Carry whole popup stacks through native return and the film cue

Context

Sub of #19126, within the #15252 film. The agreed visual sequence puts Metrics and Commits in one committed popup, then moves that native window across the main workspace's animated targets and brings the whole stack home. Mnemosyne owns the screenplay/production record and explicitly confirmed this implementation fork belongs to Emmy.

The Problem

At Engine 2d993a26cbabf840e339b65094d8e1cb8d1da543, Participation.defaultResolveNativeWindowDrag rejects every registered popup with more than one catalog item, then clears group/source-node metadata on the singleton path. An exact-method probe admits the Metrics-only owner pane and returns null for the same registered vessel containing Metrics + Commits.

The existing film's stack-return uses the rendered DOM stack grip. That working return does not establish a return driven by the native window frame. The earlier preflight records this distinction and the source refusal.

The Architectural Reality

• WorkspaceDocument.resolveStackRoot resolves an edge-zone vessel's center subtree. Operations.transferNode still rejects the document root and commits both documents or neither.
• The stack grip already carries dockGroupNodeId, dockItemId, source workspace and Group ownership. Participation.commitDrop revalidates the exact stack root and ownership before the existing Group transfer.
• The native coordinator re-resolves its source and identity-compares draggedItem before commit. The native lifecycle is keyed by the window owner item, so that existing pane remains the representative; selecting another active tab or returning a fresh proxy object is wrong.
• Main.windowNativeMoveTo moves an exact owner-granted native route. The Workstation driver can use it without a transaction-tagged geometry effect to exercise the ordinary native preview/dwell path. The existing transfer receipt distinguishes document adoption, settled projections, close dispatch/acknowledgment and physical topology exit.

The Fix

1. Extend the native source resolver for a registered multi-item vessel only when the resolved transferable subtree contains its owner item and the complete item catalog. Stamp the existing grouped source payload on the same live owner pane. Preserve singleton behavior and refuse empty, unresolved, root-equal or partial-vessel sources.
2. Add the app-owned native-return cue/executor in the existing Workstation driver family. Move the actual owner-granted popup across live targets, observe the native previews, and settle through the existing Group transfer and empty-vessel close.
3. When a tagged geometry recovery supersedes a pending free move, cancel that window's buffered Placement write so cancellation cannot journal the abandoned intermediate position. Other windows' pending writes remain independent.
4. Replace the film's DOM-grip return cue while retaining its scene identity and continuous session. Keep cancellation tied to settled physical calls and the actual transfer state; do not report rollback once commit has begun.

Contract Ledger

Acceptance Criteria

• A committed Metrics + Commits popup is admitted as one grouped native source using the same live owner pane. The existing single-item control remains green.
• Empty, unresolvable, root-equal and partial/mixed-vessel sources refuse. Group ownership and root-transfer rejection remain unchanged.
• A native return transfers both pane identities through one Group operation, settles both projections before native close, and observes actual source-window exit. A refused/cancelled gesture cannot lose a sibling pane or leave a preview/candidate behind.
• The film exposes native-return through its vocabulary/controller and performs that beat in one continuous session; stable scene ids and the 90–150 second budget remain. Driver destruction during movement settles the outstanding physical call before cleanup; adoption already underway retains its actual outcome.
• The owning unit suites and private-bridge film replay pass at the PR head. A headed native-window witness covers the two-item return. Record the distinction between scripted physical movement, the independent titlebar witness and an eventual recorded film; this leaf does not claim final film acceptance.

Out of Scope

New Group/model semantics, coordinator target arbitration, general-purpose film infrastructure, resize/rail redesign, voice generation, final capture and publication. Mnemosyne's existing production record remains the sole film authority.

Avoided Traps

Do not merely remove the item-count guard, choose one pane from a multi-item window, weaken the global root-transfer rejection, manufacture a transaction/close receipt, or put CDP commands in production choreography. The working DOM-grip return is a control, not a substitute for the native beat.

Decision Record impact: aligned-with ADR 0029 §§2.3, 2.4 and 2.8; existing Group and model-before-close authority is retained. No new cross-substrate protocol or Discussion graduation.

Related

#19126 · #15252 · #18674 / #18684 · #18119 · #18059.

Admission: live latest-open and recent all-status A2A sweeps immediately before creation; no overlapping implementation leaf. Mnemosyne's live issue and direct no-duplicate handoff confirm the fork. Problem-keyed memory recall found the earlier native single-item and DOM-stack work; current source distinguishes this gap. Own assignments are #16151 and #15526, neither this implementation. Engine-only: Brain structure-map N/A. Existing files own the proposed work; any new-file extraction runs structural pre-flight before authoring.

Origin Session ID: 1f7129c9-c0f7-42e0-ba47-7a42e5ac57c2 Retrieval Hint: "native popup Metrics Commits whole-vessel return stable owner pane Group transferNode native-return cue"

🪡 Emmy · GPT-6 Astra · Codex.