrated — other packs can depend on MCE with guaranteed load order
• Versioned API (load.status score for dependency checks)

Requirements

• Minecraft 1.19.3+ (pack_format 10+)
• mce:api/cooldown/check requires 1.20.2+ (return command)
• LanternLoad is bundled — no separate installation needed

Installation

1. Download the latest release zip.
2. Place the marker-command-engine folder into your world's datapacks/ folder.
3. Run /reload.
4. You should see [MCE] Marker Command Engine v2.2.0 loaded! in chat.

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Usage

Run a Command

data modify storage mce:cmd Command set value "say Hello World!"
function mce:api/run/cmd

Run as Entity

# Tag the target entity first
tag @a[name=Steve,limit=1] add mce.executor

# Set the command and call
data modify storage mce:cmd Command set value "execute as @a[tag=mce.executor] run say I am Steve!"
function mce:api/run/as
# mce.executor tag is removed automatically

Run at Coordinates

# Execute a command from a fixed world position
data modify storage mce:cmd Command set value "say Hello from coords!"
data modify storage mce:cmd AtX set value 0
data modify storage mce:cmd AtY set value 64
data modify storage mce:cmd AtZ set value 0
function mce:api/run/at

All three coordinates (AtX, AtY, AtZ) must be set before calling. Values are integers.

Queue

data modify storage mce:cmd Command set value "say First!"
function mce:api/queue/add
data modify storage mce:cmd Command set value "say Second!"
function mce:api/queue/add
function mce:api/queue/run

Batch

data modify storage mce:batch commands set value ["say One","say Two","say Three"]
function mce:api/batch/run

Schedule

# Replaces /schedule
data modify storage mce:cmd Command set value "say Delayed!"
data modify storage mce:cmd Delay set value 40
function mce:api/schedule/run

Cooldown

# Set a 5-second (100 tick) cooldown on @s
data modify storage mce:cd Ticks set value 100
function mce:api/cooldown/set

# Check before running a command (requires 1.20.2+)
execute as @s if function mce:api/cooldown/check run function ns:your/action

# Get remaining ticks
execute as @s run function mce:api/cooldown/get
# Result -> mce:output Cooldown.remaining

# Clear cooldown immediately
function mce:api/cooldown/clear

Announce

# Send title, subtitle, and/or actionbar in a single call.
# All three keys are optional — omit any to skip that slot.
data modify storage mce:announce Title set value "Welcome!"
data modify storage mce:announce Subtitle set value "Enjoy your stay."
data modify storage mce:announce Actionbar set value "Server online"
function mce:api/util/announce

With custom timing (call before announce):

# Presets: fast (5/30/5), normal (10/70/20), slow (20/100/20), instant (0/40/0)
data modify storage mce:announce_times Preset set value "fast"
function mce:api/util/announce_times

data modify storage mce:announce Title set value "Go!"
function mce:api/util/announce

Log

# Write an entry using level shorthands (recommended)
data modify storage mce:log_write msg set value "Player joined the arena."
function mce:api/log/info   # severity 0 — white

data modify storage mce:log_write msg set value "Cooldown nearly expired."
function mce:api/log/warn   # severity 1 — yellow

data modify storage mce:log_write msg set value "Command failed."
function mce:api/log/error  # severity 2 — red

# Or set lvl manually and call write
data modify storage mce:log_write msg set value "Custom entry."
data modify storage mce:log_write lvl set value 1
function mce:api/log/write

# Show all entries to @s (colored by level)
function mce:api/log/show

# Clear all entries
function mce:api/log/clear

The log holds the last 64 entries. Older entries are dropped automatically. Each entry is stored as {n: <int>, lvl: <0|1|2>, msg: "<string>"}.

Version

# Prints version to chat and writes to storage.
function mce:api/util/version
# mce:output Version.string  -> "2.2.0"
# mce:output Version.numeric -> 2002000

Help

function mce:api/util/help

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Public API

Only mce:api/* functions are part of the public API. All mce:core/* functions are private and may change without notice.

mce:api/run/

Function	Description
mce:api/run/cmd	Execute command from mce:cmd Command immediately
mce:api/run/as	Execute as tagged entities (mce.executor tag + mce:cmd Command)
mce:api/run/at	Execute command from fixed coordinates (mce:cmd AtX/AtY/AtZ)

mce:api/queue/

Function	Description
mce:api/queue/add	Add mce:cmd Command to queue
mce:api/queue/run	Start executing the queue (one command per 3 ticks)
mce:api/queue/clear	Clear queue without executing

mce:api/schedule/

Function	Description
mce:api/schedule/run	Schedule command after mce:cmd Delay ticks (minimum: 1)
mce:api/schedule/clear	Cancel all pending scheduled jobs

mce:api/batch/

Function	Description
mce:api/batch/run	Add mce:batch commands list to queue and run
mce:api/batch/clear	Clear batch staging area without queuing

mce:api/cooldown/

Function	Min Version	Description
mce:api/cooldown/set	1.19.3+	Set cooldown ticks for @s from mce:cd Ticks
mce:api/cooldown/check	1.20.2+	Returns 1 if @s is ready, 0 if on cooldown
mce:api/cooldown/clear	1.19.3+	Clear cooldown for @s immediately
mce:api/cooldown/get	1.19.3+	Write remaining ticks to mce:output Cooldown.remaining

mce:api/log/

Function	Description
mce:api/log/write	Append entry from mce:log_write {msg, lvl}
mce:api/log/info	Shorthand: write with lvl=0 (INFO)
mce:api/log/warn	Shorthand: write with lvl=1 (WARN)
mce:api/log/error	Shorthand: write with lvl=2 (ERROR)
mce:api/log/show	Print all entries to @s (colored by level)
mce:api/log/clear	Clear all entries and reset counter

mce:api/util/

Function	Description
mce:api/util/announce	Send title/subtitle/actionbar from mce:announce storage
mce:api/util/announce_times	Set title timing preset from mce:announce_times Preset
mce:api/util/version	Print MCE version and write to mce:output Version
mce:api/util/cancel	Abort active command execution (does not affect queue)
mce:api/util/debug_toggle	Toggle debug output on/off
mce:api/util/help	Print usage in chat
mce:api/util/broadcast	Send message to all players from mce:broadcast {Msg, Prefix}
mce:api/util/error_clear	Reset mce:error state and counter

mce:api/util/log and mce:api/util/log_clear are deprecated — use mce:api/log/* instead.

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Depending on MCE (LanternLoad)

To make your pack load after MCE, add your load function to #load:post_load and verify the version score:

// data/yourpack/tags/function/post_load.json
{
    "values": ["yourpack:load"]
}

# yourpack:load
# Require MCE v2.2.0+ (score format: major*1000000 + minor*1000 + patch)
execute unless score mce load.status matches 2002000.. run tellraw @a {"text":"[YourPack] ERROR: MCE v2.2.0+ required!","color":"red"}
execute unless score mce load.status matches 2002000.. run return 0

# Your init here...

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Technical Details

• Marker tag: mce.cmd
• Command block position: 0 -64 0
• Reset delay: 3 ticks after execution
• Queue interval: 3 ticks between commands
• Version score: mce load.status = 2002000 (v2.2.0)

Storage Reference

Storage	Key	Type	Description
mce:cmd	Command	String	Command to execute
mce:cmd	Delay	Int	Delay in ticks for schedule/run (min: 1)
mce:cmd	AtX	Int	X coordinate for run/at
mce:cmd	AtY	Int	Y coordinate for run/at
mce:cmd	AtZ	Int	Z coordinate for run/at
mce:cd	Ticks	Int	Cooldown duration in ticks for cooldown/set
mce:queue	commands	List	Pending queue commands
mce:batch	commands	List	Batch staging area
mce:schedule	jobs	List	Scheduled job list
mce:config	mce.debug	Byte	Debug mode flag (1b = on)
mce:config	mce.version	String	MCE version string
mce:announce	Title	String	Title text for util/announce
mce:announce	Subtitle	String	Subtitle text for util/announce
mce:announce	Actionbar	String	Actionbar text for util/announce
mce:announce_times	Preset	String	Timing preset: fast normal slow instant
mce:log_write	msg	String	Message to write (input for log/write)
mce:log_write	lvl	Int	Severity level: 0=INFO 1=WARN 2=ERROR
mce:log	entries	List	Log entries: {n, lvl, msg} (max 64)
mce:broadcast	Msg	String	Message text for util/broadcast
mce:broadcast	Prefix	String	Optional prefix for util/broadcast
mce:output	Cooldown.ready	Byte	1b if @s is ready, 0b if on cooldown
mce:output	Cooldown.remaining	Int	Remaining cooldown ticks
mce:output	Version.string	String	MCE version string (e.g. "2.2.0")
mce:output	Version.numeric	Int	MCE version as int (e.g. 2002000)
mce:error	Last	String	Last error message
mce:error	Code	String	Last error code (e.g. ERR_NO_CMD)
mce:error	Count	Int	Total error count since load

Scoreboard Reference

Objective	Description
mce.queue	Queue state and error counter
mce.tick	Internal tick counters
mce.compat	Compat system flags
mce.cd	Per-player cooldown (remaining ticks, 0 = ready)
mce.log	Log entry counter and size tracking

Note: mce:cmd Executor is no longer used. Tag your target entity with mce.executor before calling mce:api/run/as.

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Changelog

v2.2.0

• Added mce:api/log/write — structured log entries {n, lvl, msg}, 64-entry cap
• Added mce:api/log/info / log/warn / log/error — level shorthands
• Added mce:api/log/show — level-colored tellraw output, macro-free
• Added mce:api/log/clear — clears entries and resets counter
• Added mce:api/util/error_clear — resets error state and counter
• Added missing function tags for api/run/at, api/util/announce, announce_times, version, api/multi/run
• Deprecated mce:api/util/log and util/log_clear (compat wrappers kept)
• Added mce.log scoreboard objective

v2.1.0

• Added mce:api/multi/run — execute title, subtitle, actionbar, message, and commands in a single call
• Added mce:api/util/broadcast — send a message to all players from storage
• Added mce:api/util/log — append command string to in-memory audit log

v2.0.0

• Added mce:api/run/at — execute commands from fixed world coordinates
• Added mce:api/util/announce — send title, subtitle, actionbar in one call
• Added mce:api/util/announce_times — configure title timing via presets
• Added mce:api/util/version — query MCE version at runtime
• Updated mce:api/util/help with all new APIs
• Bumped LanternLoad version score to 2000000

v1.1.0

• Initial public release

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License

MIT License — free to use, modify, and distribute.