fix: Context Overload in Read File Tool

src/core/tools/__tests__/contextValidator.test.ts

@@ -0,0 +1,380 @@
+import { describe, it, expect, vi, beforeEach } from "vitest"
+import { validateFileSizeForContext } from "../contextValidator"
+import { Task } from "../../task/Task"
+import { promises as fs } from "fs"
+import { readLines } from "../../../integrations/misc/read-lines"
+import * as sharedApi from "../../../shared/api"
+
+vi.mock("fs", () => ({
+	promises: {
+		stat: vi.fn(),
+	},
+}))
+
+vi.mock("../../../integrations/misc/read-lines", () => ({
+	readLines: vi.fn(),
+}))
+
+vi.mock("../../../shared/api", () => ({
+	getModelMaxOutputTokens: vi.fn(),
+}))
+
+describe("contextValidator", () => {
+	let mockTask: Task
+
+	beforeEach(() => {
+		vi.clearAllMocks()
+
+		// Mock Task instance
+		mockTask = {
+			api: {
+				getModel: vi.fn().mockReturnValue({
+					id: "test-model",
+					info: {
+						contextWindow: 100000,
+						maxTokens: 4096,
+					},
+				}),
+				countTokens: vi.fn().mockResolvedValue(1000),
+			},
+			getTokenUsage: vi.fn().mockReturnValue({
+				contextTokens: 10000,
+			}),
+			apiConfiguration: {
+				apiProvider: "anthropic",
+			},
+			providerRef: {
+				deref: vi.fn().mockReturnValue({
+					getState: vi.fn().mockResolvedValue({}),
+				}),
+			},
+		} as any
+
+		// Mock getModelMaxOutputTokens to return a consistent value
+		vi.mocked(sharedApi.getModelMaxOutputTokens).mockReturnValue(4096)
+	})
+
+	describe("validateFileSizeForContext", () => {
+		it("should apply 25% buffer to remaining context and read incrementally", async () => {
+			const mockStats = { size: 50000 }
+			vi.mocked(fs.stat).mockResolvedValue(mockStats as any)
+
+			// Mock readLines to return content in batches
+			// Each batch is 100 lines, returning content that results in 1200 tokens per batch
+			vi.mocked(readLines).mockImplementation(async (path, endLine, startLine) => {
+				const start = startLine ?? 0
+				const end = endLine ?? 99
+				const lines = end - start + 1
+				return `test content line\n`.repeat(lines)
+			})
+
+			// Mock token count - 12 tokens per line (1200 per 100-line batch)
+			let callCount = 0
+			mockTask.api.countTokens = vi.fn().mockImplementation(async (content) => {
+				callCount++
+				const text = content[0].text
+				const lines = text.split("\n").length - 1
+				return lines * 12 // 12 tokens per line
+			})
+
+			const result = await validateFileSizeForContext(
+				"/test/file.ts",
+				1000, // totalLines
+				-1, // currentMaxReadFileLine
+				mockTask,
+			)
+
+			// New calculation:
+			// Context window = 100k, current usage = 10k
+			// Remaining = 90k
+			// With 25% buffer on remaining: usable = 90k * 0.75 = 67.5k
+			// Reserved for response ~2k
+			// Available should be around 65.5k tokens
+			// File needs 12k tokens total (1000 lines * 12 tokens)
+			expect(result.shouldLimit).toBe(false)
+
+			// Verify readLines was called multiple times (incremental reading)
+			expect(readLines).toHaveBeenCalled()
+
+			// Verify the new calculation approach
+			const remaining = 100000 - 10000 // 90k remaining
+			const usableRemaining = remaining * 0.75 // 67.5k with 25% buffer
+			expect(usableRemaining).toBe(67500)
+		})
+
+		it("should handle different context usage levels correctly", async () => {
+			const mockStats = { size: 50000 }
+			vi.mocked(fs.stat).mockResolvedValue(mockStats as any)
+
+			// Mock readLines
+			vi.mocked(readLines).mockImplementation(async (path, endLine, startLine) => {
+				const start = startLine ?? 0
+				const end = endLine ?? 99
+				const lines = end - start + 1
+				return `test content line\n`.repeat(lines)
+			})
+
+			// Mock token count - 50 tokens per line
+			mockTask.api.countTokens = vi.fn().mockImplementation(async (content) => {
+				const text = content[0].text
+				const lines = text.split("\n").length - 1
+				return lines * 50
+			})
+
+			// Test with 50% context already used
+			mockTask.getTokenUsage = vi.fn().mockReturnValue({
+				contextTokens: 50000, // 50% of 100k context used
+			})
+
+			const result = await validateFileSizeForContext(
+				"/test/file.ts",
+				2000, // totalLines
+				-1,
+				mockTask,
+			)
+
+			// With 50k remaining and 25% buffer: 50k * 0.75 = 37.5k usable
+			// Minus ~2k for response = ~35.5k available
+			// File needs 100k tokens (2000 lines * 50 tokens)
+			// Should limit the file
+			expect(result.shouldLimit).toBe(true)
+			expect(result.safeMaxLines).toBeLessThan(2000)
+			expect(result.reason).toContain("exceeds available context space")
+		})
+
+		it("should limit file when it exceeds available space with buffer", async () => {
+			// Set up a scenario where file is too large
+			const mockStats = { size: 500000 } // Large file
+			vi.mocked(fs.stat).mockResolvedValue(mockStats as any)
+
+			// Mock readLines to return content in batches
+			vi.mocked(readLines).mockImplementation(async (path, endLine, startLine) => {
+				const start = startLine ?? 0
+				const end = endLine ?? 99
+				const lines = end - start + 1
+				return `large content line\n`.repeat(lines)
+			})
+
+			// Mock large token count - 100 tokens per line
+			mockTask.api.countTokens = vi.fn().mockImplementation(async (content) => {
+				const text = content[0].text
+				const lines = text.split("\n").length - 1
+				return lines * 100 // 100 tokens per line
+			})
+
+			const result = await validateFileSizeForContext(
+				"/test/largefile.ts",
+				10000, // totalLines
+				-1,
+				mockTask,
+			)
+
+			expect(result.shouldLimit).toBe(true)
+			expect(result.safeMaxLines).toBeGreaterThan(0)
+			expect(result.safeMaxLines).toBeLessThan(10000) // Should stop before reading all lines
+			expect(result.reason).toContain("exceeds available context space")
+		})
+
+		it("should handle very large files through incremental reading", async () => {
+			// Set up a file larger than 50MB
+			const mockStats = { size: 60_000_000 } // 60MB file
+			vi.mocked(fs.stat).mockResolvedValue(mockStats as any)
+
+			// Mock readLines to return content in batches
+			vi.mocked(readLines).mockImplementation(async (path, endLine, startLine) => {
+				const start = startLine ?? 0
+				const end = endLine ?? 99
+				const lines = end - start + 1
+				return `large file content line\n`.repeat(lines)
+			})
+
+			// Mock very high token count per line (simulating dense content)
+			mockTask.api.countTokens = vi.fn().mockImplementation(async (content) => {
+				const text = content[0].text
+				const lines = text.split("\n").length - 1
+				return lines * 200 // 200 tokens per line for very large file
+			})
+
+			const result = await validateFileSizeForContext(
+				"/test/hugefile.ts",
+				100000, // totalLines
+				-1,
+				mockTask,
+			)
+
+			expect(result.shouldLimit).toBe(true)
+			// Should have attempted to read the file incrementally
+			expect(readLines).toHaveBeenCalled()
+			// Should stop early due to token limits
+			expect(result.safeMaxLines).toBeLessThan(1000)
+			expect(result.reason).toContain("exceeds available context space")
+		})
+
+		it("should handle read failures gracefully", async () => {
+			const mockStats = { size: 100000 } // 100KB file
+			vi.mocked(fs.stat).mockResolvedValue(mockStats as any)
+
+			// Mock readLines to fail
+			vi.mocked(readLines).mockRejectedValue(new Error("Read error"))
+
+			const result = await validateFileSizeForContext(
+				"/test/problematic.ts",
+				2000, // totalLines
+				-1,
+				mockTask,
+			)
+
+			// Should return a safe default when reading fails
+			expect(result.shouldLimit).toBe(true)
+			expect(result.safeMaxLines).toBe(50) // Minimum useful lines
+		})
+
+		it("should handle very limited context space", async () => {
+			const mockStats = { size: 10000 } // 10KB file
+			vi.mocked(fs.stat).mockResolvedValue(mockStats as any)
+
+			// Set very high context usage
+			// With new calculation: 100k - 95k = 5k remaining
+			// 5k * 0.75 = 3.75k usable
+			// Minus ~2k for response = ~1.75k available
+			mockTask.getTokenUsage = vi.fn().mockReturnValue({
+				contextTokens: 95000, // 95% of context used
+			})
+
+			// Mock small token count
+			mockTask.api.countTokens = vi.fn().mockImplementation(async (content) => {
+				const text = content[0].text
+				const lines = text.split("\n").length - 1
+				return lines * 10 // 10 tokens per line
+			})
+
+			// Mock readLines
+			vi.mocked(readLines).mockImplementation(async (path, endLine, startLine) => {
+				const start = startLine ?? 0
+				const end = endLine ?? 99
+				const lines = end - start + 1
+				return `test line\n`.repeat(lines)
+			})
+
+			const result = await validateFileSizeForContext(
+				"/test/smallfile.ts",
+				500, // totalLines
+				-1,
+				mockTask,
+			)
+
+			expect(result.shouldLimit).toBe(true)
+			// With the new calculation using full model max tokens (4096),
+			// we have less space available, so we get the minimum 50 lines
+			expect(result.safeMaxLines).toBe(50)
+			expect(result.reason).toContain("Very limited context space")
+		})
+
+		it("should handle negative available space gracefully", async () => {
+			const mockStats = { size: 10000 } // 10KB file
+			vi.mocked(fs.stat).mockResolvedValue(mockStats as any)
+
+			// Set extremely high context usage
+			// With 100k - 99k = 1k remaining
+			// 1k * 0.75 = 750 tokens usable
+			// Minus 2k for response = negative available space
+			mockTask.getTokenUsage = vi.fn().mockReturnValue({
+				contextTokens: 99000, // 99% of context used
+			})
+
+			const result = await validateFileSizeForContext(
+				"/test/smallfile.ts",
+				500, // totalLines
+				-1,
+				mockTask,
+			)
+
+			expect(result.shouldLimit).toBe(true)
+			expect(result.safeMaxLines).toBe(50) // Should be limited to minimum useful lines
+			expect(result.reason).toContain("Very limited context space")
+			// With negative available space, readLines won't be called
+			expect(readLines).not.toHaveBeenCalled()
+		})
+
+		it("should limit file when it is too large and would be truncated", async () => {
+			const filePath = "/test/large-file.ts"
+			const totalLines = 10000
+			const currentMaxReadFileLine = -1 // Unlimited
+
+			// Set up context to have limited space
+			mockTask.getTokenUsage = vi.fn().mockReturnValue({
+				contextTokens: 90000, // 90% of context used
+			})
+
+			// Mock token counting to simulate a large file
+			mockTask.api.countTokens = vi.fn().mockResolvedValue(1000) // Each batch is 1000 tokens
+
+			// Mock readLines to return some content
+			vi.mocked(readLines).mockResolvedValue("line content")
+
+			const result = await validateFileSizeForContext(filePath, totalLines, currentMaxReadFileLine, mockTask)
+
+			expect(result.shouldLimit).toBe(true)
+			expect(result.safeMaxLines).toBeGreaterThan(0)
+			expect(result.safeMaxLines).toBeLessThan(totalLines)
+			expect(result.reason).toContain("File exceeds available context space")
+			expect(result.reason).toContain("Use line_range to read specific sections")
+		})
+
+		it("should limit file when very limited context space", async () => {
+			const filePath = "/test/file.ts"
+			const totalLines = 1000
+			const currentMaxReadFileLine = -1
+
+			// Mock very high token usage leaving little room
+			mockTask.getTokenUsage = vi.fn().mockReturnValue({
+				contextTokens: 98000, // Almost all context used (98% of 100k)
+			})
+
+			// Mock token counting to quickly exceed limit
+			mockTask.api.countTokens = vi.fn().mockResolvedValue(500) // Each batch uses a lot of tokens
+
+			vi.mocked(readLines).mockResolvedValue("line content")
+
+			const result = await validateFileSizeForContext(filePath, totalLines, currentMaxReadFileLine, mockTask)
+
+			expect(result.shouldLimit).toBe(true)
+			expect(result.reason).toContain("Very limited context space")
+			expect(result.reason).toContain("Consider using search_files or line_range")
+		})
+
+		it("should not limit when file fits within context", async () => {
+			const filePath = "/test/small-file.ts"
+			const totalLines = 100
+			const currentMaxReadFileLine = -1
+
+			// Mock low token usage
+			mockTask.api.countTokens = vi.fn().mockResolvedValue(10) // Small token count per batch
+
+			vi.mocked(readLines).mockResolvedValue("line content")
+
+			const result = await validateFileSizeForContext(filePath, totalLines, currentMaxReadFileLine, mockTask)
+
+			expect(result.shouldLimit).toBe(false)
+			expect(result.safeMaxLines).toBe(currentMaxReadFileLine)
+		})
+
+		it("should handle errors gracefully", async () => {
+			const filePath = "/test/error-file.ts"
+			const totalLines = 20000 // Large file
+			const currentMaxReadFileLine = -1
+
+			// Mock an error in the API
+			mockTask.api.getModel = vi.fn().mockImplementation(() => {
+				throw new Error("API Error")
+			})
+
+			const result = await validateFileSizeForContext(filePath, totalLines, currentMaxReadFileLine, mockTask)
+
+			// Should fall back to conservative limits
+			expect(result.shouldLimit).toBe(true)
+			expect(result.safeMaxLines).toBe(1000)
+			expect(result.reason).toContain("Large file detected")
+		})
+	})
+})