fwkit CLI

fwkit is the offline half of the project: it parses the firmware containers, rebuilds them byte-for-byte, and applies targeted edits. It never talks to a watch.

uv run fwkit --help

AOTA container

Command	Purpose
`fwkit info <image>`	Header, entry table, per-entry sizes and CRC status
`fwkit verify <image>`	Header CRC and every entry CRC
`fwkit unpack <image> <dir>`	Header, `ota.xml`, AGPS trailer and each partition
`fwkit pack <dir> <image>`	Rebuild an image from an unpacked directory

SDFS filesystem

Command	Purpose
`fwkit sdfs-list <image>`	File table of an SDFS partition
`fwkit sdfs-extract <image> <dir>`	Extract all files
`fwkit sdfs-pack <dir> <image>`	Rebuild from a directory
`fwkit edit-sdfs <image> <partition> <name> <input> <out>`	Replace one file inside a partition of an AOTA image

fwkit.sdfs.pad_to(image, size) rebuilds a filesystem and pads it back to a fixed partition length while refreshing total_size and the body checksum. Partitions embedded in an AOTA image keep their original length that way.

RES strings and pictures

Command	Purpose
`fwkit res-list <resfile>`	Strings in a RES table
`fwkit res-set <resfile> <key> <value>`	Replace one string
`fwkit pic-list <resfile>`	Pictures and their codecs
`fwkit pic-decode <resfile> <index> <png>`	Decode a picture to PNG
`fwkit pic-set <resfile> <index> <png>`	Replace a picture from PNG
`fwkit edit-res <image> <partition> <resfile> <key> <value> <out>`	Replace a string inside an AOTA image
`fwkit edit-pic <image> <partition> <resfile> <index> <png> <out>`	Replace a picture inside an AOTA image

STY scene bundles

Command	Purpose
`fwkit sty-info <file>`	Header and scene table
`fwkit sty-nodes <file>`	Nodes of the bundle
`fwkit sty-tree <file> <scene>`	Node tree of one scene
`fwkit sty-add-scene <file> ...`	Add a scene with fresh node ids
`fwkit sty-del-scene <file> ...`	Remove a scene and compact records
`fwkit sty-set-pic <file> ...`	Repoint an image node at another picture
`fwkit edit-sty-pic <image> ...`	Repoint a node inside an AOTA image

AJS animations

Command	Purpose
`fwkit ajs-info <file>`	Record layout, frame count, fps and tiles
`fwkit ajs-extract <file> <dir>`	Extract frames as JPEG
`fwkit ajs-repack <dir> <file>`	Rebuild from JPEG frames
`fwkit ajs-set-frame <file> <index> <jpeg> <out>`	Replace a single frame

WFDL watch faces

Command	Purpose
`fwkit wf-info <file>`	Package header and structure
`fwkit wf-res <file>`	Resource list with indices
`fwkit wf-tree <file>`	TLV node tree
`fwkit wf-unpack <file> <dir>`	Header, tree, resources and raw LZ4 blocks
`fwkit wf-set-res <file> <index> <png> -o <out>`	Replace one resource from PNG
`fwkit wf-build <base> <out> --resources <dir>`	Rebuild, replacing `NNN_*.png`

app.bin

Command	Purpose
`fwkit act-info <app>`	ACTH header fields
`fwkit app-scene-refs <app>`	Scene-id references in the app image
`fwkit app-patch-scene <app> ...`	Rewrite a scene-id literal and rebuild the header
`fwkit edit-app <image> <input> <out>`	Replace `app.bin` inside `TEMP` and rebuild the image

Conventions

The toolkit preserves unknown fields, so a rebuild of an unmodified image is byte-identical.
Formats are documented per device in the device section; the layouts differ between firmware generations.
tooling/tests/selftest.py runs the round-trip checks:

uv run python tooling/tests/selftest.py firmware/JX402_V1.0.0.73.bin

The selftest requires a firmware image supplied locally; the published dumps under dumps/binaries/ work as well.