diff --git a/src/integrations/misc/__tests__/extract-text-unicode.spec.ts b/src/integrations/misc/__tests__/extract-text-unicode.spec.ts
new file mode 100644
index 0000000000..de67340bc5
--- /dev/null
+++ b/src/integrations/misc/__tests__/extract-text-unicode.spec.ts
@@ -0,0 +1,245 @@
+import { describe, it, expect, beforeEach, afterEach } from "vitest"
+import * as fs from "fs/promises"
+import * as path from "path"
+import { extractTextFromFile } from "../extract-text"
+import { readLines } from "../read-lines"
+import { tmpdir } from "os"
+
+describe("Unicode and UTF-8 handling", () => {
+	let tempDir: string
+	let testFilePath: string
+
+	beforeEach(async () => {
+		// Create a temporary directory for test files
+		tempDir = await fs.mkdtemp(path.join(tmpdir(), "unicode-test-"))
+	})
+
+	afterEach(async () => {
+		// Clean up temporary directory
+		await fs.rm(tempDir, { recursive: true, force: true })
+	})
+
+	describe("extractTextFromFile with Unicode content", () => {
+		it("should handle Chinese characters correctly", async () => {
+			const content = `# 测试文件
+-   **时间戳 (Timestamp)**: 2025-07-26 15:41
+-   **任务/目标 (Task/Goal)**: 实现问卷的前端核心交互逻辑。`
+
+			testFilePath = path.join(tempDir, "chinese.md")
+			await fs.writeFile(testFilePath, content, "utf8")
+
+			const result = await extractTextFromFile(testFilePath)
+			expect(result).toContain("时间戳")
+			expect(result).toContain("任务/目标")
+			expect(result).toContain("实现问卷的前端核心交互逻辑")
+		})
+
+		it("should handle mixed Unicode content (emoji, various languages)", async () => {
+			const content = `# Unicode Test
+😀 Emoji test 🎉
+日本語: こんにちは世界
+한국어: 안녕하세요 세계
+العربية: مرحبا بالعالم
+עברית: שלום עולם
+Русский: Привет мир`
+
+			testFilePath = path.join(tempDir, "mixed-unicode.md")
+			await fs.writeFile(testFilePath, content, "utf8")
+
+			const result = await extractTextFromFile(testFilePath)
+			expect(result).toContain("😀")
+			expect(result).toContain("🎉")
+			expect(result).toContain("こんにちは世界")
+			expect(result).toContain("안녕하세요")
+			expect(result).toContain("مرحبا بالعالم")
+			expect(result).toContain("שלום עולם")
+			expect(result).toContain("Привет мир")
+		})
+
+		it("should handle special Unicode characters", async () => {
+			const content = `Special chars:
+Non-breaking space: test test
+Zero-width space: test\u200Btest
+Quotes: "test" 'test' „test" «test»
+Math: ∑ ∏ ∫ √ ∞ ≈ ≠ ≤ ≥`
+
+			testFilePath = path.join(tempDir, "special-chars.md")
+			await fs.writeFile(testFilePath, content, "utf8")
+
+			const result = await extractTextFromFile(testFilePath)
+			expect(result).toContain("Non-breaking space")
+			expect(result).toContain("Zero-width space")
+			expect(result).toContain('"test"')
+			expect(result).toContain("∑")
+			expect(result).toContain("∞")
+		})
+
+		it("should handle files with BOM (Byte Order Mark)", async () => {
+			const content = "Test content with BOM"
+			const bom = "\uFEFF"
+
+			testFilePath = path.join(tempDir, "bom-file.txt")
+			await fs.writeFile(testFilePath, bom + content, "utf8")
+
+			const result = await extractTextFromFile(testFilePath)
+			// Should handle BOM gracefully
+			expect(result).toContain("Test content with BOM")
+		})
+
+		it("should handle invalid UTF-8 sequences gracefully", async () => {
+			// Create a file with potentially problematic byte sequences
+			testFilePath = path.join(tempDir, "invalid-utf8.md") // Use .md extension
+
+			// Write raw bytes that might cause UTF-8 decoding issues
+			const buffer = Buffer.from([
+				0x48,
+				0x65,
+				0x6c,
+				0x6c,
+				0x6f, // "Hello"
+				0x20, // space
+				0xff,
+				0xfe, // Invalid UTF-8 sequence
+				0x20, // space
+				0x57,
+				0x6f,
+				0x72,
+				0x6c,
+				0x64, // "World"
+			])
+			await fs.writeFile(testFilePath, buffer)
+
+			// Should not throw and should return readable content
+			const result = await extractTextFromFile(testFilePath)
+			expect(result).toContain("Hello")
+			expect(result).toContain("World")
+		})
+	})
+
+	describe("readLines with Unicode content", () => {
+		it("should handle Chinese characters in line ranges", async () => {
+			const content = `第一行
+第二行：时间戳
+第三行：任务/目标
+第四行：关键决策`
+
+			testFilePath = path.join(tempDir, "chinese-lines.txt")
+			await fs.writeFile(testFilePath, content, "utf8")
+
+			const result = await readLines(testFilePath, 2, 1)
+			expect(result).toContain("第二行")
+			expect(result).toContain("第三行")
+			expect(result).not.toContain("第一行")
+			expect(result).not.toContain("第四行")
+		})
+
+		it("should handle emoji in specific line ranges", async () => {
+			const content = `Line 1: Regular text
+Line 2: 😀 Happy emoji
+Line 3: 🚀 Rocket emoji
+Line 4: Regular text again`
+
+			testFilePath = path.join(tempDir, "emoji-lines.txt")
+			await fs.writeFile(testFilePath, content, "utf8")
+
+			const result = await readLines(testFilePath, 2, 1)
+			expect(result).toContain("😀")
+			expect(result).toContain("🚀")
+		})
+
+		it("should handle mixed scripts in line reading", async () => {
+			const lines = [
+				"English line",
+				"中文行",
+				"日本語の行",
+				"한국어 줄",
+				"Русская строка",
+				"שורה בעברית",
+				"سطر عربي",
+			]
+
+			testFilePath = path.join(tempDir, "mixed-scripts.txt")
+			await fs.writeFile(testFilePath, lines.join("\n"), "utf8")
+
+			// Read middle lines
+			const result = await readLines(testFilePath, 4, 2)
+			expect(result).toContain("日本語の行")
+			expect(result).toContain("한국어 줄")
+			expect(result).toContain("Русская строка")
+			expect(result).not.toContain("English line")
+			expect(result).not.toContain("שורה בעברית")
+		})
+
+		it("should handle invalid UTF-8 in line reading gracefully", async () => {
+			testFilePath = path.join(tempDir, "invalid-utf8-lines.txt")
+
+			// Create content with invalid sequences
+			const validLine1 = Buffer.from("First line\n", "utf8")
+			const invalidLine = Buffer.concat([
+				Buffer.from("Second ", "utf8"),
+				Buffer.from([0xff, 0xfe]), // Invalid UTF-8
+				Buffer.from(" line\n", "utf8"),
+			])
+			const validLine3 = Buffer.from("Third line\n", "utf8")
+
+			await fs.writeFile(testFilePath, Buffer.concat([validLine1, invalidLine, validLine3]))
+
+			// Should handle gracefully
+			const result = await readLines(testFilePath, 2, 0)
+			expect(result).toContain("First line")
+			expect(result).toContain("line") // Should contain parts of the second line
+			expect(result).toContain("Third line")
+		})
+	})
+
+	describe("Edge cases and stress tests", () => {
+		it("should handle very long lines with Unicode", async () => {
+			// Create a very long line with repeated Unicode characters
+			const longLine = "测试".repeat(10000) + "\n" + "第二行"
+
+			testFilePath = path.join(tempDir, "long-unicode.txt")
+			await fs.writeFile(testFilePath, longLine, "utf8")
+
+			const result = await extractTextFromFile(testFilePath)
+			expect(result).toContain("测试")
+			expect(result).toContain("第二行")
+		})
+
+		it("should handle empty files", async () => {
+			testFilePath = path.join(tempDir, "empty.txt")
+			await fs.writeFile(testFilePath, "", "utf8")
+
+			const result = await extractTextFromFile(testFilePath)
+			expect(result).toBe("")
+		})
+
+		it("should handle files with only Unicode characters", async () => {
+			const content = "中文中文中文中文中文"
+
+			testFilePath = path.join(tempDir, "only-unicode.txt")
+			await fs.writeFile(testFilePath, content, "utf8")
+
+			const result = await extractTextFromFile(testFilePath)
+			expect(result).toContain("中文中文中文中文中文")
+		})
+
+		it("should handle the exact reproduction case from the issue", async () => {
+			const content = `-   **时间戳 (Timestamp)**: 2025-07-26 15:41
+-   **任务/目标 (Task/Goal)**: 实现问卷的前端核心交互逻辑。
+-   **关键决策/操作 (Key Decision/Action)**:
+		  1.  在 \`questionnaire-server/public/index.html\` 中添加了 \`<div id="questionnaire-container"></div>\` 作为动态内容的挂载点。
+		  2.  在 \`questionnaire-server/public/style.css\` 中添加了完整的基础样式，确保界面干净、可用，并对问卷的各个部分（欢迎页、问题页、选项）进行了样式设置。`
+
+			testFilePath = path.join(tempDir, "issue-reproduction.md")
+			await fs.writeFile(testFilePath, content, "utf8")
+
+			// This should not throw or hang
+			const result = await extractTextFromFile(testFilePath)
+			expect(result).toContain("时间戳 (Timestamp)")
+			expect(result).toContain("任务/目标 (Task/Goal)")
+			expect(result).toContain("关键决策/操作")
+			expect(result).toContain("questionnaire-server/public/index.html")
+			expect(result).toContain("questionnaire-container")
+		}, 30000) // Increase timeout to 30 seconds
+	})
+})
diff --git a/src/integrations/misc/extract-text.ts b/src/integrations/misc/extract-text.ts
index 8231c609be..a8424872b9 100644
--- a/src/integrations/misc/extract-text.ts
+++ b/src/integrations/misc/extract-text.ts
@@ -8,6 +8,44 @@ import { extractTextFromXLSX } from "./extract-text-from-xlsx"
 import { countFileLines } from "./line-counter"
 import { readLines } from "./read-lines"
 
+/**
+ * Safely reads a text file with UTF-8 encoding, handling potential encoding errors gracefully.
+ * If the file contains invalid UTF-8 sequences, it attempts to read with error replacement.
+ *
+ * @param filePath - Path to the file to read
+ * @returns Promise resolving to the file content as a string
+ */
+async function safeReadTextFile(filePath: string): Promise<string> {
+	try {
+		// First attempt: standard UTF-8 reading
+		return await fs.readFile(filePath, "utf8")
+	} catch (error: any) {
+		// If it's an encoding error, try reading as buffer and converting with replacement
+		if (
+			error.code === "ERR_INVALID_ARG_TYPE" ||
+			error.code === "ERR_ENCODING_INVALID_ENCODED_DATA" ||
+			error.message?.includes("encoding") ||
+			error.message?.includes("Invalid") ||
+			error.errno === -92
+		) {
+			// EILSEQ error code for invalid byte sequence
+
+			try {
+				// Read as buffer
+				const buffer = await fs.readFile(filePath)
+				// Convert to string, replacing invalid sequences with replacement character
+				// This ensures we can still read the file even with encoding issues
+				return buffer.toString("utf8")
+			} catch (bufferError) {
+				// If buffer reading also fails, throw the original error
+				throw error
+			}
+		}
+		// For non-encoding errors, throw as-is
+		throw error
+	}
+}
+
 async function extractTextFromPDF(filePath: string): Promise<string> {
 	const dataBuffer = await fs.readFile(filePath)
 	const data = await pdf(dataBuffer)
@@ -20,7 +58,7 @@ async function extractTextFromDOCX(filePath: string): Promise<string> {
 }
 
 async function extractTextFromIPYNB(filePath: string): Promise<string> {
-	const data = await fs.readFile(filePath, "utf8")
+	const data = await safeReadTextFile(filePath)
 	const notebook = JSON.parse(data)
 	let extractedText = ""
 
@@ -86,9 +124,70 @@ export async function extractTextFromFile(filePath: string, maxReadFileLine?: nu
 	}
 
 	// Handle other files
-	const isBinary = await isBinaryFile(filePath).catch(() => false)
+	// For text-like extensions, always try to read as text regardless of binary detection
+	const textExtensions = [
+		".txt",
+		".md",
+		".markdown",
+		".text",
+		".log",
+		".csv",
+		".json",
+		".xml",
+		".html",
+		".htm",
+		".css",
+		".js",
+		".ts",
+		".jsx",
+		".tsx",
+		".py",
+		".java",
+		".c",
+		".cpp",
+		".h",
+		".hpp",
+		".cs",
+		".rb",
+		".go",
+		".rs",
+		".php",
+		".swift",
+		".kt",
+		".scala",
+		".r",
+		".m",
+		".mm",
+		".sh",
+		".bash",
+		".zsh",
+		".fish",
+		".ps1",
+		".bat",
+		".cmd",
+		".yaml",
+		".yml",
+		".toml",
+		".ini",
+		".cfg",
+		".conf",
+		".properties",
+	]
+	const isTextExtension = textExtensions.includes(fileExtension.toLowerCase())
 
-	if (!isBinary) {
+	let isBinary = false
+	if (!isTextExtension) {
+		// Only check binary for non-text extensions
+		try {
+			isBinary = await isBinaryFile(filePath)
+		} catch (error) {
+			// If isBinaryFile throws an error, assume it's a text file and try to read it
+			console.warn(`Warning: isBinaryFile check failed for ${filePath}, treating as text file:`, error)
+			isBinary = false
+		}
+	}
+
+	if (!isBinary || isTextExtension) {
 		// Check if we need to apply line limit
 		if (maxReadFileLine !== undefined && maxReadFileLine !== -1) {
 			const totalLines = await countFileLines(filePath)
@@ -103,7 +202,7 @@ export async function extractTextFromFile(filePath: string, maxReadFileLine?: nu
 			}
 		}
 		// Read the entire file if no limit or file is within limit
-		return addLineNumbers(await fs.readFile(filePath, "utf8"))
+		return addLineNumbers(await safeReadTextFile(filePath))
 	} else {
 		throw new Error(`Cannot read text for file type: ${fileExtension}`)
 	}
diff --git a/src/integrations/misc/read-lines.ts b/src/integrations/misc/read-lines.ts
index 5a5eda9f83..fd05a5a530 100644
--- a/src/integrations/misc/read-lines.ts
+++ b/src/integrations/misc/read-lines.ts
@@ -52,19 +52,65 @@ export function readLines(filepath: string, endLine?: number, startLine?: number
 			)
 		}
 
-		// Set up stream
-		const input = createReadStream(filepath)
+		// Set up stream with UTF-8 encoding
+		const input = createReadStream(filepath, { encoding: "utf8" })
 		let buffer = ""
 		let lineCount = 0
 		let result = ""
 
 		// Handle errors
-		input.on("error", reject)
+		input.on("error", (error: any) => {
+			// If it's an encoding error, try to handle it gracefully
+			if (
+				error.code === "ERR_INVALID_ARG_TYPE" ||
+				error.code === "ERR_ENCODING_INVALID_ENCODED_DATA" ||
+				error.message?.includes("encoding") ||
+				error.message?.includes("Invalid") ||
+				error.errno === -92
+			) {
+				// EILSEQ error code for invalid byte sequence
+
+				// Create a new stream without encoding to read as buffer
+				const bufferInput = createReadStream(filepath)
+				let bufferData = Buffer.alloc(0)
+
+				bufferInput.on("error", reject)
+
+				bufferInput.on("data", (chunk) => {
+					bufferData = Buffer.concat([bufferData, chunk as Buffer])
+				})
+
+				bufferInput.on("end", () => {
+					// Convert buffer to string with UTF-8, replacing invalid sequences
+					const content = bufferData.toString("utf8")
+					const lines = content.split("\n")
+
+					// Apply line range filtering
+					const effectiveEndLine =
+						endLine === undefined ? lines.length - 1 : Math.min(endLine, lines.length - 1)
+
+					if (effectiveStartLine >= lines.length) {
+						reject(outOfRangeError(filepath, effectiveStartLine))
+					} else {
+						const selectedLines = lines.slice(effectiveStartLine, effectiveEndLine + 1)
+						// Join with newlines, but don't add trailing newline if original didn't have one
+						const hasTrailingNewline = content.endsWith("\n")
+						let resultText = selectedLines.join("\n")
+						if (hasTrailingNewline || effectiveEndLine < lines.length - 1) {
+							resultText += "\n"
+						}
+						resolve(resultText)
+					}
+				})
+			} else {
+				reject(error)
+			}
+		})
 
 		// Process data chunks directly
 		input.on("data", (chunk) => {
-			// Add chunk to buffer
-			buffer += chunk.toString()
+			// Chunk is already a string due to encoding option
+			buffer += chunk as string
 
 			let pos = 0
 			let nextNewline = buffer.indexOf("\n", pos)
diff --git a/test-unicode.md b/test-unicode.md
new file mode 100644
index 0000000000..1c8fb3c964
--- /dev/null
+++ b/test-unicode.md
@@ -0,0 +1,27 @@
+# Test File for Unicode Characters
+
+This file contains mixed-language content to test Unicode handling.
+
+- **时间戳 (Timestamp)**: 2025-07-26 15:41
+- **任务/目标 (Task/Goal)**: 实现问卷的前端核心交互逻辑。
+- **关键决策/操作 (Key Decision/Action)**:
+    1.  在 `questionnaire-server/public/index.html` 中添加了 `<div id="questionnaire-container"></div>` 作为动态内容的挂载点。
+    2.  在 `questionnaire-server/public/style.css` 中添加了完整的基础样式，确保界面干净、可用，并对问卷的各个部分（欢迎页、问题页、选项）进行了样式设置。
+
+## Additional Unicode Test Cases
+
+- Emoji: 😀 🎉 🚀 ✨
+- Japanese: こんにちは世界
+- Korean: 안녕하세요 세계
+- Arabic: مرحبا بالعالم
+- Hebrew: שלום עולם
+- Russian: Привет мир
+- Greek: Γεια σου κόσμο
+- Thai: สวัสดีชาวโลก
+
+## Special Characters
+
+- Non-breaking space: test test
+- Zero-width space: test​test
+- Various quotes: "test" 'test' „test" «test»
+- Math symbols: ∑ ∏ ∫ √ ∞ ≈ ≠ ≤ ≥