diff --git a/packages/opencode/src/provider/transform.ts b/packages/opencode/src/provider/transform.ts
index 08b2f49221..c67c0bca65 100644
--- a/packages/opencode/src/provider/transform.ts
+++ b/packages/opencode/src/provider/transform.ts
@@ -596,8 +596,16 @@ function openaiCompatibleReasoningEfforts(id: string) {
   return gpt5CodexReasoningEfforts(apiId) ?? versionedGpt5ReasoningEfforts(apiId) ?? OPENAI_EFFORTS
 }
 
+function anthropicOpus47OrLater(apiId: string) {
+  const version = /opus-(\d+)[.-](\d+)(?:[.-]|$)/i.exec(apiId)
+  if (!version) return false
+  const major = Number(version[1])
+  const minor = Number(version[2])
+  return major > 4 || (major === 4 && minor >= 7)
+}
+
 function anthropicAdaptiveEfforts(apiId: string): string[] | null {
-  if (["opus-4-7", "opus-4.7"].some((v) => apiId.includes(v))) {
+  if (anthropicOpus47OrLater(apiId)) {
     return ["low", "medium", "high", "xhigh", "max"]
   }
   if (["opus-4-6", "opus-4.6", "sonnet-4-6", "sonnet-4.6"].some((v) => apiId.includes(v))) {
@@ -625,6 +633,7 @@ export function variants(model: Provider.Model): Record<string, Record<string, a
   if (!model.capabilities.reasoning) return {}
 
   const id = model.id.toLowerCase()
+  const adaptiveOpus = anthropicOpus47OrLater(model.api.id)
   const adaptiveEfforts = anthropicAdaptiveEfforts(model.api.id)
   if (
     id.includes("deepseek-chat") ||
@@ -833,9 +842,7 @@ export function variants(model: Provider.Model): Record<string, Record<string, a
             {
               thinking: {
                 type: "adaptive",
-                ...(model.api.id.includes("opus-4-7") || model.api.id.includes("opus-4.7")
-                  ? { display: "summarized" }
-                  : {}),
+                ...(adaptiveOpus ? { display: "summarized" } : {}),
               },
               effort,
             },
@@ -872,9 +879,7 @@ export function variants(model: Provider.Model): Record<string, Record<string, a
               reasoningConfig: {
                 type: "adaptive",
                 maxReasoningEffort: effort,
-                ...(model.api.id.includes("opus-4-7") || model.api.id.includes("opus-4.7")
-                  ? { display: "summarized" }
-                  : {}),
+                ...(adaptiveOpus ? { display: "summarized" } : {}),
               },
             },
           ]),
diff --git a/packages/opencode/test/provider/transform.test.ts b/packages/opencode/test/provider/transform.test.ts
index 2bce158560..bd491f89bb 100644
--- a/packages/opencode/test/provider/transform.test.ts
+++ b/packages/opencode/test/provider/transform.test.ts
@@ -3223,6 +3223,12 @@ describe("ProviderTransform.variants", () => {
         efforts: ["low", "medium", "high", "xhigh", "max"],
         expectedHigh: { thinking: { type: "adaptive", display: "summarized" }, effort: "high" },
       },
+      {
+        name: "opus 4.8",
+        apiIds: ["claude-opus-4-8", "claude-opus-4.8"],
+        efforts: ["low", "medium", "high", "xhigh", "max"],
+        expectedHigh: { thinking: { type: "adaptive", display: "summarized" }, effort: "high" },
+      },
     ]) {
       for (const apiId of testCase.apiIds) {
         test(`${testCase.name} ${apiId} returns supported reasoning efforts`, () => {
@@ -3341,6 +3347,28 @@ describe("ProviderTransform.variants", () => {
       })
     })
 
+    test("anthropic opus 4.8 returns adaptive reasoning options with xhigh", () => {
+      const result = ProviderTransform.variants(
+        createMockModel({
+          id: "bedrock/anthropic-claude-opus-4.8",
+          providerID: "bedrock",
+          api: {
+            id: "anthropic.claude-opus-4.8",
+            url: "https://bedrock.amazonaws.com",
+            npm: "@ai-sdk/amazon-bedrock",
+          },
+        }),
+      )
+      expect(Object.keys(result)).toEqual(["low", "medium", "high", "xhigh", "max"])
+      expect(result.high).toEqual({
+        reasoningConfig: {
+          type: "adaptive",
+          maxReasoningEffort: "high",
+          display: "summarized",
+        },
+      })
+    })
+
     test("returns WIDELY_SUPPORTED_EFFORTS with reasoningConfig", () => {
       const model = createMockModel({
         id: "bedrock/llama-4",