WebMCP: AI Functionality for the Browser
Blink2866 Marras 2025

WebMCP: AI Functionality for the Browser

The provided sources introduce and detail WebMCP (Web Model-Context Protocol), an emerging web standard designed to enable seamless, structured communication between AI agents (like LLM-based assistants) and web pages. Building upon the broader Model Context Protocol (MCP) standard, WebMCP allows web developers to expose specific front-end JavaScript functions as "tools" that AI agents can invoke directly, moving away from brittle UI scraping or simulation. The text examines the technical implementation, primarily within the Chromium (Blink) engine, describing the required JavaScript API surface, browser-side registry, and security protocols requiring explicit user consent to ensure safe human-in-the-loop collaboration. Finally, the sources outline use cases, such as reliable form filling and improved accessibility, while noting that the protocol is in the incubation and W3C standardization stage.

Jaksot(417)

blink::PrePaintTreeWalk

blink::PrePaintTreeWalk

cross‑frame pre‑paint traversal. Runs in the InPrePaint lifecycle phase. Walks the entire layout tree starting at the root LocalFrameView, updating paint invalidation state and computing the context n...

10 Loka 202531min

blink::NGPhysicalFragment and friends

blink::NGPhysicalFragment and friends

Layout takes the styled DOM and produces a fragment tree of positioned boxes. In modern Blink this is LayoutNG; the core artifact is NGPhysicalFragment, which stores geometry and is used downstream fo...

10 Loka 202537min

blink::StyleEngine

blink::StyleEngine

style invalidation & resolution (recalc). 
Given DOM/style changes since the last frame, StyleEngine computes updated ComputedStyles, manages active stylesheets/media query state, and marks the right ...

10 Loka 202534min

blink::Document & blink::DocumentLifecycle

blink::Document & blink::DocumentLifecycle

states that gate phases. The document owns the DOM and keeps a DocumentLifecycle state machine that ensures we do things in phase order (style before layout, pre‑paint before paint, etc.). Lifecycle t...

10 Loka 202535min

blink::LocalFrameView

blink::LocalFrameView

orchestrates style → layout → pre‑paint/paint for a frame. This is the workhorse that actually runs lifecycle phases. On a frame tick from WebFrameWidgetImpl, it goes through style recalc, layout (Lay...

9 Loka 202544min

blink::LocalFrame

blink::LocalFrame

the document host and local‑root boundary.
The local frame owns the Document and its LocalFrameView. The local root frame coordinates lifecycle for its subtree (including OOPIF boundaries handled late...

9 Loka 202532min

blink::Page

blink::Page

the page container and animation clock keeper. Page holds frame trees and the PageAnimator that services script‑driven animations on each tick. It’s the top‑level context for the document/view that We...

9 Loka 202534min

blink::WebFrameWidgetImpl

blink::WebFrameWidgetImpl

renderer‑main entry to Blink’s lifecycle. This is where a compositor BeginFrame (coming in via content/public and mojo plumbing) first turns into Blink work on the renderer main thread. It receives th...

9 Loka 202532min