encapsulate ContextManager (RooCodeInc#2337)

Co-authored-by: Saoud Rizwan <[email protected]>

Author: 0xToshii

src/core/Cline.ts

@@ -57,7 +57,7 @@ import { ClineIgnoreController, LOCK_TEXT_SYMBOL } from "./ignore/ClineIgnoreCon
 import { parseMentions } from "./mentions"
 import { formatResponse } from "./prompts/responses"
 import { addUserInstructions, SYSTEM_PROMPT } from "./prompts/system"
-import { getNextTruncationRange, getTruncatedMessages } from "./sliding-window"
+import { ContextManager } from "./context-management/ContextManager"
 import { OpenAiHandler } from "../api/providers/openai"
 import { ApiStream } from "../api/transform/stream"
 import { ClineHandler } from "../api/providers/cline"
@@ -78,6 +78,7 @@ export class Cline {
 	private terminalManager: TerminalManager
 	private urlContentFetcher: UrlContentFetcher
 	browserSession: BrowserSession
+	contextManager: ContextManager
 	private didEditFile: boolean = false
 	customInstructions?: string
 	autoApprovalSettings: AutoApprovalSettings
@@ -139,6 +140,7 @@ export class Cline {
 		this.terminalManager = new TerminalManager()
 		this.urlContentFetcher = new UrlContentFetcher(provider.context)
 		this.browserSession = new BrowserSession(provider.context, browserSettings)
+		this.contextManager = new ContextManager()
 		this.diffViewProvider = new DiffViewProvider(cwd)
 		this.customInstructions = customInstructions
 		this.autoApprovalSettings = autoApprovalSettings
@@ -1380,7 +1382,7 @@ export class Cline {
 					const keep = totalTokens / 2 > maxAllowedSize ? "quarter" : "half"
 
 					// NOTE: it's okay that we overwriteConversationHistory in resume task since we're only ever removing the last user message and not anything in the middle which would affect this range
-					this.conversationHistoryDeletedRange = getNextTruncationRange(
+					this.conversationHistoryDeletedRange = this.contextManager.getNextTruncationRange(
 						this.apiConversationHistory,
 						this.conversationHistoryDeletedRange,
 						keep,
@@ -1392,7 +1394,7 @@ export class Cline {
 		}
 
 		// conversationHistoryDeletedRange is updated only when we're close to hitting the context window, so we don't continuously break the prompt cache
-		const truncatedConversationHistory = getTruncatedMessages(
+		const truncatedConversationHistory = this.contextManager.getTruncatedMessages(
 			this.apiConversationHistory,
 			this.conversationHistoryDeletedRange,
 		)

src/core/context-management/ContextManager.ts

@@ -0,0 +1,47 @@
+import { Anthropic } from "@anthropic-ai/sdk"
+
+export class ContextManager {
+	getNextTruncationRange(
+		messages: Anthropic.Messages.MessageParam[],
+		currentDeletedRange: [number, number] | undefined = undefined,
+		keep: "half" | "quarter" = "half",
+	): [number, number] {
+		// Since we always keep the first message, currentDeletedRange[0] will always be 1 (for now until we have a smarter truncation algorithm)
+		const rangeStartIndex = 1
+		const startOfRest = currentDeletedRange ? currentDeletedRange[1] + 1 : 1
+
+		let messagesToRemove: number
+		if (keep === "half") {
+			// Remove half of user-assistant pairs
+			messagesToRemove = Math.floor((messages.length - startOfRest) / 4) * 2 // Keep even number
+		} else {
+			// Remove 3/4 of user-assistant pairs
+			messagesToRemove = Math.floor((messages.length - startOfRest) / 8) * 3 * 2
+		}
+
+		let rangeEndIndex = startOfRest + messagesToRemove - 1
+
+		// Make sure the last message being removed is a user message, so that the next message after the initial task message is an assistant message. This preservers the user-assistant-user-assistant structure.
+		// NOTE: anthropic format messages are always user-assistant-user-assistant, while openai format messages can have multiple user messages in a row (we use anthropic format throughout cline)
+		if (messages[rangeEndIndex].role !== "user") {
+			rangeEndIndex -= 1
+		}
+
+		// this is an inclusive range that will be removed from the conversation history
+		return [rangeStartIndex, rangeEndIndex]
+	}
+
+	getTruncatedMessages(
+		messages: Anthropic.Messages.MessageParam[],
+		deletedRange: [number, number] | undefined,
+	): Anthropic.Messages.MessageParam[] {
+		if (!deletedRange) {
+			return messages
+		}
+
+		const [start, end] = deletedRange
+		// the range is inclusive - both start and end indices and everything in between will be removed from the final result.
+		// NOTE: if you try to console log these, don't forget that logging a reference to an array may not provide the same result as logging a slice() snapshot of that array at that exact moment. The following DOES in fact include the latest assistant message.
+		return [...messages.slice(0, start), ...messages.slice(end + 1)]
+	}
+}