fix(tools): Add an end of file list marker to ReadManyFilesTool (#5967)

Co-authored-by: Gal Zahavi <38544478+galz10@users.noreply.github.com>
Co-authored-by: Allen Hutchison <adh@google.com>

docs/tools/multi-file.md

@@ -29,6 +29,7 @@ Use `read_many_files` to read content from multiple files specified by paths or
 `read_many_files` searches for files matching the provided `paths` and `include` patterns, while respecting `exclude` patterns and default excludes (if enabled).
 
 - For text files: it reads the content of each matched file (attempting to skip binary files not explicitly requested as image/PDF) and concatenates it into a single string, with a separator `--- {filePath} ---` between the content of each file. Uses UTF-8 encoding by default.
+- The tool inserts a `--- End of content ---` after the last file.
 - For image and PDF files: if explicitly requested by name or extension (e.g., `paths: ["logo.png"]` or `include: ["*.pdf"]`), the tool reads the file and returns its content as a base64 encoded string.
 - The tool attempts to detect and skip other binary files (those not matching common image/PDF types or not explicitly requested) by checking for null bytes in their initial content.
 

packages/cli/src/ui/hooks/atCommandProcessor.ts

@@ -447,7 +447,6 @@ export async function handleAtCommand({
           processedQueryParts.push(part);
         }
       }
-      processedQueryParts.push({ text: '\n--- End of content ---' });
     } else {
       onDebugMessage(
         'read_many_files tool returned no content or empty content.',

packages/cli/src/zed-integration/zedIntegration.ts

@@ -750,7 +750,6 @@ class Session {
             processedQueryParts.push(part);
           }
         }
-        processedQueryParts.push({ text: '\n--- End of content ---' });
       } else {
         console.warn(
           'read_many_files tool returned no content or empty content.',

packages/core/src/tools/read-many-files.test.ts

@@ -221,6 +221,7 @@ describe('ReadManyFilesTool', () => {
       const expectedPath = path.join(tempRootDir, 'file1.txt');
       expect(result.llmContent).toEqual([
         `--- ${expectedPath} ---\n\nContent of file1\n\n`,
+        `\n--- End of content ---`,
       ]);
       expect(result.returnDisplay).toContain(
         'Successfully read and concatenated content from **1 file(s)**',
@@ -285,7 +286,10 @@ describe('ReadManyFilesTool', () => {
       const result = await invocation.execute(new AbortController().signal);
       const content = result.llmContent as string[];
       const expectedPath = path.join(tempRootDir, 'src/main.ts');
-      expect(content).toEqual([`--- ${expectedPath} ---\n\nMain content\n\n`]);
+      expect(content).toEqual([
+        `--- ${expectedPath} ---\n\nMain content\n\n`,
+        `\n--- End of content ---`,
+      ]);
       expect(
         content.find((c) => c.includes('src/main.test.ts')),
       ).toBeUndefined();
@@ -314,7 +318,10 @@ describe('ReadManyFilesTool', () => {
       const result = await invocation.execute(new AbortController().signal);
       const content = result.llmContent as string[];
       const expectedPath = path.join(tempRootDir, 'src/app.js');
-      expect(content).toEqual([`--- ${expectedPath} ---\n\napp code\n\n`]);
+      expect(content).toEqual([
+        `--- ${expectedPath} ---\n\napp code\n\n`,
+        `\n--- End of content ---`,
+      ]);
       expect(
         content.find((c) => c.includes('node_modules/some-lib/index.js')),
       ).toBeUndefined();
@@ -367,6 +374,7 @@ describe('ReadManyFilesTool', () => {
             mimeType: 'image/png',
           },
         },
+        '\n--- End of content ---',
       ]);
       expect(result.returnDisplay).toContain(
         'Successfully read and concatenated content from **1 file(s)**',
@@ -390,6 +398,7 @@ describe('ReadManyFilesTool', () => {
             mimeType: 'image/png',
           },
         },
+        '\n--- End of content ---',
       ]);
     });
 
@@ -426,6 +435,7 @@ describe('ReadManyFilesTool', () => {
             mimeType: 'application/pdf',
           },
         },
+        '\n--- End of content ---',
       ]);
     });
 
@@ -441,6 +451,7 @@ describe('ReadManyFilesTool', () => {
             mimeType: 'application/pdf',
           },
         },
+        '\n--- End of content ---',
       ]);
     });
 
@@ -549,6 +560,7 @@ describe('ReadManyFilesTool', () => {
 Content of receive-detail
 
 `,
+        `\n--- End of content ---`,
       ]);
       expect(result.returnDisplay).toContain(
         'Successfully read and concatenated content from **1 file(s)**',
@@ -567,6 +579,7 @@ Content of receive-detail
 Content of file[1]
 
 `,
+        `\n--- End of content ---`,
       ]);
       expect(result.returnDisplay).toContain(
         'Successfully read and concatenated content from **1 file(s)**',
@@ -634,9 +647,10 @@ Content of file[1]
       const invocation = tool.build(params);
       const result = await invocation.execute(new AbortController().signal);
 
-      // Verify all files were processed
+      // Verify all files were processed. The content should have fileCount
+      // entries + 1 for the output terminator.
       const content = result.llmContent as string[];
-      expect(content).toHaveLength(fileCount);
+      expect(content).toHaveLength(fileCount + 1);
       for (let i = 0; i < fileCount; i++) {
         expect(content.join('')).toContain(`Batch test ${i}`);
       }

packages/core/src/tools/read-many-files.ts

@@ -143,6 +143,7 @@ const DEFAULT_EXCLUDES: string[] = [
 ];
 
 const DEFAULT_OUTPUT_SEPARATOR_FORMAT = '--- {filePath} ---';
+const DEFAULT_OUTPUT_TERMINATOR = '\n--- End of content ---';
 
 class ReadManyFilesToolInvocation extends BaseToolInvocation<
   ReadManyFilesParams,
@@ -534,7 +535,9 @@ ${finalExclusionPatternsForDescription
       displayMessage += `No files were read and concatenated based on the criteria.\n`;
     }
 
-    if (contentParts.length === 0) {
+    if (contentParts.length > 0) {
+      contentParts.push(DEFAULT_OUTPUT_TERMINATOR);
+    } else {
       contentParts.push(
         'No files matching the criteria were found or all were skipped.',
       );
@@ -636,7 +639,7 @@ This tool is useful when you need to understand or analyze a collection of files
 - Gathering context from multiple configuration files.
 - When the user asks to "read all files in X directory" or "show me the content of all Y files".
 
-Use this tool when the user's query implies needing the content of several files simultaneously for context, analysis, or summarization. For text files, it uses default UTF-8 encoding and a '--- {filePath} ---' separator between file contents. Ensure paths are relative to the target directory. Glob patterns like 'src/**/*.js' are supported. Avoid using for single files if a more specific single-file reading tool is available, unless the user specifically requests to process a list containing just one file via this tool. Other binary files (not explicitly requested as image/PDF) are generally skipped. Default excludes apply to common non-text files (except for explicitly requested images/PDFs) and large dependency directories unless 'useDefaultExcludes' is false.`,
+Use this tool when the user's query implies needing the content of several files simultaneously for context, analysis, or summarization. For text files, it uses default UTF-8 encoding and a '--- {filePath} ---' separator between file contents. The tool inserts a '--- End of content ---' after the last file. Ensure paths are relative to the target directory. Glob patterns like 'src/**/*.js' are supported. Avoid using for single files if a more specific single-file reading tool is available, unless the user specifically requests to process a list containing just one file via this tool. Other binary files (not explicitly requested as image/PDF) are generally skipped. Default excludes apply to common non-text files (except for explicitly requested images/PDFs) and large dependency directories unless 'useDefaultExcludes' is false.`,
       Kind.Read,
       parameterSchema,
     );