Saddle — Minecraft Datapack Debugger

Saddle: A Datapack Debugger for Live Editing

Debug datapack .mcfunction files in VS Code through the Saddle Fabric mod: put a saddle on your datapack's execution — stop it, back it up, and steer it while it runs.

Requirements

• Minecraft 26.2 with Fabric Loader, Fabric API and the Saddle mod installed. Start a world/server; Saddle listens on 127.0.0.1:16352 (-Dsaddle.host / -Dsaddle.port to change).

Usage

1. Open your datapack workspace (any layout containing data/<ns>/function/*.mcfunction).
2. Set breakpoints in .mcfunction files — plain commands and macro ($...) lines are breakable; breakpoints on comments/blank lines shift to the next executable line.
3. Run and Debug → Attach to Minecraft (Saddle) (or press F5 in a .mcfunction file), launch.json:

{
	"type": "saddle",
	"request": "attach",
	"name": "Attach to Minecraft (Saddle)",
	"host": "127.0.0.1",
	"port": 16352
}

4. Trigger the function in game (/function ..., tick functions, …) or from the Debug Console, which runs real Minecraft commands — also while stopped at a breakpoint.

While stopped you get the call stack, stepping (over/into/out), pause, and live scopes per frame — Executor (position/rotation/dimension plus the executing entity's editable NBT tree), Macro Arguments ($(...) values of the current macro frame), Command (the pending command with its selectors resolved to matched entities and coordinate triples resolved to blocks), Scoreboard (editable scores) and Storage (editable NBT) — edit values directly in the Variables view.

Features

• Hover: point at $(name), @e[...] or coordinate triples (1 2 3, ~ ~2 ~) in .mcfunction files while stopped to see the value / matched entities / targeted block inline.
• Watch & pin: the WATCH panel accepts @e[type=pig], storage <id> [path], entity <uuid> [path], block <x> <y> <z> [path], score <objective> <holder> and $(macroArg) — each re-resolves at every stop and expands into live (editable) trees. Saddle: Watch Expression (Pin to Variables) pins the same expressions as a persistent Watched scope in the Variables view; Saddle: Unpin Watched Expression removes them.
• Debug Console autocomplete: command input is completed by the server's own Brigadier suggestions, like in-game chat. (VS Code does not support syntax highlighting for console input.)
• Chat mirroring: everything shown in the in-game chat — /say broadcasts, player chat, /tellraw//msg deliveries — streams into the Debug Console while attached.
• Time travel: while stopped, the Step Back and Reverse Continue toolbar buttons walk backwards through the recorded execution. The editor highlights the past command, the call stack is reconstructed for that moment, and the Scoreboard (recorded) / Storage (recorded) scopes show the values as they were right before that command ran. Stepping forward replays the recording to the present; Continue past the recording resumes the live game. Saddle: Show Execution Trace prints the recent command history.

Commands (palette)

• Saddle: Run Minecraft Command
• Saddle: Show Scoreboard / Saddle: Set Scoreboard Score
• Saddle: List Entities
• Saddle: Get NBT Data / Saddle: Set NBT Data (storage / entity / block)
• Saddle: Inspect Block
• Saddle: Watch Expression (Pin to Variables) / Saddle: Unpin Watched Expression
• Saddle: Show Execution Trace

Install from source

cd vscode-extension
npx --yes @vscode/vsce package --allow-missing-repository   # produces saddle-debug-<version>.vsix
code --install-extension saddle-debug-*.vsix

Or open vscode-extension/ in VS Code and press F5 to try it in an Extension Development Host.