diff --git a/javascript/selenium-webdriver/normalize_bidi_ast.mjs b/javascript/selenium-webdriver/normalize_bidi_ast.mjs
index a388d62e1ecb8..6812d750fb826 100644
--- a/javascript/selenium-webdriver/normalize_bidi_ast.mjs
+++ b/javascript/selenium-webdriver/normalize_bidi_ast.mjs
@@ -97,6 +97,16 @@ function groupRef(value) {
   return { Type: 'group', Value: value, Unwrapped: false }
 }
 
+/** True when `entry` is a string/number/bool literal (`{Type:'literal', Value}`). */
+function isLiteral(entry) {
+  return entry && typeof entry === 'object' && entry.Type === 'literal'
+}
+
+/** True when `entry` is the CDDL null keyword (bare `'null'`) or a `nil`/`null` prelude ref. */
+function isNullArm(entry) {
+  return entry === 'null' || (isGroupRef(entry) && (entry.Value === 'null' || entry.Value === 'nil'))
+}
+
 /**
  * Drop the leading run of `label` that restates `ownerLocal`, backing off to a
  * camelCase boundary, so `ContinueWithAuthParameters` + `ContinueWithAuthCredentials`
@@ -151,9 +161,11 @@ function eachPropertyDeep(properties, fn) {
 }
 
 /**
- * Rewrite fields whose type is a union of >= 2 string literals into a reference
- * to a synthetic enum def, and append those enum defs. Single-literal fields
- * (discriminators) are left untouched. Returns a new AST array.
+ * Rewrite fields whose type is a choice of >= 2 string literals (optionally with a
+ * null alternative) into a reference to a synthetic enum def, and append those enum
+ * defs. A null alternative is kept on the field so the enum stays nullable; the enum
+ * def itself holds only the literals. Single-literal fields (discriminators) are left
+ * untouched. Returns a new AST array.
  * @param {object[]} ast The AST to transform.
  * @returns {object[]} A new AST array with inline enums hoisted to named defs.
  */
@@ -167,9 +179,12 @@ export function hoistInlineEnums(ast) {
     const owner = splitName(def.Name ?? '')
     eachPropertyDeep(def.Properties, (prop) => {
       const entries = typeList(prop.Type)
-      const allLiterals =
-        entries.length >= 2 && entries.every((e) => e && typeof e === 'object' && e.Type === 'literal')
-      if (!allLiterals) return
+      const literals = entries.filter(isLiteral)
+      const nullArms = entries.filter(isNullArm)
+      // Hoist a choice of >= 2 string literals, tolerating a null alternative so a nullable inline
+      // enum (`("a" / "b") / null`) is still named. The null stays on the field (below), never in the
+      // enum def; anything else in the choice (a ref, a single literal discriminator) is left untouched.
+      if (literals.length < 2 || literals.length + nullArms.length !== entries.length) return
 
       const base = pascal(prop.Name) || `Value${created.length}`
       const localName = `${owner.local}${base}`
@@ -179,13 +194,13 @@ export function hoistInlineEnums(ast) {
         Type: 'variable',
         Name: synthName,
         IsChoiceAddition: false,
-        PropertyType: entries.map((e) => structuredClone(e)),
+        PropertyType: literals.map((e) => structuredClone(e)),
         Comments: prop.Comments ?? [],
         'x-selenium-synthetic': true,
         'x-selenium-owner': def.Name,
         'x-selenium-label': base,
       })
-      prop.Type = [groupRef(synthName)]
+      prop.Type = [groupRef(synthName), ...nullArms.map((e) => structuredClone(e))]
     })
   }
 
diff --git a/javascript/selenium-webdriver/normalize_bidi_ast_test.mjs b/javascript/selenium-webdriver/normalize_bidi_ast_test.mjs
index e90329db1166b..6a6c1262c4fc5 100644
--- a/javascript/selenium-webdriver/normalize_bidi_ast_test.mjs
+++ b/javascript/selenium-webdriver/normalize_bidi_ast_test.mjs
@@ -56,6 +56,18 @@ describe('hoistInlineEnums', () => {
     )
   })
 
+  it('hoists a nullable literal choice, keeping the null on the field and out of the enum', () => {
+    const ast = [def('x.T', [field('scrollbarType', [lit('classic'), lit('overlay'), 'null'])])]
+    const out = hoistInlineEnums(ast)
+
+    const enumName = 'x.TScrollbarType'
+    assert.deepEqual(byName(out, 'x.T').Properties[0].Type, [ref(enumName), 'null'])
+    assert.deepEqual(
+      byName(out, enumName).PropertyType.map((e) => e.Value),
+      ['classic', 'overlay'],
+    )
+  })
+
   it('does NOT hoist a single-literal (discriminator) field', () => {
     const ast = [def('x.T', [field('type', [lit('password')])])]
     const out = hoistInlineEnums(ast)
diff --git a/javascript/selenium-webdriver/package.json b/javascript/selenium-webdriver/package.json
index b4b3b05c5ef3e..9689ea5e9facb 100644
--- a/javascript/selenium-webdriver/package.json
+++ b/javascript/selenium-webdriver/package.json
@@ -30,7 +30,7 @@
   },
   "devDependencies": {
     "@eslint/js": "^10.0.1",
-    "cddl": "^0.21.0",
+    "cddl": "^0.21.1",
     "cddl2ts": "^0.10.0",
     "clean-jsdoc-theme": "^4.3.3",
     "eslint": "^10.7.0",
diff --git a/javascript/selenium-webdriver/project_bidi_schema.mjs b/javascript/selenium-webdriver/project_bidi_schema.mjs
index 53b99dd205776..1128108bf6412 100644
--- a/javascript/selenium-webdriver/project_bidi_schema.mjs
+++ b/javascript/selenium-webdriver/project_bidi_schema.mjs
@@ -195,8 +195,12 @@ function projectEntry(e) {
   if (e.Type === 'array') return { list: projectRef(e.Values?.[0]?.Type) }
   if (e.Type === 'map') return { map: projectRef(e.ValueType ?? e.Values?.[0]?.Type), extensible: true }
   if (e.Type === 'range') {
-    const intRange = Number.isInteger(e.Value?.Min?.Value) && Number.isInteger(e.Value?.Max?.Value)
-    return { primitive: intRange ? 'integer' : 'number' } // e.g. js-uint (0..MAX) vs scale (0.1..2)
+    // A bound written as a float (`1.0`) parses to an integer `Value` carrying an `IsFloat`
+    // marker; consult it so `(0.0..1.0)` is a number range, not — as its integral bounds alone
+    // would read — an integer one. A bound with no marker falls back to its value's integralness.
+    const intBound = (b) => b && !b.IsFloat && Number.isInteger(b.Value)
+    const intRange = intBound(e.Value?.Min) && intBound(e.Value?.Max)
+    return { primitive: intRange ? 'integer' : 'number' } // e.g. js-uint (0..MAX) vs latitude (-90.0..90.0)
   }
   return { primitive: PRIMITIVES[e.Type] ?? 'unknown' }
 }
diff --git a/javascript/selenium-webdriver/project_bidi_schema_test.mjs b/javascript/selenium-webdriver/project_bidi_schema_test.mjs
index 6420031d65fa8..ed0d0d235414c 100644
--- a/javascript/selenium-webdriver/project_bidi_schema_test.mjs
+++ b/javascript/selenium-webdriver/project_bidi_schema_test.mjs
@@ -182,11 +182,20 @@ describe('projectType (list / union / alias defs)', () => {
           Name: 'x.F',
           PropertyType: [{ Type: 'range', Value: { Min: { Value: 0.1 }, Max: { Value: 2 } } }],
         },
+        {
+          // `(0.0..1.0)` — integral bounds, but the `IsFloat` marker makes it a number range.
+          Type: 'variable',
+          Name: 'x.W',
+          PropertyType: [
+            { Type: 'range', Value: { Min: { Value: 0, IsFloat: true }, Max: { Value: 1, IsFloat: true } } },
+          ],
+        },
       ],
       {},
     )
     assert.deepEqual(s.types['x.U'], { kind: 'alias', type: { primitive: 'integer' } })
     assert.deepEqual(s.types['x.F'], { kind: 'alias', type: { primitive: 'number' } })
+    assert.deepEqual(s.types['x.W'], { kind: 'alias', type: { primitive: 'number' } })
   })
 
   it('unwraps a control-operator (.default / .ge) wrapped field type to its inner type', () => {
@@ -446,15 +455,14 @@ describe('schema signals (objectOnly / preserveExtras / enum primitive)', () =>
     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.
+  it('hoists a nullable literal choice to a named enum, referenced with the null preserved', () => {
+    // A nullable literal choice (`("classic" / "overlay") / null`) is hoisted (normalize_bidi_ast)
+    // to a named enum and referenced with the null kept on the field — a nullable enum ref, not an
+    // inline enum carrying a primitive.
     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(s.types['x.R'].fields[0].type, { ref: 'x.RKind', nullable: true })
+    assert.equal(s.types['x.RKind'].kind, 'enum')
+    assert.deepEqual(s.types['x.RKind'].values, ['classic', 'overlay'])
     assert.deepEqual(checkSchema(s), [])
   })
 
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 1b5b2701edea3..4c75f3f00a2fa 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -138,8 +138,8 @@ importers:
         specifier: ^10.0.1
         version: 10.0.1(eslint@10.7.0(supports-color@10.2.2))
       cddl:
-        specifier: ^0.21.0
-        version: 0.21.0
+        specifier: ^0.21.1
+        version: 0.21.1
       cddl2ts:
         specifier: ^0.10.0
         version: 0.10.0
@@ -1435,6 +1435,10 @@ packages:
     resolution: {integrity: sha512-/2lnDcCA/7DRDChH2szAW4tKzZeqYFQKhw2nGqi6WqBr7N9mx2yObATLnc01pqG9pXJrw3auT1X5O58azNBTMQ==}
     hasBin: true
 
+  cddl@0.21.1:
+    resolution: {integrity: sha512-Sv4ZR4ZDODrcCaOjedZ2dxOIcVBcahQm/z/jbVonBO2hRbUvTpJiCq1syM5h4ZTWst0Ld2wOZP26voYXeZr4Dg==}
+    hasBin: true
+
   chalk@4.1.2:
     resolution: {integrity: sha512-oKnbhFyRIXpUuez8iBMmyEa4nbj4IOQyuhc/wy9kY7/WVPcwIO9VA668Pu8RkO7+0G76SLROeyw9CpQ061i4mA==}
     engines: {node: '>=10'}
@@ -5642,6 +5646,11 @@ snapshots:
       camelcase: 9.0.0
       yargs: 18.0.0
 
+  cddl@0.21.1:
+    dependencies:
+      camelcase: 9.0.0
+      yargs: 18.0.0
+
   chalk@4.1.2:
     dependencies:
       ansi-styles: 4.3.0
diff --git a/rb/lib/selenium/webdriver/bidi/protocol/browsing_context.rb b/rb/lib/selenium/webdriver/bidi/protocol/browsing_context.rb
index eaf27d8a96acc..859a8d6c71b12 100644
--- a/rb/lib/selenium/webdriver/bidi/protocol/browsing_context.rb
+++ b/rb/lib/selenium/webdriver/bidi/protocol/browsing_context.rb
@@ -211,7 +211,7 @@ class Locator < Serialization::Union
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-browsingcontextimageformat
           ImageFormat = Serialization::Record.define(
             type: {wire_key: 'type', primitive: 'string'},
-            quality: {wire_key: 'quality', required: false, primitive: 'integer'}
+            quality: {wire_key: 'quality', required: false, primitive: 'number'}
           )
 
           # @api private
diff --git a/rb/lib/selenium/webdriver/bidi/protocol/emulation.rb b/rb/lib/selenium/webdriver/bidi/protocol/emulation.rb
index 3126a4f10b19d..b1680174313f0 100644
--- a/rb/lib/selenium/webdriver/bidi/protocol/emulation.rb
+++ b/rb/lib/selenium/webdriver/bidi/protocol/emulation.rb
@@ -48,6 +48,11 @@ class Emulation < Domain
             landscape_secondary: 'landscape-secondary'
           }.freeze
 
+          SET_SCROLLBAR_TYPE_OVERRIDE_PARAMETERS_SCROLLBAR_TYPE = {
+            classic: 'classic',
+            overlay: 'overlay'
+          }.freeze
+
           # @api private
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-emulationsetforcedcolorsmodethemeoverrideparameters
@@ -88,12 +93,12 @@ class SetGeolocationOverrideParameters < Serialization::Union
           # @see https://www.selenium.dev/documentation/warnings/bidi-implementation/
           # @see https://w3c.github.io/webdriver-bidi/#cddl-type-emulationgeolocationcoordinates
           GeolocationCoordinates = Serialization::Record.define(
-            latitude: {wire_key: 'latitude', primitive: 'integer'},
-            longitude: {wire_key: 'longitude', primitive: 'integer'},
+            latitude: {wire_key: 'latitude', primitive: 'number'},
+            longitude: {wire_key: 'longitude', primitive: 'number'},
             accuracy: {wire_key: 'accuracy', required: false, primitive: 'number'},
             altitude: {wire_key: 'altitude', required: false, nullable: true, primitive: 'number'},
             altitude_accuracy: {wire_key: 'altitudeAccuracy', required: false, nullable: true, primitive: 'number'},
-            heading: {wire_key: 'heading', required: false, nullable: true, primitive: 'integer'},
+            heading: {wire_key: 'heading', required: false, nullable: true, primitive: 'number'},
             speed: {wire_key: 'speed', required: false, nullable: true, primitive: 'number'}
           )
 
@@ -185,7 +190,11 @@ 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, primitive: 'string'},
+            scrollbar_type: {
+              wire_key: 'scrollbarType',
+              nullable: true,
+              enum: 'Emulation::SET_SCROLLBAR_TYPE_OVERRIDE_PARAMETERS_SCROLLBAR_TYPE'
+            },
             contexts: {wire_key: 'contexts', required: false, list: true},
             user_contexts: {wire_key: 'userContexts', required: false, list: true}
           )
@@ -319,6 +328,11 @@ def set_scrollbar_type_override(
             contexts: Serialization::UNSET,
             user_contexts: Serialization::UNSET
           )
+            Serialization.validate!(
+              'scrollbarType',
+              scrollbar_type,
+              Emulation::SET_SCROLLBAR_TYPE_OVERRIDE_PARAMETERS_SCROLLBAR_TYPE
+            )
             params = SetScrollbarTypeOverrideParameters.new(
               scrollbar_type: scrollbar_type,
               contexts: contexts,
diff --git a/rb/lib/selenium/webdriver/bidi/protocol/input.rb b/rb/lib/selenium/webdriver/bidi/protocol/input.rb
index 42db9c9c51068..4e3e0c1d69bf4 100644
--- a/rb/lib/selenium/webdriver/bidi/protocol/input.rb
+++ b/rb/lib/selenium/webdriver/bidi/protocol/input.rb
@@ -197,8 +197,8 @@ class WheelSourceAction < Serialization::Union
             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'},
+            pressure: {wire_key: 'pressure', required: false, primitive: 'number'},
+            tangential_pressure: {wire_key: 'tangentialPressure', required: false, primitive: 'number'},
             twist: {wire_key: 'twist', required: false, primitive: 'integer'},
             altitude_angle: {wire_key: 'altitudeAngle', required: false, primitive: 'number'},
             azimuth_angle: {wire_key: 'azimuthAngle', required: false, primitive: 'number'}
@@ -215,8 +215,8 @@ class WheelSourceAction < Serialization::Union
             origin: {wire_key: 'origin', required: false, ref: 'Input::Origin'},
             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'},
+            pressure: {wire_key: 'pressure', required: false, primitive: 'number'},
+            tangential_pressure: {wire_key: 'tangentialPressure', required: false, primitive: 'number'},
             twist: {wire_key: 'twist', required: false, primitive: 'integer'},
             altitude_angle: {wire_key: 'altitudeAngle', required: false, primitive: 'number'},
             azimuth_angle: {wire_key: 'azimuthAngle', required: false, primitive: 'number'}
@@ -241,8 +241,8 @@ class WheelSourceAction < Serialization::Union
           PointerCommonProperties = Serialization::Record.define(
             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'},
+            pressure: {wire_key: 'pressure', required: false, primitive: 'number'},
+            tangential_pressure: {wire_key: 'tangentialPressure', required: false, primitive: 'number'},
             twist: {wire_key: 'twist', required: false, primitive: 'integer'},
             altitude_angle: {wire_key: 'altitudeAngle', required: false, primitive: 'number'},
             azimuth_angle: {wire_key: 'azimuthAngle', required: false, primitive: 'number'}
diff --git a/rb/lib/selenium/webdriver/bidi/serialization/record.rb b/rb/lib/selenium/webdriver/bidi/serialization/record.rb
index 7285c8b5c44a9..086b4bc51d15e 100644
--- a/rb/lib/selenium/webdriver/bidi/serialization/record.rb
+++ b/rb/lib/selenium/webdriver/bidi/serialization/record.rb
@@ -102,9 +102,10 @@ def from_json(json_payload)
             # Checks each field's value: a required field cannot be omitted (UNSET), a non-nullable
             # field cannot be nil (nil is neither a value nor the UNSET omit-sentinel, so it would be
             # silently dropped on the wire), a nullable-const field must carry its literal (not some
-            # other value), and an enum field must be in its allowed set. The enum constant is resolved
-            # lazily so a cross-domain enum need not be loaded first. Outbound only (from +new+);
-            # inbound presence/enum are checked separately in +wire_value+/+read+.
+            # other value), a primitive field must be the matching Ruby type, and an enum field must be
+            # in its allowed set. The enum constant is resolved lazily so a cross-domain enum need not be
+            # loaded first. Outbound only (from +new+); inbound presence/primitive/enum are checked
+            # separately in +wire_value+/+read+.
             def validate_values(attributes)
               fields.each do |f|
                 value = attributes[f.name]
@@ -112,12 +113,20 @@ def validate_values(attributes)
                 raise ::ArgumentError, "#{name}##{f.name} cannot be nil" if value.nil? && !f.nullable
                 next if value.nil? || UNSET.equal?(value)
 
-                validate_const(f, value)
-                check_outbound_shape(f, value)
-                Serialization.validate!("#{name}##{f.name}", value, Protocol.const_get(f.enum)) if f.enum
+                validate_present(f, value)
               end
             end
 
+            # Checks a field that carries an actual value (neither omitted nor nil): a nullable-const
+            # field against its literal, list/scalar shape, primitive type (lists excepted, as inbound
+            # does), and enum membership (resolved lazily so a cross-domain enum need not load first).
+            def validate_present(field, value)
+              validate_const(field, value)
+              check_outbound_shape(field, value)
+              check_outbound_primitive(field, value) unless field.list
+              Serialization.validate!("#{name}##{field.name}", value, Protocol.const_get(field.enum)) if field.enum
+            end
+
             # A nullable constant (`literal / null`) is caller-settable but its only non-null value is
             # the literal, so a value that is neither the literal nor nil (nil is handled above) is a
             # local error rather than a wire round-trip. A non-const field carries UNSET here and passes.
@@ -137,6 +146,17 @@ def check_outbound_shape(field, value)
               raise ::ArgumentError, "#{name}##{field.name} expected #{kind}, got #{value.inspect}"
             end
 
+            # Outbound mirror of check_primitive: a primitive-typed arg (`string`/`integer`/…) must be
+            # the matching Ruby type, so a caller mistake (a string width, a float count) is a local
+            # ArgumentError here rather than a rejection the browser reports a round-trip later. A field
+            # with no primitive descriptor (enum, ref, opaque) passes; lists are skipped, as inbound does.
+            def check_outbound_primitive(field, value)
+              expected = PRIMITIVE_TYPES[field.primitive]
+              return if expected.nil? || expected.any? { |type| value.is_a?(type) }
+
+              raise ::ArgumentError, "#{name}##{field.name} expected #{field.primitive}, got #{value.inspect}"
+            end
+
             def fixed?(field)
               !UNSET.equal?(field.fixed)
             end
diff --git a/rb/sig/lib/selenium/webdriver/bidi/protocol/browsing_context.rbs b/rb/sig/lib/selenium/webdriver/bidi/protocol/browsing_context.rbs
index 64ea159abaf1c..13213ce399014 100644
--- a/rb/sig/lib/selenium/webdriver/bidi/protocol/browsing_context.rbs
+++ b/rb/sig/lib/selenium/webdriver/bidi/protocol/browsing_context.rbs
@@ -129,7 +129,7 @@ module Selenium
           class ImageFormat < ::Selenium::WebDriver::BiDi::Serialization::Record
             attr_reader type: String
             attr_reader quality: untyped
-            def self.new: (type: String, ?quality: Integer) -> instance
+            def self.new: (type: String, ?quality: Numeric) -> instance
           end
 
           class ClipRectangle < ::Selenium::WebDriver::BiDi::Serialization::Union
diff --git a/rb/sig/lib/selenium/webdriver/bidi/protocol/emulation.rbs b/rb/sig/lib/selenium/webdriver/bidi/protocol/emulation.rbs
index 56a5bff727130..d6b01bb0bc8b1 100644
--- a/rb/sig/lib/selenium/webdriver/bidi/protocol/emulation.rbs
+++ b/rb/sig/lib/selenium/webdriver/bidi/protocol/emulation.rbs
@@ -29,6 +29,8 @@ module Selenium
 
           SCREEN_ORIENTATION_TYPE: Hash[Symbol, String]
 
+          SET_SCROLLBAR_TYPE_OVERRIDE_PARAMETERS_SCROLLBAR_TYPE: Hash[Symbol, String]
+
           class SetForcedColorsModeThemeOverrideParameters < ::Selenium::WebDriver::BiDi::Serialization::Record
             attr_reader theme: Symbol?
             attr_reader contexts: untyped
@@ -52,14 +54,14 @@ module Selenium
           end
 
           class GeolocationCoordinates < ::Selenium::WebDriver::BiDi::Serialization::Record
-            attr_reader latitude: Integer
-            attr_reader longitude: Integer
+            attr_reader latitude: Numeric
+            attr_reader longitude: Numeric
             attr_reader accuracy: untyped
             attr_reader altitude: untyped
             attr_reader altitude_accuracy: untyped
             attr_reader heading: untyped
             attr_reader speed: untyped
-            def self.new: (latitude: Integer, longitude: Integer, ?accuracy: Numeric, ?altitude: Numeric?, ?altitude_accuracy: Numeric?, ?heading: Integer?, ?speed: Numeric?) -> instance
+            def self.new: (latitude: Numeric, longitude: Numeric, ?accuracy: Numeric, ?altitude: Numeric?, ?altitude_accuracy: Numeric?, ?heading: Numeric?, ?speed: Numeric?) -> instance
           end
 
           class GeolocationPositionError < ::Selenium::WebDriver::BiDi::Serialization::Record
@@ -127,10 +129,10 @@ module Selenium
           end
 
           class SetScrollbarTypeOverrideParameters < ::Selenium::WebDriver::BiDi::Serialization::Record
-            attr_reader scrollbar_type: String?
+            attr_reader scrollbar_type: Symbol?
             attr_reader contexts: untyped
             attr_reader user_contexts: untyped
-            def self.new: (scrollbar_type: String?, ?contexts: Array[String], ?user_contexts: Array[String]) -> instance
+            def self.new: (scrollbar_type: Symbol?, ?contexts: Array[String], ?user_contexts: Array[String]) -> instance
           end
 
           class SetTimezoneOverrideParameters < ::Selenium::WebDriver::BiDi::Serialization::Record
@@ -154,7 +156,7 @@ 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: String?, ?contexts: Array[String], ?user_contexts: Array[String]) -> untyped
+          def set_scrollbar_type_override: (scrollbar_type: Symbol?, ?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/input.rbs b/rb/sig/lib/selenium/webdriver/bidi/protocol/input.rbs
index 720e921bef469..57e242b4ebbe8 100644
--- a/rb/sig/lib/selenium/webdriver/bidi/protocol/input.rbs
+++ b/rb/sig/lib/selenium/webdriver/bidi/protocol/input.rbs
@@ -119,7 +119,7 @@ module Selenium
             attr_reader twist: untyped
             attr_reader altitude_angle: untyped
             attr_reader azimuth_angle: untyped
-            def self.new: (?type: String, button: Integer, ?width: Integer, ?height: Integer, ?pressure: Integer, ?tangential_pressure: Integer, ?twist: Integer, ?altitude_angle: Numeric, ?azimuth_angle: Numeric) -> instance
+            def self.new: (?type: String, button: Integer, ?width: Integer, ?height: Integer, ?pressure: Numeric, ?tangential_pressure: Numeric, ?twist: Integer, ?altitude_angle: Numeric, ?azimuth_angle: Numeric) -> instance
           end
 
           class PointerMoveAction < ::Selenium::WebDriver::BiDi::Serialization::Record
@@ -135,7 +135,7 @@ module Selenium
             attr_reader twist: untyped
             attr_reader altitude_angle: untyped
             attr_reader azimuth_angle: untyped
-            def self.new: (?type: String, x: Numeric, y: Numeric, ?duration: Integer, ?origin: ::Selenium::WebDriver::BiDi::Protocol::Input::Origin, ?width: Integer, ?height: Integer, ?pressure: Integer, ?tangential_pressure: Integer, ?twist: Integer, ?altitude_angle: Numeric, ?azimuth_angle: Numeric) -> instance
+            def self.new: (?type: String, x: Numeric, y: Numeric, ?duration: Integer, ?origin: ::Selenium::WebDriver::BiDi::Protocol::Input::Origin, ?width: Integer, ?height: Integer, ?pressure: Numeric, ?tangential_pressure: Numeric, ?twist: Integer, ?altitude_angle: Numeric, ?azimuth_angle: Numeric) -> instance
           end
 
           class WheelScrollAction < ::Selenium::WebDriver::BiDi::Serialization::Record
@@ -157,7 +157,7 @@ module Selenium
             attr_reader twist: untyped
             attr_reader altitude_angle: untyped
             attr_reader azimuth_angle: untyped
-            def self.new: (?width: Integer, ?height: Integer, ?pressure: Integer, ?tangential_pressure: Integer, ?twist: Integer, ?altitude_angle: Numeric, ?azimuth_angle: Numeric) -> instance
+            def self.new: (?width: Integer, ?height: Integer, ?pressure: Numeric, ?tangential_pressure: Numeric, ?twist: Integer, ?altitude_angle: Numeric, ?azimuth_angle: Numeric) -> instance
           end
 
           class Origin < ::Selenium::WebDriver::BiDi::Serialization::Union
diff --git a/rb/sig/lib/selenium/webdriver/bidi/serialization.rbs b/rb/sig/lib/selenium/webdriver/bidi/serialization.rbs
index 40837e6740134..b21395d5ee219 100644
--- a/rb/sig/lib/selenium/webdriver/bidi/serialization.rbs
+++ b/rb/sig/lib/selenium/webdriver/bidi/serialization.rbs
@@ -62,10 +62,14 @@ module Selenium
 
             def validate_values: (Hash[Symbol, untyped] attributes) -> void
 
+            def validate_present: (untyped field, untyped value) -> void
+
             def validate_const: (untyped field, untyped value) -> void
 
             def check_outbound_shape: (untyped field, untyped value) -> void
 
+            def check_outbound_primitive: (untyped field, untyped value) -> void
+
             def fixed?: (untyped field) -> bool
 
             def wire_value: (untyped field, Hash[untyped, untyped] json_payload) -> untyped
diff --git a/rb/spec/unit/selenium/webdriver/bidi/serialization_spec.rb b/rb/spec/unit/selenium/webdriver/bidi/serialization_spec.rb
index 2b0525b33ec7e..cd3c5e60e1451 100644
--- a/rb/spec/unit/selenium/webdriver/bidi/serialization_spec.rb
+++ b/rb/spec/unit/selenium/webdriver/bidi/serialization_spec.rb
@@ -378,6 +378,25 @@ def moz_install(**kwargs)
             end
           end
 
+          describe 'outbound primitive validation' do
+            it 'rejects a wrong-typed primitive at construction, so an invalid object cannot exist' do
+              expect { BrowsingContext::NavigateParameters.new(context: 'c', url: 123) }
+                .to raise_error(ArgumentError, /NavigateParameters#url expected string/)
+            end
+
+            it 'rejects a float for an integer field, mirroring the wire integer/number split' do
+              expect { Emulation::ScreenArea.new(width: 5.0, height: 5) }
+                .to raise_error(ArgumentError, /ScreenArea#width expected integer/)
+            end
+
+            it 'accepts either an integer or a float for a number field' do
+              klass = Emulation::GeolocationCoordinates
+
+              expect(klass.new(latitude: 0, longitude: 0, accuracy: 1.5).accuracy).to eq(1.5)
+              expect(klass.new(latitude: 0, longitude: 0, accuracy: 2).accuracy).to eq(2)
+            end
+          end
+
           describe 'enum symbol coercion' do
             it 'takes an idiomatic symbol and serializes the wire token (kebab included)' do
               params = Bluetooth::SimulateAdapterParameters.new(context: 'c', state: :powered_off)
@@ -404,6 +423,19 @@ def moz_install(**kwargs)
               expect(Network::AddInterceptParameters.from_json(params.as_json).phases)
                 .to eq(%i[before_request_sent auth_required])
             end
+
+            # A nullable inline literal choice (scrollbarType = "classic" / "overlay" / null) is
+            # hoisted to a named enum, so it validates as a closed vocabulary in both directions
+            # (and still admits null) rather than passing any string through as it did when opaque.
+            it 'validates a hoisted nullable inline enum, still admitting null' do
+              klass = Emulation::SetScrollbarTypeOverrideParameters
+
+              expect(klass.new(scrollbar_type: :overlay).as_json).to eq('scrollbarType' => 'overlay')
+              expect(klass.new(scrollbar_type: nil).as_json).to eq('scrollbarType' => nil)
+              expect { klass.new(scrollbar_type: :banana) }.to raise_error(ArgumentError, /must be one of/)
+              expect { klass.from_json('scrollbarType' => 'banana') }
+                .to raise_error(Error::WebDriverError, /received an unknown value/)
+            end
           end
 
           describe 'inbound shape validation' do
@@ -457,13 +489,6 @@ def moz_install(**kwargs)
               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