feat(core): add session form service (#34855)

packages/schema/src/form.ts

@@ -0,0 +1,149 @@
+export * as Form from "./form.js"
+
+import { Schema } from "effect"
+import { define, inventory } from "./event.js"
+import { ascending } from "./identifier.js"
+import { NonNegativeInt, optional, statics } from "./schema.js"
+
+const IDSchema = Schema.String.check(Schema.isStartsWith("frm_")).pipe(Schema.brand("Form.ID"))
+
+export const ID = IDSchema.pipe(
+  statics((schema: typeof IDSchema) => ({ create: (id?: string) => schema.make(id ?? "frm_" + ascending()) })),
+)
+export type ID = typeof ID.Type
+
+export const Metadata = Schema.Record(Schema.String, Schema.Unknown).annotate({ identifier: "Form.Metadata" })
+export type Metadata = typeof Metadata.Type
+
+export const Option = Schema.Struct({
+  value: Schema.String,
+  label: Schema.String,
+  description: Schema.String.pipe(optional),
+}).annotate({ identifier: "Form.Option" })
+export interface Option extends Schema.Schema.Type<typeof Option> {}
+
+export const When = Schema.Struct({
+  key: Schema.String,
+  op: Schema.Literals(["eq", "neq"]),
+  value: Schema.String,
+}).annotate({ identifier: "Form.When" })
+export interface When extends Schema.Schema.Type<typeof When> {}
+
+const FieldBase = {
+  key: Schema.String,
+  title: Schema.String.pipe(optional),
+  description: Schema.String.pipe(optional),
+  required: Schema.Boolean.pipe(optional),
+  when: When.pipe(optional),
+}
+
+export const StringField = Schema.Struct({
+  ...FieldBase,
+  type: Schema.Literal("string"),
+  format: Schema.Literals(["email", "uri", "date", "date-time"]).pipe(optional),
+  minLength: NonNegativeInt.pipe(optional),
+  maxLength: NonNegativeInt.pipe(optional),
+  pattern: Schema.String.pipe(optional),
+  placeholder: Schema.String.pipe(optional),
+  default: Schema.String.pipe(optional),
+  options: Schema.Array(Option).pipe(optional),
+  custom: Schema.Boolean.pipe(optional),
+}).annotate({ identifier: "Form.StringField" })
+export interface StringField extends Schema.Schema.Type<typeof StringField> {}
+
+export const NumberField = Schema.Struct({
+  ...FieldBase,
+  type: Schema.Literal("number"),
+  minimum: Schema.Number.pipe(optional),
+  maximum: Schema.Number.pipe(optional),
+  default: Schema.Number.pipe(optional),
+}).annotate({ identifier: "Form.NumberField" })
+export interface NumberField extends Schema.Schema.Type<typeof NumberField> {}
+
+export const IntegerField = Schema.Struct({
+  ...FieldBase,
+  type: Schema.Literal("integer"),
+  minimum: Schema.Number.pipe(optional),
+  maximum: Schema.Number.pipe(optional),
+  default: Schema.Number.pipe(optional),
+}).annotate({ identifier: "Form.IntegerField" })
+export interface IntegerField extends Schema.Schema.Type<typeof IntegerField> {}
+
+export const BooleanField = Schema.Struct({
+  ...FieldBase,
+  type: Schema.Literal("boolean"),
+  default: Schema.Boolean.pipe(optional),
+}).annotate({ identifier: "Form.BooleanField" })
+export interface BooleanField extends Schema.Schema.Type<typeof BooleanField> {}
+
+export const MultiselectField = Schema.Struct({
+  ...FieldBase,
+  type: Schema.Literal("multiselect"),
+  options: Schema.Array(Option),
+  minItems: NonNegativeInt.pipe(optional),
+  maxItems: NonNegativeInt.pipe(optional),
+  custom: Schema.Boolean.pipe(optional),
+  default: Schema.Array(Schema.String).pipe(optional),
+}).annotate({ identifier: "Form.MultiselectField" })
+export interface MultiselectField extends Schema.Schema.Type<typeof MultiselectField> {}
+
+export const Field = Schema.Union([StringField, NumberField, IntegerField, BooleanField, MultiselectField]).pipe(
+  Schema.toTaggedUnion("type"),
+)
+export type Field = StringField | NumberField | IntegerField | BooleanField | MultiselectField
+
+const InfoBase = {
+  id: ID,
+  // Public form flows are session-owned. This is intentionally `string` because the server
+  // currently accepts an undocumented `global` sentinel for MCP elicitation forms that cannot
+  // be attributed to a concrete session yet. Do not document or rely on `global` outside our
+  // own clients; remove the sentinel path once MCP elicitation can carry session ownership.
+  sessionID: Schema.String,
+  title: Schema.String.pipe(optional),
+  metadata: Metadata.pipe(optional),
+}
+
+export const FormInfo = Schema.Struct({
+  ...InfoBase,
+  mode: Schema.Literal("form"),
+  fields: Schema.Array(Field),
+}).annotate({ identifier: "Form.FormInfo" })
+export interface FormInfo extends Schema.Schema.Type<typeof FormInfo> {}
+
+export const UrlInfo = Schema.Struct({
+  ...InfoBase,
+  mode: Schema.Literal("url"),
+  url: Schema.String,
+}).annotate({ identifier: "Form.UrlInfo" })
+export interface UrlInfo extends Schema.Schema.Type<typeof UrlInfo> {}
+
+export const Info = Schema.Union([FormInfo, UrlInfo]).pipe(Schema.toTaggedUnion("mode"))
+export type Info = FormInfo | UrlInfo
+
+export const Value = Schema.Union([Schema.String, Schema.Number, Schema.Boolean, Schema.Array(Schema.String)]).annotate({
+  identifier: "Form.Value",
+})
+export type Value = typeof Value.Type
+
+export const Answer = Schema.Record(Schema.String, Value).annotate({ identifier: "Form.Answer" })
+export type Answer = typeof Answer.Type
+
+export const State = Schema.Union([
+  Schema.Struct({ status: Schema.Literal("pending") }),
+  Schema.Struct({ status: Schema.Literal("answered"), answer: Answer }),
+  Schema.Struct({ status: Schema.Literal("cancelled") }),
+])
+  .pipe(Schema.toTaggedUnion("status"))
+  .annotate({ identifier: "Form.State" })
+export type State = typeof State.Type
+
+export const Reply = Schema.Struct({
+  answer: Answer,
+}).annotate({ identifier: "Form.Reply" })
+export interface Reply extends Schema.Schema.Type<typeof Reply> {}
+
+const Created = define({ type: "form.created", schema: { form: Info } })
+const Replied = define({ type: "form.replied", schema: { id: ID, sessionID: Schema.String, answer: Answer } })
+const Cancelled = define({ type: "form.cancelled", schema: { id: ID, sessionID: Schema.String } })
+
+export const Event = { Created, Replied, Cancelled, Definitions: inventory(Created, Replied, Cancelled) }