feat: add configurable context window limit for Qwen CLI provider

- Add qwenCodeMaxContextWindow setting to provider-settings schema
- Update QwenCodeHandler to apply context window limit when configured
- Add comprehensive tests for the new functionality
- Addresses issue #7598 where large context windows cause performance issues

Author: roomote

packages/types/src/provider-settings.ts

@@ -318,6 +318,7 @@ const ioIntelligenceSchema = apiModelIdProviderModelSchema.extend({
 
 const qwenCodeSchema = apiModelIdProviderModelSchema.extend({
 	qwenCodeOauthPath: z.string().optional(),
+	qwenCodeMaxContextWindow: z.number().int().min(1000).max(1000000).optional(),
 })
 
 const rooSchema = apiModelIdProviderModelSchema.extend({

src/api/providers/__tests__/qwen-code.spec.ts

@@ -0,0 +1,98 @@
+import { describe, it, expect, vi, beforeEach } from "vitest"
+import { QwenCodeHandler } from "../qwen-code"
+import { qwenCodeDefaultModelId, qwenCodeModels } from "@roo-code/types"
+
+// Mock fs module
+vi.mock("node:fs", () => ({
+	promises: {
+		readFile: vi.fn(),
+		writeFile: vi.fn(),
+	},
+}))
+
+// Mock fetch
+global.fetch = vi.fn()
+
+describe("QwenCodeHandler", () => {
+	beforeEach(() => {
+		vi.clearAllMocks()
+	})
+
+	describe("getModel", () => {
+		it("should return default model when no model is specified", () => {
+			const handler = new QwenCodeHandler({})
+			const { id, info } = handler.getModel()
+
+			expect(id).toBe(qwenCodeDefaultModelId)
+			expect(info).toEqual(qwenCodeModels[qwenCodeDefaultModelId])
+		})
+
+		it("should return specified model when valid model is provided", () => {
+			const testModelId = "qwen3-coder-flash"
+			const handler = new QwenCodeHandler({
+				apiModelId: testModelId,
+			})
+			const { id, info } = handler.getModel()
+
+			expect(id).toBe(testModelId)
+			expect(info).toEqual(qwenCodeModels[testModelId])
+		})
+
+		it("should use default context window when qwenCodeMaxContextWindow is not set", () => {
+			const handler = new QwenCodeHandler({})
+			const { info } = handler.getModel()
+
+			expect(info.contextWindow).toBe(1_000_000) // Default context window
+		})
+
+		it("should limit context window when qwenCodeMaxContextWindow is set", () => {
+			const maxContextWindow = 256_000
+			const handler = new QwenCodeHandler({
+				qwenCodeMaxContextWindow: maxContextWindow,
+			})
+			const { info } = handler.getModel()
+
+			expect(info.contextWindow).toBe(maxContextWindow)
+		})
+
+		it("should use original context window when qwenCodeMaxContextWindow is larger", () => {
+			const handler = new QwenCodeHandler({
+				qwenCodeMaxContextWindow: 2_000_000, // Larger than default
+			})
+			const { info } = handler.getModel()
+
+			expect(info.contextWindow).toBe(1_000_000) // Should not exceed original
+		})
+
+		it("should ignore qwenCodeMaxContextWindow when it's 0 or negative", () => {
+			const handler1 = new QwenCodeHandler({
+				qwenCodeMaxContextWindow: 0,
+			})
+			const { info: info1 } = handler1.getModel()
+
+			expect(info1.contextWindow).toBe(1_000_000) // Should use default
+
+			const handler2 = new QwenCodeHandler({
+				qwenCodeMaxContextWindow: -1,
+			})
+			const { info: info2 } = handler2.getModel()
+
+			expect(info2.contextWindow).toBe(1_000_000) // Should use default
+		})
+
+		it("should apply context window limit to different models", () => {
+			const maxContextWindow = 200_000
+			const handler = new QwenCodeHandler({
+				apiModelId: "qwen3-coder-flash",
+				qwenCodeMaxContextWindow: maxContextWindow,
+			})
+			const { id, info } = handler.getModel()
+
+			expect(id).toBe("qwen3-coder-flash")
+			expect(info.contextWindow).toBe(maxContextWindow)
+			// Other properties should remain unchanged
+			expect(info.maxTokens).toBe(qwenCodeModels["qwen3-coder-flash"].maxTokens)
+			expect(info.description).toBe(qwenCodeModels["qwen3-coder-flash"].description)
+		})
+	})
+})

src/api/providers/qwen-code.ts

@@ -30,6 +30,7 @@ interface QwenOAuthCredentials {
 
 interface QwenCodeHandlerOptions extends ApiHandlerOptions {
 	qwenCodeOauthPath?: string
+	qwenCodeMaxContextWindow?: number
 }
 
 function getQwenCachedCredentialPath(customPath?: string): string {
@@ -286,7 +287,16 @@ export class QwenCodeHandler extends BaseProvider implements SingleCompletionHan
 
 	override getModel(): { id: string; info: ModelInfo } {
 		const id = this.options.apiModelId ?? qwenCodeDefaultModelId
-		const info = qwenCodeModels[id as keyof typeof qwenCodeModels] || qwenCodeModels[qwenCodeDefaultModelId]
+		let info = qwenCodeModels[id as keyof typeof qwenCodeModels] || qwenCodeModels[qwenCodeDefaultModelId]
+
+		// Apply custom context window limit if configured
+		if (this.options.qwenCodeMaxContextWindow && this.options.qwenCodeMaxContextWindow > 0) {
+			info = {
+				...info,
+				contextWindow: Math.min(info.contextWindow, this.options.qwenCodeMaxContextWindow),
+			}
+		}
+
 		return { id, info }
 	}