fix: support line range regardless of max line read

Author: elianiva

src/core/prompts/tools/read-file.ts

@@ -9,11 +9,11 @@ Description: Request to read the contents of ${isMultipleReadsEnabled ? "one or
 
 ${isMultipleReadsEnabled ? `**IMPORTANT: You can read a maximum of ${maxConcurrentReads} files in a single request.** If you need to read more files, use multiple sequential read_file requests.` : "**IMPORTANT: Multiple file reads are currently disabled. You can only read one file at a time.**"}
 
-${args.partialReadsEnabled ? `By specifying line ranges, you can efficiently read specific portions of large files without loading the entire file into memory.` : ""}
+${args.partialReadsEnabled ? `**Line ranges bypass the "Always read entire file" setting** - when you specify explicit line ranges, you can read any lines from any file regardless of the maxReadFileLine configuration. This is useful for targeted work based on tool outputs that reference specific line numbers (e.g., linters, search results, diffs).` : ""}
 Parameters:
 - args: Contains one or more file elements, where each file contains:
   - path: (required) File path (relative to workspace directory ${args.cwd})
-  ${args.partialReadsEnabled ? `- line_range: (optional) One or more line range elements in format "start-end" (1-based, inclusive)` : ""}
+  ${args.partialReadsEnabled ? `- line_range: (optional) One or more line range elements in format "start-end" (1-based, inclusive). Line ranges always bypass maxReadFileLine restrictions.` : ""}
 
 Usage:
 <read_file>

src/core/task/Task.ts

@@ -2434,7 +2434,7 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 				enableMcpServerCreation,
 				language,
 				rooIgnoreInstructions,
-				maxReadFileLine !== -1,
+				true, // Always enable partial reads - line ranges bypass maxReadFileLine
 				{
 					maxConcurrentFileReads: maxConcurrentFileReads ?? 5,
 					todoListEnabled: apiConfiguration?.todoListEnabled ?? true,

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

@@ -9,8 +9,6 @@ import { parseSourceCodeDefinitionsForFile } from "../../../services/tree-sitter
 import { isBinaryFile } from "isbinaryfile"
 import { ReadFileToolUse, ToolParamName, ToolResponse } from "../../../shared/tools"
 import { readFileTool } from "../readFileTool"
-import { formatResponse } from "../../prompts/responses"
-import { DEFAULT_MAX_IMAGE_FILE_SIZE_MB, DEFAULT_MAX_TOTAL_IMAGE_SIZE_MB } from "../helpers/imageHelpers"
 
 vi.mock("path", async () => {
 	const originalPath = await vi.importActual("path")
@@ -475,6 +473,85 @@ describe("read_file tool with maxReadFileLine setting", () => {
 			expect(rangeResult).toContain(`<file><path>${testFilePath}</path>`)
 			expect(rangeResult).toContain(`<content lines="2-4">`)
 		})
+
+		it("should bypass maxReadFileLine when line ranges are specified", async () => {
+			// Setup - file has 1000 lines, maxReadFileLine is 100, but we request lines 500-600
+			mockedCountFileLines.mockResolvedValue(1000)
+			mockedReadLines.mockResolvedValue("Line 500\nLine 501\n...Line 600")
+			addLineNumbersMock.mockReturnValue("500 | Line 500\n501 | Line 501\n...600 | Line 600")
+
+			// Execute with maxReadFileLine=100 but requesting lines 500-600
+			const result = await executeReadFileTool(
+				{},
+				{
+					maxReadFileLine: 100,
+					totalLines: 1000,
+					start_line: "500",
+					end_line: "600",
+				},
+			)
+
+			// Verify that we got the requested range, not limited by maxReadFileLine
+			expect(result).toContain(`<file><path>${testFilePath}</path>`)
+			expect(result).toContain(`<content lines="500-600">`)
+			expect(result).not.toContain("Showing only 100 of 1000 total lines")
+
+			// Verify readLines was called with the correct range
+			expect(mockedReadLines).toHaveBeenCalledWith(absoluteFilePath, 599, 499) // end-1, start-1
+		})
+
+		it("should bypass maxReadFileLine=0 (definitions only) when line ranges are specified", async () => {
+			// Setup - maxReadFileLine is 0 (definitions only), but we request specific lines
+			mockedCountFileLines.mockResolvedValue(100)
+			mockedReadLines.mockResolvedValue("Line 10\nLine 11\nLine 12")
+			addLineNumbersMock.mockReturnValue("10 | Line 10\n11 | Line 11\n12 | Line 12")
+
+			// Execute with maxReadFileLine=0 but requesting lines 10-12
+			const result = await executeReadFileTool(
+				{},
+				{
+					maxReadFileLine: 0,
+					totalLines: 100,
+					start_line: "10",
+					end_line: "12",
+					skipAddLineNumbersCheck: true,
+				},
+			)
+
+			// Verify that we got the actual content, not just definitions
+			expect(result).toContain(`<file><path>${testFilePath}</path>`)
+			expect(result).toContain(`<content lines="10-12">`)
+			expect(result).not.toContain("<list_code_definition_names>")
+
+			// Verify readLines was called
+			expect(mockedReadLines).toHaveBeenCalledWith(absoluteFilePath, 11, 9) // end-1, start-1
+		})
+
+		it("should bypass maxReadFileLine=-1 (always read entire file) when line ranges are specified", async () => {
+			// Setup - maxReadFileLine is -1 (always read entire file), but we request specific lines
+			mockedCountFileLines.mockResolvedValue(1000)
+			mockedReadLines.mockResolvedValue("Line 250\nLine 251\nLine 252")
+			addLineNumbersMock.mockReturnValue("250 | Line 250\n251 | Line 251\n252 | Line 252")
+
+			// Execute with maxReadFileLine=-1 but requesting lines 250-252
+			const result = await executeReadFileTool(
+				{},
+				{
+					maxReadFileLine: -1,
+					totalLines: 1000,
+					start_line: "250",
+					end_line: "252",
+				},
+			)
+
+			// Verify that we got the requested range, not the entire file
+			expect(result).toContain(`<file><path>${testFilePath}</path>`)
+			expect(result).toContain(`<content lines="250-252">`)
+			expect(result).not.toContain("lines=\"1-1000\"") // Should not read entire file
+
+			// Verify readLines was called with the correct range
+			expect(mockedReadLines).toHaveBeenCalledWith(absoluteFilePath, 251, 249) // end-1, start-1
+		})
 	})
 })