feat: modelMaxContextWindow for context condensing

Author: HahaBill

src/core/task/Task.ts

@@ -1623,7 +1623,10 @@ export class Task extends EventEmitter<ClineEvents> {
 				? this.apiConfiguration.modelMaxTokens || DEFAULT_THINKING_MODEL_MAX_TOKENS
 				: modelInfo.maxTokens
 
-			const contextWindow = modelInfo.contextWindow
+			const contextWindow =
+				this.apiConfiguration.apiProvider === "gemini" && this.apiConfiguration.modelMaxContextWindow
+					? this.apiConfiguration.modelMaxContextWindow
+					: modelInfo.contextWindow
 
 			const truncateResult = await truncateConversationIfNeeded({
 				messages: this.apiConversationHistory,