What is the 'Neural Link'?

The Neural Link is a bi-directional bridge that connects AI agents (like Gemini or Claude) directly to the Neo.mjs runtime. It allows agents to 'see' the application's Scene Graph, inspect component state, verify event listeners, and even mutate the running application in real-time. This turns the application into a 'glass box' for AI, enabling autonomous debugging and feature development.

Why is Neo.mjs called an 'Application Engine' instead of a framework?

Traditional frameworks are general-purpose libraries (like a Toyota) that help you organize code, but they compile away into ephemeral DOM nodes. Neo.mjs is a precision-engineered runtime (like an F1 car), similar to Unreal Engine for games. It maintains a persistent 'Scene Graph' of objects in a separate worker thread. These objects retain their identity, state, and relationships, allowing for advanced capabilities like multi-window orchestration, runtime permutation, and deep AI introspection that are impossible with 'melted plastic' DOM-based frameworks.

What is 'Context Engineering'?

Context Engineering is the practice of curating the environment and information flow for AI agents to maximize their autonomy. In Neo.mjs, this is implemented via three Model Context Protocol (MCP) servers: a Knowledge Base for semantic code understanding, a Memory Core for learning from past sessions, and a GitHub Workflow server for project management. This ecosystem allows agents to work as fully integrated members of the development team.

What is 'Object Permanence' in the context of Neo.mjs?

In Neo.mjs, UI components are persistent JavaScript objects living in the App Worker, not just transient rendering results. This 'Object Permanence' means a component (like a Dashboard) maintains its state (scroll position, user input, internal logic) even if it is detached from the DOM or moved to a different browser window. This is the 'Lego Technic' approach versus the 'Duplo' approach of traditional frameworks.

What is an 'Agent Operating System'?

Neo.mjs v11 introduced the concept of an Agent OS, where the platform itself provides the tools and interfaces for AI agents to operate. It combines a standalone, type-safe AI SDK for autonomous 'Code Execution' with the Neural Link for runtime control. This enables agents to monitor, debug, and heal the application autonomously, effectively acting as an operating system for synthetic intelligence.

How does Neo.mjs handle multi-window applications?

Neo.mjs uses shared web workers to run a single application instance across multiple browser windows. All windows share the same application state and data in real-time. Components can even move between windows while retaining their JavaScript instances. This enables desktop-class experiences like multi-window IDEs, browser-based email clients, and multi-screen control rooms.

What makes Neo.mjs different from React, Angular, or Vue?

Neo.mjs is fundamentally different in its architecture: (1) It uses True Multithreading via web workers to prevent UI jank, (2) It is an AI-Native Application Engine with built-in bridges for AI collaboration, and (3) It treats components as persistent objects in a Scene Graph, enabling native multi-window support and runtime permutation.

Frontmatter

id	8829
title	Fix VDOM Merge Race Condition during In-Flight Updates
state	Closed
labels	bugaitestingcore
assignees	tobiu
createdAt	Jan 20, 2026, 5:03 PM
updatedAt	Jan 20, 2026, 5:05 PM
githubUrl	https://github.com/neomjs/neo/issues/8829
author	tobiu
commentsCount	1
parentIssue	null
subIssues	[]
subIssuesCompleted	0
subIssuesTotal	0
blockedBy	[]
blocking	[]
closedAt	Jan 20, 2026, 5:05 PM

Fix VDOM Merge Race Condition during In-Flight Updates

Name: Neo.mjs Application Engine
Author: Neo.mjs

Closed v11.23.0 bugaitestingcore

tobiu commented on Jan 20, 2026, 5:03 PM

This ticket addresses a race condition where child components correctly registered for a merged update, but their request was lost if the parent component was already in the middle of executing its update cycle.

The Problem:

Parent starts a VDOM update (isVdomUpdating = true).
Parent captures the current list of merged children (getMergedChildIds).
Child (running in parallel) attempts to update. It sees the Parent is updating and registers itself to be merged (mergeIntoParentUpdate).
Parent finishes its update cycle. resolveVdomUpdate calls executeCallbacks.
Critically, executeCallbacks blindly cleared all pending merges for that parent, assuming they were all handled.
The Child's "late" merge request (which was not in the Parent's initial snapshot) was deleted without being processed.

The Solution:

Snapshot Tracking: VdomLifecycle.executeVdomUpdate now captures the exact set of child IDs included in the update payload.
Precise Resolution: This snapshot is passed to resolveVdomUpdate and then VDomUpdate.executeCallbacks.
Selective Clearing: executeCallbacks now only removes the specific child IDs that were actually processed. Any new merge requests that arrived during the in-flight window are preserved.
Automatic Recovery: The preserved merge requests trigger the needsVdomUpdate flag on the parent (or remain pending), ensuring they are picked up in the next update cycle.

Additional Fixes:

Fixed VdomLifecycle.spec.mjs test expectation: A component hidden with removeDom correctly has mounted: false.

Verification:

RaceCondition.spec.mjs passes all tests.
VdomLifecycle.spec.mjs passes all tests.
RealWorldUpdates.spec.mjs passes all tests.

tobiu added the bug label on Jan 20, 2026, 5:03 PM

tobiu added the ai label on Jan 20, 2026, 5:03 PM

tobiu added the testing label on Jan 20, 2026, 5:03 PM

tobiu added the core label on Jan 20, 2026, 5:03 PM

tobiu referenced in commit 74e4742 - "fix: VDOM Merge Race Condition during In-Flight Updates (#8829)" on Jan 20, 2026, 5:05 PM

tobiu assigned to @tobiu on Jan 20, 2026, 5:05 PM

tobiu Jan 20, 2026, 5:05 PM

Input from Gemini 3 Pro:

✦ I have implemented the fix for the race condition where merged child updates were lost if the parent was already executing an update.

Changes:

src/mixin/VdomLifecycle.mjs:

Updated executeVdomUpdate to capture the mergedChildIds used for the current update cycle.

Passed this snapshot to resolveVdomUpdate.

src/manager/VDomUpdate.mjs:

Updated executeCallbacks to accept the processedChildIds snapshot.

It now selectively removes only the processed child IDs from the mergedCallbackMap, ensuring that any new merges that arrived during the update execution are preserved for the next cycle.

test/playwright/unit/vdom/VdomLifecycle.spec.mjs:

Corrected the test expectation for vnode should PERSIST when component is hidden (removeDom). mounted should be false when hidden via removeDom.

Verification:

test/playwright/unit/vdom/RaceCondition.spec.mjs: All 4 tests passed.

test/playwright/unit/vdom/VdomLifecycle.spec.mjs: All tests passed.

test/playwright/unit/vdom/RealWorldUpdates.spec.mjs: All 8 tests passed.

This ensures robust VDOM update merging even under heavy parallel load.

tobiu closed this issue on Jan 20, 2026, 5:05 PM