fix: replace echoed text with bytesWritten in writeTextFile

.changeset/write-text-file-drop-echo.md

@@ -0,0 +1,6 @@
+---
+"@perstack/base": patch
+"perstack": patch
+---
+
+Replace echoed text with bytesWritten in writeTextFile tool result

apps/base/src/tools/write-text-file.test.ts

@@ -2,7 +2,6 @@ import { afterEach, describe, expect, it } from "bun:test"
 import { existsSync } from "node:fs"
 import fs from "node:fs/promises"
 import { join } from "node:path"
-import { MAX_TOOL_OUTPUT_CHARS } from "@perstack/core"
 import { validatePath } from "../lib/path.js"
 import { writeTextFile } from "./write-text-file.js"
 
@@ -19,7 +18,7 @@ describe("writeTextFile tool", () => {
     expect(existsSync(testFile)).toBe(true)
     expect(await fs.readFile(testFile, "utf-8")).toBe(content)
     expect(result.path).toBe(await validatePath(testFile))
-    expect(result.text).toBe(content)
+    expect(result.bytesWritten).toBe(Buffer.byteLength(content, "utf-8"))
   })
 
   it("overwrites existing file", async () => {
@@ -28,7 +27,7 @@ describe("writeTextFile tool", () => {
     const result = await writeTextFile({ path: testFile, text: newContent })
     expect(await fs.readFile(testFile, "utf-8")).toBe(newContent)
     expect(result.path).toBe(await validatePath(testFile))
-    expect(result.text).toBe(newContent)
+    expect(result.bytesWritten).toBe(Buffer.byteLength(newContent, "utf-8"))
   })
 
   it("creates file in nested directory", async () => {
@@ -38,23 +37,22 @@ describe("writeTextFile tool", () => {
     const result = await writeTextFile({ path: nestedFile, text: content })
     expect(existsSync(nestedFile)).toBe(true)
     expect(await fs.readFile(nestedFile, "utf-8")).toBe(content)
-    expect(result.text).toBe(content)
+    expect(result.bytesWritten).toBe(Buffer.byteLength(content, "utf-8"))
   })
 
   it("handles empty content", async () => {
     const result = await writeTextFile({ path: testFile, text: "" })
     expect(existsSync(testFile)).toBe(true)
     expect(await fs.readFile(testFile, "utf-8")).toBe("")
-    expect(result.text).toBe("")
+    expect(result.bytesWritten).toBe(0)
   })
 
-  it("truncates echoed text exceeding 30K characters", async () => {
-    const largeText = "B".repeat(50_000)
-    const result = await writeTextFile({ path: testFile, text: largeText })
-    expect(result.text.length).toBeLessThanOrEqual(MAX_TOOL_OUTPUT_CHARS)
-    expect(result.text).toContain("... [truncated:")
-    // File itself should contain the full content
-    expect(await fs.readFile(testFile, "utf-8")).toBe(largeText)
+  it("returns correct bytesWritten for multi-byte characters", async () => {
+    const content = "hello world \u00e9\u00e0\u00fc"
+    const result = await writeTextFile({ path: testFile, text: content })
+    expect(await fs.readFile(testFile, "utf-8")).toBe(content)
+    expect(result.bytesWritten).toBe(Buffer.byteLength(content, "utf-8"))
+    expect(result.bytesWritten).toBeGreaterThan(content.length)
   })
 
   it("throws error if existing file is not writable", async () => {

apps/base/src/tools/write-text-file.ts

@@ -1,7 +1,6 @@
 import { mkdir, stat } from "node:fs/promises"
 import { dirname } from "node:path"
 import type { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js"
-import { truncateText } from "@perstack/core"
 import { z } from "zod/v4"
 import { validatePath } from "../lib/path.js"
 import { safeWriteFile } from "../lib/safe-file.js"
@@ -19,7 +18,7 @@ export async function writeTextFile(input: { path: string; text: string }) {
   await safeWriteFile(validatedPath, text)
   return {
     path: validatedPath,
-    text: truncateText(text),
+    bytesWritten: Buffer.byteLength(text, "utf-8"),
   }
 }