fix(readFileTool): fix legacy format detection and test mocks

- Enhance isLegacyReadFileParams to also detect bare 'files' array (real legacy chat data)
- Fix batch approval test: add explicit readWithSlice mocks for file content
- Fix partial display test: mock fs.readFile to return string for utf8 encoding

Author: proyectoauraorg

packages/types/src/tool-params.ts

@@ -89,7 +89,10 @@ export type ReadFileToolParams = ReadFileParams | LegacyReadFileParams
  * Type guard to check if params are in legacy format.
  */
 export function isLegacyReadFileParams(params: ReadFileToolParams): params is LegacyReadFileParams {
-	return "_legacyFormat" in params && params._legacyFormat === true
+	// Detect explicit flag (new code path) or bare `files` array (real legacy chat data)
+	const hasLegacyFlag = "_legacyFormat" in params && params._legacyFormat === true
+	const hasFilesArray = "files" in params && Array.isArray((params as unknown as Record<string, unknown>).files)
+	return hasLegacyFlag || hasFilesArray
 }
 
 export interface Coordinate {

src/core/tools/__tests__/readFileTool.spec.ts

@@ -768,6 +768,23 @@ describe("ReadFileTool", () => {
 			mockedFsReadFile.mockResolvedValueOnce(Buffer.from("file1 content"))
 			mockedFsReadFile.mockResolvedValueOnce(Buffer.from("file2 content"))
 
+			// Override readWithSlice to return content that reflects the actual file data
+			mockedReadWithSlice
+				.mockReturnValueOnce({
+					content: "1 | file1 content",
+					returnedLines: 1,
+					totalLines: 1,
+					wasTruncated: false,
+					includedRanges: [[1, 1]],
+				})
+				.mockReturnValueOnce({
+					content: "1 | file2 content",
+					returnedLines: 1,
+					totalLines: 1,
+					wasTruncated: false,
+					includedRanges: [[1, 1]],
+				})
+
 			vi.spyOn(console, "warn").mockImplementation(() => {})
 
 			await readFileTool.execute(
@@ -823,7 +840,8 @@ describe("ReadFileTool", () => {
 			const callbacks = createMockCallbacks()
 
 			mockTask.ask.mockResolvedValue({ response: "yesButtonClicked", text: undefined, images: undefined })
-			mockedFsReadFile.mockResolvedValue(Buffer.from("line1\nline2\nline3\nline4\nline5"))
+			// fs.readFile with "utf8" encoding returns a string, not a Buffer
+			mockedFsReadFile.mockResolvedValue("line1\nline2\nline3\nline4\nline5" as any)
 			vi.spyOn(console, "warn").mockImplementation(() => {})
 
 			await readFileTool.execute(