diff --git a/packages/opencode/src/provider/transform.ts b/packages/opencode/src/provider/transform.ts
index b659799c1b6..6f6ffdcd3ba 100644
--- a/packages/opencode/src/provider/transform.ts
+++ b/packages/opencode/src/provider/transform.ts
@@ -447,7 +447,6 @@ export namespace ProviderTransform {
             effort,
             {
               reasoningEffort: effort,
-              reasoningSummary: "auto",
               include: ["reasoning.encrypted_content"],
             },
           ]),
@@ -478,7 +477,6 @@ export namespace ProviderTransform {
             effort,
             {
               reasoningEffort: effort,
-              reasoningSummary: "auto",
               include: ["reasoning.encrypted_content"],
             },
           ]),
@@ -508,7 +506,6 @@ export namespace ProviderTransform {
             effort,
             {
               reasoningEffort: effort,
-              reasoningSummary: "auto",
               include: ["reasoning.encrypted_content"],
             },
           ]),
@@ -759,7 +756,6 @@ export namespace ProviderTransform {
     if (input.model.api.id.includes("gpt-5") && !input.model.api.id.includes("gpt-5-chat")) {
       if (!input.model.api.id.includes("gpt-5-pro")) {
         result["reasoningEffort"] = "medium"
-        result["reasoningSummary"] = "auto"
       }
 
       // Only set textVerbosity for non-chat gpt-5.x models
@@ -776,7 +772,6 @@ export namespace ProviderTransform {
       if (input.model.providerID.startsWith("opencode")) {
         result["promptCacheKey"] = input.sessionID
         result["include"] = ["reasoning.encrypted_content"]
-        result["reasoningSummary"] = "auto"
       }
     }
 
diff --git a/packages/opencode/test/provider/transform.test.ts b/packages/opencode/test/provider/transform.test.ts
index 189bdfd32b4..88249f7d8e6 100644
--- a/packages/opencode/test/provider/transform.test.ts
+++ b/packages/opencode/test/provider/transform.test.ts
@@ -1823,7 +1823,6 @@ describe("ProviderTransform.variants", () => {
       expect(Object.keys(result)).toEqual(["low", "medium", "high"])
       expect(result.low).toEqual({
         reasoningEffort: "low",
-        reasoningSummary: "auto",
         include: ["reasoning.encrypted_content"],
       })
     })
@@ -1884,7 +1883,6 @@ describe("ProviderTransform.variants", () => {
       expect(Object.keys(result)).toEqual(["low", "medium", "high", "xhigh"])
       expect(result.xhigh).toEqual({
         reasoningEffort: "xhigh",
-        reasoningSummary: "auto",
         include: ["reasoning.encrypted_content"],
       })
     })
@@ -2023,7 +2021,7 @@ describe("ProviderTransform.variants", () => {
       expect(result).toEqual({})
     })
 
-    test("standard azure models return custom efforts with reasoningSummary", () => {
+    test("standard azure models return custom efforts", () => {
       const model = createMockModel({
         id: "o1",
         providerID: "azure",
@@ -2037,7 +2035,6 @@ describe("ProviderTransform.variants", () => {
       expect(Object.keys(result)).toEqual(["low", "medium", "high"])
       expect(result.low).toEqual({
         reasoningEffort: "low",
-        reasoningSummary: "auto",
         include: ["reasoning.encrypted_content"],
       })
     })
@@ -2072,7 +2069,7 @@ describe("ProviderTransform.variants", () => {
       expect(result).toEqual({})
     })
 
-    test("standard openai models return custom efforts with reasoningSummary", () => {
+    test("standard openai models return custom efforts", () => {
       const model = createMockModel({
         id: "gpt-5",
         providerID: "openai",
@@ -2087,7 +2084,6 @@ describe("ProviderTransform.variants", () => {
       expect(Object.keys(result)).toEqual(["minimal", "low", "medium", "high"])
       expect(result.low).toEqual({
         reasoningEffort: "low",
-        reasoningSummary: "auto",
         include: ["reasoning.encrypted_content"],
       })
     })