fix(provider): enable sonnet 5 adaptive thinking (#34673)

packages/opencode/src/provider/transform.ts

@@ -605,8 +605,14 @@ function anthropicOpus47OrLater(apiId: string) {
   return major > 4 || (major === 4 && minor >= 7)
 }
 
+function anthropicSonnet5OrLater(apiId: string) {
+  const version = /sonnet-(\d+)(?:[.@-]|$)|claude-(\d+)-sonnet(?:[.@-]|$)/i.exec(apiId)
+  if (!version) return false
+  return Number(version[1] ?? version[2]) >= 5
+}
+
 function anthropicAdaptiveEfforts(apiId: string): string[] | null {
-  if (anthropicOpus47OrLater(apiId) || apiId.includes("fable-5")) {
+  if (anthropicOpus47OrLater(apiId) || anthropicSonnet5OrLater(apiId) || apiId.includes("fable-5")) {
     return ["low", "medium", "high", "xhigh", "max"]
   }
   if (
@@ -620,7 +626,7 @@ function anthropicAdaptiveEfforts(apiId: string): string[] | null {
 }
 
 function anthropicOmitsThinking(apiId: string) {
-  return anthropicOpus47OrLater(apiId) || apiId.includes("fable-5")
+  return anthropicOpus47OrLater(apiId) || anthropicSonnet5OrLater(apiId) || apiId.includes("fable-5")
 }
 
 function googleThinkingLevelEfforts(apiId: string) {

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

@@ -3290,6 +3290,27 @@ describe("ProviderTransform.variants", () => {
       })
     })
 
+    test("anthropic sonnet 5 returns adaptive thinking options with xhigh", () => {
+      const model = createMockModel({
+        id: "anthropic/claude-sonnet-5",
+        providerID: "gateway",
+        api: {
+          id: "anthropic/claude-sonnet-5",
+          url: "https://gateway.ai",
+          npm: "@ai-sdk/gateway",
+        },
+      })
+      const result = ProviderTransform.variants(model)
+      expect(Object.keys(result)).toEqual(["low", "medium", "high", "xhigh", "max"])
+      expect(result.high).toEqual({
+        thinking: {
+          type: "adaptive",
+          display: "summarized",
+        },
+        effort: "high",
+      })
+    })
+
     test("anthropic opus 4.6 omits display so it keeps the summarized default", () => {
       const model = createMockModel({
         id: "anthropic/claude-opus-4-6",
@@ -3877,6 +3898,12 @@ describe("ProviderTransform.variants", () => {
         efforts: ["low", "medium", "high", "xhigh", "max"],
         expectedHigh: { thinking: { type: "adaptive", display: "summarized" }, effort: "high" },
       },
+      {
+        name: "sonnet 5",
+        apiIds: ["claude-sonnet-5", "claude-sonnet-5-20260630"],
+        efforts: ["low", "medium", "high", "xhigh", "max"],
+        expectedHigh: { thinking: { type: "adaptive", display: "summarized" }, effort: "high" },
+      },
       {
         name: "fable 5",
         apiIds: ["claude-fable-5"],
@@ -3974,6 +4001,28 @@ describe("ProviderTransform.variants", () => {
         effort: "high",
       })
     })
+
+    test("sonnet 5 uses adaptive reasoning for Vertex model IDs", () => {
+      const result = ProviderTransform.variants(
+        createMockModel({
+          id: "google-vertex-anthropic/claude-sonnet-5@default",
+          providerID: "google-vertex-anthropic",
+          api: {
+            id: "claude-sonnet-5@default",
+            url: "https://us-central1-aiplatform.googleapis.com",
+            npm: "@ai-sdk/google-vertex/anthropic",
+          },
+        }),
+      )
+      expect(Object.keys(result)).toEqual(["low", "medium", "high", "xhigh", "max"])
+      expect(result.high).toEqual({
+        thinking: {
+          type: "adaptive",
+          display: "summarized",
+        },
+        effort: "high",
+      })
+    })
   })
 
   describe("@ai-sdk/amazon-bedrock", () => {
@@ -4047,6 +4096,28 @@ describe("ProviderTransform.variants", () => {
       })
     })
 
+    test("anthropic sonnet 5 returns adaptive reasoning options with xhigh", () => {
+      const result = ProviderTransform.variants(
+        createMockModel({
+          id: "bedrock/anthropic-claude-sonnet-5",
+          providerID: "bedrock",
+          api: {
+            id: "anthropic.claude-sonnet-5",
+            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",
@@ -4229,6 +4300,12 @@ describe("ProviderTransform.variants", () => {
         efforts: ["low", "medium", "high", "xhigh", "max"],
         thinking: { type: "adaptive", display: "summarized" },
       },
+      {
+        name: "sonnet 5",
+        apiIds: ["anthropic--claude-sonnet-5", "anthropic--claude-5-sonnet"],
+        efforts: ["low", "medium", "high", "xhigh", "max"],
+        thinking: { type: "adaptive", display: "summarized" },
+      },
     ]) {
       for (const apiId of testCase.apiIds) {
         test(`${testCase.name} ${apiId} returns adaptive thinking variants under modelParams`, () => {