diff --git a/javascript/selenium-webdriver/project_bidi_schema.mjs b/javascript/selenium-webdriver/project_bidi_schema.mjs
index ba85e81a2f55b..72e10a93ac7b5 100644
--- a/javascript/selenium-webdriver/project_bidi_schema.mjs
+++ b/javascript/selenium-webdriver/project_bidi_schema.mjs
@@ -21,15 +21,15 @@
  * The normalizer has already removed the awkward CDDL shapes, so this is a
  * straight mapping into a small vocabulary:
  *
- *   type node:  { kind: 'record', fields: [field], map?, extensible?, specHref? }
+ *   type node:  { kind: 'record', fields: [field], map?, extensible?, preserveExtras?, specHref? }
  *             | { kind: 'enum',   values: [string], specHref? }
- *             | { kind: 'union',  variants: [ref], selector, specHref? }
+ *             | { kind: 'union',  variants: [ref], selector, objectOnly?, specHref? }
  *             | { kind: 'alias',  type, specHref? }
  *   selector:   { by, variants: [{ value, ref }], default? }   // discriminated
  *             | { ordered: [{ ref, requires: [key] }] }        // structural, spec order
  *             | { correlated: true }                           // resolved by request id, not the payload
  *   field:      { name, wire, required, type }
- *   type ref:   { primitive } | { const } | { ref } | { enum } | { list } | { map, extensible? } | { union }
+ *   type ref:   { primitive } | { const } | { ref } | { enum, primitive? } | { list } | { map, extensible? } | { union, scalar? }
  *               any ref may also carry `nullable: true` (a `/ null` alternative). On a
  *               record node, `map` is the value type of `* key => value` entries and
  *               `extensible: true` marks an open `* text => any` record.
@@ -43,6 +43,20 @@
  * points at the editor's draft, so for an older generated artifact the target drifts
  * from the pinned source; synthetic types (and anything neither source covers) omit it.
  *
+ * Three derived signals let a binding validate the wire boundary without re-deriving
+ * anything itself:
+ *   `objectOnly: true`   — a union all of whose arms are object (record) types, so a
+ *                          non-object payload is a schema violation, not a scalar arm.
+ *   `preserveExtras: true` — an `extensible` type that can also be *sent* (reachable
+ *                          from a command's params), so unknown properties received on
+ *                          the wire must be stored and echoed back rather than dropped.
+ *   an inline `enum` ref carries the `primitive` its literals share, so even a scalar
+ *   the normalizer did not hoist to a named enum is typed rather than opaque.
+ *   `scalar` on an inline `union` ref marks a union with a bare-scalar arm (a map entry's
+ *   `RemoteValue / text`) and carries that arm's primitive: a binding collapsing it onto its
+ *   object_only ref arm passes a non-object payload (the string keys) through, but only when
+ *   it matches the primitive — a wrong-typed scalar is still rejected.
+ *
  * Types the normalizer synthesized for anonymous CDDL constructs additionally
  * carry `{ synthetic: true, owner, label }`: `owner` is the type the construct
  * was lifted out of and `label` is the member name within it, so a binding can
@@ -94,6 +108,49 @@ const isRef = (e) => e && typeof e === 'object' && e.Type === 'group' && typeof
 const isNullAlt = (e) =>
   e === 'null' || (e && typeof e === 'object' && e.Type === 'group' && PRELUDE[e.Value] === 'null')
 
+// The primitive a set of literal values shares (all strings → string, etc.), or
+// undefined when they are mixed. Used to type an inline literal choice.
+function literalPrimitive(values) {
+  if (values.every((v) => typeof v === 'string')) return 'string'
+  if (values.every((v) => typeof v === 'boolean')) return 'boolean'
+  if (values.every((v) => Number.isInteger(v))) return 'integer'
+  if (values.every((v) => typeof v === 'number')) return 'number'
+  return undefined
+}
+
+// An inline literal choice (e.g. `("classic" / "overlay") / null`) the normalizer did
+// not hoist to a named enum. Carry the literals' shared primitive so the scalar is
+// typed rather than opaque — a binding can then reject a wrong-primitive wire value.
+function enumNode(entries) {
+  const values = entries.map((e) => e.Value)
+  const node = { enum: values }
+  const primitive = literalPrimitive(values)
+  if (primitive) node.primitive = primitive
+  return node
+}
+
+// The primitive a bare-scalar union arm accepts: a `{ primitive }` arm directly, or the
+// value type of a `{ const }` arm. Undefined for an object / list / ref arm.
+function scalarArmPrimitive(arm) {
+  if (arm.primitive !== undefined) return arm.primitive
+  if (arm.const !== undefined) return literalPrimitive([arm.const])
+  return undefined
+}
+
+// An inline union of projected arms. `scalar` marks a union that has a bare-scalar arm (a
+// primitive or a const) alongside object arms — e.g. a map entry's `RemoteValue / text` —
+// and carries that arm's primitive (or the array of primitives when the scalar arms differ).
+// A binding that collapses such a union onto its object (object_only) ref arm must still let
+// a non-object payload through here, but only when it matches this primitive — a wrong-typed
+// scalar is still a wire error. Derived once, in the schema, rather than re-detected per binding.
+function unionNode(arms) {
+  const node = { union: arms }
+  const primitives = [...new Set(arms.map(scalarArmPrimitive).filter((p) => p !== undefined))]
+  if (primitives.length === 1) node.scalar = primitives[0]
+  else if (primitives.length > 1) node.scalar = primitives
+  return node
+}
+
 function projectRef(type) {
   const all = typeList(type)
   // A missing type (undefined/empty input, e.g. a malformed array element or map
@@ -104,8 +161,8 @@ function projectRef(type) {
   const node =
     entries.length > 1
       ? entries.every(isLiteral)
-        ? { enum: entries.map((e) => e.Value) }
-        : { union: entries.map(projectEntry) }
+        ? enumNode(entries)
+        : unionNode(entries.map(projectEntry))
       : projectEntry(entries[0])
   if (entries.length < all.length) node.nullable = true // a `null` alternative means the value may be null
   return node
@@ -124,7 +181,7 @@ function projectEntry(e) {
     // An inline group that only wraps anonymous ref(s) — e.g. a union arm
     // `{ DateLocalValue }` — is that ref (or a union of them), not a record.
     const refs = unionMemberRefs(e)
-    if (refs) return refs.length === 1 ? { ref: refs[0] } : { union: refs.map((r) => ({ ref: r })) }
+    if (refs) return refs.length === 1 ? { ref: refs[0] } : unionNode(refs.map((r) => ({ ref: r })))
     return {
       record: e.Properties.flat()
         .filter((p) => p?.Name)
@@ -242,6 +299,66 @@ function unionLeaves(ref, types, seen = new Set()) {
   return []
 }
 
+// Whether a union variant is an object (record) type — following aliases and nested
+// unions to their leaves. An enum, or an alias to a primitive/list/map (or an inline
+// union arm with a scalar member), is not an object. `objectOnly` is true for a union
+// only when every variant is one, so a non-object payload is a schema violation there.
+function variantIsObject(ref, types, seen = new Set()) {
+  if (seen.has(ref)) return true // a cycle bottoms out in records; treat as object
+  seen.add(ref)
+  const t = types[ref]
+  if (!t) return false
+  if (t.kind === 'record') return true
+  if (t.kind === 'union') return t.variants.every((v) => variantIsObject(v, types, seen))
+  if (t.kind === 'alias') {
+    if (t.type?.ref) return variantIsObject(t.type.ref, types, seen)
+    if (t.type?.union) return t.type.union.every((a) => a.ref !== undefined && variantIsObject(a.ref, types, seen))
+    return false // alias to a primitive / list / map / const
+  }
+  return false // enum
+}
+
+// The type-name refs a projected ref node points at, recursing through list / map /
+// inline union / inline record. (checkSchema has an equivalent local walk for its own
+// referential checks; this module-level one feeds the reachability closure below.)
+function refNames(node) {
+  if (!node) return []
+  if (node.ref) return [node.ref]
+  if (node.list) return refNames(node.list)
+  if (node.map) return refNames(node.map)
+  if (node.union) return node.union.flatMap(refNames)
+  if (node.record) return node.record.flatMap((f) => refNames(f.type))
+  return []
+}
+
+// The type-name refs a type *node* (record / union / alias) points at: a record's
+// field and map value types, a union's variants, an alias's target.
+function typeRefNames(node) {
+  if (node.kind === 'record') {
+    const refs = node.fields.flatMap((f) => refNames(f.type))
+    if (node.map) refs.push(...refNames(node.map))
+    return refs
+  }
+  if (node.kind === 'union') return node.variants
+  if (node.kind === 'alias') return refNames(node.type)
+  return []
+}
+
+// The set of types that can be *sent*: reachable from some command's params, through
+// fields, lists, unions, maps, and nested records/aliases. Results and events are not
+// roots — a type reached only through them is received-only. `preserveExtras` gates the
+// extras store on this, so only a type you can hand back keeps unknown wire properties.
+function reSendableTypes(commands, types) {
+  const reachable = new Set()
+  const visit = (name) => {
+    if (!name || reachable.has(name) || !types[name]) return
+    reachable.add(name)
+    for (const r of typeRefNames(types[name])) visit(r)
+  }
+  for (const c of commands) if (c.params?.ref) visit(c.params.ref)
+  return reachable
+}
+
 // The constant value a record pins on wire key `k`, as `{ value }` (a string or
 // `null`), or `{ open: true }` when the field exists but is not constant (a base
 // type acting as the catch-all, e.g. log.GenericLogEntry.type), or null when the
@@ -467,6 +584,11 @@ export function projectSchema(ast, model, links = {}) {
   // Override the result-grouping unions: they are dispatched by request id, so a
   // payload selector for them is meaningless (and would be empty/ambiguous).
   for (const name of correlatedUnions(types)) types[name].selector = { correlated: true }
+  // A first-class union whose every arm is an object rejects a non-object payload
+  // instead of passing it through. (An alias-union like input.Origin, which carries
+  // bare-string arms, is intentionally left unflagged so those arms still pass through.)
+  for (const node of Object.values(types))
+    if (node.kind === 'union' && node.variants.every((v) => variantIsObject(v, types))) node.objectOnly = true
 
   const commands = []
   const events = []
@@ -496,6 +618,13 @@ export function projectSchema(ast, model, links = {}) {
     }
   }
 
+  // An extensible type keeps unknown wire properties only when it is also re-sendable
+  // (reachable from a command's params) — a type you receive and can hand back, so its
+  // extras must round-trip. A received-only extensible type drops them.
+  const reSendable = reSendableTypes(commands, types)
+  for (const [name, node] of Object.entries(types))
+    if (node.extensible && reSendable.has(name)) node.preserveExtras = true
+
   // Per-domain module links, for a binding that emits one class/namespace per domain.
   const domains = {}
   for (const domain of Object.keys(model)) {
diff --git a/javascript/selenium-webdriver/project_bidi_schema_test.mjs b/javascript/selenium-webdriver/project_bidi_schema_test.mjs
index d007ca7911467..1fc7aeddeeea6 100644
--- a/javascript/selenium-webdriver/project_bidi_schema_test.mjs
+++ b/javascript/selenium-webdriver/project_bidi_schema_test.mjs
@@ -152,6 +152,7 @@ describe('projectType (list / union / alias defs)', () => {
           { ref: 'x.Other', requires: ['b'] },
         ],
       },
+      objectOnly: true, // both arms are records
     })
   })
   it('projects a single-member dispatch choice group as an alias to its ref', () => {
@@ -375,6 +376,93 @@ describe('unionSelector', () => {
   })
 })
 
+describe('schema signals (objectOnly / preserveExtras / enum primitive)', () => {
+  const rec = (name, typeConst) => group(name, [field('type', [lit(typeConst)])])
+  const union = (name, refs) => ({
+    Type: 'variable',
+    Name: name,
+    IsChoiceAddition: false,
+    Comments: [],
+    PropertyType: refs.map(ref),
+  })
+  const enumDef = (name, values) => ({
+    Type: 'variable',
+    Name: name,
+    IsChoiceAddition: false,
+    Comments: [],
+    PropertyType: values.map(lit),
+  })
+
+  it('flags a union whose every arm is an object type as objectOnly', () => {
+    const s = projectSchema([union('x.U', ['x.A', 'x.B']), rec('x.A', 'a'), rec('x.B', 'b')], {})
+    assert.equal(s.types['x.U'].objectOnly, true)
+    assert.deepEqual(checkSchema(s), [])
+  })
+
+  it('does not flag a first-class union with an enum (scalar) arm as objectOnly', () => {
+    const s = projectSchema([union('x.U', ['x.A', 'x.E']), rec('x.A', 'a'), enumDef('x.E', ['one', 'two'])], {})
+    assert.equal(s.types['x.E'].kind, 'enum')
+    assert.equal(s.types['x.U'].objectOnly, undefined)
+  })
+
+  it('does not flag a bare-scalar alias-union (input.Origin shape) as objectOnly', () => {
+    // "viewport" / "pointer" / ElementOrigin — the const arms keep it an alias-union
+    // that must still pass a bare-string payload through, so it stays unflagged.
+    const origin = {
+      Type: 'variable',
+      Name: 'x.Origin',
+      IsChoiceAddition: false,
+      Comments: [],
+      PropertyType: [lit('viewport'), lit('pointer'), ref('x.Element')],
+    }
+    const s = projectSchema([origin, group('x.Element', [field('type', [lit('element')]), field('id', ['text'])])], {})
+    assert.equal(s.types['x.Origin'].kind, 'alias')
+    assert.equal(s.types['x.Origin'].objectOnly, undefined)
+  })
+
+  it('marks an extensible type reachable from command params as preserveExtras, but not a result-only one', () => {
+    const ast = [
+      group('x.SetParams', [field('cfg', [ref('x.Config')])]),
+      group('x.Config', [field('text', ['any'], { n: 0, m: null })]),
+      group('x.GetResult', [field('info', [ref('x.Info')])]),
+      group('x.Info', [field('text', ['any'], { n: 0, m: null })]),
+    ]
+    const model = { x: { commands: [{ method: 'x.set', name: 'set', params: 'x.SetParams', result: 'x.GetResult' }] } }
+    const s = projectSchema(ast, model)
+    assert.equal(s.types['x.Config'].extensible, true)
+    assert.equal(s.types['x.Config'].preserveExtras, true) // reachable through the command's params
+    assert.equal(s.types['x.Info'].extensible, true)
+    assert.equal(s.types['x.Info'].preserveExtras, undefined) // reachable only through the result
+    assert.deepEqual(checkSchema(s), [])
+  })
+
+  it('types an inline (non-hoisted) literal choice with the primitive its literals share', () => {
+    // A nullable literal choice (`("classic" / "overlay") / null`) the normalizer leaves
+    // inline — carry `primitive: string` so the scalar is typed rather than opaque.
+    const s = projectSchema([group('x.R', [field('kind', [lit('classic'), lit('overlay'), 'null'])])], {})
+    assert.deepEqual(s.types['x.R'].fields[0].type, {
+      enum: ['classic', 'overlay'],
+      primitive: 'string',
+      nullable: true,
+    })
+    assert.deepEqual(checkSchema(s), [])
+  })
+
+  it('flags an inline union with a bare-scalar arm as scalar-tolerant (map key: Ref / text)', () => {
+    const ast = [
+      group('x.R', [field('entry', [ref('x.U'), 'text']), field('objects', [ref('x.A'), ref('x.B')])]),
+      union('x.U', ['x.A', 'x.B']),
+      rec('x.A', 'a'),
+      rec('x.B', 'b'),
+    ]
+    const s = projectSchema(ast, {}).types['x.R'].fields
+    // The `Ref / text` arm makes the union scalar-tolerant, carrying the arm's primitive...
+    assert.deepEqual(s[0].type, { union: [{ ref: 'x.U' }, { primitive: 'string' }], scalar: 'string' })
+    // ...but an all-object union is not flagged (no scalar arm to pass through).
+    assert.deepEqual(s[1].type, { union: [{ ref: 'x.A' }, { ref: 'x.B' }] })
+  })
+})
+
 describe('checkCompleteness (input vs output, generator-independent)', () => {
   it('fails when a command/event present in the AST is missing from the schema', () => {
     const astWithExtra = [
diff --git a/rb/lib/selenium/webdriver/bidi/protocol/bluetooth.rb b/rb/lib/selenium/webdriver/bidi/protocol/bluetooth.rb
index baf35f93f411f..8f1fb06bab127 100644
--- a/rb/lib/selenium/webdriver/bidi/protocol/bluetooth.rb
+++ b/rb/lib/selenium/webdriver/bidi/protocol/bluetooth.rb
@@ -104,7 +104,7 @@ class Bluetooth < Domain
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://webbluetoothcg.github.io/web-bluetooth/#cddl-type-bluetoothrequestdeviceinfo
           RequestDeviceInfo = Serialization::Record.define(
-            id: 'id',
+            id: {wire_key: 'id', primitive: 'string'},
             name: {wire_key: 'name', nullable: true, primitive: 'string'}
           )
 
@@ -132,14 +132,15 @@ class HandleRequestDevicePromptParameters < Serialization::Union
               true => 'Bluetooth::HandleRequestDevicePromptParameters::AcceptParameters',
               false => 'Bluetooth::HandleRequestDevicePromptParameters::CancelParameters'
             )
+            object_only
 
             # @api private
             # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
             AcceptParameters = Serialization::Record.define(
               accept: {fixed: true},
               context: {wire_key: 'context', primitive: 'string'},
-              prompt: 'prompt',
-              device: 'device'
+              prompt: {wire_key: 'prompt', primitive: 'string'},
+              device: {wire_key: 'device', primitive: 'string'}
             )
 
             # @api private
@@ -147,7 +148,7 @@ class HandleRequestDevicePromptParameters < Serialization::Union
             CancelParameters = Serialization::Record.define(
               accept: {fixed: false},
               context: {wire_key: 'context', primitive: 'string'},
-              prompt: 'prompt'
+              prompt: {wire_key: 'prompt', primitive: 'string'}
             )
           end
 
@@ -218,7 +219,7 @@ class HandleRequestDevicePromptParameters < Serialization::Union
           SimulateServiceParameters = Serialization::Record.define(
             context: {wire_key: 'context', primitive: 'string'},
             address: {wire_key: 'address', primitive: 'string'},
-            uuid: 'uuid',
+            uuid: {wire_key: 'uuid', primitive: 'string'},
             type: {wire_key: 'type', enum: 'Bluetooth::SIMULATE_SERVICE_PARAMETERS_TYPE'}
           )
 
@@ -228,8 +229,8 @@ class HandleRequestDevicePromptParameters < Serialization::Union
           SimulateCharacteristicParameters = Serialization::Record.define(
             context: {wire_key: 'context', primitive: 'string'},
             address: {wire_key: 'address', primitive: 'string'},
-            service_uuid: 'serviceUuid',
-            characteristic_uuid: 'characteristicUuid',
+            service_uuid: {wire_key: 'serviceUuid', primitive: 'string'},
+            characteristic_uuid: {wire_key: 'characteristicUuid', primitive: 'string'},
             characteristic_properties: {
               wire_key: 'characteristicProperties',
               required: false,
@@ -244,8 +245,8 @@ class HandleRequestDevicePromptParameters < Serialization::Union
           SimulateCharacteristicResponseParameters = Serialization::Record.define(
             context: {wire_key: 'context', primitive: 'string'},
             address: {wire_key: 'address', primitive: 'string'},
-            service_uuid: 'serviceUuid',
-            characteristic_uuid: 'characteristicUuid',
+            service_uuid: {wire_key: 'serviceUuid', primitive: 'string'},
+            characteristic_uuid: {wire_key: 'characteristicUuid', primitive: 'string'},
             type: {wire_key: 'type', enum: 'Bluetooth::SIMULATE_CHARACTERISTIC_RESPONSE_PARAMETERS_TYPE'},
             code: {wire_key: 'code', primitive: 'integer'},
             data: {wire_key: 'data', required: false, list: true}
@@ -257,9 +258,9 @@ class HandleRequestDevicePromptParameters < Serialization::Union
           SimulateDescriptorParameters = Serialization::Record.define(
             context: {wire_key: 'context', primitive: 'string'},
             address: {wire_key: 'address', primitive: 'string'},
-            service_uuid: 'serviceUuid',
-            characteristic_uuid: 'characteristicUuid',
-            descriptor_uuid: 'descriptorUuid',
+            service_uuid: {wire_key: 'serviceUuid', primitive: 'string'},
+            characteristic_uuid: {wire_key: 'characteristicUuid', primitive: 'string'},
+            descriptor_uuid: {wire_key: 'descriptorUuid', primitive: 'string'},
             type: {wire_key: 'type', enum: 'Bluetooth::SIMULATE_DESCRIPTOR_PARAMETERS_TYPE'}
           )
 
@@ -269,9 +270,9 @@ class HandleRequestDevicePromptParameters < Serialization::Union
           SimulateDescriptorResponseParameters = Serialization::Record.define(
             context: {wire_key: 'context', primitive: 'string'},
             address: {wire_key: 'address', primitive: 'string'},
-            service_uuid: 'serviceUuid',
-            characteristic_uuid: 'characteristicUuid',
-            descriptor_uuid: 'descriptorUuid',
+            service_uuid: {wire_key: 'serviceUuid', primitive: 'string'},
+            characteristic_uuid: {wire_key: 'characteristicUuid', primitive: 'string'},
+            descriptor_uuid: {wire_key: 'descriptorUuid', primitive: 'string'},
             type: {wire_key: 'type', enum: 'Bluetooth::SIMULATE_DESCRIPTOR_RESPONSE_PARAMETERS_TYPE'},
             code: {wire_key: 'code', primitive: 'integer'},
             data: {wire_key: 'data', required: false, list: true}
@@ -282,7 +283,7 @@ class HandleRequestDevicePromptParameters < Serialization::Union
           # @see https://webbluetoothcg.github.io/web-bluetooth/#cddl-type-bluetoothrequestdevicepromptupdatedparameters
           RequestDevicePromptUpdatedParameters = Serialization::Record.define(
             context: {wire_key: 'context', primitive: 'string'},
-            prompt: 'prompt',
+            prompt: {wire_key: 'prompt', primitive: 'string'},
             devices: {wire_key: 'devices', ref: 'Bluetooth::RequestDeviceInfo', list: true}
           )
 
@@ -300,8 +301,8 @@ class HandleRequestDevicePromptParameters < Serialization::Union
           CharacteristicEventGeneratedParameters = Serialization::Record.define(
             context: {wire_key: 'context', primitive: 'string'},
             address: {wire_key: 'address', primitive: 'string'},
-            service_uuid: 'serviceUuid',
-            characteristic_uuid: 'characteristicUuid',
+            service_uuid: {wire_key: 'serviceUuid', primitive: 'string'},
+            characteristic_uuid: {wire_key: 'characteristicUuid', primitive: 'string'},
             type: {wire_key: 'type', enum: 'Bluetooth::CHARACTERISTIC_EVENT_GENERATED_PARAMETERS_TYPE'},
             data: {wire_key: 'data', required: false, list: true}
           )
@@ -312,9 +313,9 @@ class HandleRequestDevicePromptParameters < Serialization::Union
           DescriptorEventGeneratedParameters = Serialization::Record.define(
             context: {wire_key: 'context', primitive: 'string'},
             address: {wire_key: 'address', primitive: 'string'},
-            service_uuid: 'serviceUuid',
-            characteristic_uuid: 'characteristicUuid',
-            descriptor_uuid: 'descriptorUuid',
+            service_uuid: {wire_key: 'serviceUuid', primitive: 'string'},
+            characteristic_uuid: {wire_key: 'characteristicUuid', primitive: 'string'},
+            descriptor_uuid: {wire_key: 'descriptorUuid', primitive: 'string'},
             type: {wire_key: 'type', enum: 'Bluetooth::DESCRIPTOR_EVENT_GENERATED_PARAMETERS_TYPE'},
             data: {wire_key: 'data', required: false, list: true}
           )
diff --git a/rb/lib/selenium/webdriver/bidi/protocol/browser.rb b/rb/lib/selenium/webdriver/bidi/protocol/browser.rb
index 2d69c9cf02152..af8c70a1ac648 100644
--- a/rb/lib/selenium/webdriver/bidi/protocol/browser.rb
+++ b/rb/lib/selenium/webdriver/bidi/protocol/browser.rb
@@ -46,18 +46,18 @@ class Browser < Domain
           # @see https://w3c.github.io/webdriver-bidi/#type-browser-ClientWindowInfo
           ClientWindowInfo = Serialization::Record.define(
             active: {wire_key: 'active', primitive: 'boolean'},
-            client_window: 'clientWindow',
-            height: 'height',
+            client_window: {wire_key: 'clientWindow', primitive: 'string'},
+            height: {wire_key: 'height', primitive: 'integer'},
             state: {wire_key: 'state', enum: 'Browser::CLIENT_WINDOW_INFO_STATE'},
-            width: 'width',
-            x: 'x',
-            y: 'y'
+            width: {wire_key: 'width', primitive: 'integer'},
+            x: {wire_key: 'x', primitive: 'integer'},
+            y: {wire_key: 'y', primitive: 'integer'}
           )
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#type-browser-UserContextInfo
-          UserContextInfo = Serialization::Record.define(user_context: 'userContext')
+          UserContextInfo = Serialization::Record.define(user_context: {wire_key: 'userContext', primitive: 'string'})
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
@@ -89,7 +89,9 @@ class Browser < Domain
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browserremoveusercontextparameters
-          RemoveUserContextParameters = Serialization::Record.define(user_context: 'userContext')
+          RemoveUserContextParameters = Serialization::Record.define(
+            user_context: {wire_key: 'userContext', primitive: 'string'}
+          )
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
@@ -100,11 +102,12 @@ class SetClientWindowStateParameters < Serialization::Union
               normal: 'Browser::SetClientWindowStateParameters::ClientWindowRectState'
             )
             fallback 'Browser::SetClientWindowStateParameters::ClientWindowNamedState'
+            object_only
 
             # @api private
             # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
             ClientWindowNamedState = Serialization::Record.define(
-              client_window: 'clientWindow',
+              client_window: {wire_key: 'clientWindow', primitive: 'string'},
               state: {wire_key: 'state', enum: 'Browser::CLIENT_WINDOW_NAMED_STATE_STATE'}
             )
 
@@ -112,11 +115,11 @@ class SetClientWindowStateParameters < Serialization::Union
             # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
             ClientWindowRectState = Serialization::Record.define(
               state: {fixed: 'normal'},
-              client_window: 'clientWindow',
-              width: {wire_key: 'width', required: false},
-              height: {wire_key: 'height', required: false},
-              x: {wire_key: 'x', required: false},
-              y: {wire_key: 'y', required: false}
+              client_window: {wire_key: 'clientWindow', primitive: 'string'},
+              width: {wire_key: 'width', required: false, primitive: 'integer'},
+              height: {wire_key: 'height', required: false, primitive: 'integer'},
+              x: {wire_key: 'x', required: false, primitive: 'integer'},
+              y: {wire_key: 'y', required: false, primitive: 'integer'}
             )
           end
 
@@ -137,6 +140,7 @@ class DownloadBehavior < Serialization::Union
               allowed: 'Browser::DownloadBehavior::Allowed',
               denied: 'Browser::DownloadBehavior::Denied'
             )
+            object_only
 
             # @api private
             # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
diff --git a/rb/lib/selenium/webdriver/bidi/protocol/browsing_context.rb b/rb/lib/selenium/webdriver/bidi/protocol/browsing_context.rb
index 99fb54e962daa..d51de6cf9d2a3 100644
--- a/rb/lib/selenium/webdriver/bidi/protocol/browsing_context.rb
+++ b/rb/lib/selenium/webdriver/bidi/protocol/browsing_context.rb
@@ -86,12 +86,12 @@ class BrowsingContext < Domain
           # @see https://w3c.github.io/webdriver-bidi/#type-browsingContext-Info
           Info = Serialization::Record.define(
             children: {wire_key: 'children', nullable: true, ref: 'BrowsingContext::Info', list: true},
-            client_window: 'clientWindow',
-            context: 'context',
-            original_opener: {wire_key: 'originalOpener', nullable: true},
+            client_window: {wire_key: 'clientWindow', primitive: 'string'},
+            context: {wire_key: 'context', primitive: 'string'},
+            original_opener: {wire_key: 'originalOpener', nullable: true, primitive: 'string'},
             url: {wire_key: 'url', primitive: 'string'},
-            user_context: 'userContext',
-            parent: {wire_key: 'parent', required: false, nullable: true}
+            user_context: {wire_key: 'userContext', primitive: 'string'},
+            parent: {wire_key: 'parent', required: false, nullable: true, primitive: 'string'}
           )
 
           # @api private
@@ -112,6 +112,7 @@ class Locator < Serialization::Union
               inner_text: 'BrowsingContext::InnerTextLocator',
               xpath: 'BrowsingContext::XPathLocator'
             )
+            object_only
           end
 
           # @api private
@@ -147,7 +148,7 @@ class Locator < Serialization::Union
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
-          ContextLocator::Value = Serialization::Record.define(context: 'context')
+          ContextLocator::Value = Serialization::Record.define(context: {wire_key: 'context', primitive: 'string'})
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
@@ -157,7 +158,7 @@ class Locator < Serialization::Union
             value: {wire_key: 'value', primitive: 'string'},
             ignore_case: {wire_key: 'ignoreCase', required: false, primitive: 'boolean'},
             match_type: {wire_key: 'matchType', required: false, enum: 'BrowsingContext::INNER_TEXT_LOCATOR_MATCH_TYPE'},
-            max_depth: {wire_key: 'maxDepth', required: false}
+            max_depth: {wire_key: 'maxDepth', required: false, primitive: 'integer'}
           )
 
           # @api private
@@ -172,34 +173,34 @@ class Locator < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontextbasenavigationinfo
           BaseNavigationInfo = Serialization::Record.define(
-            context: 'context',
-            navigation: {wire_key: 'navigation', nullable: true},
-            timestamp: 'timestamp',
+            context: {wire_key: 'context', primitive: 'string'},
+            navigation: {wire_key: 'navigation', nullable: true, primitive: 'string'},
+            timestamp: {wire_key: 'timestamp', primitive: 'integer'},
             url: {wire_key: 'url', primitive: 'string'},
-            user_context: {wire_key: 'userContext', required: false}
+            user_context: {wire_key: 'userContext', required: false, primitive: 'string'}
           )
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#type-browsingContext-NavigationInfo
           NavigationInfo = Serialization::Record.define(
-            context: 'context',
-            navigation: {wire_key: 'navigation', nullable: true},
-            timestamp: 'timestamp',
+            context: {wire_key: 'context', primitive: 'string'},
+            navigation: {wire_key: 'navigation', nullable: true, primitive: 'string'},
+            timestamp: {wire_key: 'timestamp', primitive: 'integer'},
             url: {wire_key: 'url', primitive: 'string'},
-            user_context: {wire_key: 'userContext', required: false}
+            user_context: {wire_key: 'userContext', required: false, primitive: 'string'}
           )
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontextactivateparameters
-          ActivateParameters = Serialization::Record.define(context: 'context')
+          ActivateParameters = Serialization::Record.define(context: {wire_key: 'context', primitive: 'string'})
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontextcapturescreenshotparameters
           CaptureScreenshotParameters = Serialization::Record.define(
-            context: 'context',
+            context: {wire_key: 'context', primitive: 'string'},
             origin: {wire_key: 'origin', required: false, enum: 'BrowsingContext::CAPTURE_SCREENSHOT_PARAMETERS_ORIGIN'},
             format: {wire_key: 'format', required: false, ref: 'BrowsingContext::ImageFormat'},
             clip: {wire_key: 'clip', required: false, ref: 'BrowsingContext::ClipRectangle'}
@@ -222,6 +223,7 @@ class ClipRectangle < Serialization::Union
               box: 'BrowsingContext::BoxClipRectangle',
               element: 'BrowsingContext::ElementClipRectangle'
             )
+            object_only
           end
 
           # @api private
@@ -252,7 +254,7 @@ class ClipRectangle < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontextcloseparameters
           CloseParameters = Serialization::Record.define(
-            context: 'context',
+            context: {wire_key: 'context', primitive: 'string'},
             prompt_unload: {wire_key: 'promptUnload', required: false, primitive: 'boolean'}
           )
 
@@ -261,25 +263,25 @@ class ClipRectangle < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontextcreateparameters
           CreateParameters = Serialization::Record.define(
             type: {wire_key: 'type', enum: 'BrowsingContext::CREATE_TYPE'},
-            reference_context: {wire_key: 'referenceContext', required: false},
+            reference_context: {wire_key: 'referenceContext', required: false, primitive: 'string'},
             background: {wire_key: 'background', required: false, primitive: 'boolean'},
-            user_context: {wire_key: 'userContext', required: false}
+            user_context: {wire_key: 'userContext', required: false, primitive: 'string'}
           )
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontextcreateresult
           CreateResult = Serialization::Record.define(
-            context: 'context',
-            user_context: {wire_key: 'userContext', required: false}
+            context: {wire_key: 'context', primitive: 'string'},
+            user_context: {wire_key: 'userContext', required: false, primitive: 'string'}
           )
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontextgettreeparameters
           GetTreeParameters = Serialization::Record.define(
-            max_depth: {wire_key: 'maxDepth', required: false},
-            root: {wire_key: 'root', required: false}
+            max_depth: {wire_key: 'maxDepth', required: false, primitive: 'integer'},
+            root: {wire_key: 'root', required: false, primitive: 'string'}
           )
 
           # @api private
@@ -293,7 +295,7 @@ class ClipRectangle < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontexthandleuserpromptparameters
           HandleUserPromptParameters = Serialization::Record.define(
-            context: 'context',
+            context: {wire_key: 'context', primitive: 'string'},
             accept: {wire_key: 'accept', required: false, primitive: 'boolean'},
             user_text: {wire_key: 'userText', required: false, primitive: 'string'}
           )
@@ -302,9 +304,9 @@ class ClipRectangle < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontextlocatenodesparameters
           LocateNodesParameters = Serialization::Record.define(
-            context: 'context',
+            context: {wire_key: 'context', primitive: 'string'},
             locator: {wire_key: 'locator', ref: 'BrowsingContext::Locator'},
-            max_node_count: {wire_key: 'maxNodeCount', required: false},
+            max_node_count: {wire_key: 'maxNodeCount', required: false, primitive: 'integer'},
             serialization_options: {
               wire_key: 'serializationOptions',
               required: false,
@@ -324,7 +326,7 @@ class ClipRectangle < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontextnavigateparameters
           NavigateParameters = Serialization::Record.define(
-            context: 'context',
+            context: {wire_key: 'context', primitive: 'string'},
             url: {wire_key: 'url', primitive: 'string'},
             wait: {wire_key: 'wait', required: false, enum: 'BrowsingContext::READINESS_STATE'}
           )
@@ -333,7 +335,7 @@ class ClipRectangle < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontextnavigateresult
           NavigateResult = Serialization::Record.define(
-            navigation: {wire_key: 'navigation', nullable: true},
+            navigation: {wire_key: 'navigation', nullable: true, primitive: 'string'},
             url: {wire_key: 'url', primitive: 'string'}
           )
 
@@ -341,7 +343,7 @@ class ClipRectangle < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontextprintparameters
           PrintParameters = Serialization::Record.define(
-            context: 'context',
+            context: {wire_key: 'context', primitive: 'string'},
             background: {wire_key: 'background', required: false, primitive: 'boolean'},
             margin: {wire_key: 'margin', required: false, ref: 'BrowsingContext::PrintMarginParameters'},
             orientation: {
@@ -382,7 +384,7 @@ class ClipRectangle < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontextreloadparameters
           ReloadParameters = Serialization::Record.define(
-            context: 'context',
+            context: {wire_key: 'context', primitive: 'string'},
             ignore_cache: {wire_key: 'ignoreCache', required: false, primitive: 'boolean'},
             wait: {wire_key: 'wait', required: false, enum: 'BrowsingContext::READINESS_STATE'}
           )
@@ -400,7 +402,7 @@ class ClipRectangle < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontextsetviewportparameters
           SetViewportParameters = Serialization::Record.define(
-            context: {wire_key: 'context', required: false},
+            context: {wire_key: 'context', required: false, primitive: 'string'},
             viewport: {wire_key: 'viewport', required: false, nullable: true, ref: 'BrowsingContext::Viewport'},
             device_pixel_ratio: {wire_key: 'devicePixelRatio', required: false, nullable: true, primitive: 'number'},
             user_contexts: {wire_key: 'userContexts', required: false, list: true}
@@ -409,13 +411,16 @@ class ClipRectangle < Serialization::Union
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontextviewport
-          Viewport = Serialization::Record.define(width: 'width', height: 'height')
+          Viewport = Serialization::Record.define(
+            width: {wire_key: 'width', primitive: 'integer'},
+            height: {wire_key: 'height', primitive: 'integer'}
+          )
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontextstartscreencastparameters
           StartScreencastParameters = Serialization::Record.define(
-            context: 'context',
+            context: {wire_key: 'context', primitive: 'string'},
             mime_type: {wire_key: 'mimeType', required: false, primitive: 'string'},
             video: {wire_key: 'video', required: false, ref: 'BrowsingContext::MediaTrackConstraints'},
             audio: {wire_key: 'audio', required: false, primitive: 'boolean'}
@@ -425,23 +430,25 @@ class ClipRectangle < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontextmediatrackconstraints
           MediaTrackConstraints = Serialization::Record.define(
-            width: {wire_key: 'width', required: false},
-            height: {wire_key: 'height', required: false},
-            frame_rate: {wire_key: 'frameRate', required: false}
+            width: {wire_key: 'width', required: false, primitive: 'integer'},
+            height: {wire_key: 'height', required: false, primitive: 'integer'},
+            frame_rate: {wire_key: 'frameRate', required: false, primitive: 'integer'}
           )
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontextstartscreencastresult
           StartScreencastResult = Serialization::Record.define(
-            screencast: 'screencast',
+            screencast: {wire_key: 'screencast', primitive: 'string'},
             path: {wire_key: 'path', primitive: 'string'}
           )
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontextstopscreencastparameters
-          StopScreencastParameters = Serialization::Record.define(screencast: 'screencast')
+          StopScreencastParameters = Serialization::Record.define(
+            screencast: {wire_key: 'screencast', primitive: 'string'}
+          )
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
@@ -454,29 +461,32 @@ class ClipRectangle < Serialization::Union
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontexttraversehistoryparameters
-          TraverseHistoryParameters = Serialization::Record.define(context: 'context', delta: 'delta')
+          TraverseHistoryParameters = Serialization::Record.define(
+            context: {wire_key: 'context', primitive: 'string'},
+            delta: {wire_key: 'delta', primitive: 'integer'}
+          )
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontexthistoryupdatedparameters
           HistoryUpdatedParameters = Serialization::Record.define(
-            context: 'context',
-            timestamp: 'timestamp',
+            context: {wire_key: 'context', primitive: 'string'},
+            timestamp: {wire_key: 'timestamp', primitive: 'integer'},
             url: {wire_key: 'url', primitive: 'string'},
-            user_context: {wire_key: 'userContext', required: false}
+            user_context: {wire_key: 'userContext', required: false, primitive: 'string'}
           )
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontextdownloadwillbeginparams
           DownloadWillBeginParams = Serialization::Record.define(
-            download: 'download',
+            download: {wire_key: 'download', primitive: 'string'},
             suggested_filename: {wire_key: 'suggestedFilename', primitive: 'string'},
-            context: 'context',
-            navigation: {wire_key: 'navigation', nullable: true},
-            timestamp: 'timestamp',
+            context: {wire_key: 'context', primitive: 'string'},
+            navigation: {wire_key: 'navigation', nullable: true, primitive: 'string'},
+            timestamp: {wire_key: 'timestamp', primitive: 'integer'},
             url: {wire_key: 'url', primitive: 'string'},
-            user_context: {wire_key: 'userContext', required: false}
+            user_context: {wire_key: 'userContext', required: false, primitive: 'string'}
           )
 
           # @api private
@@ -488,30 +498,31 @@ class DownloadEndParams < Serialization::Union
               canceled: 'BrowsingContext::DownloadEndParams::CanceledParams',
               complete: 'BrowsingContext::DownloadEndParams::CompleteParams'
             )
+            object_only
 
             # @api private
             # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
             CanceledParams = Serialization::Record.define(
               status: {fixed: 'canceled'},
-              download: 'download',
-              context: 'context',
-              navigation: {wire_key: 'navigation', nullable: true},
-              timestamp: 'timestamp',
+              download: {wire_key: 'download', primitive: 'string'},
+              context: {wire_key: 'context', primitive: 'string'},
+              navigation: {wire_key: 'navigation', nullable: true, primitive: 'string'},
+              timestamp: {wire_key: 'timestamp', primitive: 'integer'},
               url: {wire_key: 'url', primitive: 'string'},
-              user_context: {wire_key: 'userContext', required: false}
+              user_context: {wire_key: 'userContext', required: false, primitive: 'string'}
             )
 
             # @api private
             # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
             CompleteParams = Serialization::Record.define(
               status: {fixed: 'complete'},
-              download: 'download',
+              download: {wire_key: 'download', primitive: 'string'},
               filepath: {wire_key: 'filepath', nullable: true, primitive: 'string'},
-              context: 'context',
-              navigation: {wire_key: 'navigation', nullable: true},
-              timestamp: 'timestamp',
+              context: {wire_key: 'context', primitive: 'string'},
+              navigation: {wire_key: 'navigation', nullable: true, primitive: 'string'},
+              timestamp: {wire_key: 'timestamp', primitive: 'integer'},
               url: {wire_key: 'url', primitive: 'string'},
-              user_context: {wire_key: 'userContext', required: false}
+              user_context: {wire_key: 'userContext', required: false, primitive: 'string'}
             )
           end
 
@@ -519,10 +530,10 @@ class DownloadEndParams < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontextuserpromptclosedparameters
           UserPromptClosedParameters = Serialization::Record.define(
-            context: 'context',
+            context: {wire_key: 'context', primitive: 'string'},
             accepted: {wire_key: 'accepted', primitive: 'boolean'},
             type: {wire_key: 'type', enum: 'BrowsingContext::USER_PROMPT_TYPE'},
-            user_context: {wire_key: 'userContext', required: false},
+            user_context: {wire_key: 'userContext', required: false, primitive: 'string'},
             user_text: {wire_key: 'userText', required: false, primitive: 'string'}
           )
 
@@ -530,11 +541,11 @@ class DownloadEndParams < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontextuserpromptopenedparameters
           UserPromptOpenedParameters = Serialization::Record.define(
-            context: 'context',
+            context: {wire_key: 'context', primitive: 'string'},
             handler: {wire_key: 'handler', enum: 'Session::USER_PROMPT_HANDLER_TYPE'},
             message: {wire_key: 'message', primitive: 'string'},
             type: {wire_key: 'type', enum: 'BrowsingContext::USER_PROMPT_TYPE'},
-            user_context: {wire_key: 'userContext', required: false},
+            user_context: {wire_key: 'userContext', required: false, primitive: 'string'},
             default_value: {wire_key: 'defaultValue', required: false, primitive: 'string'}
           )
 
diff --git a/rb/lib/selenium/webdriver/bidi/protocol/emulation.rb b/rb/lib/selenium/webdriver/bidi/protocol/emulation.rb
index 04320d687ebea..4cb7a12aa7407 100644
--- a/rb/lib/selenium/webdriver/bidi/protocol/emulation.rb
+++ b/rb/lib/selenium/webdriver/bidi/protocol/emulation.rb
@@ -65,6 +65,7 @@ class SetGeolocationOverrideParameters < Serialization::Union
               'Emulation::SetGeolocationOverrideParameters::Coordinates' => ['coordinates'],
               'Emulation::SetGeolocationOverrideParameters::Error' => ['error']
             )
+            object_only
 
             # @api private
             # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
@@ -131,7 +132,10 @@ class SetGeolocationOverrideParameters < Serialization::Union
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-emulationscreenarea
-          ScreenArea = Serialization::Record.define(width: 'width', height: 'height')
+          ScreenArea = Serialization::Record.define(
+            width: {wire_key: 'width', primitive: 'integer'},
+            height: {wire_key: 'height', primitive: 'integer'}
+          )
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
@@ -181,7 +185,7 @@ class SetGeolocationOverrideParameters < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-emulationsetscrollbartypeoverrideparameters
           SetScrollbarTypeOverrideParameters = Serialization::Record.define(
-            scrollbar_type: {wire_key: 'scrollbarType', nullable: true},
+            scrollbar_type: {wire_key: 'scrollbarType', nullable: true, primitive: 'string'},
             contexts: {wire_key: 'contexts', required: false, list: true},
             user_contexts: {wire_key: 'userContexts', required: false, list: true}
           )
@@ -199,7 +203,7 @@ class SetGeolocationOverrideParameters < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-emulationsettouchoverrideparameters
           SetTouchOverrideParameters = Serialization::Record.define(
-            max_touch_points: {wire_key: 'maxTouchPoints', nullable: true},
+            max_touch_points: {wire_key: 'maxTouchPoints', nullable: true, primitive: 'integer'},
             contexts: {wire_key: 'contexts', required: false, list: true},
             user_contexts: {wire_key: 'userContexts', required: false, list: true}
           )
diff --git a/rb/lib/selenium/webdriver/bidi/protocol/input.rb b/rb/lib/selenium/webdriver/bidi/protocol/input.rb
index e49b48a49f740..bd7ab0b8e306c 100644
--- a/rb/lib/selenium/webdriver/bidi/protocol/input.rb
+++ b/rb/lib/selenium/webdriver/bidi/protocol/input.rb
@@ -51,7 +51,7 @@ class Input < Domain
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-inputperformactionsparameters
           PerformActionsParameters = Serialization::Record.define(
-            context: 'context',
+            context: {wire_key: 'context', primitive: 'string'},
             actions: {wire_key: 'actions', ref: 'Input::SourceActions', list: true}
           )
 
@@ -66,6 +66,7 @@ class SourceActions < Serialization::Union
               pointer: 'Input::PointerSourceActions',
               wheel: 'Input::WheelSourceActions'
             )
+            object_only
           end
 
           # @api private
@@ -96,6 +97,7 @@ class KeySourceAction < Serialization::Union
               key_down: 'Input::KeyDownAction',
               key_up: 'Input::KeyUpAction'
             )
+            object_only
           end
 
           # @api private
@@ -131,6 +133,7 @@ class PointerSourceAction < Serialization::Union
               pointer_up: 'Input::PointerUpAction',
               pointer_move: 'Input::PointerMoveAction'
             )
+            object_only
           end
 
           # @api private
@@ -151,6 +154,7 @@ class WheelSourceAction < Serialization::Union
               pause: 'Input::PauseAction',
               scroll: 'Input::WheelScrollAction'
             )
+            object_only
           end
 
           # @api private
@@ -158,7 +162,7 @@ class WheelSourceAction < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-inputpauseaction
           PauseAction = Serialization::Record.define(
             type: {fixed: 'pause'},
-            duration: {wire_key: 'duration', required: false}
+            duration: {wire_key: 'duration', required: false, primitive: 'integer'}
           )
 
           # @api private
@@ -180,16 +184,19 @@ class WheelSourceAction < Serialization::Union
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-inputpointerupaction
-          PointerUpAction = Serialization::Record.define(type: {fixed: 'pointerUp'}, button: 'button')
+          PointerUpAction = Serialization::Record.define(
+            type: {fixed: 'pointerUp'},
+            button: {wire_key: 'button', primitive: 'integer'}
+          )
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-inputpointerdownaction
           PointerDownAction = Serialization::Record.define(
             type: {fixed: 'pointerDown'},
-            button: 'button',
-            width: {wire_key: 'width', required: false},
-            height: {wire_key: 'height', required: false},
+            button: {wire_key: 'button', primitive: 'integer'},
+            width: {wire_key: 'width', required: false, primitive: 'integer'},
+            height: {wire_key: 'height', required: false, primitive: 'integer'},
             pressure: {wire_key: 'pressure', required: false, primitive: 'integer'},
             tangential_pressure: {wire_key: 'tangentialPressure', required: false, primitive: 'integer'},
             twist: {wire_key: 'twist', required: false, primitive: 'integer'},
@@ -204,10 +211,10 @@ class WheelSourceAction < Serialization::Union
             type: {fixed: 'pointerMove'},
             x: {wire_key: 'x', primitive: 'number'},
             y: {wire_key: 'y', primitive: 'number'},
-            duration: {wire_key: 'duration', required: false},
+            duration: {wire_key: 'duration', required: false, primitive: 'integer'},
             origin: {wire_key: 'origin', required: false, ref: 'Input::Origin'},
-            width: {wire_key: 'width', required: false},
-            height: {wire_key: 'height', required: false},
+            width: {wire_key: 'width', required: false, primitive: 'integer'},
+            height: {wire_key: 'height', required: false, primitive: 'integer'},
             pressure: {wire_key: 'pressure', required: false, primitive: 'integer'},
             tangential_pressure: {wire_key: 'tangentialPressure', required: false, primitive: 'integer'},
             twist: {wire_key: 'twist', required: false, primitive: 'integer'},
@@ -220,11 +227,11 @@ class WheelSourceAction < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-inputwheelscrollaction
           WheelScrollAction = Serialization::Record.define(
             type: {fixed: 'scroll'},
-            x: 'x',
-            y: 'y',
-            delta_x: 'deltaX',
-            delta_y: 'deltaY',
-            duration: {wire_key: 'duration', required: false},
+            x: {wire_key: 'x', primitive: 'integer'},
+            y: {wire_key: 'y', primitive: 'integer'},
+            delta_x: {wire_key: 'deltaX', primitive: 'integer'},
+            delta_y: {wire_key: 'deltaY', primitive: 'integer'},
+            duration: {wire_key: 'duration', required: false, primitive: 'integer'},
             origin: {wire_key: 'origin', required: false, ref: 'Input::Origin'}
           )
 
@@ -232,8 +239,8 @@ class WheelSourceAction < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-inputpointercommonproperties
           PointerCommonProperties = Serialization::Record.define(
-            width: {wire_key: 'width', required: false},
-            height: {wire_key: 'height', required: false},
+            width: {wire_key: 'width', required: false, primitive: 'integer'},
+            height: {wire_key: 'height', required: false, primitive: 'integer'},
             pressure: {wire_key: 'pressure', required: false, primitive: 'integer'},
             tangential_pressure: {wire_key: 'tangentialPressure', required: false, primitive: 'integer'},
             twist: {wire_key: 'twist', required: false, primitive: 'integer'},
@@ -254,13 +261,13 @@ class Origin < Serialization::Union
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-inputreleaseactionsparameters
-          ReleaseActionsParameters = Serialization::Record.define(context: 'context')
+          ReleaseActionsParameters = Serialization::Record.define(context: {wire_key: 'context', primitive: 'string'})
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-inputsetfilesparameters
           SetFilesParameters = Serialization::Record.define(
-            context: 'context',
+            context: {wire_key: 'context', primitive: 'string'},
             element: {wire_key: 'element', ref: 'Script::SharedReference'},
             files: {wire_key: 'files', list: true}
           )
@@ -269,8 +276,8 @@ class Origin < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-inputfiledialoginfo
           FileDialogInfo = Serialization::Record.define(
-            context: 'context',
-            user_context: {wire_key: 'userContext', required: false},
+            context: {wire_key: 'context', primitive: 'string'},
+            user_context: {wire_key: 'userContext', required: false, primitive: 'string'},
             element: {wire_key: 'element', required: false, ref: 'Script::SharedReference'},
             multiple: {wire_key: 'multiple', primitive: 'boolean'}
           )
diff --git a/rb/lib/selenium/webdriver/bidi/protocol/log.rb b/rb/lib/selenium/webdriver/bidi/protocol/log.rb
index 35b133f3c59fc..bbbd1ee211754 100644
--- a/rb/lib/selenium/webdriver/bidi/protocol/log.rb
+++ b/rb/lib/selenium/webdriver/bidi/protocol/log.rb
@@ -50,6 +50,7 @@ class Entry < Serialization::Union
               javascript: 'Log::JavascriptLogEntry'
             )
             fallback 'Log::GenericLogEntry'
+            object_only
           end
 
           # @api private
@@ -59,7 +60,7 @@ class Entry < Serialization::Union
             level: {wire_key: 'level', enum: 'Log::LEVEL'},
             source: {wire_key: 'source', ref: 'Script::Source'},
             text: {wire_key: 'text', nullable: true, primitive: 'string'},
-            timestamp: 'timestamp',
+            timestamp: {wire_key: 'timestamp', primitive: 'integer'},
             stack_trace: {wire_key: 'stackTrace', required: false, ref: 'Script::StackTrace'}
           )
 
@@ -70,7 +71,7 @@ class Entry < Serialization::Union
             level: {wire_key: 'level', enum: 'Log::LEVEL'},
             source: {wire_key: 'source', ref: 'Script::Source'},
             text: {wire_key: 'text', nullable: true, primitive: 'string'},
-            timestamp: 'timestamp',
+            timestamp: {wire_key: 'timestamp', primitive: 'integer'},
             stack_trace: {wire_key: 'stackTrace', required: false, ref: 'Script::StackTrace'},
             type: {wire_key: 'type', primitive: 'string'}
           )
@@ -83,7 +84,7 @@ class Entry < Serialization::Union
             level: {wire_key: 'level', enum: 'Log::LEVEL'},
             source: {wire_key: 'source', ref: 'Script::Source'},
             text: {wire_key: 'text', nullable: true, primitive: 'string'},
-            timestamp: 'timestamp',
+            timestamp: {wire_key: 'timestamp', primitive: 'integer'},
             stack_trace: {wire_key: 'stackTrace', required: false, ref: 'Script::StackTrace'},
             method_: {wire_key: 'method', primitive: 'string'},
             args: {wire_key: 'args', ref: 'Script::RemoteValue', list: true}
@@ -97,7 +98,7 @@ class Entry < Serialization::Union
             level: {wire_key: 'level', enum: 'Log::LEVEL'},
             source: {wire_key: 'source', ref: 'Script::Source'},
             text: {wire_key: 'text', nullable: true, primitive: 'string'},
-            timestamp: 'timestamp',
+            timestamp: {wire_key: 'timestamp', primitive: 'integer'},
             stack_trace: {wire_key: 'stackTrace', required: false, ref: 'Script::StackTrace'}
           )
 
diff --git a/rb/lib/selenium/webdriver/bidi/protocol/network.rb b/rb/lib/selenium/webdriver/bidi/protocol/network.rb
index cc9b81dd58f5a..326fd994f5eaf 100644
--- a/rb/lib/selenium/webdriver/bidi/protocol/network.rb
+++ b/rb/lib/selenium/webdriver/bidi/protocol/network.rb
@@ -100,13 +100,13 @@ class Network < Domain
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#type-network-BaseParameters
           BaseParameters = Serialization::Record.define(
-            context: {wire_key: 'context', nullable: true},
+            context: {wire_key: 'context', nullable: true, primitive: 'string'},
             is_blocked: {wire_key: 'isBlocked', primitive: 'boolean'},
-            navigation: {wire_key: 'navigation', nullable: true},
-            redirect_count: 'redirectCount',
+            navigation: {wire_key: 'navigation', nullable: true, primitive: 'string'},
+            redirect_count: {wire_key: 'redirectCount', primitive: 'integer'},
             request: {wire_key: 'request', ref: 'Network::RequestData'},
-            timestamp: 'timestamp',
-            user_context: {wire_key: 'userContext', required: false, nullable: true},
+            timestamp: {wire_key: 'timestamp', primitive: 'integer'},
+            user_context: {wire_key: 'userContext', required: false, nullable: true, primitive: 'string'},
             intercepts: {wire_key: 'intercepts', required: false, list: true}
           )
 
@@ -119,6 +119,7 @@ class BytesValue < Serialization::Union
               string: 'Network::StringValue',
               base64: 'Network::Base64Value'
             )
+            object_only
           end
 
           # @api private
@@ -145,12 +146,11 @@ class BytesValue < Serialization::Union
             value: {wire_key: 'value', ref: 'Network::BytesValue'},
             domain: {wire_key: 'domain', primitive: 'string'},
             path: {wire_key: 'path', primitive: 'string'},
-            size: 'size',
+            size: {wire_key: 'size', primitive: 'integer'},
             http_only: {wire_key: 'httpOnly', primitive: 'boolean'},
             secure: {wire_key: 'secure', primitive: 'boolean'},
             same_site: {wire_key: 'sameSite', enum: 'Network::SAME_SITE'},
-            expiry: {wire_key: 'expiry', required: false},
-            extensible: true
+            expiry: {wire_key: 'expiry', required: false, primitive: 'integer'}
           )
 
           # @api private
@@ -192,9 +192,9 @@ class BytesValue < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#type-network-Initiator
           Initiator = Serialization::Record.define(
-            column_number: {wire_key: 'columnNumber', required: false},
-            line_number: {wire_key: 'lineNumber', required: false},
-            request: {wire_key: 'request', required: false},
+            column_number: {wire_key: 'columnNumber', required: false, primitive: 'integer'},
+            line_number: {wire_key: 'lineNumber', required: false, primitive: 'integer'},
+            request: {wire_key: 'request', required: false, primitive: 'string'},
             stack_trace: {wire_key: 'stackTrace', required: false, ref: 'Script::StackTrace'},
             type: {wire_key: 'type', required: false, enum: 'Network::INITIATOR_TYPE'}
           )
@@ -203,13 +203,13 @@ class BytesValue < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#type-network-RequestData
           RequestData = Serialization::Record.define(
-            request: 'request',
+            request: {wire_key: 'request', primitive: 'string'},
             url: {wire_key: 'url', primitive: 'string'},
             method_: {wire_key: 'method', primitive: 'string'},
             headers: {wire_key: 'headers', ref: 'Network::Header', list: true},
             cookies: {wire_key: 'cookies', ref: 'Network::Cookie', list: true},
-            headers_size: 'headersSize',
-            body_size: {wire_key: 'bodySize', nullable: true},
+            headers_size: {wire_key: 'headersSize', primitive: 'integer'},
+            body_size: {wire_key: 'bodySize', nullable: true, primitive: 'integer'},
             destination: {wire_key: 'destination', primitive: 'string'},
             initiator_type: {wire_key: 'initiatorType', nullable: true, primitive: 'string'},
             timings: {wire_key: 'timings', ref: 'Network::FetchTimingInfo'}
@@ -218,7 +218,7 @@ class BytesValue < Serialization::Union
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#type-network-ResponseContent
-          ResponseContent = Serialization::Record.define(size: 'size')
+          ResponseContent = Serialization::Record.define(size: {wire_key: 'size', primitive: 'integer'})
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
@@ -226,14 +226,14 @@ class BytesValue < Serialization::Union
           ResponseData = Serialization::Record.define(
             url: {wire_key: 'url', primitive: 'string'},
             protocol: {wire_key: 'protocol', primitive: 'string'},
-            status: 'status',
+            status: {wire_key: 'status', primitive: 'integer'},
             status_text: {wire_key: 'statusText', primitive: 'string'},
             from_cache: {wire_key: 'fromCache', primitive: 'boolean'},
             headers: {wire_key: 'headers', ref: 'Network::Header', list: true},
             mime_type: {wire_key: 'mimeType', primitive: 'string'},
-            bytes_received: 'bytesReceived',
-            headers_size: {wire_key: 'headersSize', nullable: true},
-            body_size: {wire_key: 'bodySize', nullable: true},
+            bytes_received: {wire_key: 'bytesReceived', primitive: 'integer'},
+            headers_size: {wire_key: 'headersSize', nullable: true, primitive: 'integer'},
+            body_size: {wire_key: 'bodySize', nullable: true, primitive: 'integer'},
             content: {wire_key: 'content', ref: 'Network::ResponseContent'},
             auth_challenges: {wire_key: 'authChallenges', required: false, ref: 'Network::AuthChallenge', list: true}
           )
@@ -247,7 +247,7 @@ class BytesValue < Serialization::Union
             domain: {wire_key: 'domain', required: false, primitive: 'string'},
             http_only: {wire_key: 'httpOnly', required: false, primitive: 'boolean'},
             expiry: {wire_key: 'expiry', required: false, primitive: 'string'},
-            max_age: {wire_key: 'maxAge', required: false},
+            max_age: {wire_key: 'maxAge', required: false, primitive: 'integer'},
             path: {wire_key: 'path', required: false, primitive: 'string'},
             same_site: {wire_key: 'sameSite', required: false, enum: 'Network::SAME_SITE'},
             secure: {wire_key: 'secure', required: false, primitive: 'boolean'}
@@ -262,6 +262,7 @@ class UrlPattern < Serialization::Union
               pattern: 'Network::UrlPatternPattern',
               string: 'Network::UrlPatternString'
             )
+            object_only
           end
 
           # @api private
@@ -289,7 +290,7 @@ class UrlPattern < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-networkadddatacollectorparameters
           AddDataCollectorParameters = Serialization::Record.define(
             data_types: {wire_key: 'dataTypes', list: true, enum: 'Network::DATA_TYPE'},
-            max_encoded_data_size: 'maxEncodedDataSize',
+            max_encoded_data_size: {wire_key: 'maxEncodedDataSize', primitive: 'integer'},
             collector_type: {wire_key: 'collectorType', required: false, enum: 'Network::COLLECTOR_TYPE'},
             contexts: {wire_key: 'contexts', required: false, list: true},
             user_contexts: {wire_key: 'userContexts', required: false, list: true}
@@ -298,7 +299,7 @@ class UrlPattern < Serialization::Union
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-networkadddatacollectorresult
-          AddDataCollectorResult = Serialization::Record.define(collector: 'collector')
+          AddDataCollectorResult = Serialization::Record.define(collector: {wire_key: 'collector', primitive: 'string'})
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
@@ -312,13 +313,13 @@ class UrlPattern < Serialization::Union
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-networkaddinterceptresult
-          AddInterceptResult = Serialization::Record.define(intercept: 'intercept')
+          AddInterceptResult = Serialization::Record.define(intercept: {wire_key: 'intercept', primitive: 'string'})
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-networkcontinuerequestparameters
           ContinueRequestParameters = Serialization::Record.define(
-            request: 'request',
+            request: {wire_key: 'request', primitive: 'string'},
             body: {wire_key: 'body', required: false, ref: 'Network::BytesValue'},
             cookies: {wire_key: 'cookies', required: false, ref: 'Network::CookieHeader', list: true},
             headers: {wire_key: 'headers', required: false, ref: 'Network::Header', list: true},
@@ -330,12 +331,12 @@ class UrlPattern < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-networkcontinueresponseparameters
           ContinueResponseParameters = Serialization::Record.define(
-            request: 'request',
+            request: {wire_key: 'request', primitive: 'string'},
             cookies: {wire_key: 'cookies', required: false, ref: 'Network::SetCookieHeader', list: true},
             credentials: {wire_key: 'credentials', required: false, ref: 'Network::AuthCredentials'},
             headers: {wire_key: 'headers', required: false, ref: 'Network::Header', list: true},
             reason_phrase: {wire_key: 'reasonPhrase', required: false, primitive: 'string'},
-            status_code: {wire_key: 'statusCode', required: false}
+            status_code: {wire_key: 'statusCode', required: false, primitive: 'integer'}
           )
 
           # @api private
@@ -347,19 +348,20 @@ class ContinueWithAuthParameters < Serialization::Union
               provide_credentials: 'Network::ContinueWithAuthParameters::Credentials'
             )
             fallback 'Network::ContinueWithAuthParameters::NoCredentials'
+            object_only
 
             # @api private
             # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
             Credentials = Serialization::Record.define(
               action: {fixed: 'provideCredentials'},
-              request: 'request',
+              request: {wire_key: 'request', primitive: 'string'},
               credentials: {wire_key: 'credentials', ref: 'Network::AuthCredentials'}
             )
 
             # @api private
             # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
             NoCredentials = Serialization::Record.define(
-              request: 'request',
+              request: {wire_key: 'request', primitive: 'string'},
               action: {wire_key: 'action', enum: 'Network::CONTINUE_WITH_AUTH_NO_CREDENTIALS_ACTION'}
             )
           end
@@ -369,23 +371,23 @@ class ContinueWithAuthParameters < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-networkdisowndataparameters
           DisownDataParameters = Serialization::Record.define(
             data_type: {wire_key: 'dataType', enum: 'Network::DATA_TYPE'},
-            collector: 'collector',
-            request: 'request'
+            collector: {wire_key: 'collector', primitive: 'string'},
+            request: {wire_key: 'request', primitive: 'string'}
           )
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-networkfailrequestparameters
-          FailRequestParameters = Serialization::Record.define(request: 'request')
+          FailRequestParameters = Serialization::Record.define(request: {wire_key: 'request', primitive: 'string'})
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-networkgetdataparameters
           GetDataParameters = Serialization::Record.define(
             data_type: {wire_key: 'dataType', enum: 'Network::DATA_TYPE'},
-            collector: {wire_key: 'collector', required: false},
+            collector: {wire_key: 'collector', required: false, primitive: 'string'},
             disown: {wire_key: 'disown', required: false, primitive: 'boolean'},
-            request: 'request'
+            request: {wire_key: 'request', primitive: 'string'}
           )
 
           # @api private
@@ -397,23 +399,27 @@ class ContinueWithAuthParameters < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-networkprovideresponseparameters
           ProvideResponseParameters = Serialization::Record.define(
-            request: 'request',
+            request: {wire_key: 'request', primitive: 'string'},
             body: {wire_key: 'body', required: false, ref: 'Network::BytesValue'},
             cookies: {wire_key: 'cookies', required: false, ref: 'Network::SetCookieHeader', list: true},
             headers: {wire_key: 'headers', required: false, ref: 'Network::Header', list: true},
             reason_phrase: {wire_key: 'reasonPhrase', required: false, primitive: 'string'},
-            status_code: {wire_key: 'statusCode', required: false}
+            status_code: {wire_key: 'statusCode', required: false, primitive: 'integer'}
           )
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-networkremovedatacollectorparameters
-          RemoveDataCollectorParameters = Serialization::Record.define(collector: 'collector')
+          RemoveDataCollectorParameters = Serialization::Record.define(
+            collector: {wire_key: 'collector', primitive: 'string'}
+          )
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-networkremoveinterceptparameters
-          RemoveInterceptParameters = Serialization::Record.define(intercept: 'intercept')
+          RemoveInterceptParameters = Serialization::Record.define(
+            intercept: {wire_key: 'intercept', primitive: 'string'}
+          )
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
@@ -436,13 +442,13 @@ class ContinueWithAuthParameters < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-networkauthrequiredparameters
           AuthRequiredParameters = Serialization::Record.define(
-            context: {wire_key: 'context', nullable: true},
+            context: {wire_key: 'context', nullable: true, primitive: 'string'},
             is_blocked: {wire_key: 'isBlocked', primitive: 'boolean'},
-            navigation: {wire_key: 'navigation', nullable: true},
-            redirect_count: 'redirectCount',
+            navigation: {wire_key: 'navigation', nullable: true, primitive: 'string'},
+            redirect_count: {wire_key: 'redirectCount', primitive: 'integer'},
             request: {wire_key: 'request', ref: 'Network::RequestData'},
-            timestamp: 'timestamp',
-            user_context: {wire_key: 'userContext', required: false, nullable: true},
+            timestamp: {wire_key: 'timestamp', primitive: 'integer'},
+            user_context: {wire_key: 'userContext', required: false, nullable: true, primitive: 'string'},
             intercepts: {wire_key: 'intercepts', required: false, list: true},
             response: {wire_key: 'response', ref: 'Network::ResponseData'}
           )
@@ -451,13 +457,13 @@ class ContinueWithAuthParameters < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-networkbeforerequestsentparameters
           BeforeRequestSentParameters = Serialization::Record.define(
-            context: {wire_key: 'context', nullable: true},
+            context: {wire_key: 'context', nullable: true, primitive: 'string'},
             is_blocked: {wire_key: 'isBlocked', primitive: 'boolean'},
-            navigation: {wire_key: 'navigation', nullable: true},
-            redirect_count: 'redirectCount',
+            navigation: {wire_key: 'navigation', nullable: true, primitive: 'string'},
+            redirect_count: {wire_key: 'redirectCount', primitive: 'integer'},
             request: {wire_key: 'request', ref: 'Network::RequestData'},
-            timestamp: 'timestamp',
-            user_context: {wire_key: 'userContext', required: false, nullable: true},
+            timestamp: {wire_key: 'timestamp', primitive: 'integer'},
+            user_context: {wire_key: 'userContext', required: false, nullable: true, primitive: 'string'},
             intercepts: {wire_key: 'intercepts', required: false, list: true},
             initiator: {wire_key: 'initiator', required: false, ref: 'Network::Initiator'}
           )
@@ -466,13 +472,13 @@ class ContinueWithAuthParameters < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-networkfetcherrorparameters
           FetchErrorParameters = Serialization::Record.define(
-            context: {wire_key: 'context', nullable: true},
+            context: {wire_key: 'context', nullable: true, primitive: 'string'},
             is_blocked: {wire_key: 'isBlocked', primitive: 'boolean'},
-            navigation: {wire_key: 'navigation', nullable: true},
-            redirect_count: 'redirectCount',
+            navigation: {wire_key: 'navigation', nullable: true, primitive: 'string'},
+            redirect_count: {wire_key: 'redirectCount', primitive: 'integer'},
             request: {wire_key: 'request', ref: 'Network::RequestData'},
-            timestamp: 'timestamp',
-            user_context: {wire_key: 'userContext', required: false, nullable: true},
+            timestamp: {wire_key: 'timestamp', primitive: 'integer'},
+            user_context: {wire_key: 'userContext', required: false, nullable: true, primitive: 'string'},
             intercepts: {wire_key: 'intercepts', required: false, list: true},
             error_text: {wire_key: 'errorText', primitive: 'string'}
           )
@@ -481,13 +487,13 @@ class ContinueWithAuthParameters < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-networkresponsecompletedparameters
           ResponseCompletedParameters = Serialization::Record.define(
-            context: {wire_key: 'context', nullable: true},
+            context: {wire_key: 'context', nullable: true, primitive: 'string'},
             is_blocked: {wire_key: 'isBlocked', primitive: 'boolean'},
-            navigation: {wire_key: 'navigation', nullable: true},
-            redirect_count: 'redirectCount',
+            navigation: {wire_key: 'navigation', nullable: true, primitive: 'string'},
+            redirect_count: {wire_key: 'redirectCount', primitive: 'integer'},
             request: {wire_key: 'request', ref: 'Network::RequestData'},
-            timestamp: 'timestamp',
-            user_context: {wire_key: 'userContext', required: false, nullable: true},
+            timestamp: {wire_key: 'timestamp', primitive: 'integer'},
+            user_context: {wire_key: 'userContext', required: false, nullable: true, primitive: 'string'},
             intercepts: {wire_key: 'intercepts', required: false, list: true},
             response: {wire_key: 'response', ref: 'Network::ResponseData'}
           )
@@ -496,13 +502,13 @@ class ContinueWithAuthParameters < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-networkresponsestartedparameters
           ResponseStartedParameters = Serialization::Record.define(
-            context: {wire_key: 'context', nullable: true},
+            context: {wire_key: 'context', nullable: true, primitive: 'string'},
             is_blocked: {wire_key: 'isBlocked', primitive: 'boolean'},
-            navigation: {wire_key: 'navigation', nullable: true},
-            redirect_count: 'redirectCount',
+            navigation: {wire_key: 'navigation', nullable: true, primitive: 'string'},
+            redirect_count: {wire_key: 'redirectCount', primitive: 'integer'},
             request: {wire_key: 'request', ref: 'Network::RequestData'},
-            timestamp: 'timestamp',
-            user_context: {wire_key: 'userContext', required: false, nullable: true},
+            timestamp: {wire_key: 'timestamp', primitive: 'integer'},
+            user_context: {wire_key: 'userContext', required: false, nullable: true, primitive: 'string'},
             intercepts: {wire_key: 'intercepts', required: false, list: true},
             response: {wire_key: 'response', ref: 'Network::ResponseData'}
           )
diff --git a/rb/lib/selenium/webdriver/bidi/protocol/script.rb b/rb/lib/selenium/webdriver/bidi/protocol/script.rb
index 659531d6f09ac..1147504269a8f 100644
--- a/rb/lib/selenium/webdriver/bidi/protocol/script.rb
+++ b/rb/lib/selenium/webdriver/bidi/protocol/script.rb
@@ -83,7 +83,7 @@ class Script < Domain
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptchannelproperties
           ChannelProperties = Serialization::Record.define(
-            channel: 'channel',
+            channel: {wire_key: 'channel', primitive: 'string'},
             serialization_options: {
               wire_key: 'serializationOptions',
               required: false,
@@ -101,6 +101,7 @@ class EvaluateResult < Serialization::Union
               success: 'Script::EvaluateResultSuccess',
               exception: 'Script::EvaluateResultException'
             )
+            object_only
           end
 
           # @api private
@@ -109,7 +110,7 @@ class EvaluateResult < Serialization::Union
           EvaluateResultSuccess = Serialization::Record.define(
             type: {fixed: 'success'},
             result: {wire_key: 'result', ref: 'Script::RemoteValue'},
-            realm: 'realm'
+            realm: {wire_key: 'realm', primitive: 'string'}
           )
 
           # @api private
@@ -118,16 +119,16 @@ class EvaluateResult < Serialization::Union
           EvaluateResultException = Serialization::Record.define(
             type: {fixed: 'exception'},
             exception_details: {wire_key: 'exceptionDetails', ref: 'Script::ExceptionDetails'},
-            realm: 'realm'
+            realm: {wire_key: 'realm', primitive: 'string'}
           )
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#type-script-ExceptionDetails
           ExceptionDetails = Serialization::Record.define(
-            column_number: 'columnNumber',
+            column_number: {wire_key: 'columnNumber', primitive: 'integer'},
             exception: {wire_key: 'exception', ref: 'Script::RemoteValue'},
-            line_number: 'lineNumber',
+            line_number: {wire_key: 'lineNumber', primitive: 'integer'},
             stack_trace: {wire_key: 'stackTrace', ref: 'Script::StackTrace'},
             text: {wire_key: 'text', primitive: 'string'}
           )
@@ -167,6 +168,7 @@ class LocalValue < Serialization::Union
               set: 'Script::SetLocalValue'
             )
             fallback 'Script::RemoteReference'
+            object_only
           end
 
           # @api private
@@ -190,7 +192,7 @@ class LocalValue < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptmaplocalvalue
           MapLocalValue = Serialization::Record.define(
             type: {fixed: 'map'},
-            value: {wire_key: 'value', ref: 'Script::LocalValue', list: true}
+            value: {wire_key: 'value', ref: 'Script::LocalValue', list: true, scalar: 'string'}
           )
 
           # @api private
@@ -198,7 +200,7 @@ class LocalValue < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptobjectlocalvalue
           ObjectLocalValue = Serialization::Record.define(
             type: {fixed: 'object'},
-            value: {wire_key: 'value', ref: 'Script::LocalValue', list: true}
+            value: {wire_key: 'value', ref: 'Script::LocalValue', list: true, scalar: 'string'}
           )
 
           # @api private
@@ -245,6 +247,7 @@ class PrimitiveProtocolValue < Serialization::Union
               boolean: 'Script::BooleanValue',
               bigint: 'Script::BigIntValue'
             )
+            object_only
           end
 
           # @api private
@@ -310,13 +313,14 @@ class RealmInfo < Serialization::Union
               audio_worklet: 'Script::AudioWorkletRealmInfo',
               worklet: 'Script::WorkletRealmInfo'
             )
+            object_only
           end
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptbaserealminfo
           BaseRealmInfo = Serialization::Record.define(
-            realm: 'realm',
+            realm: {wire_key: 'realm', primitive: 'string'},
             origin: {wire_key: 'origin', primitive: 'string'}
           )
 
@@ -325,10 +329,10 @@ class RealmInfo < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptwindowrealminfo
           WindowRealmInfo = Serialization::Record.define(
             type: {fixed: 'window'},
-            realm: 'realm',
+            realm: {wire_key: 'realm', primitive: 'string'},
             origin: {wire_key: 'origin', primitive: 'string'},
-            context: 'context',
-            user_context: {wire_key: 'userContext', required: false},
+            context: {wire_key: 'context', primitive: 'string'},
+            user_context: {wire_key: 'userContext', required: false, primitive: 'string'},
             sandbox: {wire_key: 'sandbox', required: false, primitive: 'string'}
           )
 
@@ -337,7 +341,7 @@ class RealmInfo < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptdedicatedworkerrealminfo
           DedicatedWorkerRealmInfo = Serialization::Record.define(
             type: {fixed: 'dedicated-worker'},
-            realm: 'realm',
+            realm: {wire_key: 'realm', primitive: 'string'},
             origin: {wire_key: 'origin', primitive: 'string'},
             owners: {wire_key: 'owners', list: true}
           )
@@ -347,7 +351,7 @@ class RealmInfo < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptsharedworkerrealminfo
           SharedWorkerRealmInfo = Serialization::Record.define(
             type: {fixed: 'shared-worker'},
-            realm: 'realm',
+            realm: {wire_key: 'realm', primitive: 'string'},
             origin: {wire_key: 'origin', primitive: 'string'}
           )
 
@@ -356,7 +360,7 @@ class RealmInfo < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptserviceworkerrealminfo
           ServiceWorkerRealmInfo = Serialization::Record.define(
             type: {fixed: 'service-worker'},
-            realm: 'realm',
+            realm: {wire_key: 'realm', primitive: 'string'},
             origin: {wire_key: 'origin', primitive: 'string'}
           )
 
@@ -365,7 +369,7 @@ class RealmInfo < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptworkerrealminfo
           WorkerRealmInfo = Serialization::Record.define(
             type: {fixed: 'worker'},
-            realm: 'realm',
+            realm: {wire_key: 'realm', primitive: 'string'},
             origin: {wire_key: 'origin', primitive: 'string'}
           )
 
@@ -374,7 +378,7 @@ class RealmInfo < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptpaintworkletrealminfo
           PaintWorkletRealmInfo = Serialization::Record.define(
             type: {fixed: 'paint-worklet'},
-            realm: 'realm',
+            realm: {wire_key: 'realm', primitive: 'string'},
             origin: {wire_key: 'origin', primitive: 'string'}
           )
 
@@ -383,7 +387,7 @@ class RealmInfo < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptaudioworkletrealminfo
           AudioWorkletRealmInfo = Serialization::Record.define(
             type: {fixed: 'audio-worklet'},
-            realm: 'realm',
+            realm: {wire_key: 'realm', primitive: 'string'},
             origin: {wire_key: 'origin', primitive: 'string'}
           )
 
@@ -392,7 +396,7 @@ class RealmInfo < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptworkletrealminfo
           WorkletRealmInfo = Serialization::Record.define(
             type: {fixed: 'worklet'},
-            realm: 'realm',
+            realm: {wire_key: 'realm', primitive: 'string'},
             origin: {wire_key: 'origin', primitive: 'string'}
           )
 
@@ -404,14 +408,15 @@ class RemoteReference < Serialization::Union
               'Script::SharedReference' => ['sharedId'],
               'Script::RemoteObjectReference' => ['handle']
             )
+            object_only
           end
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptsharedreference
           SharedReference = Serialization::Record.define(
-            shared_id: 'sharedId',
-            handle: {wire_key: 'handle', required: false},
+            shared_id: {wire_key: 'sharedId', primitive: 'string'},
+            handle: {wire_key: 'handle', required: false, primitive: 'string'},
             extensible: true
           )
 
@@ -419,8 +424,8 @@ class RemoteReference < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptremoteobjectreference
           RemoteObjectReference = Serialization::Record.define(
-            handle: 'handle',
-            shared_id: {wire_key: 'sharedId', required: false},
+            handle: {wire_key: 'handle', primitive: 'string'},
+            shared_id: {wire_key: 'sharedId', required: false, primitive: 'string'},
             extensible: true
           )
 
@@ -484,6 +489,7 @@ class RemoteValue < Serialization::Union
               node: 'Script::NodeRemoteValue',
               window: 'Script::WindowProxyRemoteValue'
             )
+            object_only
           end
 
           # @api private
@@ -491,8 +497,8 @@ class RemoteValue < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptsymbolremotevalue
           SymbolRemoteValue = Serialization::Record.define(
             type: {fixed: 'symbol'},
-            handle: {wire_key: 'handle', required: false},
-            internal_id: {wire_key: 'internalId', required: false}
+            handle: {wire_key: 'handle', required: false, primitive: 'string'},
+            internal_id: {wire_key: 'internalId', required: false, primitive: 'string'}
           )
 
           # @api private
@@ -500,8 +506,8 @@ class RemoteValue < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptarrayremotevalue
           ArrayRemoteValue = Serialization::Record.define(
             type: {fixed: 'array'},
-            handle: {wire_key: 'handle', required: false},
-            internal_id: {wire_key: 'internalId', required: false},
+            handle: {wire_key: 'handle', required: false, primitive: 'string'},
+            internal_id: {wire_key: 'internalId', required: false, primitive: 'string'},
             value: {wire_key: 'value', required: false, ref: 'Script::RemoteValue', list: true}
           )
 
@@ -510,9 +516,9 @@ class RemoteValue < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptobjectremotevalue
           ObjectRemoteValue = Serialization::Record.define(
             type: {fixed: 'object'},
-            handle: {wire_key: 'handle', required: false},
-            internal_id: {wire_key: 'internalId', required: false},
-            value: {wire_key: 'value', required: false, ref: 'Script::RemoteValue', list: true}
+            handle: {wire_key: 'handle', required: false, primitive: 'string'},
+            internal_id: {wire_key: 'internalId', required: false, primitive: 'string'},
+            value: {wire_key: 'value', required: false, ref: 'Script::RemoteValue', list: true, scalar: 'string'}
           )
 
           # @api private
@@ -520,8 +526,8 @@ class RemoteValue < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptfunctionremotevalue
           FunctionRemoteValue = Serialization::Record.define(
             type: {fixed: 'function'},
-            handle: {wire_key: 'handle', required: false},
-            internal_id: {wire_key: 'internalId', required: false}
+            handle: {wire_key: 'handle', required: false, primitive: 'string'},
+            internal_id: {wire_key: 'internalId', required: false, primitive: 'string'}
           )
 
           # @api private
@@ -530,8 +536,8 @@ class RemoteValue < Serialization::Union
           RegExpRemoteValue = Serialization::Record.define(
             type: {fixed: 'regexp'},
             value: {wire_key: 'value', ref: 'Script::RegExpValue'},
-            handle: {wire_key: 'handle', required: false},
-            internal_id: {wire_key: 'internalId', required: false}
+            handle: {wire_key: 'handle', required: false, primitive: 'string'},
+            internal_id: {wire_key: 'internalId', required: false, primitive: 'string'}
           )
 
           # @api private
@@ -540,8 +546,8 @@ class RemoteValue < Serialization::Union
           DateRemoteValue = Serialization::Record.define(
             type: {fixed: 'date'},
             value: {wire_key: 'value', primitive: 'string'},
-            handle: {wire_key: 'handle', required: false},
-            internal_id: {wire_key: 'internalId', required: false}
+            handle: {wire_key: 'handle', required: false, primitive: 'string'},
+            internal_id: {wire_key: 'internalId', required: false, primitive: 'string'}
           )
 
           # @api private
@@ -549,9 +555,9 @@ class RemoteValue < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptmapremotevalue
           MapRemoteValue = Serialization::Record.define(
             type: {fixed: 'map'},
-            handle: {wire_key: 'handle', required: false},
-            internal_id: {wire_key: 'internalId', required: false},
-            value: {wire_key: 'value', required: false, ref: 'Script::RemoteValue', list: true}
+            handle: {wire_key: 'handle', required: false, primitive: 'string'},
+            internal_id: {wire_key: 'internalId', required: false, primitive: 'string'},
+            value: {wire_key: 'value', required: false, ref: 'Script::RemoteValue', list: true, scalar: 'string'}
           )
 
           # @api private
@@ -559,8 +565,8 @@ class RemoteValue < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptsetremotevalue
           SetRemoteValue = Serialization::Record.define(
             type: {fixed: 'set'},
-            handle: {wire_key: 'handle', required: false},
-            internal_id: {wire_key: 'internalId', required: false},
+            handle: {wire_key: 'handle', required: false, primitive: 'string'},
+            internal_id: {wire_key: 'internalId', required: false, primitive: 'string'},
             value: {wire_key: 'value', required: false, ref: 'Script::RemoteValue', list: true}
           )
 
@@ -569,8 +575,8 @@ class RemoteValue < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptweakmapremotevalue
           WeakMapRemoteValue = Serialization::Record.define(
             type: {fixed: 'weakmap'},
-            handle: {wire_key: 'handle', required: false},
-            internal_id: {wire_key: 'internalId', required: false}
+            handle: {wire_key: 'handle', required: false, primitive: 'string'},
+            internal_id: {wire_key: 'internalId', required: false, primitive: 'string'}
           )
 
           # @api private
@@ -578,8 +584,8 @@ class RemoteValue < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptweaksetremotevalue
           WeakSetRemoteValue = Serialization::Record.define(
             type: {fixed: 'weakset'},
-            handle: {wire_key: 'handle', required: false},
-            internal_id: {wire_key: 'internalId', required: false}
+            handle: {wire_key: 'handle', required: false, primitive: 'string'},
+            internal_id: {wire_key: 'internalId', required: false, primitive: 'string'}
           )
 
           # @api private
@@ -587,8 +593,8 @@ class RemoteValue < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptgeneratorremotevalue
           GeneratorRemoteValue = Serialization::Record.define(
             type: {fixed: 'generator'},
-            handle: {wire_key: 'handle', required: false},
-            internal_id: {wire_key: 'internalId', required: false}
+            handle: {wire_key: 'handle', required: false, primitive: 'string'},
+            internal_id: {wire_key: 'internalId', required: false, primitive: 'string'}
           )
 
           # @api private
@@ -596,8 +602,8 @@ class RemoteValue < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scripterrorremotevalue
           ErrorRemoteValue = Serialization::Record.define(
             type: {fixed: 'error'},
-            handle: {wire_key: 'handle', required: false},
-            internal_id: {wire_key: 'internalId', required: false}
+            handle: {wire_key: 'handle', required: false, primitive: 'string'},
+            internal_id: {wire_key: 'internalId', required: false, primitive: 'string'}
           )
 
           # @api private
@@ -605,8 +611,8 @@ class RemoteValue < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptproxyremotevalue
           ProxyRemoteValue = Serialization::Record.define(
             type: {fixed: 'proxy'},
-            handle: {wire_key: 'handle', required: false},
-            internal_id: {wire_key: 'internalId', required: false}
+            handle: {wire_key: 'handle', required: false, primitive: 'string'},
+            internal_id: {wire_key: 'internalId', required: false, primitive: 'string'}
           )
 
           # @api private
@@ -614,8 +620,8 @@ class RemoteValue < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptpromiseremotevalue
           PromiseRemoteValue = Serialization::Record.define(
             type: {fixed: 'promise'},
-            handle: {wire_key: 'handle', required: false},
-            internal_id: {wire_key: 'internalId', required: false}
+            handle: {wire_key: 'handle', required: false, primitive: 'string'},
+            internal_id: {wire_key: 'internalId', required: false, primitive: 'string'}
           )
 
           # @api private
@@ -623,8 +629,8 @@ class RemoteValue < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scripttypedarrayremotevalue
           TypedArrayRemoteValue = Serialization::Record.define(
             type: {fixed: 'typedarray'},
-            handle: {wire_key: 'handle', required: false},
-            internal_id: {wire_key: 'internalId', required: false}
+            handle: {wire_key: 'handle', required: false, primitive: 'string'},
+            internal_id: {wire_key: 'internalId', required: false, primitive: 'string'}
           )
 
           # @api private
@@ -632,8 +638,8 @@ class RemoteValue < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptarraybufferremotevalue
           ArrayBufferRemoteValue = Serialization::Record.define(
             type: {fixed: 'arraybuffer'},
-            handle: {wire_key: 'handle', required: false},
-            internal_id: {wire_key: 'internalId', required: false}
+            handle: {wire_key: 'handle', required: false, primitive: 'string'},
+            internal_id: {wire_key: 'internalId', required: false, primitive: 'string'}
           )
 
           # @api private
@@ -641,8 +647,8 @@ class RemoteValue < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptnodelistremotevalue
           NodeListRemoteValue = Serialization::Record.define(
             type: {fixed: 'nodelist'},
-            handle: {wire_key: 'handle', required: false},
-            internal_id: {wire_key: 'internalId', required: false},
+            handle: {wire_key: 'handle', required: false, primitive: 'string'},
+            internal_id: {wire_key: 'internalId', required: false, primitive: 'string'},
             value: {wire_key: 'value', required: false, ref: 'Script::RemoteValue', list: true}
           )
 
@@ -651,8 +657,8 @@ class RemoteValue < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scripthtmlcollectionremotevalue
           HTMLCollectionRemoteValue = Serialization::Record.define(
             type: {fixed: 'htmlcollection'},
-            handle: {wire_key: 'handle', required: false},
-            internal_id: {wire_key: 'internalId', required: false},
+            handle: {wire_key: 'handle', required: false, primitive: 'string'},
+            internal_id: {wire_key: 'internalId', required: false, primitive: 'string'},
             value: {wire_key: 'value', required: false, ref: 'Script::RemoteValue', list: true}
           )
 
@@ -661,9 +667,9 @@ class RemoteValue < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptnoderemotevalue
           NodeRemoteValue = Serialization::Record.define(
             type: {fixed: 'node'},
-            shared_id: {wire_key: 'sharedId', required: false},
-            handle: {wire_key: 'handle', required: false},
-            internal_id: {wire_key: 'internalId', required: false},
+            shared_id: {wire_key: 'sharedId', required: false, primitive: 'string'},
+            handle: {wire_key: 'handle', required: false, primitive: 'string'},
+            internal_id: {wire_key: 'internalId', required: false, primitive: 'string'},
             value: {wire_key: 'value', required: false, ref: 'Script::NodeProperties'}
           )
 
@@ -671,8 +677,8 @@ class RemoteValue < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptnodeproperties
           NodeProperties = Serialization::Record.define(
-            node_type: 'nodeType',
-            child_node_count: 'childNodeCount',
+            node_type: {wire_key: 'nodeType', primitive: 'integer'},
+            child_node_count: {wire_key: 'childNodeCount', primitive: 'integer'},
             attributes: {wire_key: 'attributes', required: false},
             children: {wire_key: 'children', required: false, ref: 'Script::NodeRemoteValue', list: true},
             local_name: {wire_key: 'localName', required: false, primitive: 'string'},
@@ -688,21 +694,21 @@ class RemoteValue < Serialization::Union
           WindowProxyRemoteValue = Serialization::Record.define(
             type: {fixed: 'window'},
             value: {wire_key: 'value', ref: 'Script::WindowProxyProperties'},
-            handle: {wire_key: 'handle', required: false},
-            internal_id: {wire_key: 'internalId', required: false}
+            handle: {wire_key: 'handle', required: false, primitive: 'string'},
+            internal_id: {wire_key: 'internalId', required: false, primitive: 'string'}
           )
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptwindowproxyproperties
-          WindowProxyProperties = Serialization::Record.define(context: 'context')
+          WindowProxyProperties = Serialization::Record.define(context: {wire_key: 'context', primitive: 'string'})
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#type-script-SerializationOptions
           SerializationOptions = Serialization::Record.define(
-            max_dom_depth: {wire_key: 'maxDomDepth', required: false, nullable: true},
-            max_object_depth: {wire_key: 'maxObjectDepth', required: false, nullable: true},
+            max_dom_depth: {wire_key: 'maxDomDepth', required: false, nullable: true, primitive: 'integer'},
+            max_object_depth: {wire_key: 'maxObjectDepth', required: false, nullable: true, primitive: 'integer'},
             include_shadow_tree: {
               wire_key: 'includeShadowTree',
               required: false,
@@ -714,9 +720,9 @@ class RemoteValue < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#type-script-StackFrame
           StackFrame = Serialization::Record.define(
-            column_number: 'columnNumber',
+            column_number: {wire_key: 'columnNumber', primitive: 'integer'},
             function_name: {wire_key: 'functionName', primitive: 'string'},
-            line_number: 'lineNumber',
+            line_number: {wire_key: 'lineNumber', primitive: 'integer'},
             url: {wire_key: 'url', primitive: 'string'}
           )
 
@@ -731,21 +737,21 @@ class RemoteValue < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#type-script-Source
           Source = Serialization::Record.define(
-            realm: 'realm',
-            context: {wire_key: 'context', required: false},
-            user_context: {wire_key: 'userContext', required: false}
+            realm: {wire_key: 'realm', primitive: 'string'},
+            context: {wire_key: 'context', required: false, primitive: 'string'},
+            user_context: {wire_key: 'userContext', required: false, primitive: 'string'}
           )
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptrealmtarget
-          RealmTarget = Serialization::Record.define(realm: 'realm')
+          RealmTarget = Serialization::Record.define(realm: {wire_key: 'realm', primitive: 'string'})
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptcontexttarget
           ContextTarget = Serialization::Record.define(
-            context: 'context',
+            context: {wire_key: 'context', primitive: 'string'},
             sandbox: {wire_key: 'sandbox', required: false, primitive: 'string'}
           )
 
@@ -757,6 +763,7 @@ class Target < Serialization::Union
               'Script::ContextTarget' => ['context'],
               'Script::RealmTarget' => ['realm']
             )
+            object_only
           end
 
           # @api private
@@ -773,7 +780,7 @@ class Target < Serialization::Union
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptaddpreloadscriptresult
-          AddPreloadScriptResult = Serialization::Record.define(script: 'script')
+          AddPreloadScriptResult = Serialization::Record.define(script: {wire_key: 'script', primitive: 'string'})
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
@@ -821,7 +828,7 @@ class Target < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptgetrealmsparameters
           GetRealmsParameters = Serialization::Record.define(
-            context: {wire_key: 'context', required: false},
+            context: {wire_key: 'context', required: false, primitive: 'string'},
             type: {wire_key: 'type', required: false, enum: 'Script::REALM_TYPE'}
           )
 
@@ -835,13 +842,15 @@ class Target < Serialization::Union
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptremovepreloadscriptparameters
-          RemovePreloadScriptParameters = Serialization::Record.define(script: 'script')
+          RemovePreloadScriptParameters = Serialization::Record.define(
+            script: {wire_key: 'script', primitive: 'string'}
+          )
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptmessageparameters
           MessageParameters = Serialization::Record.define(
-            channel: 'channel',
+            channel: {wire_key: 'channel', primitive: 'string'},
             data: {wire_key: 'data', ref: 'Script::RemoteValue'},
             source: {wire_key: 'source', ref: 'Script::Source'}
           )
@@ -849,7 +858,7 @@ class Target < Serialization::Union
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-scriptrealmdestroyedparameters
-          RealmDestroyedParameters = Serialization::Record.define(realm: 'realm')
+          RealmDestroyedParameters = Serialization::Record.define(realm: {wire_key: 'realm', primitive: 'string'})
 
           EVENT_TYPES = {
             'script.message' => Script::MessageParameters,
diff --git a/rb/lib/selenium/webdriver/bidi/protocol/session.rb b/rb/lib/selenium/webdriver/bidi/protocol/session.rb
index fa394de87953c..f6080ff60094e 100644
--- a/rb/lib/selenium/webdriver/bidi/protocol/session.rb
+++ b/rb/lib/selenium/webdriver/bidi/protocol/session.rb
@@ -78,6 +78,7 @@ class ProxyConfiguration < Serialization::Union
               pac: 'Session::PacProxyConfiguration',
               system: 'Session::SystemProxyConfiguration'
             )
+            object_only
           end
 
           # @api private
@@ -203,14 +204,13 @@ class ProxyConfiguration < Serialization::Union
               required: false,
               ref: 'Session::UserPromptHandler'
             },
-            web_socket_url: {wire_key: 'webSocketUrl', required: false, primitive: 'string'},
-            extensible: true
+            web_socket_url: {wire_key: 'webSocketUrl', required: false, primitive: 'string'}
           )
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-sessionsubscriberesult
-          SubscribeResult = Serialization::Record.define(subscription: 'subscription')
+          SubscribeResult = Serialization::Record.define(subscription: {wire_key: 'subscription', primitive: 'string'})
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
@@ -220,6 +220,7 @@ class UnsubscribeParameters < Serialization::Union
               'Session::UnsubscribeByAttributesRequest' => ['events'],
               'Session::UnsubscribeByIDRequest' => ['subscriptions']
             )
+            object_only
           end
 
           # @api private
diff --git a/rb/lib/selenium/webdriver/bidi/protocol/storage.rb b/rb/lib/selenium/webdriver/bidi/protocol/storage.rb
index 2cfaf4e54b2f3..6b50b696a83ce 100644
--- a/rb/lib/selenium/webdriver/bidi/protocol/storage.rb
+++ b/rb/lib/selenium/webdriver/bidi/protocol/storage.rb
@@ -33,8 +33,7 @@ class Storage < Domain
           # @see https://w3c.github.io/webdriver-bidi/#type-storage-PartitionKey
           PartitionKey = Serialization::Record.define(
             user_context: {wire_key: 'userContext', required: false, primitive: 'string'},
-            source_origin: {wire_key: 'sourceOrigin', required: false, primitive: 'string'},
-            extensible: true
+            source_origin: {wire_key: 'sourceOrigin', required: false, primitive: 'string'}
           )
 
           # @api private
@@ -45,11 +44,11 @@ class Storage < Domain
             value: {wire_key: 'value', required: false, ref: 'Network::BytesValue'},
             domain: {wire_key: 'domain', required: false, primitive: 'string'},
             path: {wire_key: 'path', required: false, primitive: 'string'},
-            size: {wire_key: 'size', required: false},
+            size: {wire_key: 'size', required: false, primitive: 'integer'},
             http_only: {wire_key: 'httpOnly', required: false, primitive: 'boolean'},
             secure: {wire_key: 'secure', required: false, primitive: 'boolean'},
             same_site: {wire_key: 'sameSite', required: false, enum: 'Network::SAME_SITE'},
-            expiry: {wire_key: 'expiry', required: false},
+            expiry: {wire_key: 'expiry', required: false, primitive: 'integer'},
             extensible: true
           )
 
@@ -58,7 +57,7 @@ class Storage < Domain
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-storagebrowsingcontextpartitiondescriptor
           BrowsingContextPartitionDescriptor = Serialization::Record.define(
             type: {fixed: 'context'},
-            context: 'context'
+            context: {wire_key: 'context', primitive: 'string'}
           )
 
           # @api private
@@ -80,6 +79,7 @@ class PartitionDescriptor < Serialization::Union
               context: 'Storage::BrowsingContextPartitionDescriptor',
               storage_key: 'Storage::StorageKeyPartitionDescriptor'
             )
+            object_only
           end
 
           # @api private
@@ -109,7 +109,7 @@ class PartitionDescriptor < Serialization::Union
             http_only: {wire_key: 'httpOnly', required: false, primitive: 'boolean'},
             secure: {wire_key: 'secure', required: false, primitive: 'boolean'},
             same_site: {wire_key: 'sameSite', required: false, enum: 'Network::SAME_SITE'},
-            expiry: {wire_key: 'expiry', required: false},
+            expiry: {wire_key: 'expiry', required: false, primitive: 'integer'},
             extensible: true
           )
 
diff --git a/rb/lib/selenium/webdriver/bidi/protocol/web_extension.rb b/rb/lib/selenium/webdriver/bidi/protocol/web_extension.rb
index e131eff0f4e75..68c4751e92252 100644
--- a/rb/lib/selenium/webdriver/bidi/protocol/web_extension.rb
+++ b/rb/lib/selenium/webdriver/bidi/protocol/web_extension.rb
@@ -45,6 +45,7 @@ class ExtensionData < Serialization::Union
               base64: 'WebExtension::ExtensionBase64Encoded',
               path: 'WebExtension::ExtensionPath'
             )
+            object_only
           end
 
           # @api private
@@ -74,12 +75,12 @@ class ExtensionData < Serialization::Union
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-webextensioninstallresult
-          InstallResult = Serialization::Record.define(extension: 'extension')
+          InstallResult = Serialization::Record.define(extension: {wire_key: 'extension', primitive: 'string'})
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-webextensionuninstallparameters
-          UninstallParameters = Serialization::Record.define(extension: 'extension')
+          UninstallParameters = Serialization::Record.define(extension: {wire_key: 'extension', primitive: 'string'})
 
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
diff --git a/rb/lib/selenium/webdriver/bidi/serialization/record.rb b/rb/lib/selenium/webdriver/bidi/serialization/record.rb
index ca5280e6f1990..a8364bc876e53 100644
--- a/rb/lib/selenium/webdriver/bidi/serialization/record.rb
+++ b/rb/lib/selenium/webdriver/bidi/serialization/record.rb
@@ -29,7 +29,7 @@ module Serialization
         # @api private
         class Record < ::Data
           # Named Field, not Member, to avoid colliding with +::Data#members+.
-          Field = ::Data.define(:name, :wire_key, :nullable, :ref, :list, :fixed, :enum, :required, :primitive)
+          Field = ::Data.define(:name, :wire_key, :nullable, :ref, :list, :fixed, :enum, :required, :primitive, :scalar)
 
           def self.define(**spec)
             extensible = spec.delete(:extensible) || false
@@ -59,7 +59,8 @@ def self.field(name, meta)
             Field.new(name: name.to_sym, wire_key: meta.fetch(:wire_key, name.to_s),
                       nullable: meta[:nullable] || false, ref: meta[:ref],
                       list: meta[:list] || false, fixed: meta.fetch(:fixed, UNSET), enum: meta[:enum],
-                      required: meta.fetch(:required, true), primitive: meta[:primitive])
+                      required: meta.fetch(:required, true), primitive: meta[:primitive],
+                      scalar: meta[:scalar])
           end
           private_class_method :field
 
@@ -147,8 +148,18 @@ def read(field, raw)
                 return raw
               end
 
+              read_ref(field, raw)
+            end
+
+            # Reads a ref-typed value into its class. A `scalar` position is an inline union with
+            # a scalar arm collapsed onto its union ref (a map's string keys): a non-object leaf
+            # passes through instead of being handed to the object_only union, but only when it
+            # matches the arm's primitive (+scalar+ carries it). A list recurses per element.
+            def read_ref(field, raw)
               klass = (@refs ||= {})[field.name] ||= Protocol.const_get(field.ref)
-              field.list ? read_list(raw, klass) : klass.from_json(raw)
+              return read_list(field, raw, klass) if field.list
+
+              field.scalar && !raw.is_a?(::Hash) ? scalar_value(field, raw) : klass.from_json(raw)
             end
 
             # A declared list must arrive as an array; a scalar-shaped field (enum or ref, not a
@@ -181,10 +192,48 @@ def enum_hash(field)
               (@enums ||= {})[field.name] ||= Protocol.const_get(field.enum)
             end
 
-            # Parses each element, recursing into nested lists (e.g. a map's [key, value] pairs)
-            # so their entries become typed too.
-            def read_list(raw, klass)
-              raw.map { |element| element.is_a?(::Array) ? read_list(element, klass) : klass.from_json(element) }
+            # Parses each element. A `scalar` field is a map encoded as `[key, value]` pairs, so
+            # every element must be a 2-item pair — each is read as one, and a malformed entry is
+            # rejected. Non-scalar lists recurse into nested lists; other elements deserialize.
+            def read_list(field, raw, klass)
+              raw.map do |element|
+                if field.scalar
+                  read_map_entry(field, element, klass)
+                elsif element.is_a?(::Array)
+                  read_list(field, element, klass)
+                else
+                  klass.from_json(element)
+                end
+              end
+            end
+
+            # A map entry is a `[key, value]` pair. The key is `Ref / text` — an object key
+            # deserializes, a bare-string key passes through once validated against the arm's
+            # primitive. The value is the object-only Ref and always deserializes, so a bare scalar
+            # there is rejected (object_only holds at the value position). A non-pair element is a
+            # malformed entry and is rejected outright.
+            def read_map_entry(field, element, klass)
+              unless element.is_a?(::Array) && element.size == 2
+                raise Error::WebDriverError,
+                      "#{name}##{field.name} expected a [key, value] pair, got #{element.inspect}"
+              end
+
+              key, value = element
+              key = key.is_a?(::Hash) ? klass.from_json(key) : scalar_value(field, key)
+              [key, klass.from_json(value)]
+            end
+
+            # A bare scalar at a scalar-tolerant union position must match one of the union's
+            # scalar-arm primitives (+scalar+ is a primitive name or an array of them); a
+            # wrong-typed scalar (a number where a string is expected) is a wire error, not
+            # something to pass through. An unrecognized primitive (none in PRIMITIVE_TYPES) is
+            # left unchecked, matching the lenient default elsewhere.
+            def scalar_value(field, value)
+              expected = Array(field.scalar).flat_map { |primitive| PRIMITIVE_TYPES[primitive] || [] }
+              return value if expected.empty? || expected.any? { |type| value.is_a?(type) }
+
+              raise Error::WebDriverError,
+                    "#{name}##{field.name} expected #{Array(field.scalar).join(' or ')}, got #{value.inspect}"
             end
 
             def extra(json_payload)
diff --git a/rb/lib/selenium/webdriver/bidi/serialization/union.rb b/rb/lib/selenium/webdriver/bidi/serialization/union.rb
index c0ae135d6c755..b0e9ff29b3455 100644
--- a/rb/lib/selenium/webdriver/bidi/serialization/union.rb
+++ b/rb/lib/selenium/webdriver/bidi/serialization/union.rb
@@ -44,10 +44,19 @@ def variants(table) = @variants = table
             def presence(rules) = @presence = rules
             def fallback(path) = @fallback = path
 
-            # A non-Hash payload is a bare scalar arm (e.g. input.Origin's "viewport") with
-            # no object to dispatch on, so it is returned unchanged.
+            # Declared (via the schema's `objectOnly` signal) on a union whose every arm is an
+            # object, so a non-Hash payload is a schema violation rather than a scalar arm.
+            def object_only = @object_only = true
+
+            # A non-Hash payload is a bare scalar arm (e.g. input.Origin's "viewport") with no
+            # object to dispatch on, so it is returned unchanged — unless every arm is an object
+            # (object_only), where a non-Hash cannot match any variant and is a wire error.
             def from_json(json_payload)
-              return json_payload unless json_payload.is_a?(::Hash)
+              unless json_payload.is_a?(::Hash)
+                return json_payload unless @object_only
+
+                raise Error::WebDriverError, "#{name} expected an object on the wire, got #{json_payload.inspect}"
+              end
 
               variant = select(json_payload)
               unless variant
diff --git a/rb/lib/selenium/webdriver/bidi/support/bidi_generate.rb b/rb/lib/selenium/webdriver/bidi/support/bidi_generate.rb
index 677afd970823b..0e88f5b39451f 100644
--- a/rb/lib/selenium/webdriver/bidi/support/bidi_generate.rb
+++ b/rb/lib/selenium/webdriver/bidi/support/bidi_generate.rb
@@ -236,7 +236,7 @@ def type_entry = "'#{wire_name}' => #{payload_ref || 'nil'}"
   # ref is the Protocol-relative class path for a nested structured field (nil
   # for a scalar/opaque field); list wraps it in an array. wire_key is the exact
   # JSON payload key (the schema's `wire` name, baked verbatim).
-  FieldIR = Struct.new(:ruby_name, :wire_key, :required, :nullable, :ref, :list, :enum, :primitive, :rbs,
+  FieldIR = Struct.new(:ruby_name, :wire_key, :required, :nullable, :ref, :list, :enum, :primitive, :scalar, :rbs,
                        keyword_init: true) do
     # A `Serialization::Record.define` spec entry: `name: 'jsonKey'` shorthand, or
     # `name: {wire_key:, …}` when the field carries JSON facts beyond its name.
@@ -247,6 +247,7 @@ def spec_entry(indent = 0)
       meta << 'nullable: true' if nullable
       meta << "ref: '#{ref}'" if ref
       meta << 'list: true' if list
+      meta << "scalar: #{scalar_literal}" if scalar
       meta << "enum: '#{enum}'" if enum
       meta << "primitive: '#{primitive}'" if primitive
       return "#{ruby_name}: '#{wire_key}'" if meta.empty?
@@ -255,6 +256,12 @@ def spec_entry(indent = 0)
       BiDiGenerate.wrap_call("#{ruby_name}: ", meta, indent, open: '{', close: '}')
     end
 
+    # The `scalar` primitive(s) a bare non-object wire value must match at a scalar-tolerant
+    # union position: a single primitive string, or an array when the union's scalar arms differ.
+    def scalar_literal
+      scalar.is_a?(::Array) ? "[#{scalar.map { |s| "'#{s}'" }.join(', ')}]" : "'#{scalar}'"
+    end
+
     # The `self.new` keyword for this field — a user-supplied input carrying the field's
     # value type. The `?` prefix marks the field omittable; its value type already carries
     # the schema's nullability, so nil is admitted only for a nullable field.
@@ -350,8 +357,10 @@ def discriminator_pair
 
   # A generated discriminated union (< Serialization::Union, resolved by lexical scope).
   # nested holds its synthetic variant records (see nest_synthetic). spec_href links to
-  # the union's definition in the live spec (nil when the schema has none).
-  UnionClass = Struct.new(:ruby_name, :discriminator_wire, :variants, :schema_name, :nested, :spec_href,
+  # the union's definition in the live spec (nil when the schema has none). object_only
+  # mirrors the schema's `objectOnly` signal: when true, a non-Hash payload is rejected
+  # rather than passed through (every arm is an object, so it can match no variant).
+  UnionClass = Struct.new(:ruby_name, :discriminator_wire, :variants, :schema_name, :nested, :spec_href, :object_only,
                           keyword_init: true) do
     def union? = true
     def value_variants = variants.select { |v| v.mode == :value }
@@ -533,29 +542,33 @@ def resolve(node)
       nullable = node['nullable'] ? true : false
       if node.key?('list')
         element = resolve(node['list'])
-        return {ref: element[:ref], list: true, nullable: nullable, rbs: nilable("Array[#{element[:rbs]}]", nullable)}
+        return {ref: element[:ref], list: true, nullable: nullable, scalar: element[:scalar],
+                rbs: nilable("Array[#{element[:rbs]}]", nullable)}
       end
       if node.key?('ref')
         named = resolve_named(node['ref'])
-        return {ref: named[:ref], list: named[:list], nullable: nullable, rbs: nilable(named[:rbs], nullable)}
+        return {ref: named[:ref], list: named[:list], nullable: nullable, scalar: named[:scalar],
+                rbs: nilable(named[:rbs], nullable)}
       end
       return resolve_union(node, nullable) if node.key?('union')
 
-      {ref: nil, list: false, nullable: nullable, primitive: checkable_primitive(node),
-       rbs: nilable(scalar_rbs(node), nullable)}
+      {ref: nil, list: false, nullable: nullable, rbs: nilable(scalar_rbs(node), nullable)}
     end
 
     # An inline union of one union-typed arm plus scalars (e.g. a MappingRemoteValue entry,
-    # RemoteValue / string) parses through that arm — its from_json returns a non-Hash value
-    # unchanged, so the scalar siblings pass through. Carry its ref so nested entries are typed;
-    # any other shape (a record arm, multiple structured arms, all scalars) stays opaque.
+    # RemoteValue / string) is carried as that union ref so nested entries are typed. Because
+    # the union is object_only, a bare-scalar sibling would raise there — so the projector's
+    # `scalar` signal (a bare-scalar arm is present) is forwarded, and the runtime passes a
+    # non-object leaf through instead (the map's string keys). Any other shape (a record arm,
+    # multiple structured arms, all scalars) stays opaque.
     def resolve_union(node, nullable)
       refs = node['union'].select { |arm| arm.key?('ref') }
       opaque = {ref: nil, list: false, nullable: nullable, rbs: nilable('untyped', nullable)}
       return opaque unless refs.one? && union_ref?(refs.first['ref'])
 
       named = resolve_named(refs.first['ref'])
-      {ref: named[:ref], list: named[:list], nullable: nullable, rbs: nilable('untyped', nullable)}
+      {ref: named[:ref], list: named[:list], nullable: nullable, scalar: node['scalar'],
+       rbs: nilable('untyped', nullable)}
     end
 
     # True when a ref (following aliases) is a union — the only arm whose from_json tolerates a
@@ -602,7 +615,7 @@ def resolve_named_alias(name, inner, seen)
 
       if inner.key?('list')
         element = resolve(inner['list'])
-        return {ref: element[:ref], list: true, rbs: "Array[#{element[:rbs]}]"}
+        return {ref: element[:ref], list: true, scalar: element[:scalar], rbs: "Array[#{element[:rbs]}]"}
       end
 
       {ref: nil, list: false, rbs: scalar_rbs(inner)}
@@ -618,8 +631,11 @@ def record_class(name, type)
                                 wire: const['wire'], value: const['type']['const'],
                                 rbs: rbs_const(const['type']['const'])}
       fields = type['fields'].reject { |f| baked_discriminator?(f) }.map { |f| field_ir(f) }
+      # Gate the extensions store on `preserveExtras` (extensible AND re-sendable), not raw
+      # `extensible`: only a type you receive and can hand back keeps unknown wire keys. A
+      # received-only extensible type gets no store, so its unknown keys are silently ignored.
       TypeClass.new(ruby_name: BiDiGenerate.type_class_name(name), fields: fields,
-                    discriminator: discriminator, extensible: type['extensible'] ? true : false,
+                    discriminator: discriminator, extensible: type['preserveExtras'] ? true : false,
                     schema_name: name, synthetic: type['synthetic'] ? true : false,
                     owner: type['owner'], label: type['label'], spec_href: type['specHref'])
     end
@@ -638,7 +654,25 @@ def field_ir(field)
       FieldIR.new(ruby_name: ruby_name, wire_key: field['wire'],
                   required: field['required'], nullable: resolved[:nullable],
                   ref: resolved[:ref], list: resolved[:list], enum: enum_const(field['type']),
-                  primitive: resolved[:primitive], rbs: resolved[:rbs])
+                  primitive: leaf_primitive(field['type']), scalar: resolved[:scalar],
+                  rbs: resolved[:rbs])
+    end
+
+    # The runtime-checkable scalar primitive of a field, following alias chains so a
+    # scalar hidden behind a named alias (js-uint -> integer, browsingContext.BrowsingContext
+    # -> string) is typed rather than opaque. The projector carries the primitive on the
+    # alias node; this surfaces it onto the field. Nil for a list (its elements are not
+    # scalar-checked), a record/union ref, an enum, a const, or an opaque value.
+    def leaf_primitive(node, seen = {})
+      return node['primitive'] if node.key?('primitive') && CHECKABLE_PRIMITIVES.include?(node['primitive'])
+      return nil unless node.key?('ref')
+
+      name = node['ref']
+      type = @types[name]
+      return nil if seen[name] || type.nil? || type['kind'] != 'alias'
+
+      seen[name] = true
+      leaf_primitive(type['type'], seen)
     end
 
     def union_class(name)
@@ -672,7 +706,7 @@ def union_from_selector(name, selector)
 
       UnionClass.new(ruby_name: BiDiGenerate.type_class_name(name),
                      discriminator_wire: selector['by'], variants: variants, schema_name: name,
-                     spec_href: @types[name]['specHref'])
+                     spec_href: @types[name]['specHref'], object_only: @types[name]['objectOnly'] ? true : false)
     end
 
     def discriminated_variants(selector)
@@ -704,9 +738,11 @@ def union_from_alias(name)
       variants = consts.map do |ref, const|
         VariantIR.new(mode: :value, value: const['type']['const'], ref: ruby_path(ref), requires: nil)
       end
+      # An alias-union carries bare-scalar arms (input.Origin's "viewport"/"pointer"), so it
+      # is never object_only — those arms must still pass a non-Hash payload through.
       UnionClass.new(ruby_name: BiDiGenerate.type_class_name(name),
                      discriminator_wire: consts.values.first['wire'], variants: variants, schema_name: name,
-                     spec_href: @types[name]['specHref'])
+                     spec_href: @types[name]['specHref'], object_only: @types[name]['objectOnly'] ? true : false)
     end
 
     def record_params(fields)
@@ -738,10 +774,6 @@ def rbs_type(node)
     # check fails open rather than a wrong strict default rejecting valid data.
     CHECKABLE_PRIMITIVES = %w[string number integer boolean].freeze
 
-    def checkable_primitive(node)
-      node['primitive'] if node.key?('primitive') && CHECKABLE_PRIMITIVES.include?(node['primitive'])
-    end
-
     # The leaf of +resolve+: the bare scalar type, before any nullable wrap. An alias's
     # own nullable is intentionally left off — only the referencing node's is applied.
     def scalar_rbs(node)
diff --git a/rb/lib/selenium/webdriver/bidi/support/templates/module.rb.erb b/rb/lib/selenium/webdriver/bidi/support/templates/module.rb.erb
index 4eef796649883..8206f96ac084b 100644
--- a/rb/lib/selenium/webdriver/bidi/support/templates/module.rb.erb
+++ b/rb/lib/selenium/webdriver/bidi/support/templates/module.rb.erb
@@ -67,6 +67,9 @@ module Selenium
 <%- if type.fallback_variant -%>
             fallback '<%= type.fallback_variant.ref %>'
 <%- end -%>
+<%- if type.object_only -%>
+            object_only
+<%- end -%>
 <%- type.nested_types.each do |nested| -%>
 
             # @api private
diff --git a/rb/sig/lib/selenium/webdriver/bidi/protocol/emulation.rbs b/rb/sig/lib/selenium/webdriver/bidi/protocol/emulation.rbs
index cf0216b8c14cc..b34c6368e8ba1 100644
--- a/rb/sig/lib/selenium/webdriver/bidi/protocol/emulation.rbs
+++ b/rb/sig/lib/selenium/webdriver/bidi/protocol/emulation.rbs
@@ -127,10 +127,10 @@ module Selenium
           end
 
           class SetScrollbarTypeOverrideParameters < ::Selenium::WebDriver::BiDi::Serialization::Record
-            attr_reader scrollbar_type: untyped
+            attr_reader scrollbar_type: String?
             attr_reader contexts: untyped
             attr_reader user_contexts: untyped
-            def self.new: (scrollbar_type: untyped, ?contexts: Array[String], ?user_contexts: Array[String]) -> instance
+            def self.new: (scrollbar_type: String?, ?contexts: Array[String], ?user_contexts: Array[String]) -> instance
           end
 
           class SetTimezoneOverrideParameters < ::Selenium::WebDriver::BiDi::Serialization::Record
@@ -154,7 +154,7 @@ module Selenium
           def set_screen_orientation_override: (screen_orientation: ::Selenium::WebDriver::BiDi::Protocol::Emulation::ScreenOrientation?, ?contexts: Array[String], ?user_contexts: Array[String]) -> untyped
           def set_screen_settings_override: (screen_area: ::Selenium::WebDriver::BiDi::Protocol::Emulation::ScreenArea?, ?contexts: Array[String], ?user_contexts: Array[String]) -> untyped
           def set_scripting_enabled: (enabled: bool?, ?contexts: Array[String], ?user_contexts: Array[String]) -> untyped
-          def set_scrollbar_type_override: (scrollbar_type: untyped, ?contexts: Array[String], ?user_contexts: Array[String]) -> untyped
+          def set_scrollbar_type_override: (scrollbar_type: String?, ?contexts: Array[String], ?user_contexts: Array[String]) -> untyped
           def set_timezone_override: (timezone: String?, ?contexts: Array[String], ?user_contexts: Array[String]) -> untyped
           def set_touch_override: (max_touch_points: Integer?, ?contexts: Array[String], ?user_contexts: Array[String]) -> untyped
           def set_user_agent_override: (user_agent: String?, ?contexts: Array[String], ?user_contexts: Array[String]) -> untyped
diff --git a/rb/sig/lib/selenium/webdriver/bidi/protocol/network.rbs b/rb/sig/lib/selenium/webdriver/bidi/protocol/network.rbs
index c10f1ba1a5c79..025217212748e 100644
--- a/rb/sig/lib/selenium/webdriver/bidi/protocol/network.rbs
+++ b/rb/sig/lib/selenium/webdriver/bidi/protocol/network.rbs
@@ -89,8 +89,7 @@ module Selenium
             attr_reader secure: bool
             attr_reader same_site: Symbol
             attr_reader expiry: untyped
-            attr_reader extensions: Hash[String, untyped]
-            def self.new: (name: String, value: ::Selenium::WebDriver::BiDi::Protocol::Network::BytesValue, domain: String, path: String, size: Integer, http_only: bool, secure: bool, same_site: Symbol, ?expiry: Integer, ?extensions: untyped) -> instance
+            def self.new: (name: String, value: ::Selenium::WebDriver::BiDi::Protocol::Network::BytesValue, domain: String, path: String, size: Integer, http_only: bool, secure: bool, same_site: Symbol, ?expiry: Integer) -> instance
           end
 
           class CookieHeader < ::Selenium::WebDriver::BiDi::Serialization::Record
diff --git a/rb/sig/lib/selenium/webdriver/bidi/protocol/session.rbs b/rb/sig/lib/selenium/webdriver/bidi/protocol/session.rbs
index 34b66a5127ba3..6a958e006dbc2 100644
--- a/rb/sig/lib/selenium/webdriver/bidi/protocol/session.rbs
+++ b/rb/sig/lib/selenium/webdriver/bidi/protocol/session.rbs
@@ -140,8 +140,7 @@ module Selenium
               attr_reader proxy: untyped
               attr_reader unhandled_prompt_behavior: untyped
               attr_reader web_socket_url: untyped
-              attr_reader extensions: Hash[String, untyped]
-              def self.new: (accept_insecure_certs: bool, browser_name: String, browser_version: String, platform_name: String, set_window_rect: bool, user_agent: String, ?proxy: ::Selenium::WebDriver::BiDi::Protocol::Session::ProxyConfiguration, ?unhandled_prompt_behavior: ::Selenium::WebDriver::BiDi::Protocol::Session::UserPromptHandler, ?web_socket_url: String, ?extensions: untyped) -> instance
+              def self.new: (accept_insecure_certs: bool, browser_name: String, browser_version: String, platform_name: String, set_window_rect: bool, user_agent: String, ?proxy: ::Selenium::WebDriver::BiDi::Protocol::Session::ProxyConfiguration, ?unhandled_prompt_behavior: ::Selenium::WebDriver::BiDi::Protocol::Session::UserPromptHandler, ?web_socket_url: String) -> instance
             end
           end
 
diff --git a/rb/sig/lib/selenium/webdriver/bidi/protocol/storage.rbs b/rb/sig/lib/selenium/webdriver/bidi/protocol/storage.rbs
index 366b3b2692bf3..055432d048148 100644
--- a/rb/sig/lib/selenium/webdriver/bidi/protocol/storage.rbs
+++ b/rb/sig/lib/selenium/webdriver/bidi/protocol/storage.rbs
@@ -26,8 +26,7 @@ module Selenium
           class PartitionKey < ::Selenium::WebDriver::BiDi::Serialization::Record
             attr_reader user_context: untyped
             attr_reader source_origin: untyped
-            attr_reader extensions: Hash[String, untyped]
-            def self.new: (?user_context: String, ?source_origin: String, ?extensions: untyped) -> instance
+            def self.new: (?user_context: String, ?source_origin: String) -> instance
           end
 
           class CookieFilter < ::Selenium::WebDriver::BiDi::Serialization::Record
diff --git a/rb/sig/lib/selenium/webdriver/bidi/serialization.rbs b/rb/sig/lib/selenium/webdriver/bidi/serialization.rbs
index 4079feb2faa24..ba4fbf6504b69 100644
--- a/rb/sig/lib/selenium/webdriver/bidi/serialization.rbs
+++ b/rb/sig/lib/selenium/webdriver/bidi/serialization.rbs
@@ -68,13 +68,19 @@ module Selenium
 
             def read: (untyped field, untyped raw) -> untyped
 
+            def read_ref: (untyped field, untyped raw) -> untyped
+
             def check_shape: (untyped field, untyped raw) -> void
 
             def check_primitive: (untyped field, untyped raw) -> void
 
             def enum_hash: (untyped field) -> untyped
 
-            def read_list: (untyped raw, untyped klass) -> untyped
+            def read_list: (untyped field, untyped raw, untyped klass) -> untyped
+
+            def read_map_entry: (untyped field, untyped element, untyped klass) -> untyped
+
+            def scalar_value: (untyped field, untyped value) -> untyped
 
             def extra: (Hash[untyped, untyped] json_payload) -> Hash[untyped, untyped]
           end
@@ -101,6 +107,8 @@ module Selenium
 
           def self.fallback: (String path) -> String
 
+          def self.object_only: () -> bool
+
           def self.from_json: (untyped json_payload) -> untyped
 
           def self.build: (**untyped kwargs) -> untyped
diff --git a/rb/spec/unit/selenium/webdriver/bidi/serialization_spec.rb b/rb/spec/unit/selenium/webdriver/bidi/serialization_spec.rb
index 340726e74eb93..b0adce8300080 100644
--- a/rb/spec/unit/selenium/webdriver/bidi/serialization_spec.rb
+++ b/rb/spec/unit/selenium/webdriver/bidi/serialization_spec.rb
@@ -81,6 +81,25 @@ def valid_cookie_attrs
               expect { BrowsingContext::Locator.from_json(payload) }
                 .to raise_error(Error::WebDriverError, /variant not in this Selenium's BiDi schema/)
             end
+
+            it 'raises when an object-only union receives a bare scalar (no arm can match)' do
+              expect { Script::RemoteValue.from_json('not-an-object') }
+                .to raise_error(Error::WebDriverError, /RemoteValue expected an object/)
+            end
+
+            it 'passes a bare scalar through a union that has a scalar arm (input.Origin)' do
+              expect(Input::Origin.from_json('viewport')).to eq('viewport')
+            end
+
+            it 'keeps a map string key while typing its object value (object-only value union)' do
+              parsed = Script::ObjectRemoteValue.from_json(
+                'type' => 'object', 'value' => [['k', {'type' => 'number', 'value' => 2}]]
+              )
+              key, value = parsed.value.first
+
+              expect(key).to eq('k') # a bare-string key survives, not rejected by the object-only union
+              expect(value).to be_a(Script::NumberValue)
+            end
           end
 
           describe 'nested structured fields' do
@@ -124,6 +143,45 @@ def valid_cookie_attrs
               expect(value).to be_a(Script::NumberValue)
               expect(value.value).to eq(2)
             end
+
+            # The outbound mirror of the map-key case: a bare-string key serializes through the
+            # scalar-tolerant union untouched while its object value is typed, and round-trips back.
+            it 'serializes and round-trips a map LocalValue whose key is a bare string' do
+              obj = Script::ObjectLocalValue.new(value: [['k', Script::StringValue.new(value: 'x')]])
+
+              expect(obj.as_json).to eq(
+                'type' => 'object',
+                'value' => [['k', {'type' => 'string', 'value' => 'x'}]]
+              )
+              expect(Script::LocalValue.from_json(obj.as_json)).to eq(obj)
+            end
+
+            # A scalar-tolerant position still validates the scalar arm's type: the map entry is
+            # `RemoteValue / text`, so a non-string bare value is a wire error, not passed through.
+            it 'rejects a wrong-typed scalar at a map key position instead of passing it through' do
+              wire = {'type' => 'object', 'value' => [[42, {'type' => 'number', 'value' => 2}]]}
+
+              expect { Script::ObjectRemoteValue.from_json(wire) }
+                .to raise_error(Error::WebDriverError, /value expected string, got 42/)
+            end
+
+            # Scalar tolerance is the key's alone: the value is the object-only RemoteValue union,
+            # so a bare-scalar value is rejected rather than passed through — object_only holds here.
+            it 'rejects a bare-scalar map value against the object-only value union' do
+              wire = {'type' => 'object', 'value' => [['k', 'bare string, not an object']]}
+
+              expect { Script::ObjectRemoteValue.from_json(wire) }
+                .to raise_error(Error::WebDriverError, /expected an object on the wire/)
+            end
+
+            # A map is `[key, value]` pairs; a malformed entry that is not a 2-item pair is a wire
+            # error, not something to pass through the scalar-tolerant path.
+            it 'rejects a malformed map entry that is not a [key, value] pair' do
+              wire = {'type' => 'object', 'value' => [['orphan-key']]}
+
+              expect { Script::ObjectRemoteValue.from_json(wire) }
+                .to raise_error(Error::WebDriverError, /expected a \[key, value\] pair/)
+            end
           end
 
           describe 'optional + nullable fields' do
@@ -151,6 +209,31 @@ def valid_cookie_attrs
               expect(parsed.extensions).to eq('webdriverValue' => 42)
               expect(parsed.as_json).to eq('sharedId' => 's1', 'webdriverValue' => 42)
             end
+
+            # A re-sendable type (reachable from a command's params, e.g. a cookie filter) keeps
+            # unknown properties so a received-then-resent payload round-trips them.
+            it 'preserves an unknown key on a re-sendable type across a receive/re-send round trip' do
+              parsed = Storage::CookieFilter.from_json('name' => 'sid', 'x-vendor' => 'keep-me')
+
+              expect(parsed.extensions).to eq('x-vendor' => 'keep-me')
+              expect(parsed.as_json).to eq('name' => 'sid', 'x-vendor' => 'keep-me')
+            end
+
+            # network.Cookie is extensible but received-only (not reachable from any command's
+            # params), so preserveExtras is false: unknown keys are ignored, not stored/echoed.
+            it 'drops an unknown key on an extensible-but-received-only type on re-serialize' do
+              wire = Network::Cookie.new(**valid_cookie_attrs).as_json.merge('x-vendor' => 'drop-me')
+              parsed = Network::Cookie.from_json(wire)
+
+              expect(parsed).not_to respond_to(:extensions)
+              expect(parsed.as_json).not_to include('x-vendor')
+            end
+
+            it 'ignores an unknown key without raising on a non-extensible type' do
+              wire = {'type' => 'password', 'username' => 'u', 'password' => 'p', 'x-vendor' => 'v'}
+
+              expect { Network::AuthCredentials.from_json(wire) }.not_to raise_error
+            end
           end
 
           describe 'outbound union command params' do
@@ -316,6 +399,20 @@ def valid_cookie_attrs
 
               expect(parsed.key).to eq(5)
             end
+
+            # Signal 3: an inline literal choice the projector now types as `string`
+            # (scrollbarType = "classic" / "overlay" / null), previously opaque.
+            it 'raises when an inline-enum scalar field arrives as the wrong primitive' do
+              expect { Emulation::SetScrollbarTypeOverrideParameters.from_json('scrollbarType' => 123) }
+                .to raise_error(Error::WebDriverError, /scrollbar_type expected string/)
+            end
+
+            # Signal 3: a scalar hidden behind an alias (size -> js-uint -> integer) now carries
+            # its leaf primitive, so a wrong-typed value is rejected instead of passing opaque.
+            it 'raises when an alias-typed integer field (js-uint) arrives as a string' do
+              expect { Network::Cookie.from_json(cookie_wire.merge('size' => 'big')) }
+                .to raise_error(Error::WebDriverError, /size expected integer/)
+            end
           end
         end
       end # Protocol