ns2-savekit

read, back up, restore and modify save data for any Switch 2 title, whether it is installed, on a card, or has no card inserted, over a live ns2jb session. the save path is not game-specific: it opens a title's save archive, moves files in or out, commits, and verifies by hash.

the same access is then used for one more thing: an Artemis save can be retargeted so the game resumes our Lua instead of its own script. that is the "save launch" half (payloads/, tools/artemis-save.py); the save half works on any title you own.

the exploit is not here. nothing in this repo is exploit code, keys, or game content.

what you need

• a patched ns2jb checkout (the local ~/ns2jb-rpc checkout, or run.cjs from ns2jb), an exploit session held open, and the run folder it prints (runs/switch2-XXXXXX, containing switch2/ro/root/current-root.json).
• firmware 23.0.1 and SmileBASIC 4 (retail) to deliver the exploit.
• node (no npm install; nothing to build).

quick start

# 0. patch the engine once, before the first run. the host copies engine/ into
#    every run folder at startup, so patch first, then start a new session.
sh patches/apply.sh ~/ns2jb

# 1. start the host and leave it running. <local ip> is THIS computer's LAN ip:
#    the console dials back, so it must be reachable from the switch.
cd ~/ns2jb-rpc && node run.cjs --rpc <local ip>
#   -> run folder: runs/switch2-XXXXXX

# 2. in a freshly opened SmileBASIC, with a.b.c.d = the four octets of <local ip>:
#      RUN
#      REMOVE NSR,&H60000000,&H3FFFFFFF
#      V=START(39380,a,b,c,d,0,0,0,0)

# 3. back here, drive everything from the menu
node tools/kit.cjs                    # newest run folder, or:
node tools/kit.cjs ~/ns2jb-rpc/runs/switch2-XXXXXX

the patch step is not optional; skip it only if the checkout already has the changes. docs/PATCHED-ENGINE.md explains what each patch fixes.

the kit

tools/kit.cjs adds no save logic of its own: it shells out to the proven scripts and prints the exact command before each one.

menu	what it does
list	list the files in a save (read-only)
backup	pull the save into saves/<game>/user-<uid>/<timestamp>
replace	write files from a directory, in one transaction
delete	remove one file at the save root
verify	pull again and compare every file with the backup
all saves (a)	list every archive the console's save index knows, cartridge saves included, no titledb
pull batch (p)	pull the next pending archives from that inventory (default 5)
launcher / editor	Artemis only: install the payload set or the Seedsow Lua Editor save
alula launcher	Artemis demo only: install alula's upstream Artemis Launcher against an immutable original baseline, verify it, or roll it back safely (the menu number moves with the title's other entries; read the label)
Artemis HTTP (--http)	no ns2jb session: health, Lua, stat, download, upload, delete and explicit-file backup over the launcher's port 8080

writes are fenced:

• read-only by default; a write needs a prior backup and compares the live bytes against it before replacing anything;
• only titles on the allowlist (config/titles.json, plus your config/titles.local.json) can be written;
• one open, one commit, then every file is read back and hashed;
• paths must be /name; .., nested paths and absolute paths are rejected.

Elden Ring (0400f5802371e000) is on the write allowlist. Large save files are verified in 256 KiB reads, including the game's 2.5 MiB character files.

several save operations per boot usually work; restart the console only if one actually fails. the one thing that reliably breaks the next session is leaving a previous one open (--keep-open, a diagnostic only).

titles are listed from every storage ncm has a database for (internal, sd card, game card), and named from the console's own control data, not from a catalogue: that is the only way a switch 2 title gets a name. the name comes out of the title's control NCA (the read ouncecake falls back to; its ns reader did not answer on this console), so a japanese title can carry its japanese name. names are cached in config/titles.nacp.json; --no-names skips the read.

ncm's list is the application list; the save store is a different index. save-inventory.cjs asks fs:srv for every save archive directly, so a title whose card is out (or whose program was removed) can still have its save listed and pulled. that is also why a cartridge save survives without the cartridge.

any title, by hand

# back up
node tools/save-pull-root.cjs <run> <title-id> saves/botw <uid>
node tools/pull-all.cjs <run> saves/all --batch 4      # every archive it finds
node tools/saves-report.cjs saves/all                  # what was pulled

# whole store: list every archive, then pull from the inventory
node tools/save-inventory.cjs <run> --json saves/inventory.json --names
node tools/pull-inventory.cjs <run> saves/from-inventory \
  --inventory saves/inventory.json --space 1 --type 1

# restore a pulled directory (back up -> write -> pull -> verify, in that order)
sh tools/save-restore.sh <run> <title-id> <uid> saves/botw [--space N --type N]

<uid> is the 16-byte account uid in hex; --list-uids prints them. the pull prints mounted space=… type=… uid=… - read that line, it is how you learn that the right archive opened. save-inventory.cjs is the no-catalogue path: it lists every archive in the save index and writes JSON; pull-inventory.cjs pulls exact identities from it, five at a time by default (--limit 0 = all pending), and resumes from inventory-progress.json after a reboot. docs/RESTORE.md covers the restore path and its limits; docs/SAVE-ARCHIVES.md covers which archive an open selects.

save launch (the Artemis half)

an Artemis slot save stores where execution resumes. retarget that pointer at save:/name.asb and the game resumes there; an ASB is a plain Lua container, so a few commands put our chunk in front of the engine. a second, zero-edit entry point is the suspend file: save_prefix="save" + save_suspend=9999 makes the game look for save9999.dat at boot.

• docs/LAUNCHER.md - the chain, what is proven on hardware, what is blocked.
• tools/build-untethered.sh - build the stub + body + suspend launcher from a backup; tools/inject-launcher.sh - backup, build, write, pull and verify.
• the stub/body split is built and smoke-tested, not yet installed on hardware.

alula's Artemis Launcher (a separate launcher)

alula/switch-artemis-launcher is a different thing from the payload above: a boot menu with a Hello World slot, an HTTP Lua server on port 8080 and a <name>2.lua update mechanism. kit option 8 installs it into a supported demo save; option 4 is unchanged.

node tools/artemis-launcher.cjs install <run> --title 010042d022aea000 \
  --uid <uid> --backup <pre-install-backup> --confirm
node tools/artemis-launcher.cjs verify  <run> --title 010042d022aea000 --uid <uid> \
  --backup <pre-install-backup>
node tools/artemis-launcher.cjs restore <run> --title 010042d022aea000 --uid <uid> \
  --backup <pre-install-backup> --confirm-restore

• supported titles: 010042d022aea000 (Seedsow demo) and 010012900d38a000 (Nora 2 demo). full games and other titles are refused.
• the pinned upstream revision is downloaded at install time and every file is checked against a recorded SHA-256; nothing third-party is bundled.
• it writes 7 files: six upstream scripts/font plus a save9999.dat rebuilt from the game's own suspend save, so no older upstream save container is written over yours. saveg.dat and system.dat are not touched.
• both launchers own save9999.dat, so only one can be the boot path at a time. the editor's files are not touched and do not collide.
• docs/ARTEMIS-LAUNCHER.md has the compatibility matrix, the 2026-11-01 hardware report (firmware 23.0.1, Seedsow demo 1.0.0), the backup/restore evidence and the known limits - including that the minus-at-startup update bypass was not observed on demo 1.0.0.

Artemis HTTP transport (no ns2jb)

The installed Artemis Launcher serves /status, /eval, /save and /delete on port 8080. tools/artemis-http.cjs uses only those endpoints, so it works while the game is running and no RPC session is held:

node tools/artemis-http.cjs discover --subnet 192.168.1
node tools/artemis-http.cjs health   --host <console-ip>
node tools/artemis-http.cjs eval     --host <console-ip> --code 'print("hello world")'
node tools/artemis-http.cjs get      --host <console-ip> --path save:/file.bin --out file.bin
node tools/artemis-http.cjs put      --host <console-ip> --path save:/note.txt --in note.txt
node tools/artemis-http.cjs rm       --host <console-ip> --path save:/note.txt
node tools/artemis-http.cjs backup   --host <console-ip> --out backup/
node tools/kit.cjs --http <console-ip>   # menu for the same transport

• downloads are bounded /eval hex reads with chunk hashes, a final SHA-256, resume state and local atomic promotion;
• uploads are direct /save up to the server body cap, or chunked /eval appends above it (non-atomic: os.rename on save:/ is refused on hardware); the reported hash is read back from the console and compared, and an interrupted upload is reported as incomplete;
• the backup is explicit-file, complete:false - the server has no directory listing - so it cannot authorize a destructive full restore;
• protected launcher files are refused for write/delete, and other titles' saves are not reachable.

Full details, hardware results (4/16/64 KiB, binary, relaunch) and limitations: docs/ARTEMIS-HTTP.md.

troubleshooting

what you see	what it means	what to do
0x7d402 for every account	the game has not made a save yet	launch it and close it fully (Home -> X -> Close), then retry
0xe02 opening a save	the app hosting the exploit holds its own save (SmileBASIC 4)	pull that title from a session hosted by a different app
0x7d402 for a Cache archive the inventory lists	the archive exists but did not open at rank 0/index 0	attribute unresolved; leave it for a later probe
could not tell whether … has save data / exited without listing anything	the read-only probe never listed an archive; an older puller called that "no save" (issue #2)	update the tools; the kit now names this instead of calling the save absent
Directory exceeds the N-entry probe limit	your copy predates the raised limit; the old pull gave up at 2048 entries in one directory	use the current tools (65536 in tools/lib/save-tree.cjs); no real save is that busy
INCOMPLETE PULL (exit 5)	a file in the save refused a read-only open, so it was not pulled	the file is named above and listed as failed in manifest.json; re-run to retry - the pull is read-only
could not list installed applications / could not list accounts	one of inventory.cjs's two enumerations failed; the lines under it are the child's own error and a hint	follow the hint; an account failure can be worked around with node tools/inventory.cjs <run> <uid>
EEXIST …-ncm-system-programs.bin	the engine checkout is unpatched	sh patches/apply.sh ~/ns2jb, then start a new run - an existing run folder keeps the old engine copy
ListAllUsers: transport 0xf601	the engine has no CMIF pointer descriptors; not a console fault	apply the patches and start a new run
SESSION LOST / transport 0xf601 during a pull or write	the console stopped answering	restart the console, reopen SmileBASIC, start a new session
NO LIVE HOST / memory.sock	the session folder is stale or gone	start the host again and use the run folder it prints
title listed without ✔	it is not on your write allowlist	add its id to config/titles.local.json
names are missing, ids only	the console gave no name for that id (no control data, or the read was refused) and titledb is a Switch 1 catalogue, so it cannot name a Switch 2 title	paste the stub the tools print into config/titles.local.json; console names that were read are cached in config/titles.nacp.json

tests

offline, no console, no network:

node tests/test_kit_probe.cjs        # kit save detection (5)
node tests/test_inventory.cjs        # inventory reporting (7)
node tests/test_save_attr.cjs        # save attribute packing (9)
node tests/test_save_tree.cjs        # save walk: types, failures, limit (6)
node tests/test_app_storages.cjs     # app list: storages, dedupe (8)
node tests/test_nacp.cjs             # console name block, plain and deflated (9)
node tests/test_console_names.cjs    # ns name read: services, buffers (11)
node tests/test_content_names.cjs    # control-NCA name read (7)
node tests/test_titles.cjs           # name layers and the console cache (10)
node tests/test_restore_manifest.cjs # generic restore path (6)
node tests/test_artemis_launcher.cjs # alula launcher: staging, backups, receipts, rollback (47)
node tests/test_delete_result.cjs    # delete result propagation (14)
node tests/test_artemis_http.cjs     # HTTP transport, chunking, resume (35)
node tests/test_nso_verify.cjs       # NSO0 parsing, LZ4, hashes (13)
node tests/test_smb_meta.cjs         # META name block surgery (5)
sh   tests/test_inject_dryrun.sh     # injection builder/manifest (3)
lua  tests/test_payload_lua.lua      # launcher payload decisions (13)
lua  tests/test_metadata_lua.lua     # name/thumbnail writer (12)
python3 tests/test_offline.py        # save/ASB encoders (8)

layout

tools/     pull/write/restore/list/inventory, ASB encoder, launcher builders
payloads/  Lua that runs inside the game: launcher stub, body, metadata
patches/   the engine patches the tools need (apply before the first run)
config/    write allowlist template (local config files are gitignored)
docs/      LAUNCHER, RESTORE, SAVE-ARCHIVES, TECHNICAL, PATCHED-ENGINE, RESULTS
tests/     offline suites; none of them prove console behaviour

the controller/esp32 work lives in ns2-console; the content/asset pipeline is in ns2-assets.

credits and licence

our code is MIT (see LICENSE). third-party components and links are listed in NOTICE: ns2jb (the exploit, linked not vendored), Seedsow Lua Editor (0BSD; its save is downloaded, never bundled), titledb (MIT, names only), and the Artemis engine (no affiliation, no game content).