[Fix] Background service failures can surface as unhandled rejections

src/eslint.config.mjs

@@ -59,6 +59,7 @@ export default [
 			"core/tools/**/*.ts",
 			"core/webview/**/*.ts",
 			"integrations/**/*.ts",
+			"services/**/*.ts",
 		],
 		languageOptions: {
 			parserOptions: {

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

@@ -168,6 +168,25 @@ describe("CodeIndexManager - handleSettingsChange regression", () => {
 	})
 
 	describe("handleSettingsChange", () => {
+		it("should log background indexing failures", async () => {
+			const indexingError = new Error("indexing startup failed")
+			const startIndexing = vi.fn().mockRejectedValue(indexingError)
+			const consoleErrorSpy = vi.spyOn(console, "error").mockImplementation(() => undefined)
+			Object.defineProperty(manager, "_orchestrator", {
+				value: { startIndexing, stopIndexing: vi.fn() },
+				configurable: true,
+			})
+
+			manager["startIndexingInBackground"]()
+			await Promise.resolve()
+
+			expect(consoleErrorSpy).toHaveBeenCalledWith(
+				"[CodeIndexManager] Background indexing failed:",
+				indexingError,
+			)
+			consoleErrorSpy.mockRestore()
+		})
+
 		it("should not throw when called on uninitialized manager (regression test)", async () => {
 			// This is the core regression test: handleSettingsChange() should not throw
 			// when called before the manager is initialized (during first-time configuration)

src/services/code-index/manager.ts

@@ -227,13 +227,19 @@ export class CodeIndexManager {
 				(needsServiceRecreation && (!this._orchestrator || this._orchestrator.state !== "Indexing"))
 
 			if (shouldStartOrRestartIndexing) {
-				this._orchestrator?.startIndexing()
+				this.startIndexingInBackground()
 			}
 		}
 
 		return { requiresRestart }
 	}
 
+	private startIndexingInBackground(): void {
+		void this._orchestrator?.startIndexing().catch((error) => {
+			console.error("[CodeIndexManager] Background indexing failed:", error)
+		})
+	}
+
 	/**
 	 * Initiates the indexing process (initial scan and starts watcher).
 	 * Automatically recovers from error state if needed before starting.

src/services/code-index/processors/__tests__/scanner.spec.ts

@@ -220,6 +220,36 @@ describe("DirectoryScanner", () => {
 			expect(mockVectorStore.upsertPoints).toHaveBeenCalled()
 		})
 
+		it("should clean up a threshold-triggered batch", async () => {
+			const thresholdScanner = new DirectoryScanner(
+				mockEmbedder,
+				mockVectorStore,
+				mockCodeParser,
+				mockCacheManager,
+				mockIgnoreInstance,
+				1,
+			)
+			const { listFiles } = await import("../../../glob/list-files")
+			vi.mocked(listFiles).mockResolvedValue([["test/file1.js"], false])
+			mockCodeParser.parseFile.mockResolvedValue([
+				{
+					file_path: "test/file1.js",
+					content: "test content",
+					start_line: 1,
+					end_line: 5,
+					identifier: "test",
+					type: "function",
+					fileHash: "hash",
+					segmentHash: "threshold-segment",
+				},
+			])
+
+			await thresholdScanner.scanDirectory("/test")
+
+			expect(mockEmbedder.createEmbeddings).toHaveBeenCalledTimes(1)
+			expect(mockVectorStore.upsertPoints).toHaveBeenCalledTimes(1)
+		})
+
 		it("should delete points for removed files", async () => {
 			;(mockCacheManager.getAllHashes as any).mockReturnValue({ "old/file.js": "old-hash" })
 

src/services/code-index/processors/scanner.ts

@@ -216,10 +216,11 @@ export class DirectoryScanner implements IDirectoryScanner {
 										activeBatchPromises.add(batchPromise)
 
 										// Clean up completed promises to prevent memory accumulation
-										batchPromise.finally(() => {
+										const cleanupBatch = () => {
 											activeBatchPromises.delete(batchPromise)
 											pendingBatchCount--
-										})
+										}
+										void batchPromise.then(cleanupBatch, cleanupBatch)
 									}
 								} finally {
 									release()
@@ -306,10 +307,11 @@ export class DirectoryScanner implements IDirectoryScanner {
 				activeBatchPromises.add(batchPromise)
 
 				// Clean up completed promises to prevent memory accumulation
-				batchPromise.finally(() => {
+				const cleanupBatch = () => {
 					activeBatchPromises.delete(batchPromise)
 					pendingBatchCount--
-				})
+				}
+				void batchPromise.then(cleanupBatch, cleanupBatch)
 			} finally {
 				release()
 			}

src/services/mcp/McpHub.ts

@@ -176,7 +176,9 @@ export class McpHub {
 		if (secretStorage) {
 			this.secretStorage = secretStorage
 		}
-		this.watchMcpSettingsFile()
+		void this.watchMcpSettingsFile().catch((error) => {
+			console.error("[McpHub] Failed to watch MCP settings file:", error)
+		})
 		this.watchProjectMcpFile().catch(console.error)
 		this.setupWorkspaceFoldersWatcher()
 		this.initializationPromise = Promise.all([

src/services/mcp/__tests__/McpHub.spec.ts

@@ -10,6 +10,10 @@ import { ServerConfigSchema, McpHub } from "../McpHub"
 import { OAUTH_FLOW_TIMEOUT_MS } from "../constants"
 import { t } from "../../../i18n"
 
+type McpHubPrivate = {
+	watchMcpSettingsFile: () => Promise<void>
+}
+
 // Mock fs/promises before importing anything that uses it.
 // Named exports and the default export must share the same vi.fn() instances so that
 // `import * as fs` (used by McpHub.ts) and `import fs` (default) both see the same mocks.
@@ -192,6 +196,22 @@ describe("McpHub", () => {
 		}
 	})
 
+	it("should log settings watcher startup failures", async () => {
+		const watcherError = new Error("watcher startup failed")
+		const watchSpy = vi
+			.spyOn(McpHub.prototype as unknown as McpHubPrivate, "watchMcpSettingsFile")
+			.mockRejectedValueOnce(watcherError)
+		vi.mocked(console.error).mockClear()
+
+		const failingHub = new McpHub(mockProvider as ClineProvider)
+		await failingHub.waitUntilReady()
+		await Promise.resolve()
+
+		expect(console.error).toHaveBeenCalledWith("[McpHub] Failed to watch MCP settings file:", watcherError)
+		await failingHub.dispose()
+		watchSpy.mockRestore()
+	})
+
 	describe("Discriminated union type handling", () => {
 		it("should create connected connections with proper type", async () => {
 			// Mock StdioClientTransport
@@ -2526,7 +2546,7 @@ describe("McpHub", () => {
 			})
 
 			mockSecretStorage.onDidChange.mockImplementation((_key: string, cb: () => void) => {
-				Promise.resolve().then(() => {
+				queueMicrotask(() => {
 					mockSecretStorage.getOAuthData.mockResolvedValue({
 						expires_at: Date.now() + 10 * 60 * 1000,
 					})
@@ -2811,7 +2831,7 @@ describe("McpHub", () => {
 			})
 
 			mockSecretStorage.onDidChange.mockImplementation((_key: string, cb: () => void) => {
-				Promise.resolve().then(() => {
+				queueMicrotask(() => {
 					// Dispose the hub before the token callback runs
 					;(mcpHub as any).isDisposed = true
 					mockSecretStorage.getOAuthData.mockResolvedValue({