Command line

The sgf tool reads saves and scenarios from a terminal and applies edits to them. It is on the Releases page beside the app. System ids are the numbers shown as #123 in the app. sgf --help lists every command, and sgf <command> --help its options.

sgf inspect game.sav --galaxy prints the save's header and counts its systems, lanes and nebulae. It changes nothing.

Commands

• Read a file: inspect, validate, details, special, special-layouts, gamedata. special-layouts lists the layouts a system can be rerolled from, and how many systems in the save already use each. shape and roundtrip check a save's structure: shape lists every key path with its count, and roundtrip writes the save out unchanged.
• Make a scenario: export-scenario <sav> <out> and new-scenario <name> <out>. Add --profile paint-a-galaxy to write it for Paint a Galaxy.
• Prepare a scenario for a new game: prepare <scenario> --preset faithful|fresh|shell. These are the presets from Prepare for a new game: faithful is Keep everything, fresh is Keep the galaxy and shell is Keep the layout. --row <row>=<choice> sets one row's choice over the preset's, and you can repeat it. --roll-around-seats unticks Keep leviathans, marauders and L-Gates away from starting positions.
• Edit a save or scenario: apply <file> <edit.json>....
• Generate from your game data: add-system and add-body roll a system or a body from the install's rules. planet-class changes a planet's class and nebula add names a new nebula the way the app does. They read the enabled mods too. --no-mods reads the base game only, and --install <folder> points at Stellaris.
• Copy planets: copy-planet <sav> --body 99,402 --to 216 copies the planets, each with its moons, into system 216. --at RADIUS,ANGLE places a single copy, and --from <other.sav> copies from another save.
• Decode a game texture to a PNG: texture <key> -o <file.png>, with a key such as star_class:g_star.

Add a system

add-system <sav> takes these options:

Option	Action
--seed N	The random seed the system is rolled from. The same seed, save and game data give the same system.
--at X,Y	The system's X and Y coordinates on the galaxy map.
--lane ID	A system the new one is joined to by a hyperlane. Repeat it for more.
--name NAME	The system's name. Without it, the system gets an unused star name.
--star-class sc_g	Rolls the system around that star class.
--layout NAME	Builds the system from that initializer, plain or special. A special system comes with its anomalies and dig sites, as in the app.
--no-extras	With --layout, leaves out the anomalies and dig sites.
--then-reroll N	Rolls the system again from seed N before saving, keeping its name, position and lanes.

For example: sgf add-system game.sav --seed 7 --at -310,-95 --lane 169 -o out.sav.

Edit files

Each edit file holds one change as JSON. type is the name of one of the edits the app makes, and the other fields are its values. This file moves system 123:

{ "type": "MoveSystem", "system": 123, "x": -150, "y": 80 }

sgf apply game.sav move.json applies it. If you give several files, they're applied in the order listed. A Batch holds a list of edits under ops and applies them as one step.

apply saves in place with the same backup as the app, or writes elsewhere with -o <file>. If an edit is refused, apply names the file and the edit, and writes nothing.

Some common edits:

type	Fields
MoveSystem	system, x, y
AddLane	a, b, bridge (usually false)
RemoveLane	a, b
IsolateSystem	system
RenameSystem	system, name

Every edit and its fields are in the Op enum in crates/sgf-core/src/ops/op.rs.

add-system --print-spec prints a rolled system as JSON. Put it under spec in an AddSystemFromSpec edit to add the system after you change it.