feat(provider): load catalog request variants

packages/core/src/models-dev.ts

@@ -69,6 +69,7 @@ export const Model = Schema.Struct({
   temperature: Schema.Boolean,
   tool_call: Schema.Boolean,
   reasoning_options: Schema.optional(Schema.Array(ReasoningOption)),
+  variants: Schema.optional(Schema.Record(Schema.String, Schema.Record(Schema.String, Schema.MutableJson))),
   interleaved: Schema.optional(
     Schema.Union([
       Schema.Literal(true),
@@ -109,7 +110,13 @@ export const Model = Schema.Struct({
   ),
   status: Schema.optional(CatalogModelStatus),
   provider: Schema.optional(
-    Schema.Struct({ npm: Schema.optional(Schema.String), api: Schema.optional(Schema.String) }),
+    Schema.Struct({
+      npm: Schema.optional(Schema.String),
+      api: Schema.optional(Schema.String),
+      variant: Schema.optional(Schema.String),
+      body: Schema.optional(Schema.Record(Schema.String, Schema.MutableJson)),
+      headers: Schema.optional(Schema.Record(Schema.String, Schema.String)),
+    }),
   ),
 })
 export type Model = Schema.Schema.Type<typeof Model>

packages/core/src/plugin/models-dev.ts

@@ -3,6 +3,7 @@ import type { ModelV2Info } from "@opencode-ai/sdk/v2/types"
 import { Effect, Stream } from "effect"
 import { EventV2 } from "../event"
 import { ModelsDev } from "../models-dev"
+import { ModelV2 } from "../model"
 import { ProviderV2 } from "../provider"
 
 function released(date: string) {
@@ -102,7 +103,11 @@ function applyModel(
     input: [...(model.modalities?.input ?? [])],
     output: [...(model.modalities?.output ?? [])],
   }
-  draft.variants = []
+  draft.variants = Object.entries(model.variants ?? {}).map(([id, body]) => ({
+    id: ModelV2.VariantID.make(id),
+    headers: {},
+    body: { ...body },
+  }))
   draft.time.released = released(model.release_date)
   draft.cost = input.cost ?? cost(model.cost)
   draft.status = model.status ?? "active"
@@ -112,6 +117,9 @@ function applyModel(
     input: model.limit.input,
     output: model.limit.output,
   }
+  if (model.provider?.variant !== undefined) draft.request.variant = ModelV2.VariantID.make(model.provider.variant)
+  Object.assign(draft.request.headers, model.provider?.headers ?? {})
+  Object.assign(draft.request.body, model.provider?.body ?? {})
   Object.assign(draft.request.headers, input.request?.headers ?? {})
   Object.assign(draft.request.body, input.request?.body ?? {})
 }

packages/core/test/plugin/models-dev.test.ts

@@ -48,8 +48,13 @@ describe("ModelsDevPlugin", () => {
                   release_date: "2026-01-01",
                   attachment: false,
                   reasoning: true,
+                  reasoning_options: [{ type: "toggle" }],
                   temperature: true,
                   tool_call: true,
+                  variants: {
+                    none: { thinking: { type: "disabled" } },
+                    thinking: { thinking: { type: "adaptive" } },
+                  },
                   cost: {
                     input: 2.5,
                     output: 15,
@@ -64,6 +69,11 @@ describe("ModelsDevPlugin", () => {
                     context_over_200k: { input: 5, output: 22.5, cache_read: 0.5 },
                   },
                   limit: { context: 1_050_000, input: 922_000, output: 128_000 },
+                  provider: {
+                    variant: "thinking",
+                    body: { thinking: { type: "adaptive" } },
+                    headers: { "x-model": "gpt-5.4" },
+                  },
                   experimental: {
                     modes: {
                       fast: {
@@ -93,18 +103,29 @@ describe("ModelsDevPlugin", () => {
       const base = yield* catalog.model.get(providerID, ModelV2.ID.make("gpt-5.4"))
       const fast = yield* catalog.model.get(providerID, ModelV2.ID.make("gpt-5.4-fast"))
 
-      expect(base?.variants).toEqual([])
-      expect(base?.request.body).toEqual({})
+      expect(base?.variants).toEqual([
+        { id: ModelV2.VariantID.make("none"), headers: {}, body: { thinking: { type: "disabled" } } },
+        { id: ModelV2.VariantID.make("thinking"), headers: {}, body: { thinking: { type: "adaptive" } } },
+      ])
+      expect(base?.request).toEqual({
+        variant: ModelV2.VariantID.make("thinking"),
+        headers: { "x-model": "gpt-5.4" },
+        body: { thinking: { type: "adaptive" } },
+      })
       expect(fast).toMatchObject({
         id: "gpt-5.4-fast",
         providerID: "acme",
         name: "GPT-5.4 Fast",
         api: { id: "gpt-5.4" },
         request: {
-          headers: { "x-mode": "fast" },
-          body: { service_tier: "priority" },
+          variant: ModelV2.VariantID.make("thinking"),
+          headers: { "x-model": "gpt-5.4", "x-mode": "fast" },
+          body: { thinking: { type: "adaptive" }, service_tier: "priority" },
         },
-        variants: [],
+        variants: [
+          { id: ModelV2.VariantID.make("none"), headers: {}, body: { thinking: { type: "disabled" } } },
+          { id: ModelV2.VariantID.make("thinking"), headers: {}, body: { thinking: { type: "adaptive" } } },
+        ],
       })
       expect(fast?.cost).toEqual([
         { input: 5, output: 30, cache: { read: 0.5, write: 0 } },

packages/core/test/session-runner-model.test.ts

@@ -22,7 +22,7 @@ type Api =
     }
   | { readonly type: "native"; readonly url?: string; readonly settings: Record<string, unknown> }
 
-const model = (api: Api, variants: ModelV2.Info["variants"] = []) =>
+const model = (api: Api, variants: ModelV2.Info["variants"] = [], variant?: ModelV2.VariantID) =>
   ModelV2.Info.make({
     id: ModelV2.ID.make("test-model"),
     providerID: ProviderV2.ID.make("test-provider"),
@@ -32,6 +32,7 @@ const model = (api: Api, variants: ModelV2.Info["variants"] = []) =>
     request: {
       headers: { "x-test": "header" },
       body: { apiKey: "secret", custom_extension: { enabled: true } },
+      ...(variant ? { variant } : {}),
     },
     variants,
     time: { released: 0 },
@@ -175,6 +176,44 @@ describe("SessionRunnerModel", () => {
     }),
   )
 
+  it.effect("uses the catalog default Session variant", () =>
+    Effect.gen(function* () {
+      const catalog = model(
+        { type: "aisdk", package: "@ai-sdk/anthropic", url: "https://anthropic.example/v1" },
+        [
+          {
+            id: ModelV2.VariantID.make("none"),
+            headers: {},
+            body: { thinking: { type: "disabled" } },
+          },
+          {
+            id: ModelV2.VariantID.make("thinking"),
+            headers: {},
+            body: { thinking: { type: "adaptive" } },
+          },
+        ],
+        ModelV2.VariantID.make("thinking"),
+      )
+      const session = SessionV2.Info.make({
+        id: SessionV2.ID.make("ses_default_variant"),
+        projectID: ProjectV2.ID.global,
+        title: "test",
+        model: { id: catalog.id, providerID: catalog.providerID },
+        cost: 0,
+        tokens: { input: 0, output: 0, reasoning: 0, cache: { read: 0, write: 0 } },
+        time: { created: DateTime.makeUnsafe(0), updated: DateTime.makeUnsafe(0) },
+        location: { directory: AbsolutePath.make("/project") },
+      })
+
+      const resolved = yield* SessionRunnerModel.resolve(session, catalog)
+
+      expect(resolved.route.defaults.http?.body).toEqual({
+        custom_extension: { enabled: true },
+        thinking: { type: "adaptive" },
+      })
+    }),
+  )
+
   it.effect("rejects an explicit unavailable Session variant during model resolution", () =>
     Effect.gen(function* () {
       const catalog = model({ type: "aisdk", package: "@ai-sdk/openai", url: "https://openai.example/v1" })

packages/llm/src/route/transport/http.ts

@@ -55,7 +55,6 @@ const PROTOCOL_BODY_OVERLAY_DENYLIST = new Set([
   "systemInstruction",
   "system_instruction",
   "temperature",
-  "thinking",
   "toolChoice",
   "toolConfig",
   "tool_choice",

packages/llm/test/prepare.test.ts

@@ -156,6 +156,32 @@ describe("request option precedence", () => {
     }),
   )
 
+  it.effect("allows provider thinking body overlays", () =>
+    LLMClient.generate(
+      LLM.request({
+        model: OpenAIChat.route
+          .with({
+            endpoint: { baseURL: "https://api.provider.test/v1/" },
+            auth: Auth.bearer("test"),
+            http: { body: { thinking: { type: "adaptive" } } },
+          })
+          .model({ id: "minimax-m3" }),
+        prompt: "Say hello.",
+      }),
+    ).pipe(
+      Effect.provide(
+        dynamicResponse((input) => {
+          expect(decodeJson(input.text)).toMatchObject({ thinking: { type: "adaptive" } })
+          return Effect.succeed(
+            input.respond(sseEvents(deltaChunk({}, "stop")), {
+              headers: { "content-type": "text/event-stream" },
+            }),
+          )
+        }),
+      ),
+    ),
+  )
+
   it.effect("uses model output limits after route limits and before call maxTokens", () =>
     Effect.gen(function* () {
       const route = AnthropicMessages.route.with({

packages/opencode/src/provider/provider.ts

@@ -1041,6 +1041,7 @@ export const Model = Schema.Struct({
   options: Schema.Record(Schema.String, Schema.Any),
   headers: Schema.Record(Schema.String, Schema.String),
   release_date: Schema.String,
+  variant: optional(ModelV2.VariantID),
   variants: optional(Schema.Record(Schema.String, Schema.Record(Schema.String, Schema.Any))),
 }).annotate({ identifier: "Model" })
 export type Model = Types.DeepMutable<Schema.Schema.Type<typeof Model>>
@@ -1216,8 +1217,8 @@ function fromModelsDevModel(provider: ModelsDev.Provider, model: ModelsDev.Model
       npm: model.provider?.npm ?? provider.npm ?? "@ai-sdk/openai-compatible",
     },
     status: model.status ?? "active",
-    headers: {},
-    options: {},
+    headers: { ...(model.provider?.headers ?? {}) },
+    options: { ...(model.provider?.body ?? {}) },
     cost: cost(model.cost),
     limit: {
       context: model.limit.context,
@@ -1246,10 +1247,12 @@ function fromModelsDevModel(provider: ModelsDev.Provider, model: ModelsDev.Model
       interleaved: model.interleaved ?? false,
     },
     release_date: model.release_date ?? "",
+    variant: model.provider?.variant ? ModelV2.VariantID.make(model.provider.variant) : undefined,
     variants: {},
   }
 
-  const variants = ProviderTransform.reasoningVariants(model, base) ?? ProviderTransform.variants(base)
+  const variants =
+    model.variants ?? ProviderTransform.reasoningVariants(model, base) ?? ProviderTransform.variants(base)
 
   return {
     ...base,
@@ -1498,6 +1501,7 @@ const layer = Layer.effect(
               headers: mergeDeep(existingModel?.headers ?? {}, model.headers ?? {}),
               family: model.family ?? existingModel?.family ?? "",
               release_date: model.release_date ?? existingModel?.release_date ?? "",
+              variant: existingModel?.variant,
               variants: {},
             }
             const variants =

packages/opencode/src/provider/transform.ts

@@ -689,15 +689,6 @@ export function variants(model: Provider.Model): Record<string, Record<string, a
   const glm52 = ["glm-5.2", "glm-5-2", "glm-5p2"].some(
     (name) => id.includes(name) || model.api.id.toLowerCase().includes(name),
   )
-  if (
-    model.api.id.toLowerCase().includes("minimax-m3") &&
-    ["@ai-sdk/anthropic", "@ai-sdk/openai-compatible"].includes(model.api.npm)
-  ) {
-    return {
-      none: { thinking: { type: "disabled" } },
-      thinking: { thinking: { type: "adaptive" } },
-    }
-  }
   const adaptiveThinkingOmitted = anthropicOmitsThinking(model.api.id)
   const adaptiveEfforts = anthropicAdaptiveEfforts(model.api.id)
   if (glm52 && model.api.npm === "@openrouter/ai-sdk-provider") {
@@ -1188,11 +1179,6 @@ export function options(input: {
 
   const modelId = input.model.api.id.toLowerCase()
 
-  // MiniMax's Anthropic interface defaults thinking off, unlike Chat Completions.
-  if (modelId.includes("minimax-m3") && input.model.api.npm === "@ai-sdk/anthropic") {
-    result["thinking"] = { type: "adaptive" }
-  }
-
   // Moonshot's Anthropic-compatible API uses adaptive effort rather than token budgets.
   // Request summaries so thinking content survives replay on subsequent turns.
   if (

packages/opencode/src/session/llm/request.ts

@@ -77,10 +77,9 @@ export const prepare = Effect.fn("LLMRequestPrep.prepare")(function* (input: Pre
     system.push(header, rest.join("\n"))
   }
 
-  const variant =
-    !input.small && input.model.variants && input.user.model.variant
-      ? input.model.variants[input.user.model.variant]
-      : {}
+  const variantID =
+    input.user.model.variant === "default" ? input.model.variant : (input.user.model.variant ?? input.model.variant)
+  const variant = !input.small && input.model.variants && variantID ? input.model.variants[variantID] : {}
   const base = input.small
     ? ProviderTransform.smallOptions(input.model)
     : ProviderTransform.options({

packages/opencode/test/provider/provider.test.ts

@@ -1522,6 +1522,23 @@ test("models.dev reasoning options replace generated variants and unsupported to
         provider: { npm: "@ai-sdk/anthropic" },
         limit: { context: 1_048_576, output: 131_072 },
       },
+      providerVariants: {
+        id: "minimax-m3",
+        name: "Provider Variants",
+        reasoning: true,
+        reasoning_options: [{ type: "toggle" }],
+        variants: {
+          none: { thinking: { type: "disabled" } },
+          thinking: { thinking: { type: "adaptive" } },
+        },
+        provider: {
+          npm: "@ai-sdk/anthropic",
+          variant: "thinking",
+          body: { thinking: { type: "adaptive" } },
+          headers: { "x-model": "minimax-m3" },
+        },
+        limit: { context: 1_000_000, output: 128_000 },
+      },
     },
   } as unknown as ModelsDev.Provider
 
@@ -1539,6 +1556,13 @@ test("models.dev reasoning options replace generated variants and unsupported to
     high: { thinkingConfig: { includeThoughts: true, thinkingLevel: "high" } },
   })
   expect(models.anthropicCompatible.variants).toEqual({ max: { effort: "max" } })
+  expect(models.providerVariants.options).toEqual({ thinking: { type: "adaptive" } })
+  expect(models.providerVariants.headers).toEqual({ "x-model": "minimax-m3" })
+  expect(models.providerVariants.variant).toBe(ModelV2.VariantID.make("thinking"))
+  expect(models.providerVariants.variants).toEqual({
+    none: { thinking: { type: "disabled" } },
+    thinking: { thinking: { type: "adaptive" } },
+  })
   expect(models["gemini-3-pro-fast"].variants).toEqual(models.override.variants)
 })
 

packages/opencode/test/provider/transform.test.ts

@@ -278,23 +278,57 @@ describe("ProviderTransform.options - minimax m3 thinking", () => {
       limit: { output: 64_000 },
     }) as any
 
-  test("explicitly enables adaptive thinking with the anthropic SDK", () => {
+  test.each(["@ai-sdk/anthropic", "@ai-sdk/openai-compatible"])("does not synthesize options for %s", (npm) => {
     expect(
       ProviderTransform.options({
-        model: createModel("@ai-sdk/anthropic"),
-        sessionID: "test-session-123",
-      }).thinking,
-    ).toEqual({ type: "adaptive" })
-  })
-
-  test("uses the native default with the openai-compatible SDK", () => {
-    expect(
-      ProviderTransform.options({
-        model: createModel("@ai-sdk/openai-compatible"),
+        model: createModel(npm),
         sessionID: "test-session-123",
       }).thinking,
     ).toBeUndefined()
   })
+
+  test("applies the model default variant without changing small requests", async () => {
+    const model = {
+      ...createModel("@ai-sdk/anthropic"),
+      variant: "thinking",
+      variants: {
+        none: { thinking: { type: "disabled" } },
+        thinking: { thinking: { type: "adaptive" } },
+      },
+    }
+    const prepare = (small: boolean) =>
+      Effect.runPromise(
+        LLMRequestPrep.prepare({
+          user: {
+            id: "msg_user-test",
+            sessionID: "test-session-123",
+            role: "user",
+            time: { created: Date.now() },
+            agent: "test",
+            model: { providerID: "minimax", modelID: "minimax-m3" },
+          } as any,
+          sessionID: "test-session-123",
+          model,
+          agent: { name: "test", mode: "primary", options: {}, permission: [] } as any,
+          system: [],
+          messages: [{ role: "user", content: "Hello" }],
+          small,
+          tools: {},
+          provider: { id: "minimax", options: {} } as any,
+          auth: undefined,
+          plugin: {
+            trigger: (_name: string, _input: unknown, output: unknown) => Effect.succeed(output),
+            list: () => Effect.succeed([]),
+            init: () => Effect.void,
+          } as any,
+          flags: { outputTokenMax: 32_000, client: "test" } as any,
+          isWorkflow: false,
+        }),
+      )
+
+    expect((await prepare(false)).params.options.thinking).toEqual({ type: "adaptive" })
+    expect((await prepare(true)).params.options.thinking).toEqual({ type: "disabled" })
+  })
 })
 
 describe("ProviderTransform.options - google thinkingConfig gating", () => {
@@ -3435,38 +3469,21 @@ describe("ProviderTransform.variants", () => {
     expect(result).toEqual({})
   })
 
-  test("minimax m3 using anthropic returns thinking toggles", () => {
-    const model = createMockModel({
-      id: "minimax/minimax-m3",
-      providerID: "minimax",
-      api: {
-        id: "MiniMax-M3",
-        url: "https://api.minimax.com/anthropic/v1",
-        npm: "@ai-sdk/anthropic",
-      },
-    })
-    const result = ProviderTransform.variants(model)
-    expect(result).toEqual({
-      none: { thinking: { type: "disabled" } },
-      thinking: { thinking: { type: "adaptive" } },
-    })
-  })
-
-  test("minimax m3 using openai-compatible returns thinking toggles", () => {
-    const model = createMockModel({
-      id: "minimax/minimax-m3",
-      providerID: "minimax",
-      api: {
-        id: "minimax-m3",
-        url: "https://api.minimax.com/v1",
-        npm: "@ai-sdk/openai-compatible",
-      },
-    })
-    expect(ProviderTransform.variants(model)).toEqual({
-      none: { thinking: { type: "disabled" } },
-      thinking: { thinking: { type: "adaptive" } },
-    })
-  })
+  test.each(["@ai-sdk/anthropic", "@ai-sdk/openai-compatible"])(
+    "does not synthesize minimax m3 variants for %s",
+    (npm) => {
+      const model = createMockModel({
+        id: "minimax/minimax-m3",
+        providerID: "minimax",
+        api: {
+          id: "minimax-m3",
+          url: "https://api.minimax.com/v1",
+          npm,
+        },
+      })
+      expect(ProviderTransform.variants(model)).toEqual({})
+    },
+  )
 
   test("glm returns empty object", () => {
     const model = createMockModel({