refactor(core): thread the descriptor instead of forking text-read helpers

packages/cli/src/serve/routes/workspace-file-read.test.ts

@@ -282,6 +282,23 @@ describe('GET /file', () => {
     expect(res.body.errorKind).toBe('binary_file');
   });
 
+  it('returns 422 binary_file for large non-UTF-8 text even with a finite limit', async () => {
+    const { MAX_READ_BYTES } = await import('../fs/policy.js');
+    const body = Buffer.concat([
+      Buffer.from([0xff, 0xfe]),
+      Buffer.from('中文日志行\n'.repeat(30_000), 'utf16le'),
+    ]);
+    expect(body.length).toBeGreaterThan(MAX_READ_BYTES);
+    await fsp.writeFile(path.join(h.workspace, 'large-utf16.txt'), body);
+
+    const res = await request(h.app)
+      .get('/file?path=large-utf16.txt&line=1&limit=20')
+      .set('Host', loopbackHost());
+
+    expect(res.status).toBe(422);
+    expect(res.body.errorKind).toBe('binary_file');
+  });
+
   it('truncates content above maxBytes and reports truncated=true', async () => {
     await fsp.writeFile(path.join(h.workspace, 'big.txt'), 'a'.repeat(2048));
     const res = await request(h.app)

packages/core/src/index.ts

@@ -272,6 +272,7 @@ export {
   LargeNonUtf8TextError,
   TextScanBudgetExceededError,
 } from './utils/read-text-range.js';
+export type { ReadTextRangeResult } from './utils/read-text-range.js';
 export { isUtf8CompatibleEncoding } from './utils/encoding.js';
 export * from './services/gitWorktreeService.js';
 export { DEFAULT_MAX_TOOL_CALLS_PER_TURN } from './services/loopDetectionService.js';

packages/core/src/services/fileSystemService.test.ts

@@ -80,6 +80,8 @@ describe('StandardFileSystemService', () => {
         bom: false,
         encoding: 'utf-8',
         originalLineCount: 1,
+        originalLineCountExact: true,
+        truncatedByBytes: false,
       });
 
       const result = await fileSystem.readTextFile({ path: '/test/file.txt' });
@@ -99,6 +101,8 @@ describe('StandardFileSystemService', () => {
         bom: false,
         encoding: 'utf-8',
         originalLineCount: 100,
+        originalLineCountExact: true,
+        truncatedByBytes: false,
       });
 
       const result = await fileSystem.readTextFile({
@@ -121,6 +125,8 @@ describe('StandardFileSystemService', () => {
         bom: false,
         encoding: 'utf-8',
         originalLineCount: 100,
+        originalLineCountExact: true,
+        truncatedByBytes: false,
       });
 
       await fileSystem.readTextFile({
@@ -141,6 +147,7 @@ describe('StandardFileSystemService', () => {
         bom: false,
         encoding: 'utf-8',
         originalLineCount: 100,
+        originalLineCountExact: true,
         truncatedByBytes: true,
       });
 
@@ -167,6 +174,8 @@ describe('StandardFileSystemService', () => {
         bom: false,
         encoding: 'utf-8',
         originalLineCount: 1,
+        originalLineCountExact: true,
+        truncatedByBytes: false,
       });
 
       await fileSystem.readTextFile({
@@ -312,6 +321,8 @@ describe('StandardFileSystemService', () => {
         bom: false,
         encoding: 'gb18030',
         originalLineCount: 1,
+        originalLineCountExact: true,
+        truncatedByBytes: false,
       });
 
       const result = await fileSystem.readTextFile({ path: '/test/gbk.txt' });
@@ -793,6 +804,8 @@ describe('StandardFileSystemService', () => {
         bom: false,
         encoding: 'utf-8',
         originalLineCount: 3,
+        originalLineCountExact: true,
+        truncatedByBytes: false,
       });
 
       const result = await fileSystem.readTextFile({ path: '/test/file.txt' });
@@ -806,6 +819,8 @@ describe('StandardFileSystemService', () => {
         bom: false,
         encoding: 'utf-8',
         originalLineCount: 3,
+        originalLineCountExact: true,
+        truncatedByBytes: false,
       });
 
       const result = await fileSystem.readTextFile({ path: '/test/file.txt' });

packages/core/src/utils/fileUtils.test.ts

@@ -3081,6 +3081,27 @@ describe('fileUtils', () => {
       ).rejects.toThrow(/abort/i);
     });
 
+    it('reports lineEnding and truncatedByBytes on an unbounded read', async () => {
+      actualNodeFs.writeFileSync(
+        testTextFilePath,
+        'alpha\r\nbravo\r\ncharlie\r\n',
+      );
+
+      const whole = await readFileWithLineAndLimit({
+        path: testTextFilePath,
+        limit: Number.POSITIVE_INFINITY,
+      });
+      const range = await readFileWithLineAndLimit({
+        path: testTextFilePath,
+        limit: 3,
+      });
+
+      expect(whole.lineEnding).toBe('crlf');
+      expect(whole.truncatedByBytes).toBe(false);
+      expect(whole.lineEnding).toBe(range.lineEnding);
+      expect(whole.truncatedByBytes).toBe(range.truncatedByBytes);
+    });
+
     it('should use provided stats when reading with line and byte limits', async () => {
       actualNodeFs.writeFileSync(testTextFilePath, 'hello\nworld');
       const stats = actualNodeFs.statSync(testTextFilePath);

packages/core/src/utils/fileUtils.ts

@@ -36,7 +36,11 @@ import {
 import { VISION_BRIDGE_MAX_IMAGES } from '../services/visionBridge/vision-bridge-constants.js';
 import type { VisionBridgePdfContinuation } from '../services/visionBridge/vision-bridge-service.js';
 import { readNotebookWithMetadata } from './notebook.js';
-import { readTextRange } from './read-text-range.js';
+import {
+  readTextRange,
+  type ReadTextRangeResult,
+  detectLineEndingFromContent,
+} from './read-text-range.js';
 import {
   DEFAULT_RANGE_READ_BYTES,
   TEXT_RANGE_FAST_PATH_MAX_SIZE,
@@ -330,15 +334,7 @@ export async function readFileWithLineAndLimit(params: {
   maxOutputBytes?: number;
   signal?: AbortSignal;
   stats?: import('node:fs').Stats;
-}): Promise<{
-  content: string;
-  bom?: boolean;
-  encoding?: string;
-  originalLineCount: number;
-  originalLineCountExact?: boolean;
-  lineEnding?: 'crlf' | 'lf';
-  truncatedByBytes?: boolean;
-}> {
+}): Promise<ReadTextRangeResult> {
   const { path: filePath, limit, line, maxOutputBytes, signal } = params;
   const stats = params.stats ?? (await fs.promises.stat(filePath));
   if (
@@ -372,12 +368,15 @@ export async function readFileWithLineAndLimit(params: {
   const actualStartLine = Math.min(startLine, originalLineCount);
   const selectedLines = lines.slice(actualStartLine, endLine);
 
+  const joined = selectedLines.join('\n');
   return {
-    content: selectedLines.join('\n'),
+    content: joined,
     bom,
     encoding,
     originalLineCount,
     originalLineCountExact: true,
+    truncatedByBytes: false,
+    lineEnding: detectLineEndingFromContent(joined),
   };
 }
 

packages/core/src/utils/read-text-range.test.ts

@@ -12,6 +12,7 @@ import { iconvEncode } from './iconvHelper.js';
 import {
   CursorNotAtLineBoundaryError,
   LargeNonUtf8TextError,
+  detectLineEndingFromContent,
   readTextCursorWindowFromHandle,
   readTextRange,
   readTextRangeFromHandle,
@@ -995,3 +996,13 @@ describe('readTextCursorWindowFromHandle', () => {
     });
   });
 });
+
+describe('detectLineEndingFromContent', () => {
+  it('reports crlf for small CRLF content', () => {
+    expect(detectLineEndingFromContent('line1\r\nline2\r\n')).toBe('crlf');
+  });
+
+  it('reports lf when no CRLF is present', () => {
+    expect(detectLineEndingFromContent('line1\nline2\n')).toBe('lf');
+  });
+});

packages/core/src/utils/read-text-range.ts

@@ -749,6 +749,6 @@ function truncateUtf8(
   };
 }
 
-function detectLineEndingFromContent(content: string): 'crlf' | 'lf' {
+export function detectLineEndingFromContent(content: string): 'crlf' | 'lf' {
   return content.includes('\r\n') ? 'crlf' : 'lf';
 }