feat(ai): support custom reasoning fields (#38227)

packages/core/src/aisdk.ts

@@ -344,7 +344,12 @@ function modelFromLanguage(info: ModelV2.Info, language: LanguageModelV3) {
     prepareTransport: (body) => Effect.succeed(body),
     streamPrepared: (prepared) => streamLanguage(language, prepared as LanguageModelV3CallOptions),
   }
-  return Model.make({ id: info.modelID ?? info.id, provider: info.providerID, route })
+  return Model.make({
+    id: info.modelID ?? info.id,
+    provider: info.providerID,
+    route,
+    compatibility: info.compatibility,
+  })
 }
 
 function gatewayProviderOptions(modelID: ModelV2.ID, settings: Readonly<Record<string, unknown>>) {

packages/core/src/config/plugin/provider.ts

@@ -4,7 +4,6 @@ import { define } from "@opencode-ai/plugin/v2/effect/plugin"
 import { Money } from "@opencode-ai/schema/money"
 import { Effect, Stream } from "effect"
 import { Config } from "../../config"
-import { ModelV2 } from "../../model"
 import { ProviderV2 } from "../../provider"
 
 export const Plugin = define({
@@ -59,6 +58,8 @@ export const Plugin = define({
               if (config.family !== undefined) model.family = config.family
               if (config.name !== undefined) model.name = config.name
               if (config.modelID !== undefined) model.modelID = config.modelID
+              if (config.compatibility !== undefined)
+                model.compatibility = { ...model.compatibility, ...config.compatibility }
               if (config.package !== undefined) model.package = config.package
               if (config.settings !== undefined)
                 model.settings = ProviderV2.mergeOverlay(model.settings, config.settings)

packages/core/src/config/provider.ts

@@ -42,6 +42,7 @@ class Model extends Schema.Class<Model>("ConfigV2.Model")({
   modelID: ModelV2.ID.pipe(Schema.optional),
   family: ModelV2.Family.pipe(Schema.optional),
   name: Schema.String.pipe(Schema.optional),
+  compatibility: ModelV2.Compatibility.pipe(Schema.optional),
   package: Schema.String.pipe(Schema.optional),
   ...Overlays,
   capabilities: ModelV2.Capabilities.pipe(Schema.optional),

packages/core/src/model.ts

@@ -12,6 +12,12 @@ export type VariantID = typeof VariantID.Type
 export const Family = Model.Family
 export type Family = Model.Family
 
+export const ReasoningField = Model.ReasoningField
+export type ReasoningField = Model.ReasoningField
+
+export const Compatibility = Model.Compatibility
+export type Compatibility = Model.Compatibility
+
 export const Capabilities = Model.Capabilities
 export type Capabilities = Model.Capabilities
 
@@ -25,6 +31,12 @@ export type Info = Model.Info
 
 export type MutableInfo = DeepMutable<Info>
 
+export function compatibility(input: unknown): Compatibility | undefined {
+  if (typeof input === "string") return { reasoningField: input }
+  if (typeof input !== "object" || input === null || Array.isArray(input) || !("field" in input)) return undefined
+  return typeof input.field === "string" ? { reasoningField: input.field } : undefined
+}
+
 export function parse(input: string): { providerID: ProviderV2.ID; modelID: ID } {
   const [providerID, ...modelID] = input.split("/")
   return {

packages/core/src/models-dev.ts

@@ -43,7 +43,7 @@ type SourceModel = {
   readonly reasoning_options?: readonly ReasoningOption[]
   readonly temperature?: boolean
   readonly tool_call: boolean
-  readonly interleaved?: true | { readonly field: "reasoning" | "reasoning_content" | "reasoning_details" }
+  readonly interleaved?: boolean | string | { readonly field: string }
   readonly cost?: Cost
   readonly limit: { readonly context: number; readonly input?: number; readonly output: number }
   readonly modalities?: { readonly input: readonly Modality[]; readonly output: readonly Modality[] }
@@ -495,6 +495,7 @@ function modelInfo(
     modelID: ModelV2.ID.make(model.id),
     providerID,
     name: input.name ?? model.name,
+    compatibility: ModelV2.compatibility(model.interleaved),
     family: model.family ? ModelV2.Family.make(model.family) : undefined,
     package: model.provider?.npm ? ProviderV2.aisdk(model.provider.npm) : undefined,
     settings: model.provider?.api ? { baseURL: model.provider.api } : undefined,

packages/core/src/plugin/provider/opencode.ts

@@ -134,6 +134,7 @@ export const OpencodePlugin = define<HttpClient.HttpClient | EventV2.Service | S
             if (config.family !== undefined) model.family = config.family
             if (config.name !== undefined) model.name = config.name
             if (config.id !== undefined) model.modelID = config.id
+            model.compatibility = ModelV2.compatibility(config.interleaved) ?? model.compatibility
             if (config.provider !== undefined) {
               model.package = config.provider.npm ? ProviderV2.aisdk(config.provider.npm) : undefined
               if (config.provider.api) model.settings = { ...model.settings, baseURL: config.provider.api }

packages/core/src/session/runner/model.ts

@@ -209,14 +209,14 @@ export const fromCatalogModel = (
     return Effect.succeed(
       withDefaults(resolved, OpenAIResponses.route)
         .with({ auth: key === undefined ? Auth.none : Auth.bearer(key) })
-        .model({ id: resolved.modelID ?? resolved.id }),
+        .model({ id: resolved.modelID ?? resolved.id, compatibility: resolved.compatibility }),
     )
   }
   if (ProviderV2.isAISDK(resolved.package) && packageName === "@ai-sdk/anthropic") {
     return Effect.succeed(
       withDefaults(resolved, AnthropicMessages.route)
         .with({ auth: key === undefined ? Auth.none : Auth.header("x-api-key", key) })
-        .model({ id: resolved.modelID ?? resolved.id }),
+        .model({ id: resolved.modelID ?? resolved.id, compatibility: resolved.compatibility }),
     )
   }
   if (
@@ -227,7 +227,7 @@ export const fromCatalogModel = (
     return Effect.succeed(
       withDefaults(resolved, OpenAICompatibleChat.route)
         .with({ auth: key === undefined ? Auth.none : Auth.bearer(key) })
-        .model({ id: resolved.modelID ?? resolved.id }),
+        .model({ id: resolved.modelID ?? resolved.id, compatibility: resolved.compatibility }),
     )
   }
   if (ProviderV2.isAISDK(resolved.package)) {
@@ -257,8 +257,15 @@ export const fromCatalogModel = (
       limits: { context: resolved.limit.context, output: resolved.limit.output },
     }
     return yield* Effect.try({
-      try: () =>
-        Model.update(module.model(resolved.modelID ?? resolved.id, settings), { provider: resolved.providerID }),
+      try: () => {
+        const runtime = module.model(resolved.modelID ?? resolved.id, settings)
+        return Model.update(runtime, {
+          provider: resolved.providerID,
+          compatibility: resolved.compatibility
+            ? { ...runtime.compatibility, ...resolved.compatibility }
+            : runtime.compatibility,
+        })
+      },
       catch: () => unsupported(resolved),
     })
   })
@@ -302,7 +309,7 @@ const codexModel = (
         account === undefined ? Auth.none : Auth.headers({ "chatgpt-account-id": account }),
       ),
     })
-    .model({ id: model.modelID ?? model.id })
+    .model({ id: model.modelID ?? model.id, compatibility: model.compatibility })
 }
 
 const unsupported = (model: ModelV2.Info) =>

packages/core/src/v1/config/migrate.ts

@@ -8,6 +8,7 @@ import { ConfigPermissionV1 } from "./permission"
 import { ConfigProviderV1 } from "./provider"
 import { ConfigProviderOptionsV1 } from "./provider-options"
 import { ProviderV2 } from "../../provider"
+import { ModelV2 } from "../../model"
 
 const keys = new Set([
   "logLevel",
@@ -278,6 +279,7 @@ function migrateModel(info: typeof ConfigProviderV1.Model.Type) {
     modelID: info.id,
     family: info.family,
     name: info.name,
+    compatibility: ModelV2.compatibility(info.interleaved),
     package: info.provider?.npm ? ProviderV2.aisdk(info.provider.npm) : undefined,
     settings: info.provider?.api ? { ...settings, baseURL: info.provider.api } : settings,
     capabilities,

packages/core/src/v1/config/provider.ts

@@ -16,9 +16,10 @@ export const Model = Schema.Struct({
   tool_call: Schema.optional(Schema.Boolean),
   interleaved: Schema.optional(
     Schema.Union([
-      Schema.Literal(true),
+      Schema.Boolean,
+      Schema.String,
       Schema.Struct({
-        field: Schema.Literals(["reasoning", "reasoning_content", "reasoning_details"]),
+        field: Schema.String,
       }),
     ]),
   ),