diff --git a/packages/opencode/src/provider/transform.ts b/packages/opencode/src/provider/transform.ts
index 027efc0974b0..015c1e545d10 100644
--- a/packages/opencode/src/provider/transform.ts
+++ b/packages/opencode/src/provider/transform.ts
@@ -677,6 +677,15 @@ export function variants(model: Provider.Model): Record<string, Record<string, a
   }
   const adaptiveThinkingOmitted = anthropicOmitsThinking(model.api.id)
   const adaptiveEfforts = anthropicAdaptiveEfforts(model.api.id)
+  // GLM-5.2 exposes two meaningful thinking-effort levels (high and max).
+  // Older GLM models only had a binary toggle, so they fall through to the
+  // blanket exclusion below. See: https://docs.z.ai/devpack/latest-model
+  if (id.includes("glm-5.2")) {
+    return {
+      high: { reasoningEffort: "high" },
+      max: { reasoningEffort: "max" },
+    }
+  }
   if (
     id.includes("deepseek-chat") ||
     id.includes("deepseek-reasoner") ||
diff --git a/packages/opencode/test/provider/transform.test.ts b/packages/opencode/test/provider/transform.test.ts
index c23a2aa9995c..db64c2f01b0d 100644
--- a/packages/opencode/test/provider/transform.test.ts
+++ b/packages/opencode/test/provider/transform.test.ts
@@ -2694,6 +2694,24 @@ describe("ProviderTransform.variants", () => {
     expect(result).toEqual({})
   })
 
+  test("glm-5.2 returns high and max effort variants", () => {
+    const model = createMockModel({
+      id: "zhipuai/glm-5.2",
+      providerID: "zhipuai",
+      api: {
+        id: "glm-5.2",
+        url: "https://api.z.ai/api/coding/paas/v4",
+        npm: "@ai-sdk/openai-compatible",
+      },
+      capabilities: { reasoning: true },
+    })
+    const result = ProviderTransform.variants(model)
+    expect(result).toEqual({
+      high: { reasoningEffort: "high" },
+      max: { reasoningEffort: "max" },
+    })
+  })
+
   test("mistral models with reasoning support return variants", () => {
     const model = createMockModel({
       id: "mistral/mistral-small-latest",