Tear-out staging drops a sibling tab into the source body and hides the source transition

Context

The #16498 revalidation at current dev base 0d5f8172d8 used the Workstation app's real-pointer executeTearOutStep path at the documented flagship-film stage: outer 1280x800, inner 1280x713. The rAF sampler recorded two deterministic source-region failures before the production repair: 192 frames with the Audit tab outside its toolbar and 87 frames with no resident content or explicit transition state in the connected source body.

The same failures are adjacent to, but not evidence-equivalent to, #16498's historical Take 18 F7 composition. That exact kicker-present/resident-missing composition remains on #16498; this leaf owns only the two independently reproduced staging failures so a PR does not falsely close the broader original report.

Live duplicate sweep on 2026-08-08 covered the latest 30 open issues plus all-state searches for tear-out source presentation, Audit tab toolbar drag, and dock vessel placeholder hidden. #16498 was the only overlap, and this ticket records the explicit split boundary.

The Problem

During a real window tear-out gesture, the source region loses presentational continuity in two independent ways:

1. The surviving Audit tab can be positioned relative to the wrong containing block and paint inside the live Metrics body instead of remaining in the toolbar.
2. When the live Metrics pane moves into the vessel, DockVesselEmbodiment leaves a hidden placeholder in its source slot. Until the dock document settles onto Audit, the connected source body therefore presents a black void with no explanation of the transient ownership.

Both are visible flagship-film defects. Neither is a post-settlement config/vdom/DOM reconciliation failure; the defect exists only while the gesture is in flight, so a settled programmatic detachItem probe cannot answer it.

The Architectural Reality

• Neo.dashboard.DockTabSortZone inherits the generic tab-header drag coordinates. Dock headers leave normal flow during the gesture, so measured viewport rectangles must be rebased to the toolbar and the toolbar must establish the containing block. Either half alone leaves an ancestor-origin offset.
• createDockVesselEmbodiment() intentionally preserves the exact source card index while the live pane renders in the vessel. That placeholder is therefore the correct owner of source-slot presentation during staging; hiding it turns a sound identity-preservation transaction into a visible void.
• The dock document and pane identity contracts remain unchanged. This is render-topology restoration at the two existing owners, not an app-layer workaround.

The Fix

• Enable parent-adjusted item rectangles and owner-relative positioning on DockTabSortZone.
• Keep the source placeholder visible as an explicit role=status loading state with the message Moving pane to another window….
• Add one headed Neural Link witness that samples every presented frame through both plain and film gesture pacing, plus unit pins for the inherited configs and placeholder semantic.

Acceptance Criteria

• Attribution run against pre-fix production base 0d5f8172d8 proves the real-pointer witness red for both toolbar escape and source void.
• At outer 1280x800 / inner 1280x713, the Audit tab remains inside its source toolbar on every presented frame for plain and film gesture pacing, allowing only a bounded subpixel/border tolerance.
• While the source body remains connected and presented, every sampled frame contains either resident content or the visible role=status transition message.
• Vessel birth and commit succeed with zero page errors in both profiles.
• Unit coverage pins the two dock-header coordinate configs and the visible status-placeholder contract.

Out of Scope

• #16498's exact historical Take 18 F7 internal-card composition; that issue stays open until its own evidence boundary is resolved.
• The resident-card minimum-height degradation tracked by #16716.
• Conversion-boundary timing (#16497), re-entry embodiment, or broader docking choreography.
• Human whole-film aesthetic acceptance.

Decision Record impact

None. This restores presentation inside the landed dock tear-out and vessel-embodiment contracts.

Related

#16498, #15252, #13158, #16716

Origin Session ID: 019fe0b3-53bc-7ef2-8665-41a0ef3f7b62

Retrieval Hint: query_raw_memories("tear-out staging source tab toolbar hidden vessel placeholder 1280x713")