Fixes #4875: Fix codebase re-indexing race condition

- Fixed race condition in CodeIndexOrchestrator where clearIndexData and startIndexing could conflict
- Separated _isProcessing check from state validation in startIndexing for better error reporting
- Made webview startIndexing handler properly await the operation
- Removed _isProcessing reset from stopWatcher to prevent interference with calling methods
- Added comprehensive tests for clearIndexData and startIndexing sequence
- Ensures users can successfully re-index after clearing index data

src/core/webview/webviewMessageHandler.ts

@@ -1440,7 +1440,7 @@ export const webviewMessageHandler = async (
 						await manager.initialize(provider.contextProxy)
 					}
 
-					manager.startIndexing()
+					await manager.startIndexing()
 				}
 			} catch (error) {
 				provider.log(`Error starting indexing: ${error instanceof Error ? error.message : String(error)}`)

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

@@ -115,4 +115,89 @@ describe("CodeIndexManager - handleExternalSettingsChange regression", () => {
 			await expect(manager.handleExternalSettingsChange()).resolves.not.toThrow()
 		})
 	})
+
+	describe("clearIndexData and startIndexing sequence", () => {
+		it("should allow startIndexing immediately after clearIndexData completes", async () => {
+			// Mock the required dependencies
+			const mockConfigManager = {
+				loadConfiguration: vitest.fn().mockResolvedValue({ requiresRestart: false }),
+				isFeatureEnabled: true,
+				isFeatureConfigured: true,
+			}
+			const mockOrchestrator = {
+				clearIndexData: vitest.fn().mockResolvedValue(undefined),
+				startIndexing: vitest.fn().mockResolvedValue(undefined),
+				stopWatcher: vitest.fn(),
+			}
+			const mockCacheManager = {
+				clearCacheFile: vitest.fn().mockResolvedValue(undefined),
+			}
+
+			// Set up the manager with mocked dependencies
+			;(manager as any)._configManager = mockConfigManager
+			;(manager as any)._orchestrator = mockOrchestrator
+			;(manager as any)._searchService = {}
+			;(manager as any)._cacheManager = mockCacheManager
+
+			// Mock the feature state
+			vitest.spyOn(manager, "isFeatureEnabled", "get").mockReturnValue(true)
+			vitest.spyOn(manager, "isFeatureConfigured", "get").mockReturnValue(true)
+
+			// Verify manager is considered initialized
+			expect(manager.isInitialized).toBe(true)
+
+			// Test the sequence: clearIndexData followed by startIndexing
+			await manager.clearIndexData()
+			expect(mockOrchestrator.clearIndexData).toHaveBeenCalled()
+			expect(mockCacheManager.clearCacheFile).toHaveBeenCalled()
+
+			// This should not throw an error about being in processing state
+			await expect(manager.startIndexing()).resolves.not.toThrow()
+			expect(mockOrchestrator.startIndexing).toHaveBeenCalled()
+		})
+
+		it("should handle rapid clearIndexData and startIndexing calls", async () => {
+			// Mock the required dependencies
+			const mockConfigManager = {
+				loadConfiguration: vitest.fn().mockResolvedValue({ requiresRestart: false }),
+				isFeatureEnabled: true,
+				isFeatureConfigured: true,
+			}
+			const mockOrchestrator = {
+				clearIndexData: vitest
+					.fn()
+					.mockImplementation(() => new Promise((resolve) => setTimeout(resolve, 100))),
+				startIndexing: vitest.fn().mockResolvedValue(undefined),
+				stopWatcher: vitest.fn(),
+			}
+			const mockCacheManager = {
+				clearCacheFile: vitest.fn().mockResolvedValue(undefined),
+			}
+
+			// Set up the manager with mocked dependencies
+			;(manager as any)._configManager = mockConfigManager
+			;(manager as any)._orchestrator = mockOrchestrator
+			;(manager as any)._searchService = {}
+			;(manager as any)._cacheManager = mockCacheManager
+
+			// Mock the feature state
+			vitest.spyOn(manager, "isFeatureEnabled", "get").mockReturnValue(true)
+			vitest.spyOn(manager, "isFeatureConfigured", "get").mockReturnValue(true)
+
+			// Test rapid sequence: start clearIndexData and immediately call startIndexing
+			const clearPromise = manager.clearIndexData()
+
+			// Wait a bit to ensure clearIndexData has started but not finished
+			await new Promise((resolve) => setTimeout(resolve, 50))
+
+			// This should wait for clearIndexData to complete before proceeding
+			const startPromise = manager.startIndexing()
+
+			// Both should complete successfully
+			await Promise.all([clearPromise, startPromise])
+
+			expect(mockOrchestrator.clearIndexData).toHaveBeenCalled()
+			expect(mockOrchestrator.startIndexing).toHaveBeenCalled()
+		})
+	})
 })

src/services/code-index/orchestrator.ts

@@ -93,18 +93,22 @@ export class CodeIndexOrchestrator {
 			return
 		}
 
-		if (
-			this._isProcessing ||
-			(this.stateManager.state !== "Standby" &&
-				this.stateManager.state !== "Error" &&
-				this.stateManager.state !== "Indexed")
-		) {
+		if (this._isProcessing) {
 			console.warn(
-				`[CodeIndexOrchestrator] Start rejected: Already processing or in state ${this.stateManager.state}.`,
+				`[CodeIndexOrchestrator] Start rejected: Already processing (state: ${this.stateManager.state}).`,
 			)
 			return
 		}
 
+		if (
+			this.stateManager.state !== "Standby" &&
+			this.stateManager.state !== "Error" &&
+			this.stateManager.state !== "Indexed"
+		) {
+			console.warn(`[CodeIndexOrchestrator] Start rejected: Invalid state ${this.stateManager.state}.`)
+			return
+		}
+
 		this._isProcessing = true
 		this.stateManager.setSystemState("Indexing", "Initializing services...")
 
@@ -179,7 +183,7 @@ export class CodeIndexOrchestrator {
 		if (this.stateManager.state !== "Error") {
 			this.stateManager.setSystemState("Standby", "File watcher stopped.")
 		}
-		this._isProcessing = false
+		// Note: Don't reset _isProcessing here as it may be managed by calling methods
 	}
 
 	/**
@@ -190,7 +194,8 @@ export class CodeIndexOrchestrator {
 		this._isProcessing = true
 
 		try {
-			await this.stopWatcher()
+			// Stop the watcher first
+			this.stopWatcher()
 
 			try {
 				if (this.configManager.isFeatureConfigured) {
@@ -201,6 +206,7 @@ export class CodeIndexOrchestrator {
 			} catch (error: any) {
 				console.error("[CodeIndexOrchestrator] Failed to clear vector collection:", error)
 				this.stateManager.setSystemState("Error", `Failed to clear vector collection: ${error.message}`)
+				return // Exit early on error, _isProcessing will be reset in finally
 			}
 
 			await this.cacheManager.clearCacheFile()