rigc compiles a rig spec and a motion spec into Spine 4.3 skeleton data and an\natlas, runs its named assertions — rigc's own validator in the published package,\nheld to a @esotericsoftware/spine-core round trip's verdicts in its CI, all but\nthe parse itself — and writes only if every one is green. You cannot see the\nrig you are authoring. The validator's messages and the shipped guides are the\nwhole interface, and this skill only says which of them to open.
\uD83D\uDCD6 A failure line ends with the command that prints its row of the guide —\n (see rigc guide <RULE>). Run that command first, before reading anything else:\nit prints that rule's row of the shipped guide and nothing else. rigc guide §<n>\n(and §<n>.<m>, §<n>.<m>.<k>) prints the section's heading, own prose and\nsubsection index from docs/AUTHORING.md; add --all to include subsection\nbodies. A leaf prints its full text either way. Sizes describe full ledger spans;\n--all with a rule name is refused, exit 2. A compile error points at its stable\nCE_ code row. rigc guide §5.1.<k> prints a numbered compile-error group of\nat most 30,000 UTF-8 bytes, and rigc guide §5.1 prints the introduction and\nindex within that same limit; only legacy uncoded library errors point at §5.1.
build writes nothing on a red gate; there is\nno --no-validate, and none may be added — AUTHORING §0 says so in as many\nwords. Correctness is the whole of the reason: the assertions are what make the\noutput trustworthy, and they are held to the official parser's verdicts in the\nrepository's CI — all but the parse itself, which runs only where the runtime is\ninstalled and is reported as a SKIP elsewhere.CompileError naming that field. Fill the spec; do not expect a default read off\nthe art — AUTHORING §2 and §5.check is the half of the loop that can; if not, render or preview and look —\nAUTHORING §0 and §9.bunx rig-c --help # run it without installing\nbun add -d rig-c # or pin it in the project; the command is `rigc`\nbun rigc skills install # then link these skills into .agents/skills\nCodex, Gemini CLI and Antigravity read skills from .agents/skills/ in the\nworkspace and none of them reads node_modules; rigc skills install puts every\nskill the package ships there, and rigc skills --help says what it refuses.
The package links no Spine runtime. validate, preview and vote below run\nthrough @esotericsoftware/spine-core: install it beside the package\n(bun add -d @esotericsoftware/spine-core) and the same rigc runs them, and\nbuild runs the round trip as well. Without it they are refused by name, and\nbuild writes the same files gated without the parse — rigc --version names the\nentry that ran. In the parse's place that build runs two rules of its own over\nrigc's model document, A00_MODEL_READ and A00_MODEL_REGIONS_ON_PAGES; they are\nnot registry assertions, so its summary counts two more, and AUTHORING §5.2 has a\nrow for each.
rigc build --rig <spec> --motion <spec> --images <dir> --out <dir> compiles,\ngates, and writes only on green.rigc explain --rig <spec> --motion <spec> --out <dir> when the red line is\nnot enough — the compiled rig as a table: every bone with its resolved parent,\nthe slots in draw order, every timeline key by key, and a DEFORM block per\ndeform key. It takes no --profile, it never gates, and it writes nothing, so\nthe figures are readable on a build the gate is refusing — AUTHORING §0 and\n§4.11.2.rigc render --candidate <out> or rigc preview --candidate <out> — look at\nit. A rig with its head off its torso passes the gate; looking is what catches it.\nOpen one frame at full size, not only contact.png: the sheet is for spacing\nacross frames, and a defect is read on a frame. Ask it three things — is any\npicture drawn twice, is there a straight edge where the art has none, does a part\ncover a feature the art shows — and answer each with render --hide <slot> (or\n--slot <slot,…>), which draws the frame again without that part on the same\ngrid, so the two frames say which part a pixel is. AUTHORING §0 holds the three.\nWhen the question is geometry — is this bone where the art is, which way does it\nsquash, where in rig units is this point — rigc inspect --candidate <out> --show art,bones,names --dim draws the bones over the art and writes a legend beside the\npicture that puts every mark back in world units; AUTHORING §13 maps each\nquestion to its view.rigc check --candidate <out> --frames <dir> when you have reference pictures\n(--out <dir> writes the picture each of its numbers came from — open the worst).\nRead its output from the top: the framing block says whether the figures under\nit are about placement or motion. A figure is where the loop starts, not where it\nends — keep the first green build's figure, check every later build against the\nsame frames, and stop when the figure stops moving, not when it exists; AUTHORING\n§9.2 says how to read the framing block and the floor to read a figure against.\nrigc vote --candidate <a> --candidate <b> when several candidates are green and\nonly a person can choose between them.rigc validate <out> re-gates artifacts already on disk, and\nrigc <command> --help is each command's own flag table. rigc repack <out> --out <dir> packs a build again under build --pack's packing flags when its\nparts were not kept, and writes only after every region and the skeleton are\nshown unchanged (--accept-skeleton-differences writes a rebuild whose skeleton\ndiffers, every difference printed; --stage-box <slot> reads a build's stage box)\n— AUTHORING §0.4. A mesh refused because its triangles are several pieces that\nshare no vertex: rigc split --rig … --motion … --slot <slot> --out <dir> writes\nboth specs back with one mesh per piece and every deform key renumbered — build\nthat — AUTHORING §3.4.11.rigc preview --candidate <out>, and the report\nnames the .html it wrote. The hand-off to a person is part of the work.The loop in full, with pose before it and chainfit after the first build:\nAUTHORING §0.
A Live2D model, a Unity scene or a video is a player, not a set of parts. Make the\nreference frames first: render the source at the rate you will check at, into one\ndirectory of f0000.png, f0001.png…, and rigc check --frames <that dir> --fps <rate>\nreads them with no frames.json. A port with no reference frames is unmeasured,\nnot finished. The parts are the source's own texture cut along its drawables, never\na screenshot: a screenshot is the composed result, and a part cut from it carries\nevery part under it. Where a part goes is its drawable's geometry — its vertices in\nmodel space, its UVs, its triangles — which is a mesh attachment with those three\n(AUTHORING §3.4, Mesh attachment); a region at the drawable's bounding-box centre\nkeeps only the box. rigc reads none of those formats — FACE §11, the paragraph\nthat opens No Live2D file is read or written\n(FACE.md) —\nonly the pictures they produce. The rule, the background those frames need and\nwhat a wrong one costs: AUTHORING §0, When the source is a foreign player.
Read AUTHORING.md first, whatever the need: the two\nspec files field by field, the emission rules, the loop, and the failure map. Then:
\n| The request is… | \nOpen | \nSkill | \n
|---|---|---|
| a skeleton — how many bones, where each pivot sits, what hangs off what | \nRIGGING.md | \nrigc-rigging | \n
| a movement — an idle, a loop, from this pose to that one | \nMOTION.md | \nrigc-motion | \n
| a face — a blink, a gaze, a head turn a few degrees off axis | \nFACE.md | \nrigc-face | \n
| a skeleton.json somebody else authored — read it, repair it, extend it | \nINGEST.md | \nrigc-ingest | \n
| you are the person operating the agent rather than the agent | \nPROMPTING.md | \n— | \n
Every guide linked here is in the installed package at node_modules/rig-c/docs/,\nwhich is the copy that matches the rigc you run; the links go to the repository's\nmain. Inside the Claude Code plugin the same files are at ${CLAUDE_PLUGIN_ROOT}/docs/.\nFormats, the CLI reference and the licence chain:\nREADME.md, installed at node_modules/rig-c/README.md.