Terminal "middle-out": smart truncation for terminal output

src/core/Cline.ts

@@ -25,7 +25,6 @@ import {
 	addLineNumbers,
 	stripLineNumbers,
 	everyLineHasLineNumbers,
-	truncateOutput,
 } from "../integrations/misc/extract-text"
 import { TerminalManager, ExitCodeDetails } from "../integrations/terminal/TerminalManager"
 import { UrlContentFetcher } from "../services/browser/UrlContentFetcher"
@@ -55,11 +54,12 @@ import { HistoryItem } from "../shared/HistoryItem"
 import { ClineAskResponse } from "../shared/WebviewMessage"
 import { GlobalFileNames } from "../shared/globalFileNames"
 import { defaultModeSlug, getModeBySlug, getFullModeDetails } from "../shared/modes"
+import { EXPERIMENT_IDS, experiments as Experiments, ExperimentId } from "../shared/experiments"
 import { calculateApiCost } from "../utils/cost"
 import { fileExistsAtPath } from "../utils/fs"
 import { arePathsEqual, getReadablePath } from "../utils/path"
 import { parseMentions } from "./mentions"
-import { RooIgnoreController, LOCK_TEXT_SYMBOL } from "./ignore/RooIgnoreController"
+import { RooIgnoreController } from "./ignore/RooIgnoreController"
 import { AssistantMessageContent, parseAssistantMessage, ToolParamName, ToolUseName } from "./assistant-message"
 import { formatResponse } from "./prompts/responses"
 import { SYSTEM_PROMPT } from "./prompts/system"
@@ -70,7 +70,7 @@ import { BrowserSession } from "../services/browser/BrowserSession"
 import { McpHub } from "../services/mcp/McpHub"
 import crypto from "crypto"
 import { insertGroups } from "./diff/insert-groups"
-import { EXPERIMENT_IDS, experiments as Experiments, ExperimentId } from "../shared/experiments"
+import { OutputBuilder } from "../integrations/terminal/OutputBuilder"
 
 const cwd =
 	vscode.workspace.workspaceFolders?.map((folder) => folder.uri.fsPath).at(0) ?? path.join(os.homedir(), "Desktop") // may or may not exist but fs checking existence would immediately ask for permission which would be bad UX, need to come up with a better solution
@@ -912,44 +912,52 @@ export class Cline {
 	// Tools
 
 	async executeCommandTool(command: string): Promise<[boolean, ToolResponse]> {
+		const { terminalOutputLimit } = (await this.providerRef.deref()?.getState()) ?? {}
+
 		const terminalInfo = await this.terminalManager.getOrCreateTerminal(cwd)
-		terminalInfo.terminal.show() // weird visual bug when creating new terminals (even manually) where there's an empty space at the top.
-		const process = this.terminalManager.runCommand(terminalInfo, command)
+		// Weird visual bug when creating new terminals (even manually) where
+		// there's an empty space at the top.
+		terminalInfo.terminal.show()
+		const process = this.terminalManager.runCommand(terminalInfo, command, terminalOutputLimit)
 
 		let userFeedback: { text?: string; images?: string[] } | undefined
 		let didContinue = false
-		const sendCommandOutput = async (line: string): Promise<void> => {
+
+		const sendCommandOutput = async (line: string) => {
 			try {
 				const { response, text, images } = await this.ask("command_output", line)
+
 				if (response === "yesButtonClicked") {
-					// proceed while running
+					// Proceed while running.
 				} else {
 					userFeedback = { text, images }
 				}
+
 				didContinue = true
-				process.continue() // continue past the await
+				process.continue() // Continue past the await.
 			} catch {
-				// This can only happen if this ask promise was ignored, so ignore this error
+				// This can only happen if this ask promise was ignored, so ignore this error.
 			}
 		}
 
-		let lines: string[] = []
+		let completed = false
+		let exitDetails: ExitCodeDetails | undefined
+
+		let builder = new OutputBuilder({ maxSize: terminalOutputLimit })
+		let output: string | undefined = undefined
+
 		process.on("line", (line) => {
-			lines.push(line)
+			builder.append(line)
+
 			if (!didContinue) {
 				sendCommandOutput(line)
 			} else {
 				this.say("command_output", line)
 			}
 		})
 
-		let completed = false
-		let exitDetails: ExitCodeDetails | undefined
-		process.once("completed", (output?: string) => {
-			// Use provided output if available, otherwise keep existing result.
-			if (output) {
-				lines = output.split("\n")
-			}
+		process.once("completed", (buffer?: string) => {
+			output = buffer
 			completed = true
 		})
 
@@ -965,19 +973,17 @@ export class Cline {
 
 		await process
 
-		// Wait for a short delay to ensure all messages are sent to the webview
+		// Wait for a short delay to ensure all messages are sent to the webview.
 		// This delay allows time for non-awaited promises to be created and
 		// for their associated messages to be sent to the webview, maintaining
 		// the correct order of messages (although the webview is smart about
-		// grouping command_output messages despite any gaps anyways)
+		// grouping command_output messages despite any gaps anyways).
 		await delay(50)
-
-		const { terminalOutputLineLimit } = (await this.providerRef.deref()?.getState()) ?? {}
-		const output = truncateOutput(lines.join("\n"), terminalOutputLineLimit)
-		const result = output.trim()
+		const result = output || builder.content
 
 		if (userFeedback) {
 			await this.say("user_feedback", userFeedback.text, userFeedback.images)
+
 			return [
 				true,
 				formatResponse.toolResult(
@@ -991,25 +997,28 @@ export class Cline {
 
 		if (completed) {
 			let exitStatus = "No exit code available"
+
 			if (exitDetails !== undefined) {
 				if (exitDetails.signal) {
 					exitStatus = `Process terminated by signal ${exitDetails.signal} (${exitDetails.signalName})`
+
 					if (exitDetails.coreDumpPossible) {
 						exitStatus += " - core dump possible"
 					}
 				} else {
 					exitStatus = `Exit code: ${exitDetails.exitCode}`
 				}
 			}
+
 			return [false, `Command executed. ${exitStatus}${result.length > 0 ? `\nOutput:\n${result}` : ""}`]
-		} else {
-			return [
-				false,
-				`Command is still running in the user's terminal.${
-					result.length > 0 ? `\nHere's the output so far:\n${result}` : ""
-				}\n\nYou will be updated on the terminal status and new output in the future.`,
-			]
 		}
+
+		return [
+			false,
+			`Command is still running in the user's terminal.${
+				result.length > 0 ? `\nHere's the output so far:\n${result}` : ""
+			}\n\nYou will be updated on the terminal status and new output in the future.`,
+		]
 	}
 
 	async *attemptApiRequest(previousApiReqIndex: number, retryAttempt: number = 0): ApiStream {
@@ -3495,7 +3504,7 @@ export class Cline {
 			terminalDetails += "\n\n# Actively Running Terminals"
 			for (const busyTerminal of busyTerminals) {
 				terminalDetails += `\n## Original command: \`${busyTerminal.lastCommand}\``
-				const newOutput = this.terminalManager.getUnretrievedOutput(busyTerminal.id)
+				const newOutput = this.terminalManager.readLine(busyTerminal.id)
 				if (newOutput) {
 					terminalDetails += `\n### New Output\n${newOutput}`
 				} else {
@@ -3507,7 +3516,7 @@ export class Cline {
 		if (inactiveTerminals.length > 0) {
 			const inactiveTerminalOutputs = new Map<number, string>()
 			for (const inactiveTerminal of inactiveTerminals) {
-				const newOutput = this.terminalManager.getUnretrievedOutput(inactiveTerminal.id)
+				const newOutput = this.terminalManager.readLine(inactiveTerminal.id)
 				if (newOutput) {
 					inactiveTerminalOutputs.set(inactiveTerminal.id, newOutput)
 				}

src/core/mentions/index.ts

@@ -2,13 +2,13 @@ import * as vscode from "vscode"
 import * as path from "path"
 import { openFile } from "../../integrations/misc/open-file"
 import { UrlContentFetcher } from "../../services/browser/UrlContentFetcher"
-import { mentionRegexGlobal, formatGitSuggestion, type MentionSuggestion } from "../../shared/context-mentions"
+import { mentionRegexGlobal } from "../../shared/context-mentions"
 import fs from "fs/promises"
 import { extractTextFromFile } from "../../integrations/misc/extract-text"
 import { isBinaryFile } from "isbinaryfile"
 import { diagnosticsToProblemsString } from "../../integrations/diagnostics"
 import { getCommitInfo, getWorkingState } from "../../utils/git"
-import { getLatestTerminalOutput } from "../../integrations/terminal/get-latest-output"
+import { getLatestTerminalOutput } from "../../integrations/terminal/getLatestTerminalOutput"
 
 export async function openMention(mention?: string): Promise<void> {
 	if (!mention) {

src/core/webview/ClineProvider.ts

@@ -10,17 +10,17 @@ import simpleGit from "simple-git"
 import { setPanel } from "../../activate/registerCommands"
 
 import { ApiConfiguration, ApiProvider, ModelInfo, API_CONFIG_KEYS } from "../../shared/api"
-import { CheckpointStorage } from "../../shared/checkpoints"
 import { findLast } from "../../shared/array"
-import { CustomSupportPrompts, supportPrompt } from "../../shared/support-prompt"
+import { supportPrompt } from "../../shared/support-prompt"
 import { GlobalFileNames } from "../../shared/globalFileNames"
 import { SecretKey, GlobalStateKey, SECRET_KEYS, GLOBAL_STATE_KEYS } from "../../shared/globalState"
 import { HistoryItem } from "../../shared/HistoryItem"
 import { ApiConfigMeta, ExtensionMessage } from "../../shared/ExtensionMessage"
 import { checkoutDiffPayloadSchema, checkoutRestorePayloadSchema, WebviewMessage } from "../../shared/WebviewMessage"
-import { Mode, CustomModePrompts, PromptComponent, defaultModeSlug, ModeConfig } from "../../shared/modes"
+import { Mode, PromptComponent, defaultModeSlug, ModeConfig } from "../../shared/modes"
 import { checkExistKey } from "../../shared/checkExistApiConfig"
 import { EXPERIMENT_IDS, experiments as Experiments, experimentDefault, ExperimentId } from "../../shared/experiments"
+import { TERMINAL_OUTPUT_LIMIT } from "../../shared/terminal"
 import { downloadTask } from "../../integrations/misc/export-markdown"
 import { openFile, openImage } from "../../integrations/misc/open-file"
 import { selectImages } from "../../integrations/misc/process-images"
@@ -1215,7 +1215,6 @@ export class ClineProvider implements vscode.WebviewViewProvider {
 						await this.postStateToWebview()
 						break
 					case "checkpointStorage":
-						console.log(`[ClineProvider] checkpointStorage: ${message.text}`)
 						const checkpointStorage = message.text ?? "task"
 						await this.updateGlobalState("checkpointStorage", checkpointStorage)
 						await this.postStateToWebview()
@@ -1249,8 +1248,8 @@ export class ClineProvider implements vscode.WebviewViewProvider {
 						await this.updateGlobalState("writeDelayMs", message.value)
 						await this.postStateToWebview()
 						break
-					case "terminalOutputLineLimit":
-						await this.updateGlobalState("terminalOutputLineLimit", message.value)
+					case "terminalOutputLimit":
+						await this.updateGlobalState("terminalOutputLimit", message.value)
 						await this.postStateToWebview()
 						break
 					case "mode":
@@ -2134,7 +2133,7 @@ export class ClineProvider implements vscode.WebviewViewProvider {
 			screenshotQuality,
 			preferredLanguage,
 			writeDelayMs,
-			terminalOutputLineLimit,
+			terminalOutputLimit,
 			fuzzyMatchThreshold,
 			mcpEnabled,
 			enableMcpServerCreation,
@@ -2186,7 +2185,7 @@ export class ClineProvider implements vscode.WebviewViewProvider {
 			screenshotQuality: screenshotQuality ?? 75,
 			preferredLanguage: preferredLanguage ?? "English",
 			writeDelayMs: writeDelayMs ?? 1000,
-			terminalOutputLineLimit: terminalOutputLineLimit ?? 500,
+			terminalOutputLimit: terminalOutputLimit ?? TERMINAL_OUTPUT_LIMIT,
 			fuzzyMatchThreshold: fuzzyMatchThreshold ?? 1.0,
 			mcpEnabled: mcpEnabled ?? true,
 			enableMcpServerCreation: enableMcpServerCreation ?? true,
@@ -2334,7 +2333,7 @@ export class ClineProvider implements vscode.WebviewViewProvider {
 			screenshotQuality: stateValues.screenshotQuality ?? 75,
 			fuzzyMatchThreshold: stateValues.fuzzyMatchThreshold ?? 1.0,
 			writeDelayMs: stateValues.writeDelayMs ?? 1000,
-			terminalOutputLineLimit: stateValues.terminalOutputLineLimit ?? 500,
+			terminalOutputLimit: stateValues.terminalOutputLimit ?? TERMINAL_OUTPUT_LIMIT,
 			mode: stateValues.mode ?? defaultModeSlug,
 			preferredLanguage:
 				stateValues.preferredLanguage ??

src/integrations/misc/__tests__/extract-text.test.ts

@@ -1,4 +1,4 @@
-import { addLineNumbers, everyLineHasLineNumbers, stripLineNumbers, truncateOutput } from "../extract-text"
+import { addLineNumbers, everyLineHasLineNumbers, stripLineNumbers } from "../extract-text"
 
 describe("addLineNumbers", () => {
 	it("should add line numbers starting from 1 by default", () => {
@@ -101,67 +101,3 @@ describe("stripLineNumbers", () => {
 		expect(stripLineNumbers(input)).toBe(expected)
 	})
 })
-
-describe("truncateOutput", () => {
-	it("returns original content when no line limit provided", () => {
-		const content = "line1\nline2\nline3"
-		expect(truncateOutput(content)).toBe(content)
-	})
-
-	it("returns original content when lines are under limit", () => {
-		const content = "line1\nline2\nline3"
-		expect(truncateOutput(content, 5)).toBe(content)
-	})
-
-	it("truncates content with 20/80 split when over limit", () => {
-		// Create 25 lines of content
-		const lines = Array.from({ length: 25 }, (_, i) => `line${i + 1}`)
-		const content = lines.join("\n")
-
-		// Set limit to 10 lines
-		const result = truncateOutput(content, 10)
-
-		// Should keep:
-		// - First 2 lines (20% of 10)
-		// - Last 8 lines (80% of 10)
-		// - Omission indicator in between
-		const expectedLines = [
-			"line1",
-			"line2",
-			"",
-			"[...15 lines omitted...]",
-			"",
-			"line18",
-			"line19",
-			"line20",
-			"line21",
-			"line22",
-			"line23",
-			"line24",
-			"line25",
-		]
-		expect(result).toBe(expectedLines.join("\n"))
-	})
-
-	it("handles empty content", () => {
-		expect(truncateOutput("", 10)).toBe("")
-	})
-
-	it("handles single line content", () => {
-		expect(truncateOutput("single line", 10)).toBe("single line")
-	})
-
-	it("handles windows-style line endings", () => {
-		// Create content with windows line endings
-		const lines = Array.from({ length: 15 }, (_, i) => `line${i + 1}`)
-		const content = lines.join("\r\n")
-
-		const result = truncateOutput(content, 5)
-
-		// Should keep first line (20% of 5 = 1) and last 4 lines (80% of 5 = 4)
-		// Split result by either \r\n or \n to normalize line endings
-		const resultLines = result.split(/\r?\n/)
-		const expectedLines = ["line1", "", "[...10 lines omitted...]", "", "line12", "line13", "line14", "line15"]
-		expect(resultLines).toEqual(expectedLines)
-	})
-})

src/integrations/misc/extract-text.ts

@@ -89,37 +89,3 @@ export function stripLineNumbers(content: string): string {
 	const lineEnding = content.includes("\r\n") ? "\r\n" : "\n"
 	return processedLines.join(lineEnding)
 }
-
-/**
- * Truncates multi-line output while preserving context from both the beginning and end.
- * When truncation is needed, it keeps 20% of the lines from the start and 80% from the end,
- * with a clear indicator of how many lines were omitted in between.
- *
- * @param content The multi-line string to truncate
- * @param lineLimit Optional maximum number of lines to keep. If not provided or 0, returns the original content
- * @returns The truncated string with an indicator of omitted lines, or the original content if no truncation needed
- *
- * @example
- * // With 10 line limit on 25 lines of content:
- * // - Keeps first 2 lines (20% of 10)
- * // - Keeps last 8 lines (80% of 10)
- * // - Adds "[...15 lines omitted...]" in between
- */
-export function truncateOutput(content: string, lineLimit?: number): string {
-	if (!lineLimit) {
-		return content
-	}
-
-	const lines = content.split("\n")
-	if (lines.length <= lineLimit) {
-		return content
-	}
-
-	const beforeLimit = Math.floor(lineLimit * 0.2) // 20% of lines before
-	const afterLimit = lineLimit - beforeLimit // remaining 80% after
-	return [
-		...lines.slice(0, beforeLimit),
-		`\n[...${lines.length - lineLimit} lines omitted...]\n`,
-		...lines.slice(-afterLimit),
-	].join("\n")
-}