refactor: use NotificationQueue for async LS notification handlers [IDE-1661]

[nick-y-snyk]

Summary

Refactors LanguageServer notification handlers to use a NotificationQueue for sequential async processing, eliminating race conditions and enabling proper async/await handling.

Changes

NotificationQueue (new)

• Implements sequential FIFO processing of async operations
• Uses promise chaining to ensure notifications are processed in order
• Handles errors gracefully without stopping the queue
• Supports graceful shutdown in LanguageServer.stop()

LanguageServer

• Wraps SNYK_HAS_AUTHENTICATED, SNYK_FOLDERCONFIG, and SNYK_ADD_TRUSTED_FOLDERS notifications with NotificationQueue
• Makes handleOrgSettingsFromFolderConfigs async and processes folder configs sequentially with for-loop instead of forEach
• Replaces .then()/.catch() chains with proper async/await
• Removes TODOs about awaiting calls when LS client supports async handlers

scopeDetectionService

• Renames isSettingsWithDefaultValue to shouldSkipSettingUpdate for clarity
• Adds check to skip updates when new value equals current effective value (prevents redundant writes)

Tests

• Adds comprehensive NotificationQueue tests (288 lines)
• Updates LanguageServer tests to await async handleOrgSettingsFromFolderConfigs calls
• Adds missing outputChannel mocks and restores sinon.verify() calls

Benefits

• Race condition prevention: Sequential processing ensures notifications don't interfere with each other
• Proper async handling: Can now await async operations in notification handlers
• Better error handling: Errors in one notification don't prevent others from processing
• Graceful shutdown: Queue drains before LS stops

Test Plan

• Unit tests pass (NotificationQueue + LanguageServer)
• Integration tests pass
• Manual testing of folder config notifications
• Manual testing of authentication flow

[snyk-io]

✅ Snyk checks have passed. No issues have been found so far.

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✅	Code Security	0	0	0	0	0 issues

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[gemini-code-assist]

Summary of Changes

Hello @nick-y-snyk, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a critical bug where rapid interaction with the auto organization setting in the HTML settings UI could lead to an infinite loop of configuration updates. This was due to a race condition between different components attempting to write to the same configuration simultaneously. The fix introduces a robust asynchronous processing queue and refined logic for configuration updates to prevent these circular dependencies and ensure stable behavior, significantly improving the reliability of configuration management.

Highlights

• Infinite Loop Fix: Resolved an infinite loop issue occurring when rapidly toggling the auto organization checkbox in the HTML settings page, caused by circular updates between the HTML autosave and ConfigurationWatcher.
• Asynchronous Notification Queue: Introduced a new NotificationQueue class to process asynchronous Language Server notification handlers sequentially, preventing race conditions and ensuring stable configuration updates.
• Sequential Folder Configuration Processing: Refactored handleOrgSettingsFromFolderConfigs to be asynchronous and process folder configurations one by one, eliminating potential race conditions during settings application.
• Optimized Setting Updates: Enhanced scopeDetectionService.shouldSkipSettingUpdate to prevent unnecessary configuration writes by checking if the new value is identical to the current effective value or if it's the default and not explicitly set.
• Comprehensive Testing: Added extensive unit tests for the new NotificationQueue to validate its sequential processing, error handling, and graceful shutdown capabilities.

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[gemini-code-assist]

Code Review

This pull request introduces a robust solution to prevent an infinite loop when toggling settings. The core of the fix is the new NotificationQueue, which serializes asynchronous operations coming from the language server, preventing race conditions. The implementation of the queue is well-designed and comes with a comprehensive set of unit tests. Additionally, the logic for updating settings has been improved to avoid redundant writes, further contributing to stability. The related refactoring from promise-based chains to async/await improves code readability and maintainability. I have a couple of suggestions to further improve the code quality, but overall this is a great set of changes.

[gemini-code-assist]

Using Date.now() for unique IDs is not fully reliable, as multiple notifications could arrive within the same millisecond, leading to duplicate IDs. This can make tracing and debugging difficult. To improve uniqueness, consider appending a random number. A similar change should be applied to other enqueue calls in this file (lines 252 and 270).

Suggested change

	id: `authenticated-${Date.now()}`,
	id: `authenticated-${Date.now()}-${Math.random()}`,

[gemini-code-assist]

The enqueue method is marked as async but doesn't use await, which can be slightly misleading as it resolves immediately. Since the method's logic is synchronous, you can remove the async keyword and change the return type to void to more accurately reflect its behavior. Note that this would require removing the await from calls to this method in the corresponding test file.

Suggested change

	async enqueue<T>(item: QueueItem<T>): Promise<void> {
	enqueue<T>(item: QueueItem<T>): void {