fix: use stable cache key for SSH remote workspaces

- Generate cache key using workspace name and relative path from home
- This ensures cache persistence across SSH sessions where absolute paths may change
- Add comprehensive tests for the new cache key generation logic

Fixes #6066

src/services/code-index/__tests__/cache-manager.spec.ts

@@ -3,6 +3,8 @@ import * as vscode from "vscode"
 import { createHash } from "crypto"
 import debounce from "lodash.debounce"
 import { CacheManager } from "../cache-manager"
+import * as path from "path"
+import * as os from "os"
 
 // Mock safeWriteJson utility
 vitest.mock("../../../utils/safeWriteJson", () => ({
@@ -38,6 +40,11 @@ vitest.mock("@roo-code/telemetry", () => ({
 	},
 }))
 
+// Mock os module
+vitest.mock("os", () => ({
+	homedir: vitest.fn(() => "/home/user"),
+}))
+
 describe("CacheManager", () => {
 	let mockContext: vscode.ExtensionContext
 	let mockWorkspacePath: string
@@ -63,8 +70,18 @@ describe("CacheManager", () => {
 	})
 
 	describe("constructor", () => {
-		it("should correctly set up cachePath using Uri.joinPath and crypto.createHash", () => {
-			const expectedHash = createHash("sha256").update(mockWorkspacePath).digest("hex")
+		it("should correctly set up cachePath using Uri.joinPath with stable cache key", () => {
+			// The cache key should be based on workspace name and relative path
+			const workspaceName = path.basename(mockWorkspacePath)
+			const homedir = os.homedir()
+			let relativePath = mockWorkspacePath
+
+			if (mockWorkspacePath.startsWith(homedir)) {
+				relativePath = path.relative(homedir, mockWorkspacePath)
+			}
+
+			const compositeKey = `${workspaceName}::${relativePath}`
+			const expectedHash = createHash("sha256").update(compositeKey).digest("hex")
 
 			expect(vscode.Uri.joinPath).toHaveBeenCalledWith(
 				mockContext.globalStorageUri,
@@ -75,6 +92,36 @@ describe("CacheManager", () => {
 		it("should set up debounced save function", () => {
 			expect(debounce).toHaveBeenCalledWith(expect.any(Function), 1500)
 		})
+
+		it("should generate stable cache key for workspace under home directory", () => {
+			// os.homedir is already mocked to return '/home/user'
+			const workspaceUnderHome = "/home/user/projects/myproject"
+			const cacheManagerHome = new CacheManager(mockContext, workspaceUnderHome)
+
+			// Expected key should use relative path from home
+			const expectedKey = `myproject::projects/myproject`
+			const expectedHash = createHash("sha256").update(expectedKey).digest("hex")
+
+			expect(vscode.Uri.joinPath).toHaveBeenCalledWith(
+				mockContext.globalStorageUri,
+				`roo-index-cache-${expectedHash}.json`,
+			)
+		})
+
+		it("should generate stable cache key for workspace outside home directory", () => {
+			// os.homedir is already mocked to return '/home/user'
+			const workspaceOutsideHome = "/opt/projects/myproject"
+			const cacheManagerOutside = new CacheManager(mockContext, workspaceOutsideHome)
+
+			// Expected key should use full path since it's outside home
+			const expectedKey = `myproject::/opt/projects/myproject`
+			const expectedHash = createHash("sha256").update(expectedKey).digest("hex")
+
+			expect(vscode.Uri.joinPath).toHaveBeenCalledWith(
+				mockContext.globalStorageUri,
+				`roo-index-cache-${expectedHash}.json`,
+			)
+		})
 	})
 
 	describe("initialize", () => {

src/services/code-index/cache-manager.ts

@@ -5,6 +5,8 @@ import debounce from "lodash.debounce"
 import { safeWriteJson } from "../../utils/safeWriteJson"
 import { TelemetryService } from "@roo-code/telemetry"
 import { TelemetryEventName } from "@roo-code/types"
+import * as path from "path"
+import * as os from "os"
 
 /**
  * Manages the cache for code indexing
@@ -23,15 +25,46 @@ export class CacheManager implements ICacheManager {
 		private context: vscode.ExtensionContext,
 		private workspacePath: string,
 	) {
-		this.cachePath = vscode.Uri.joinPath(
-			context.globalStorageUri,
-			`roo-index-cache-${createHash("sha256").update(workspacePath).digest("hex")}.json`,
-		)
+		// Generate a stable cache key that persists across SSH sessions
+		const cacheKey = this.generateStableCacheKey(workspacePath)
+		this.cachePath = vscode.Uri.joinPath(context.globalStorageUri, `roo-index-cache-${cacheKey}.json`)
 		this._debouncedSaveCache = debounce(async () => {
 			await this._performSave()
 		}, 1500)
 	}
 
+	/**
+	 * Generates a stable cache key for the workspace that persists across SSH sessions
+	 * @param workspacePath The workspace path
+	 * @returns A stable hash key
+	 */
+	private generateStableCacheKey(workspacePath: string): string {
+		// Get the workspace folder name
+		const workspaceName = path.basename(workspacePath)
+
+		// Try to get a relative path from home directory for additional stability
+		const homedir = os.homedir()
+		let relativePath = workspacePath
+
+		try {
+			// If the workspace is under the home directory, use the relative path
+			if (workspacePath.startsWith(homedir)) {
+				relativePath = path.relative(homedir, workspacePath)
+			}
+		} catch (error) {
+			// If we can't get relative path, just use the full path
+			console.warn("Failed to get relative path from home directory:", error)
+		}
+
+		// Create a composite key using workspace name and relative path
+		// This should be more stable across SSH sessions where the absolute path might change
+		// but the relative structure remains the same
+		const compositeKey = `${workspaceName}::${relativePath}`
+
+		// Generate hash from the composite key
+		return createHash("sha256").update(compositeKey).digest("hex")
+	}
+
 	/**
 	 * Initializes the cache manager by loading the cache file
 	 */