feat(core): widen interleaved reasoning fields

packages/schema/src/model.ts

@@ -41,11 +41,29 @@ export interface Ref extends Schema.Schema.Type<typeof Ref> {}
 export const Family = Schema.String.pipe(Schema.brand("Model.Family"))
 export type Family = typeof Family.Type
 
+export type InterleavedField =
+  | "reasoning"
+  | "reasoning_content"
+  | "reasoning_text"
+  | "reasoning_details"
+  | (string & {})
+export const InterleavedField: Schema.Codec<InterleavedField> = Schema.Union([
+  Schema.Literals(["reasoning", "reasoning_content", "reasoning_text", "reasoning_details"]),
+  Schema.String,
+]).annotate({ identifier: "Model.InterleavedField" })
+
+export type Interleaved = true | { readonly field: InterleavedField }
+export const Interleaved: Schema.Codec<Interleaved> = Schema.Union([
+  Schema.Literal(true),
+  Schema.Struct({ field: InterleavedField }),
+]).annotate({ identifier: "Model.Interleaved" })
+
 export interface Capabilities extends Schema.Schema.Type<typeof Capabilities> {}
 export const Capabilities = Schema.Struct({
   tools: Schema.Boolean,
   input: Schema.Array(Schema.String),
   output: Schema.Array(Schema.String),
+  interleaved: Interleaved.pipe(optional),
 }).annotate({ identifier: "Model.Capabilities" })
 
 export interface Cost extends Schema.Schema.Type<typeof Cost> {}

packages/schema/test/model.test.ts

@@ -1,4 +1,5 @@
 import { describe, expect, test } from "bun:test"
+import { Schema } from "effect"
 import { Model } from "../src/model.js"
 
 describe("Model.Ref", () => {
@@ -20,3 +21,13 @@ describe("Model.Ref", () => {
     expect(() => Model.Ref.parse("openai/gpt-5#high#extra")).toThrow()
   })
 })
+
+describe("Model.Interleaved", () => {
+  test("accepts known and provider-specific fields", () => {
+    const decode = Schema.decodeUnknownSync(Model.Interleaved)
+    const fields = ["reasoning", "reasoning_content", "reasoning_text", "reasoning_details", "vendor_reasoning"]
+
+    for (const field of fields) expect(decode({ field })).toEqual({ field })
+    expect(decode(true)).toBe(true)
+  })
+})