refactor(core): simplify model requests

packages/core/test/config/config.test.ts

@@ -599,9 +599,9 @@ describe("Config", () => {
               models: {
                 model: {
                   request: {
-                    body: { temperature: 0.3, reasoningEffort: "high", serviceTier: "priority" },
+                    body: { temperature: 0.3, reasoning_effort: "high", service_tier: "priority" },
                   },
-                  variants: [{ id: "high", body: { reasoningEffort: "high", reasoningSummary: "auto" } }],
+                  variants: [{ id: "high", body: { reasoning_effort: "high", reasoning_summary: "auto" } }],
                 },
               },
             })

packages/core/test/config/provider.test.ts

@@ -55,7 +55,7 @@ function request(headers: Record<string, string>, variant?: string) {
 const decode = Schema.decodeUnknownSync(Config.Info)
 
 describe("ConfigProviderPlugin.Plugin", () => {
-  it.effect("partitions existing model variant bodies without changing config shape", () =>
+  it.effect("keeps configured model variant bodies unchanged", () =>
     Effect.gen(function* () {
       const catalog = yield* Catalog.Service
       const providerID = ProviderV2.ID.opencode
@@ -96,8 +96,7 @@ describe("ConfigProviderPlugin.Plugin", () => {
       expect(model.variants).toMatchObject([
         {
           id: "high",
-          body: {},
-          options: {
+          body: {
             reasoningEffort: "high",
             reasoningSummary: "auto",
             include: ["reasoning.encrypted_content"],
@@ -107,7 +106,7 @@ describe("ConfigProviderPlugin.Plugin", () => {
     }),
   )
 
-  it.effect("uses the effective provider package across layered config", () =>
+  it.effect("keeps layered model variant bodies unchanged", () =>
     Effect.gen(function* () {
       const catalog = yield* Catalog.Service
       const providerID = ProviderV2.ID.opencode
@@ -147,8 +146,7 @@ describe("ConfigProviderPlugin.Plugin", () => {
       const model = required(yield* catalog.model.get(providerID, modelID))
       expect(model.variants[0]).toMatchObject({
         id: "high",
-        body: {},
-        options: { reasoningEffort: "high" },
+        body: { reasoningEffort: "high" },
       })
     }),
   )