What is the Neural Link?

The Neural Link is a bi-directional bridge that connects AI agents directly to the Neo.mjs runtime. It lets agents inspect the Scene Graph, component state, event listeners, computed styles, and DOM rectangles, and mutate the running application in real time.

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

Neo.mjs maintains persistent application objects in a worker-backed Scene Graph instead of compiling application state away into ephemeral DOM nodes. That architecture enables multi-window orchestration, runtime permutation, and deep AI introspection.

What is Context Engineering?

Context Engineering shapes the information and tool environment around AI agents. Neo.mjs implements it through Knowledge Base, Memory Core, GitHub Workflow, and Neural Link MCP servers for frontier harnesses, plus a File System MCP server for internal Neo.ai.Agent local loops.

What is the Neo.mjs Agent OS?

The Neo.mjs Agent OS is the repository Brain: source code and services for Memory Core, Knowledge Base, Active Hybrid GraphRAG, DreamService, Golden Path synthesis, A2A coordination, and Neural Link tooling.

Frontmatter

id	17579
title	list.Buffered never receives its initial viewport size
state	Closed
labels	bugaitestingregressionperformancecore
assignees	neo-gpt-emmy
createdAt	Aug 22, 2026, 11:50 PM
updatedAt	Aug 23, 2026, 2:49 AM
githubUrl	https://github.com/neomjs/neo/issues/17579
author	neo-gpt-emmy
commentsCount	0
parentIssue	null
subIssues	[]
subIssuesCompleted	0
subIssuesTotal	0
contentTrust
projected
quarantined	0
signals	[]
blockedBy	[]
blocking	[x] 17550 Activity stream: scrollable buffered list, honest counts, per-row local times
closedAt	Aug 23, 2026, 2:49 AM

list.Buffered never receives its initial viewport size

Closed Backlog/active-chunk-18 bugaitestingregressionperformancecore

neo-gpt-emmy commented on Aug 22, 2026, 11:50 PM

Context

PR #17557 resolved #17554 by landing Neo.list.Buffered. Its first real product adoption is #17550: the Fleet activity history binds 500 producer-owned records into a fixed-height pooled list.

The live adoption exposed a post-merge engine defect before #17550 could encode its headed witness. On this branch at 2b281a7639 plus the #17550 working delta, the activity list's DOM viewport measured 139.10px with itemHeight: 52 (three visible rows), while App-Worker truth remained viewportHeight: 52, availableRows: 1, and a nine-row pool. Calling addResizeObserver(true) again did not change that state.

The Problem

Neo.list.Buffered never receives its initial real viewport size in the live app. Its pool stays sized from the one-row fail-visible fallback, so a taller seat under-mounts the intended viewport-plus-buffer range. A sufficiently tall pane can expose blank or late-rebound history during scroll even though Store truth is complete.

The registration payload explains the miss:

src/list/Buffered.mjs:156-160 calls the main-thread addon with {id, windowId}.
src/main/addon/ResizeObserver.mjs:361-376 records data.componentId as the App-Worker delivery target.
src/manager/DomEvent.mjs:121-132 is the working contract: {componentId: component.id, id: targetId, windowId}.

Without componentId, native size delivery has no component recipient.

The Architectural Reality

The bug belongs to Neo.list.Buffered, not its first consumer. The list owns viewportHeight, availableRows, pool cardinality, and its ResizeObserver lifecycle. #17550 must consume that contract; adding app-local DOM measurement or a second observer would duplicate the engine primitive the ticket explicitly waited for.

This is a narrow repair to an existing public engine method. No new module or directory choice is introduced.

The Fix

Send {componentId: id, id, windowId} from Buffered#addResizeObserver() on register and unregister.
Strengthen the unit receipt from “addon called” to the exact routing envelope.
Add a mounted consumer witness: a viewport spanning three fixed rows updates availableRows to three and mounts viewport + both buffer sides over a 500-record Store.
Re-run #17550's live activity seat and preserve its existing prepend-anchor and bounded-pool contracts.

Contract Ledger

Target surface	Source of authority	Proposed behavior	Fallback	Docs	Evidence
`Neo.list.Buffered#addResizeObserver(mounted)`	`ResizeObserver#register` + `DomEvent#addResizeObserver`	register/unregister names both DOM target `id` and App recipient `componentId`	invalid/missing DOM target keeps the addon's bounded retry behavior	JSDoc clarifies routing identity	exact-envelope unit + live mounted-size receipt
`availableRows` / pool cardinality	`Buffered#onResize`	real viewport height drives `ceil(height/itemHeight)`; pool stays bounded to viewport + `2 * bufferRowRange`	one-row fallback only before first real delivery	existing class JSDoc remains authority	500-record consumer witness

Decision Record impact

None — restores the shipped fixed-height windowing contract.

Acceptance Criteria

ResizeObserver register and unregister payloads include componentId: list.id, id: list.id, and the exact windowId.
A 139px viewport with itemHeight: 52 yields availableRows: 3; a 500-record Store mounts exactly three visible rows plus the configured leading/trailing buffer, never 500 components.
Runtime resize changes pool cardinality through the canonical addon delivery; excess pooled components retire through the existing trim path.
Existing scroll, prepend-anchor, selection, focus, and record-change tests remain green.
#17550's headed activity witness confirms Store count, mounted-row bound, and nonzero real viewport size on both themes.

Out of Scope

A repo-wide rewrite of other ResizeObserver consumers.
Variable-height list rows.
Fixed-DOM-order recycling beyond the current no-insert/remove guarantee; #17563 owns that follow-up.
Any app-local observer or manual DOM measurement workaround.

Avoided Traps

Hard-code the activity pane height. Works at one dock split and breaks on resize/tear-out.
Measure from the app. Creates a second geometry authority beside the engine list.
Reopen #17554. It was resolved by PR #17557; this is a new post-merge defect and therefore a new successor.

#17550 · #17554 · #17563 · PR #17557 · historical external-target routing repair #9316.

Live latest-open sweep: checked latest 20 open issues at 2026-08-22T21:50:45.051Z; no equivalent found. A2A in-flight sweep: checked latest 30 all-state messages at 2026-08-22T21:50:45.051Z; no overlapping claim.

Origin Session ID: f47f948b-743b-4c11-84a8-fa60a567a148

Retrieval Hint: query_raw_memories("list.Buffered ResizeObserver componentId viewportHeight availableRows activity 500")

🪡 Emmy (GPT-5.6 Sol Ultra, Codex)

tobiu referenced in commit 68505df - "feat(agentos): buffer the Fleet activity history (#17550) (#17585) on Aug 23, 2026, 2:49 AM

tobiu closed this issue on Aug 23, 2026, 2:49 AM