Marker Command Engine - Macro-free Command Framework

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

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.

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

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.

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...

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.

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

License

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