Templates

Nearly every string in a system definition is a template. The same language runs in view values, form summaries, visibleIf conditions, filter labels, collection subtitles, combatant details and data transforms — so learning it once covers the whole system.

The engine is Stencil, a Django/Liquid-style templating language, extended with a set of filters and tags specific to this app.

Basics

{{ name }}                        variable
{{ data.abilities.str }}          dot path
{{ data.classes | join: ', ' }}   filter with an argument
{% if data.level > 0 %}…{% endif %}
{% for class in data.classes %}{{ class.name }}{% endfor %}

Stencil’s own tags and filters (if/elif/else, for with forloop.first/forloop.last, filter, default, join, uppercase, lowercase, capitalize, in) are all available.

Whitespace control uses the - suffix, which matters when generating Markdown:

{% if data.ritual -%}
**Ritual**
{% endif -%}

The context available to a template is described in Entity Definitions.

Filters

Types and localization

Filter	Does
map: 'Type'[, separator]	Looks a key up in a named type and returns its display label. Given an array, maps each element and joins with separator (default ", ").
valueMap: 'Type'	Looks a key up in a named type and returns its raw value — for lookup tables like ChallengeRatingToXP.
l	Localizes a string key: {{ 'Common.HitPoints' | l }}.
localize	Localizes with the current context available for interpolation.

Numbers

Filter	Does
signed	Prefixes a + on non-negative numbers: 3 → +3.
modifier	Converts an ability score to its modifier: 14 → +2. Also formats a modifier object.
ordinal	3 → 3rd.
format	Locale-aware number formatting.
integer	Takes the leading numeric part of a string: "15 (chain mail)" → 15.
math: 'sum'	Sums an array of numbers.
diceAverage	The average roll of a die of the given size.
units: 'ft'	Formats with a unit, converting between measurement systems — see Configuration.

Strings

Filter	Does
prefix: 's' / suffix: 's'	Adds text, but only if the value is non-empty.
wrap: 's'	Wraps the value in the given string on both sides.
brackets[: style]	Wraps in brackets — round (default), square, curly, angle.
space	Appends a single space if non-empty.
trim / trimLines	Trims whitespace, overall or per line.
capitalizeFirstLetter	Uppercases the first character only.
first	First character of a string, or first element of an array.
urlencode	Percent-encodes for use in a URL.
nameWithSource[: style]	Formats a name plus its source — short (default), long, none.

The conditional behavior of prefix, suffix, brackets and space is what makes one-line subtitles readable. This produces no stray commas or empty parens when fields are missing:

{{data.size | map: 'Size'}}{{data.type | map: 'MonsterType' | prefix: ' '}}{{data.typeDetail | brackets | prefix: ' '}}{{data.alignment | map: 'Alignment' | prefix: ', '}}

Links, dice and Markdown

Filter	Does
link: 'path'	Turns a value into a Markdown link, resolving name/source pairs into content links.
roll[: name[, type]]	Turns a dice expression into a tappable roll link.
md	Renders Markdown to HTML, with dice expressions linked.
diceFormula	Substitutes variables into a dice expression and simplifies it.
formula	Substitutes variables into an expression without simplifying.
eval	Renders the string as a template, then evaluates the result as arithmetic.
resolvePath	Resolves a relative path against the system or container folder.
json	Dumps the value as pretty-printed JSON — useful while debugging.

Tags

Beyond Stencil’s own, these are available:

include

{% include 'spell-range.md' %}
{% include 'activation.md' data.activation %}

The optional second argument pushes a sub-object as the context for the included file, and it accepts a dot path. Partials resolve against views/partials/.

eval

Evaluates its body as arithmetic after rendering it:

{% eval %}10 + {{ data.abilities.wis | modifier | default: 0 }}{% endeval %}

Non-numeric results render as Undef, which is a useful signal that a path is wrong.

set

Binds a value for later reuse:

{% set profBonus %}{{ data.cr | map: 'ProficiencyBonus' }}{% endset %}
{{ profBonus }}

or in short form, {% set name value %}.

macro and call

Define a reusable fragment and invoke it — the template-level equivalent of a function, for repetition too small to justify its own partial file.

markdown

Renders its body as Markdown to HTML, with dice expressions turned into roll links. An optional argument names the roll, either as a quoted literal or as a context path:

{% markdown "Common.Damage" %}{{ data.damage }}{% endmarkdown %}

trim

Strips stray separators — spaces, commas and semicolons — from the start and end of every line of its body. It exists for lists assembled conditionally, where the separators between missing items would otherwise be left behind.

Formulas

In data transforms, a rendered value beginning with # is evaluated as arithmetic rather than kept as text:

"data.xp": "#{{ data.cr | valueMap: 'ChallengeRatingToXP' }}",
"data.initiativeValue": "# 10 + {{ data.initiativeBonus }}"

Conditions

visibleIf and hiddenIf on a form section, form field or view accept either a template that renders to something truthy, or a bare comparison:

{ "visibleIf": "{{ unit == 'reaction' }}" }
{ "visibleIf": "{% if 'M' in data.components %}true{% endif %}" }
{ "visibleIf": "attributes.ruleset == '5.5e'" }
{ "hiddenIf": "level < 3" }

Partials

Two kinds, both living under views/partials/:

• .md text partials, included from inside a template with {% include %}. Markdown with templating in it, for prose-shaped output.
• .json view partials, included from a view with {"type": "partial", "value": "name"}. See Views.

A text partial that formats a spell’s range:

{% if data.rangeType %}{{ data.rangeType | map: 'SpellRange' }}{% else %}{{ data.range | units: 'ft' }}{% endif %}

Included by the detail view, by the compact view, and by the form’s summary row — one definition of how a range is worded.

Practical notes

• Missing values render as empty, and an empty view is dropped. Lean on that rather than guarding every line with visibleIf.
• default: is your friend: {{ data.hp.current | default: 0 }}.
• Use json to debug. { "type": "text", "value": "{{ data | json }}" } in a view dumps exactly what the context holds — including everything the transform computed.
• Templates are rendered against cached contexts. After changing a transform, reload the system so contexts are rebuilt.