diff --git a/packages/opencode/src/provider/transform.ts b/packages/opencode/src/provider/transform.ts
index 6ca089c2f0..dcc2605ab6 100644
--- a/packages/opencode/src/provider/transform.ts
+++ b/packages/opencode/src/provider/transform.ts
@@ -594,9 +594,12 @@ export namespace ProviderTransform {
         result["reasoningEffort"] = "medium"
       }
 
+      // Only set textVerbosity for non-chat gpt-5.x models
+      // Chat models (e.g. gpt-5.2-chat-latest) only support "medium" verbosity
       if (
         input.model.api.id.includes("gpt-5.") &&
         !input.model.api.id.includes("codex") &&
+        !input.model.api.id.includes("-chat") &&
         input.model.providerID !== "azure"
       ) {
         result["textVerbosity"] = "low"
diff --git a/packages/opencode/test/provider/transform.test.ts b/packages/opencode/test/provider/transform.test.ts
index 1d69a2a295..b818ab98cf 100644
--- a/packages/opencode/test/provider/transform.test.ts
+++ b/packages/opencode/test/provider/transform.test.ts
@@ -103,6 +103,78 @@ describe("ProviderTransform.options - setCacheKey", () => {
   })
 })
 
+describe("ProviderTransform.options - gpt-5 textVerbosity", () => {
+  const sessionID = "test-session-123"
+
+  const createGpt5Model = (apiId: string) =>
+    ({
+      id: `openai/${apiId}`,
+      providerID: "openai",
+      api: {
+        id: apiId,
+        url: "https://api.openai.com",
+        npm: "@ai-sdk/openai",
+      },
+      name: apiId,
+      capabilities: {
+        temperature: true,
+        reasoning: true,
+        attachment: true,
+        toolcall: true,
+        input: { text: true, audio: false, image: true, video: false, pdf: false },
+        output: { text: true, audio: false, image: false, video: false, pdf: false },
+        interleaved: false,
+      },
+      cost: { input: 0.03, output: 0.06, cache: { read: 0.001, write: 0.002 } },
+      limit: { context: 128000, output: 4096 },
+      status: "active",
+      options: {},
+      headers: {},
+    }) as any
+
+  test("gpt-5.2 should have textVerbosity set to low", () => {
+    const model = createGpt5Model("gpt-5.2")
+    const result = ProviderTransform.options({ model, sessionID, providerOptions: {} })
+    expect(result.textVerbosity).toBe("low")
+  })
+
+  test("gpt-5.1 should have textVerbosity set to low", () => {
+    const model = createGpt5Model("gpt-5.1")
+    const result = ProviderTransform.options({ model, sessionID, providerOptions: {} })
+    expect(result.textVerbosity).toBe("low")
+  })
+
+  test("gpt-5.2-chat-latest should NOT have textVerbosity set (only supports medium)", () => {
+    const model = createGpt5Model("gpt-5.2-chat-latest")
+    const result = ProviderTransform.options({ model, sessionID, providerOptions: {} })
+    expect(result.textVerbosity).toBeUndefined()
+  })
+
+  test("gpt-5.1-chat-latest should NOT have textVerbosity set (only supports medium)", () => {
+    const model = createGpt5Model("gpt-5.1-chat-latest")
+    const result = ProviderTransform.options({ model, sessionID, providerOptions: {} })
+    expect(result.textVerbosity).toBeUndefined()
+  })
+
+  test("gpt-5.2-chat should NOT have textVerbosity set", () => {
+    const model = createGpt5Model("gpt-5.2-chat")
+    const result = ProviderTransform.options({ model, sessionID, providerOptions: {} })
+    expect(result.textVerbosity).toBeUndefined()
+  })
+
+  test("gpt-5-chat should NOT have textVerbosity set", () => {
+    const model = createGpt5Model("gpt-5-chat")
+    const result = ProviderTransform.options({ model, sessionID, providerOptions: {} })
+    expect(result.textVerbosity).toBeUndefined()
+  })
+
+  test("gpt-5.2-codex should NOT have textVerbosity set (codex models excluded)", () => {
+    const model = createGpt5Model("gpt-5.2-codex")
+    const result = ProviderTransform.options({ model, sessionID, providerOptions: {} })
+    expect(result.textVerbosity).toBeUndefined()
+  })
+})
+
 describe("ProviderTransform.maxOutputTokens", () => {
   test("returns 32k when modelLimit > 32k", () => {
     const modelLimit = 100000