diff --git a/.changeset/gpt-56-oauth-context.md b/.changeset/gpt-56-oauth-context.md
new file mode 100644
index 00000000000..4e7b1d8e337
--- /dev/null
+++ b/.changeset/gpt-56-oauth-context.md
@@ -0,0 +1,5 @@
+---
+"@kilocode/cli": patch
+---
+
+Use the full Codex context window for GPT-5.6 models authenticated through ChatGPT OAuth.
diff --git a/packages/opencode/src/plugin/openai/codex.ts b/packages/opencode/src/plugin/openai/codex.ts
index 2193005dcb8..a6f0dcf2cea 100644
--- a/packages/opencode/src/plugin/openai/codex.ts
+++ b/packages/opencode/src/plugin/openai/codex.ts
@@ -422,8 +422,8 @@ export async function CodexAuthPlugin(input: PluginInput, options: CodexAuthPlug
                     }
                   : model.id.includes("gpt-5.6")
                     ? {
-                        context: 500_000,
-                        input: 372_000,
+                        context: 1_050_000, // kilocode_change - use the current Codex limits for GPT-5.6 OAuth models
+                        input: 922_000, // kilocode_change
                         output: 128_000,
                       }
                     : model.limit,
diff --git a/packages/opencode/test/plugin/codex.test.ts b/packages/opencode/test/plugin/codex.test.ts
index 177618c1612..d9094ccd6ce 100644
--- a/packages/opencode/test/plugin/codex.test.ts
+++ b/packages/opencode/test/plugin/codex.test.ts
@@ -253,9 +253,11 @@ describe("plugin.codex", () => {
 
     expect(models["gpt-5.4"]?.limit).toEqual(limit)
     expect(models["gpt-5.5"]?.limit).toEqual({ context: 400_000, input: 272_000, output: 128_000 })
-    expect(models["gpt-5.6-sol"]?.limit).toEqual({ context: 500_000, input: 372_000, output: 128_000 })
-    expect(models["gpt-5.6-terra"]?.limit).toEqual({ context: 500_000, input: 372_000, output: 128_000 })
-    expect(models["gpt-5.6-luna"]?.limit).toEqual({ context: 500_000, input: 372_000, output: 128_000 })
+    // kilocode_change start - GPT-5.6 OAuth models use the current Codex limits
+    expect(models["gpt-5.6-sol"]?.limit).toEqual(limit)
+    expect(models["gpt-5.6-terra"]?.limit).toEqual(limit)
+    expect(models["gpt-5.6-luna"]?.limit).toEqual(limit)
+    // kilocode_change end
     expect(models["gpt-5.4-pro"]).toBeUndefined()
     expect(models["gpt-5.7-pro"]).toBeDefined()
     expect(models["gpt-5.6-sol-high"]).toBeDefined()