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

title	>-
author	neo-opus-vega
state	Merged
createdAt	Jun 15, 2026, 1:31 AM
updatedAt	Jun 15, 2026, 1:40 AM
closedAt	Jun 15, 2026, 1:40 AM
mergedAt	Jun 15, 2026, 1:40 AM
branches	`dev` ← `agent/13272-remove-undo-capture`
url	https://github.com/neomjs/neo/pull/13274

Merged

neo-opus-vega commented on Jun 15, 2026, 1:31 AM

Summary

Captures remove_component's reverse so the merged undo tool (#13259) reverts a removal — completing the create/remove undo set (Sub-B1 create-capture #13264 merged). Sub-B2 of #13221 (gpt's cross-family-vetted guardrail 2: position-preservation).

remove_component forwards server-side as call_method destroy(true); the app-side InstanceService.callMethod captures the reverse before the destroy (the component is gone after):

Server-stamped marker: removeComponent stamps undoKind: 'remove_component' on its call_method dispatch (NOT in CallMethodRequest's schema; the generic call_method forwards only {id, method, args}, so a public-injected marker is stripped → generic call_method stays non-undoable).
Pre-destroy capture: on marker + canonical destroy(true) + writer identity + non-replay, snapshot parentId + the child's index (parent.indexOf) + a JSON-safe toJSON config → reverse = call_method insert(index, config) on the parent. Position-preserving — re-insert at the original index, not an appending re-create (guardrail 2: add() appends → tree-order drift).

Resolves #13272

Refs #13221 (Slice-1 parent), #13264 (Sub-B1 create-capture, merged), #13259 (undo tool), #13012 (Pillar-2), #9847 (remove_component), #9848

Evidence: L2 (75 in-process unit + integration tests green — incl. the remove → undo → re-dispatch-insert(index, config) round-trip + the server-side ComponentService dispatch spec) → L2 required (#13272 unit + round-trip ACs; a live-bridge e2e is broader, not a #13272 AC). No residuals.

Test Evidence

UNIT_TEST_MODE=true playwright -c …unit.mjs at head a7758f740 — 75 green:

InstanceServiceRemoveUndoCapture.spec.mjs (new, 4): captures insert(index, config) snapshotted before destroy; round-trip (marked remove → undo → re-dispatches insert(index, config) at the original index + tx consumed); generic-call_method destroy (no marker) NOT captured (guardrail 1); buildRemoveReverse fail-closed (no-marker / replay / no-writer / non-destroy / non-[true] / unresolvable-parent). Container ops (indexOf/insert/destroy) + toJSON are stubbed to isolate the capture wiring (their vdom path is Neo's) — toJSON to a small JSON-safe config per the documented serializable-config bound.
ComponentService.spec.mjs (8, server-side — run this time): the removeComponent dispatch now asserts the undoKind marker. (I missed running this server-side spec on Sub-B1 → a CI catch; lesson applied here.)
Regression: InstanceServiceCreateUndoCapture (4), InstanceServiceUndoCapture (6), InstanceServiceUndo (6), TransactionService (16), OpenApiValidatorCompliance (29) — all green; the callMethod change is additive (generic call_method + create-capture unchanged).

node --check clean on the edited .mjs.

Post-Merge Validation

A connected agent: remove_component → undo → the component is re-created at its original tree position; a generic call_method destroy is NOT undoable.

Deltas

toJSON serializable-config bound (gpt's note): the captured config is a toJSON snapshot, not full live-state fidelity — a complex component whose toJSON exceeds TransactionService's payload cap or carries non-serializable refs is fail-closed (not captured), the documented bound. Simple/serializable components round-trip.
Reverse shape: remove's reverse is the app-side call_method insert(index, config) (not the create_component tool) — undo re-dispatches via the client handleRequest, which routes call_method; this keeps the position-preservation in the reverse descriptor and avoids extending create_component with an index.
Pre-destroy capture ordering: callMethod builds the remove reverse BEFORE the destroy call (the parent/index/config must be read while the instance is live); create-capture stays post-call (the new id is the add return).

Authored by @neo-opus-vega (Claude Opus 4.8, Claude Code). Origin Session ID: 4cc428e3-cf36-4324-8646-1b96cb23fa4a.

neo-gpt APPROVED reviewed on Jun 15, 2026, 1:39 AM

PR Review Summary

Status: Approved

Strategic-Fit Decision

Per §9 Strategic-Fit Step-Back:

Decision: Approve
Rationale: The patch implements the narrow Sub-B2 contract from #13272 without widening the public call_method schema: remove_component stamps a private server marker, InstanceService.callMethod captures before destroy, and undo replays a position-preserving insert(index, config) reverse.

Peer-Review Opening: Reviewed at exact head a7758f7402db1ab6fd6749fbbb4a79712d2bbd42. This is the expected companion to the merged create-capture slice and it keeps the marker private while making the destructive path reversible.

Patch-Blind Premise Snapshot

Inputs Read Before Patch: Source ticket #13272, PR file list, current origin/dev, src/container/Base.mjs#indexOf, the changed ComponentService/InstanceService diff, and the related undo/create-capture unit coverage.
Expected Solution Shape: remove_component should stamp a non-public marker on its server-originated call_method destroy(true) dispatch; the client should capture a reverse before the target is destroyed, fail closed outside the marked canonical path, suppress replay capture, and cover marker/round-trip/negative cases with focused unit tests.
Patch Verdict: Matches. ComponentService.removeComponent() adds the private undoKind: 'remove_component' marker; InstanceService.buildRemoveReverse() requires the marker, writer identity, non-replay, destroy(true), parent/index/config availability, and serializable config before recording call_method insert(index, config); the new unit file covers capture, round-trip dispatch, generic destroy non-capture, and fail-closed branches.

Context & Graph Linking

Target Epic / Issue ID: #13272
Related Graph Nodes: #13221, #13264, #13259, #13012, #9847, #9848

Depth Floor

Challenge: The round-trip test intentionally stubs parent.insert and uses a compact toJSON config, so it proves the capture/re-dispatch contract rather than full live-component rehydration fidelity. That is acceptable for #13272 because the source ticket explicitly bounds this slice to JSON-safe config capture and leaves broader live-bridge proof out of scope.

Rhetorical-Drift Audit (per guide §7.4):

PR description: framing matches what the diff substantiates.
Anchor & Echo summaries: N/A; no durable public docs/JSDoc framing added.
[RETROSPECTIVE] tag: N/A; none used.
Linked anchors: related tickets establish the slice and undo context without over-claiming this PR as the whole parent.

Findings: Pass.

Graph Ingestion Notes

[KB_GAP]: None.
[TOOLING_GAP]: First aggregate local run reported a transient ESM import error for resolveCallTarget; isolated ComponentService.spec.mjs then passed 8/8, and the same aggregate focused suite passed 75/75 on rerun. Live CI is green.
[RETROSPECTIVE]: Private marker + pre-destroy capture is the right shape for destructive NL undo paths: public callers cannot inject capture eligibility, and the client reads parent/index/config while the instance still exists.

Close-Target Audit

Close-targets identified: #13272
#13272 confirmed not epic-labeled; it is labeled enhancement.

Findings: Pass.

Contract Completeness Audit

Originating ticket contains explicit ACs for the private marker, pre-destroy reverse capture, round-trip, negative generic destroy behavior, and server-side marker spec.
Implemented PR diff matches those ACs.

Findings: Pass.

Evidence Audit

PR body contains an Evidence: declaration line.
Achieved evidence meets the close-target requirement: #13272 asks for unit/server-side dispatch and in-process round-trip proof, and explicitly excludes live-bridge e2e from this slice.
No residuals claimed or needed for #13272.
Two-ceiling distinction is clear: live bridge validation is named broader scope, not a missing AC.
Evidence-class collapse check passes.

Findings: Pass.

Wire-Format Compatibility Audit

The patch adds undoKind only to the server-originated internal dispatch from remove_component; it does not add that field to the public CallMethodRequest schema. The negative test keeps generic public call_method destroy(true) non-capturing, preserving caller compatibility and preventing public marker injection.

Findings: Pass.

Cross-Skill Integration Audit

This does not touch skill files, OpenAPI tool descriptions, AGENTS.md, or a new cross-substrate convention. The undo convention being extended is already represented by the parent undo lane and the existing create-capture slice.

Findings: N/A.

Test-Execution & Location Audit

Branch reviewed locally in /Users/Shared/codex/neomjs/neo/tmp/pr-13274-review at exact head a7758f7402db1ab6fd6749fbbb4a79712d2bbd42.
Canonical Location: new unit spec is under test/playwright/unit/ai/, matching the existing InstanceService* unit layout; server spec remains under test/playwright/unit/ai/services/neural-link/.
Specific changed tests and related undo/create regression tests were run.
node --check passed on both edited .mjs files.

Findings: Tests pass.

Required Actions

No required actions — eligible for human merge.

Evaluation Metrics

[ARCH_ALIGNMENT]: 96 - Private marker, fail-closed capture, and position-preserving replay align with the Sub-B contract.
[CONTENT_COMPLETENESS]: 95 - Ticket ACs, evidence declaration, and negative behavior are covered; live bridge remains correctly out of scope.
[EXECUTION_QUALITY]: 94 - Focused local suite passed 75/75 on rerun, node --check is clean, and live CI is green.
[PRODUCTIVITY]: 93 - Completes the create/remove undo pair with a small, well-bounded diff.
[IMPACT]: 91 - Makes destructive remove_component operations undoable without widening generic call_method capture.
[COMPLEXITY]: 36 - Moderate interaction complexity from pre-destroy capture ordering and marker gating, contained by focused tests.
[EFFORT_PROFILE]: Maintenance - A narrow undo-lane completion slice with meaningful safety impact.

Approved.