<<SKILL_TITLE>>

A visill-powered hello-world skill. Given a name, the widget renders "Hello, <name>!" inline and confirms the visill toolchain is wired end to end - SDK runtime, build assembly, and render-time payload validation.

Use this skill as a starting point for your own visill widget. Replace the schema, the mustache slot in widget-src/widget.html, and the rendering logic in widget-src/widget.ts with the shape your skill needs. The data flow below stays the same.

Schema

The render-time payload must satisfy this JSON Schema. render.py validates the incoming JSON against it before chevron-rendering the widget bundle:

{{SCHEMA}}

The {{SCHEMA}} slot above is replaced at skill build time with the inlined schema, so the published SKILL.md ships a single self-contained document.

Data flow

Four layers move data from skill invocation to rendered DOM. Every visill skill follows this flow; only the field names and widget rendering change.

1. Schema input. Claude builds a JSON payload matching assets/schema.json. For this skill, that means {"name": "world"}.
2. render.py (Python, canonical). Reads stdin, validates against the schema, derives <key>_json mustache variants (JSON-encoded strings) for every top-level key, then chevron-renders widget-src/widget.html.
3. Data island. The rendered bundle carries an inline <script id="root-data" type="application/json"> whose body is {"name": <name_json>}. JSON encoding survives HTML escaping because of the triple-stache {{{name_json}}} in the source template.
4. Widget (TypeScript). widget-src/widget.ts reads the data island via readDataIsland, formats Hello, ${name}!, and renders it into #root. The widget owns presentation; render.py never builds DOM strings.

Skill authors typically only edit layers 1 and 4. The Python layer stays generic; the data island is automatically derived from the schema's top-level keys.

Usage

Construct a JSON payload matching the schema, then pipe it through render.py via stdin (heredoc) - never via a temp file, never via shell argv:

python3 ${CLAUDE_SKILL_DIR}/scripts/render.py <<'EOF'
{"name": "world"}
EOF

render.py validates the payload, derives <key>_json variants for every top-level key, and chevron-renders the widget bundle. Capture stdout and pass it to visualize:show_widget as widget_code.

Call shape for visualize:show_widget:

• title: a kebab-case identifier for this render, for example hello_world_greeting.
• loading_messages: 3-4 short messages shown while the widget mounts.
• widget_code: the stdout from render.py.

The widget displays the greeting and exposes a single button that sends the rendered text back via sendPrompt. Handle that submission in your follow-up turn to produce whatever artifact the skill is designed to deliver.