diff --git a/packages/opencode/src/provider/transform.ts b/packages/opencode/src/provider/transform.ts
index 5e9f10fe6..0ce5214a2 100644
--- a/packages/opencode/src/provider/transform.ts
+++ b/packages/opencode/src/provider/transform.ts
@@ -349,8 +349,12 @@ export namespace ProviderTransform {
         return Object.fromEntries(OPENAI_EFFORTS.map((effort) => [effort, { reasoningEffort: effort }]))
 
       case "@ai-sdk/github-copilot":
+        const copilotEfforts = iife(() => {
+          if (id.includes("5.1-codex-max") || id.includes("5.2")) return [...WIDELY_SUPPORTED_EFFORTS, "xhigh"]
+          return WIDELY_SUPPORTED_EFFORTS
+        })
         return Object.fromEntries(
-          WIDELY_SUPPORTED_EFFORTS.map((effort) => [
+          copilotEfforts.map((effort) => [
             effort,
             {
               reasoningEffort: effort,
diff --git a/packages/opencode/test/provider/transform.test.ts b/packages/opencode/test/provider/transform.test.ts
index 6ebac7d28..037083d5e 100644
--- a/packages/opencode/test/provider/transform.test.ts
+++ b/packages/opencode/test/provider/transform.test.ts
@@ -1224,6 +1224,102 @@ describe("ProviderTransform.variants", () => {
     })
   })
 
+  describe("@ai-sdk/github-copilot", () => {
+    test("standard models return low, medium, high", () => {
+      const model = createMockModel({
+        id: "gpt-4.5",
+        providerID: "github-copilot",
+        api: {
+          id: "gpt-4.5",
+          url: "https://api.githubcopilot.com",
+          npm: "@ai-sdk/github-copilot",
+        },
+      })
+      const result = ProviderTransform.variants(model)
+      expect(Object.keys(result)).toEqual(["low", "medium", "high"])
+      expect(result.low).toEqual({
+        reasoningEffort: "low",
+        reasoningSummary: "auto",
+        include: ["reasoning.encrypted_content"],
+      })
+    })
+
+    test("gpt-5.1-codex-max includes xhigh", () => {
+      const model = createMockModel({
+        id: "gpt-5.1-codex-max",
+        providerID: "github-copilot",
+        api: {
+          id: "gpt-5.1-codex-max",
+          url: "https://api.githubcopilot.com",
+          npm: "@ai-sdk/github-copilot",
+        },
+      })
+      const result = ProviderTransform.variants(model)
+      expect(Object.keys(result)).toEqual(["low", "medium", "high", "xhigh"])
+    })
+
+    test("gpt-5.1-codex-mini does not include xhigh", () => {
+      const model = createMockModel({
+        id: "gpt-5.1-codex-mini",
+        providerID: "github-copilot",
+        api: {
+          id: "gpt-5.1-codex-mini",
+          url: "https://api.githubcopilot.com",
+          npm: "@ai-sdk/github-copilot",
+        },
+      })
+      const result = ProviderTransform.variants(model)
+      expect(Object.keys(result)).toEqual(["low", "medium", "high"])
+    })
+
+    test("gpt-5.1-codex does not include xhigh", () => {
+      const model = createMockModel({
+        id: "gpt-5.1-codex",
+        providerID: "github-copilot",
+        api: {
+          id: "gpt-5.1-codex",
+          url: "https://api.githubcopilot.com",
+          npm: "@ai-sdk/github-copilot",
+        },
+      })
+      const result = ProviderTransform.variants(model)
+      expect(Object.keys(result)).toEqual(["low", "medium", "high"])
+    })
+
+    test("gpt-5.2 includes xhigh", () => {
+      const model = createMockModel({
+        id: "gpt-5.2",
+        providerID: "github-copilot",
+        api: {
+          id: "gpt-5.2",
+          url: "https://api.githubcopilot.com",
+          npm: "@ai-sdk/github-copilot",
+        },
+      })
+      const result = ProviderTransform.variants(model)
+      expect(Object.keys(result)).toEqual(["low", "medium", "high", "xhigh"])
+      expect(result.xhigh).toEqual({
+        reasoningEffort: "xhigh",
+        reasoningSummary: "auto",
+        include: ["reasoning.encrypted_content"],
+      })
+    })
+
+    test("gpt-5.2-codex includes xhigh", () => {
+      const model = createMockModel({
+        id: "gpt-5.2-codex",
+        providerID: "github-copilot",
+        api: {
+          id: "gpt-5.2-codex",
+          url: "https://api.githubcopilot.com",
+          npm: "@ai-sdk/github-copilot",
+        },
+      })
+      const result = ProviderTransform.variants(model)
+      expect(Object.keys(result)).toEqual(["low", "medium", "high", "xhigh"])
+    })
+  })
+
   describe("@ai-sdk/cerebras", () => {
     test("returns WIDELY_SUPPORTED_EFFORTS with reasoningEffort", () => {
       const model = createMockModel({