Status: Stable.
Normative home:
forms.
Why this exists
A form-content pack ships declarative form templates a host renders in its own chrome. The manifest is schemas/v2/form-content-pack-manifest.schema.json; installation and signing follow packs.md.
Conditional visibility
A field MAY carry when: <EdgeCondition>. The grammar is the WorkflowEdge.condition object { type, left, right } of schemas/v2/workflow-definition.schema.json, with the operator set of workflow-chain-packs.md §"Edge conditions". A host MUST evaluate when with its edge-condition semantics and MUST NOT accept any other expression language for visibility.
{ "id": "region", "type": "select", "label": "Region",
"when": { "type": "equals", "left": "fields.shipping", "right": "international" } }Instantiation
A form instantiated from a pack advertised through forms.contentPacks MUST be created through the same path a hand-authored form uses, and MUST remain editable afterwards: the pack is a starting point, not a managed object.
- A host MUST degrade an unrecognized field type to plain text rather than failing the instantiation.
- A host MUST NOT execute anything carried by the pack.
- A pack-authored string, and any value collected through an instantiated template, is untrusted input. When one is interpolated into a prompt, the composition MUST record
contentTrust: "untrusted"(host-services.md §Composition), so a downstream reader can tell authored text from pack-supplied text.
Localized strings
label, title, and description are localized strings. A host MUST select the rendered language by the locale-selection and fallback rules of i18n.md, and MUST treat every rendered string as untrusted: escaped for the target surface, never interpreted as markup, script, or a template directive.
Validation
| Constraint | Applies to | Rule |
|---|---|---|
required | any type | the value MUST be present |
format | text, longtext | one of email, uri, date, date-time, time, or x-<format> |
minLength | text, longtext | a host MUST reject a shorter value |
min, max | number | a host MUST reject a value outside the closed range |
pattern | text, longtext | a host MUST reject a non-matching value |
The five spec-reserved format values are the core set. A host that recognizes a format SHOULD apply it; one that does not MUST ignore it and accept plain text. A host MUST ignore format on any type other than text or longtext.
Sources: RFCs 0137, 0177.