diff --git a/packages/types/src/providers/anthropic.ts b/packages/types/src/providers/anthropic.ts
index d0f1629ee94..304670bc922 100644
--- a/packages/types/src/providers/anthropic.ts
+++ b/packages/types/src/providers/anthropic.ts
@@ -8,7 +8,7 @@ export const anthropicDefaultModelId: AnthropicModelId = "claude-sonnet-4-202505
 export const anthropicModels = {
 	"claude-sonnet-4-20250514": {
 		maxTokens: 64_000, // Overridden to 8k if `enableReasoningEffort` is false.
-		contextWindow: 200_000,
+		contextWindow: 1_000_000, // 1M token context window
 		supportsImages: true,
 		supportsComputerUse: true,
 		supportsPromptCache: true,
@@ -20,7 +20,7 @@ export const anthropicModels = {
 	},
 	"claude-opus-4-20250514": {
 		maxTokens: 32_000, // Overridden to 8k if `enableReasoningEffort` is false.
-		contextWindow: 200_000,
+		contextWindow: 1_000_000, // 1M token context window
 		supportsImages: true,
 		supportsComputerUse: true,
 		supportsPromptCache: true,
diff --git a/packages/types/src/providers/bedrock.ts b/packages/types/src/providers/bedrock.ts
index 58e860dd94a..a4f3f6a5359 100644
--- a/packages/types/src/providers/bedrock.ts
+++ b/packages/types/src/providers/bedrock.ts
@@ -69,7 +69,7 @@ export const bedrockModels = {
 	},
 	"anthropic.claude-sonnet-4-20250514-v1:0": {
 		maxTokens: 8192,
-		contextWindow: 200_000,
+		contextWindow: 1_000_000, // 1M token context window
 		supportsImages: true,
 		supportsComputerUse: true,
 		supportsPromptCache: true,
@@ -84,7 +84,7 @@ export const bedrockModels = {
 	},
 	"anthropic.claude-opus-4-20250514-v1:0": {
 		maxTokens: 8192,
-		contextWindow: 200_000,
+		contextWindow: 1_000_000, // 1M token context window
 		supportsImages: true,
 		supportsComputerUse: true,
 		supportsPromptCache: true,
diff --git a/packages/types/src/providers/openrouter.ts b/packages/types/src/providers/openrouter.ts
index bbdbc7e7328..ab4095da42b 100644
--- a/packages/types/src/providers/openrouter.ts
+++ b/packages/types/src/providers/openrouter.ts
@@ -5,7 +5,7 @@ export const openRouterDefaultModelId = "anthropic/claude-sonnet-4"
 
 export const openRouterDefaultModelInfo: ModelInfo = {
 	maxTokens: 8192,
-	contextWindow: 200_000,
+	contextWindow: 1_000_000, // 1M token context window for Claude 4 Sonnet
 	supportsImages: true,
 	supportsComputerUse: true,
 	supportsPromptCache: true,
diff --git a/packages/types/src/providers/vertex.ts b/packages/types/src/providers/vertex.ts
index c405621f82d..70f7f7316fa 100644
--- a/packages/types/src/providers/vertex.ts
+++ b/packages/types/src/providers/vertex.ts
@@ -165,7 +165,7 @@ export const vertexModels = {
 	},
 	"claude-sonnet-4@20250514": {
 		maxTokens: 8192,
-		contextWindow: 200_000,
+		contextWindow: 1_000_000, // 1M token context window
 		supportsImages: true,
 		supportsComputerUse: true,
 		supportsPromptCache: true,
@@ -177,7 +177,7 @@ export const vertexModels = {
 	},
 	"claude-opus-4@20250514": {
 		maxTokens: 8192,
-		contextWindow: 200_000,
+		contextWindow: 1_000_000, // 1M token context window
 		supportsImages: true,
 		supportsComputerUse: true,
 		supportsPromptCache: true,
diff --git a/src/api/providers/fetchers/litellm.ts b/src/api/providers/fetchers/litellm.ts
index 0891527406d..b52e2a2277a 100644
--- a/src/api/providers/fetchers/litellm.ts
+++ b/src/api/providers/fetchers/litellm.ts
@@ -51,9 +51,15 @@ export async function getLiteLLMModels(apiKey: string, baseUrl: string): Promise
 					)
 				}
 
+				// Determine default context window based on model
+				let defaultContextWindow = 200000
+				if (litellmModelName.includes("claude-sonnet-4") || litellmModelName.includes("claude-opus-4")) {
+					defaultContextWindow = 1000000 // 1M tokens for Claude 4 models
+				}
+
 				models[modelName] = {
 					maxTokens: modelInfo.max_tokens || 8192,
-					contextWindow: modelInfo.max_input_tokens || 200000,
+					contextWindow: modelInfo.max_input_tokens || defaultContextWindow,
 					supportsImages: Boolean(modelInfo.supports_vision),
 					// litellm_params.model may have a prefix like openrouter/
 					supportsComputerUse,
diff --git a/src/core/webview/__tests__/ClineProvider.spec.ts b/src/core/webview/__tests__/ClineProvider.spec.ts
index 19c9a7c9fc2..3dbcc673ca7 100644
--- a/src/core/webview/__tests__/ClineProvider.spec.ts
+++ b/src/core/webview/__tests__/ClineProvider.spec.ts
@@ -2216,7 +2216,7 @@ describe("getTelemetryProperties", () => {
 		mockCline.api = {
 			getModel: vi.fn().mockReturnValue({
 				id: "claude-sonnet-4-20250514",
-				info: { contextWindow: 200000 },
+				info: { contextWindow: 1000000 },
 			}),
 		}
 	})