feat: support enum + boolean schema properties in flow apis

api/openapi/components/flows/field.yaml

@@ -6,12 +6,13 @@ description: |
 properties:
   type:
     type: string
-    enum: [text, email, password, tel, number, url, date, hidden]
+    enum: [text, email, password, tel, number, url, date, hidden, checkbox, select]
     description: |
-      The input kind the client should render. Encodes the formats that
-      have a matching HTML input type (email, url, date). For other
-      formats (e.g. uuid) the type is `text` and `validation.format`
-      carries the rule.
+      The input kind the client should render. Encodes the formats and
+      JSON types that map to a familiar HTML input: `email`, `url`,
+      `date` come from `format`; `checkbox` from JSON `type: boolean`;
+      `select` from a closed `enum`. For other formats (e.g. uuid) the
+      type is `text` and `validation.format` carries the rule.
   text_key:
     type: string
     description: Localization key for the field label.
@@ -53,3 +54,12 @@ properties:
         type: integer
         minimum: 0
         description: Maximum length in characters (inclusive). Mirrors `maxLength`.
+      enum:
+        type: array
+        items:
+          type: string
+        description: |
+          Closed list of allowed values. Mirrors the JSON Schema `enum`
+          keyword on the underlying user property. When `type` is
+          `select` the client renders these as options; for other types
+          the rule still applies as a membership check.

internal/domain/flow_field_resolver.go

@@ -115,13 +115,15 @@ const (
 //   - Format    ↔ `format` (enum: email, date-time, uuid, uri)
 //   - MinLength ↔ `minLength`
 //   - MaxLength ↔ `maxLength`
+//   - Enum      ↔ `enum` (closed set of allowed string values)
 //
 // Zero values mean "no rule". JSON Schema's `pattern` keyword is not
 // part of the user meta-schema and is intentionally not surfaced.
 type FlowFieldValidation struct {
 	Format    string
 	MinLength int
 	MaxLength int
+	Enum      []string
 }
 
 // FlowFieldType names the input kind the client should render. Mirrors
@@ -137,6 +139,8 @@ const (
 	FlowFieldTypeURL      FlowFieldType = "url"
 	FlowFieldTypeDate     FlowFieldType = "date"
 	FlowFieldTypeHidden   FlowFieldType = "hidden"
+	FlowFieldTypeCheckbox FlowFieldType = "checkbox"
+	FlowFieldTypeSelect   FlowFieldType = "select"
 )
 
 // FlowFieldValidationRule names a schema-derived validation rule the
@@ -200,3 +204,10 @@ func ImplicitOutcomesForChallenge(c FlowFieldChallenge) []string {
 // ErrFlowFieldUnknown is returned by [FlowFieldResolver.Resolve] when a
 // requested field name is not part of the resolver's schema or catalog.
 var ErrFlowFieldUnknown = errors.New("flow field: not in resolver catalog")
+
+// ErrFlowFieldUnsupportedType is returned by [FlowFieldResolver.Resolve]
+// when a property declares a JSON `type` set the resolver cannot
+// reduce to a single input kind. The nullable idiom `["null", X]` is
+// reduced to X and does not trigger this error; any other multi-entry
+// union does.
+var ErrFlowFieldUnsupportedType = errors.New("flow field: unsupported JSON type")