diff --git a/tests/baselines/reference/contextualSignatureConditionalTypeInstantiationUsingDefault.symbols b/tests/baselines/reference/contextualSignatureConditionalTypeInstantiationUsingDefault.symbols
new file mode 100644
index 0000000000000..81e0123470ef3
--- /dev/null
+++ b/tests/baselines/reference/contextualSignatureConditionalTypeInstantiationUsingDefault.symbols
@@ -0,0 +1,67 @@
+=== tests/cases/compiler/contextualSignatureConditionalTypeInstantiationUsingDefault.ts ===
+// repro #46310
+
+export interface TypegenDisabled {
+>TypegenDisabled : Symbol(TypegenDisabled, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 0, 0))
+
+  "@@xstate/typegen": false;
+>"@@xstate/typegen" : Symbol(TypegenDisabled["@@xstate/typegen"], Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 2, 34))
+}
+export interface TypegenEnabled {
+>TypegenEnabled : Symbol(TypegenEnabled, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 4, 1))
+
+  "@@xstate/typegen": true;
+>"@@xstate/typegen" : Symbol(TypegenEnabled["@@xstate/typegen"], Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 5, 33))
+}
+
+type ActionFunction<TEvent extends { type: string }> = (event: TEvent) => void;
+>ActionFunction : Symbol(ActionFunction, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 7, 1))
+>TEvent : Symbol(TEvent, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 9, 20))
+>type : Symbol(type, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 9, 36))
+>event : Symbol(event, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 9, 56))
+>TEvent : Symbol(TEvent, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 9, 20))
+
+declare function createMachine<
+>createMachine : Symbol(createMachine, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 9, 79))
+
+  TTypesMeta extends TypegenEnabled | TypegenDisabled = TypegenDisabled
+>TTypesMeta : Symbol(TTypesMeta, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 11, 31))
+>TypegenEnabled : Symbol(TypegenEnabled, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 4, 1))
+>TypegenDisabled : Symbol(TypegenDisabled, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 0, 0))
+>TypegenDisabled : Symbol(TypegenDisabled, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 0, 0))
+
+>(
+  config: {
+>config : Symbol(config, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 13, 2))
+
+    types?: TTypesMeta;
+>types : Symbol(types, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 14, 11))
+>TTypesMeta : Symbol(TTypesMeta, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 11, 31))
+
+  },
+  implementations: TTypesMeta extends TypegenEnabled
+>implementations : Symbol(implementations, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 16, 4))
+>TTypesMeta : Symbol(TTypesMeta, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 11, 31))
+>TypegenEnabled : Symbol(TypegenEnabled, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 4, 1))
+
+    ? ActionFunction<{ type: "test" }>
+>ActionFunction : Symbol(ActionFunction, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 7, 1))
+>type : Symbol(type, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 18, 22))
+
+    : ActionFunction<{ type: string }>
+>ActionFunction : Symbol(ActionFunction, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 7, 1))
+>type : Symbol(type, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 19, 22))
+
+): void;
+
+createMachine({}, (ev) => {
+>createMachine : Symbol(createMachine, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 9, 79))
+>ev : Symbol(ev, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 22, 19))
+
+  ev.type; // should be `string`
+>ev.type : Symbol(type, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 19, 22))
+>ev : Symbol(ev, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 22, 19))
+>type : Symbol(type, Decl(contextualSignatureConditionalTypeInstantiationUsingDefault.ts, 19, 22))
+
+});
+
diff --git a/tests/baselines/reference/contextualSignatureConditionalTypeInstantiationUsingDefault.types b/tests/baselines/reference/contextualSignatureConditionalTypeInstantiationUsingDefault.types
new file mode 100644
index 0000000000000..b98593ef5bd56
--- /dev/null
+++ b/tests/baselines/reference/contextualSignatureConditionalTypeInstantiationUsingDefault.types
@@ -0,0 +1,56 @@
+=== tests/cases/compiler/contextualSignatureConditionalTypeInstantiationUsingDefault.ts ===
+// repro #46310
+
+export interface TypegenDisabled {
+  "@@xstate/typegen": false;
+>"@@xstate/typegen" : false
+>false : false
+}
+export interface TypegenEnabled {
+  "@@xstate/typegen": true;
+>"@@xstate/typegen" : true
+>true : true
+}
+
+type ActionFunction<TEvent extends { type: string }> = (event: TEvent) => void;
+>ActionFunction : ActionFunction<TEvent>
+>type : string
+>event : TEvent
+
+declare function createMachine<
+>createMachine : <TTypesMeta extends TypegenDisabled | TypegenEnabled = TypegenDisabled>(config: {    types?: TTypesMeta;}, implementations: TTypesMeta extends TypegenEnabled ? ActionFunction<{    type: "test";}> : ActionFunction<{    type: string;}>) => void
+
+  TTypesMeta extends TypegenEnabled | TypegenDisabled = TypegenDisabled
+>(
+  config: {
+>config : { types?: TTypesMeta | undefined; }
+
+    types?: TTypesMeta;
+>types : TTypesMeta | undefined
+
+  },
+  implementations: TTypesMeta extends TypegenEnabled
+>implementations : TTypesMeta extends TypegenEnabled ? ActionFunction<{ type: "test"; }> : ActionFunction<{ type: string; }>
+
+    ? ActionFunction<{ type: "test" }>
+>type : "test"
+
+    : ActionFunction<{ type: string }>
+>type : string
+
+): void;
+
+createMachine({}, (ev) => {
+>createMachine({}, (ev) => {  ev.type; // should be `string`}) : void
+>createMachine : <TTypesMeta extends TypegenDisabled | TypegenEnabled = TypegenDisabled>(config: { types?: TTypesMeta | undefined; }, implementations: TTypesMeta extends TypegenEnabled ? ActionFunction<{ type: "test"; }> : ActionFunction<{ type: string; }>) => void
+>{} : {}
+>(ev) => {  ev.type; // should be `string`} : (ev: { type: string; }) => void
+>ev : { type: string; }
+
+  ev.type; // should be `string`
+>ev.type : string
+>ev : { type: string; }
+>type : string
+
+});
+
diff --git a/tests/cases/compiler/contextualSignatureConditionalTypeInstantiationUsingDefault.ts b/tests/cases/compiler/contextualSignatureConditionalTypeInstantiationUsingDefault.ts
new file mode 100644
index 0000000000000..01949742f7a83
--- /dev/null
+++ b/tests/cases/compiler/contextualSignatureConditionalTypeInstantiationUsingDefault.ts
@@ -0,0 +1,28 @@
+// @strict: true
+// @noEmit: true
+
+// repro #46310
+
+export interface TypegenDisabled {
+  "@@xstate/typegen": false;
+}
+export interface TypegenEnabled {
+  "@@xstate/typegen": true;
+}
+
+type ActionFunction<TEvent extends { type: string }> = (event: TEvent) => void;
+
+declare function createMachine<
+  TTypesMeta extends TypegenEnabled | TypegenDisabled = TypegenDisabled
+>(
+  config: {
+    types?: TTypesMeta;
+  },
+  implementations: TTypesMeta extends TypegenEnabled
+    ? ActionFunction<{ type: "test" }>
+    : ActionFunction<{ type: string }>
+): void;
+
+createMachine({}, (ev) => {
+  ev.type; // should be `string`
+});