diff --git a/src/utils/context.test.ts b/src/utils/context.test.ts
index 59647054..a95b209e 100644
--- a/src/utils/context.test.ts
+++ b/src/utils/context.test.ts
@@ -35,3 +35,54 @@ test('deepseek-chat clamps oversized max output overrides to the provider limit'
 
   expect(getMaxOutputTokensForModel('deepseek-chat')).toBe(8_192)
 })
+
+test('gpt-4o uses provider-specific context and output caps', () => {
+  process.env.CLAUDE_CODE_USE_OPENAI = '1'
+  delete process.env.CLAUDE_CODE_MAX_OUTPUT_TOKENS
+
+  expect(getContextWindowForModel('gpt-4o')).toBe(128_000)
+  expect(getModelMaxOutputTokens('gpt-4o')).toEqual({
+    default: 16_384,
+    upperLimit: 16_384,
+  })
+  expect(getMaxOutputTokensForModel('gpt-4o')).toBe(16_384)
+})
+
+test('gpt-4o clamps oversized max output overrides to the provider limit', () => {
+  process.env.CLAUDE_CODE_USE_OPENAI = '1'
+  process.env.CLAUDE_CODE_MAX_OUTPUT_TOKENS = '32000'
+
+  expect(getMaxOutputTokensForModel('gpt-4o')).toBe(16_384)
+})
+
+test('gpt-5.4 family uses provider-specific context and output caps', () => {
+  process.env.CLAUDE_CODE_USE_OPENAI = '1'
+  delete process.env.CLAUDE_CODE_MAX_OUTPUT_TOKENS
+
+  expect(getContextWindowForModel('gpt-5.4')).toBe(1_050_000)
+  expect(getModelMaxOutputTokens('gpt-5.4')).toEqual({
+    default: 128_000,
+    upperLimit: 128_000,
+  })
+
+  expect(getContextWindowForModel('gpt-5.4-mini')).toBe(400_000)
+  expect(getModelMaxOutputTokens('gpt-5.4-mini')).toEqual({
+    default: 128_000,
+    upperLimit: 128_000,
+  })
+
+  expect(getContextWindowForModel('gpt-5.4-nano')).toBe(400_000)
+  expect(getModelMaxOutputTokens('gpt-5.4-nano')).toEqual({
+    default: 128_000,
+    upperLimit: 128_000,
+  })
+})
+
+test('gpt-5.4 family keeps large max output overrides within provider limits', () => {
+  process.env.CLAUDE_CODE_USE_OPENAI = '1'
+  process.env.CLAUDE_CODE_MAX_OUTPUT_TOKENS = '200000'
+
+  expect(getMaxOutputTokensForModel('gpt-5.4')).toBe(128_000)
+  expect(getMaxOutputTokensForModel('gpt-5.4-mini')).toBe(128_000)
+  expect(getMaxOutputTokensForModel('gpt-5.4-nano')).toBe(128_000)
+})
diff --git a/src/utils/model/openaiContextWindows.ts b/src/utils/model/openaiContextWindows.ts
index 63ac5f2c..4a31a8e5 100644
--- a/src/utils/model/openaiContextWindows.ts
+++ b/src/utils/model/openaiContextWindows.ts
@@ -13,6 +13,9 @@
 
 const OPENAI_CONTEXT_WINDOWS: Record<string, number> = {
   // OpenAI
+  'gpt-5.4':               1_050_000,
+  'gpt-5.4-mini':            400_000,
+  'gpt-5.4-nano':            400_000,
   'gpt-4o':                   128_000,
   'gpt-4o-mini':              128_000,
   'gpt-4.1':                  1_047_576,
@@ -62,6 +65,9 @@ const OPENAI_CONTEXT_WINDOWS: Record<string, number> = {
  */
 const OPENAI_MAX_OUTPUT_TOKENS: Record<string, number> = {
   // OpenAI
+  'gpt-5.4':                 128_000,
+  'gpt-5.4-mini':            128_000,
+  'gpt-5.4-nano':            128_000,
   'gpt-4o':                   16_384,
   'gpt-4o-mini':              16_384,
   'gpt-4.1':                  32_768,