fix(provider): derive variants from reasoning metadata (#36624)

packages/core/src/models-dev.ts

@@ -44,6 +44,21 @@ const Cost = Schema.Struct({
   ),
 })
 
+const ReasoningOption = Schema.Union([
+  Schema.Struct({
+    type: Schema.Literal("effort"),
+    values: Schema.Array(Schema.NullOr(Schema.String)),
+  }),
+  Schema.Struct({
+    type: Schema.Literal("toggle"),
+  }),
+  Schema.Struct({
+    type: Schema.Literal("budget_tokens"),
+    min: Schema.optional(Schema.Finite),
+    max: Schema.optional(Schema.Finite),
+  }),
+])
+
 export const Model = Schema.Struct({
   id: Schema.String,
   name: Schema.String,
@@ -51,11 +66,9 @@ export const Model = Schema.Struct({
   release_date: Schema.String,
   attachment: Schema.Boolean,
   reasoning: Schema.Boolean,
-  // models.dev is external metadata and reasoning controls are expected to evolve.
-  // Provider normalization extracts the subset understood by this client.
-  reasoning_options: Schema.optional(Schema.Unknown),
   temperature: Schema.Boolean,
   tool_call: Schema.Boolean,
+  reasoning_options: Schema.optional(Schema.Array(ReasoningOption)),
   interleaved: Schema.optional(
     Schema.Union([
       Schema.Literal(true),