fix(provider): add Merge Gateway reasoning variants (#41867)

packages/opencode/src/provider/transform.ts

@@ -84,6 +84,8 @@ function sdkKey(npm: string): string | undefined {
       return "gateway"
     case "@openrouter/ai-sdk-provider":
       return "openrouter"
+    case "merge-gateway-ai-sdk-provider":
+      return "mergeGateway"
     case "ai-gateway-provider":
       // ai-gateway-provider/unified wraps createOpenAICompatible({ name: "Unified" }),
       // and @ai-sdk/openai-compatible parses compatibleOptions from one of
@@ -1772,6 +1774,7 @@ function reasoningEffort(model: Provider.Model, effort: string) {
     case "@ai-sdk/togetherai":
     case "venice-ai-sdk-provider":
     case "ai-gateway-provider":
+    case "merge-gateway-ai-sdk-provider":
       return { reasoningEffort: effort }
     case "@ai-sdk/cohere":
     case "@ai-sdk/perplexity":

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

@@ -1548,6 +1548,33 @@ test("models.dev reasoning options replace generated variants and unsupported to
   expect(models["gemini-3-pro-fast"].variants).toEqual(models.override.variants)
 })
 
+test("MERGE Gateway exposes declared effort variants without model-specific handling", () => {
+  const provider = {
+    id: "merge-gateway",
+    name: "MERGE Gateway",
+    env: ["MERGE_GATEWAY_API_KEY"],
+    npm: "merge-gateway-ai-sdk-provider",
+    models: {
+      "openai/gpt-5.6-sol": {
+        id: "openai/gpt-5.6-sol",
+        name: "GPT-5.6 Sol",
+        reasoning: true,
+        reasoning_options: [{ type: "effort", values: ["none", "low", "medium", "high", "xhigh", "max"] }],
+        limit: { context: 128_000, output: 64_000 },
+      },
+    },
+  } as unknown as ModelsDev.Provider
+
+  expect(Provider.fromModelsDevProvider(provider).models["openai/gpt-5.6-sol"].variants).toEqual({
+    none: { reasoningEffort: "none" },
+    low: { reasoningEffort: "low" },
+    medium: { reasoningEffort: "medium" },
+    high: { reasoningEffort: "high" },
+    xhigh: { reasoningEffort: "xhigh" },
+    max: { reasoningEffort: "max" },
+  })
+})
+
 test("public provider info omits invalid models", () => {
   const provider = Provider.fromModelsDevProvider({
     id: "test",

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

@@ -3370,6 +3370,7 @@ describe("ProviderTransform.reasoningVariants", () => {
     ["@ai-sdk/togetherai", { reasoningEffort: "high" }],
     ["venice-ai-sdk-provider", { reasoningEffort: "high" }],
     ["ai-gateway-provider", { reasoningEffort: "high" }],
+    ["merge-gateway-ai-sdk-provider", { reasoningEffort: "high" }],
     ["@ai-sdk/amazon-bedrock", { reasoningConfig: { type: "enabled", maxReasoningEffort: "high" } }],
   ])("converts effort for %s", (npm, expected, ...args) => {
     const id = args[0] as string | undefined
@@ -5555,6 +5556,25 @@ describe("ProviderTransform.providerOptions - ai-gateway-provider", () => {
   })
 })
 
+describe("ProviderTransform.providerOptions - merge-gateway-ai-sdk-provider", () => {
+  const model = {
+    id: "merge-gateway/openai/gpt-5.6-sol",
+    providerID: "merge-gateway",
+    api: {
+      id: "openai/gpt-5.6-sol",
+      url: "https://api-gateway.merge.dev/v1/ai-sdk",
+      npm: "merge-gateway-ai-sdk-provider",
+    },
+    capabilities: { reasoning: true },
+  } as any
+
+  test("routes normalized effort under the adapter's mergeGateway key", () => {
+    expect(ProviderTransform.providerOptions(model, { reasoningEffort: "high" })).toEqual({
+      mergeGateway: { reasoningEffort: "high" },
+    })
+  })
+})
+
 describe("ProviderTransform.options - kimi family adaptive thinking", () => {
   const createModel = (overrides: Record<string, any> = {}) =>
     ({