Retire the main-thread DragDrop park surface nothing calls

Context

#19538 retires the worker-side pointer-path vessel conversion and park (docking design record §2.8.6, amended for #19533: a pointer drag never parks). Its PR also removes the last worker callers of the main-thread DragDrop addon's park surface:

• the pointer park called parkWindowDrag;
• the native re-show (NativeVesselTransaction.effectsFor().reshowVessel) asked resumeWindowDrag and the orphan-recovery probe and acknowledgement before the route move. Only a parked pointer drag could ever answer them, so they always fell through.

Once #19538 merges, that surface in src/main/addon/DragDrop.mjs has no caller.

The Problem

About 965 lines of main-thread code still read as live:

• src/main/addon/DragDrop.mjs lines 1069–2034 at 5698517f19;
• the park helpers at lines 490–558;
• the parked branches of the kept methods.

Every reader of the addon has to reason about a parked window drag, its recovery and its orphan-recovery serialization. test/playwright/unit/main/addon/DragDrop.spec.mjs keeps 104 references pinning that machinery. The addon is also the file-size ratchet's over-target entry (1,294 code lines).

The Architectural Reality

Caller census (grep over src, apps, examples on the #19538 branch). The worker-side resumeWindowDrag methods of TabSortZone, the dashboard Container and DragTarget are SortZone hooks, not this addon method.

The PR re-proves each row against its own head before deleting it.

The Fix

• Delete the parked-window-drag surface from the addon: its remote-method registrations, the state fields, and the parked branches of resetDragState, startWindowDrag and onDragMove.
• Delete the DragDrop.spec arms that pin it.
• Lower buildScripts/util/file-size-baseline.json with the shrink.

Kept: pointer-follow (startWindowDrag, the window branch of onDragMove), setConfigs, and everything the in-window and tear-out drags use. No behaviour change, because nothing reaches the surface.

Decision Record impact: aligned-with ADR 0029 §2.8.6 (#19533 amendment), whose pointer-path park text is already history.

Acceptance Criteria

• No parkWindowDrag, windowDragPark*, park recovery or orphan recovery remains in src/main/addon/DragDrop.mjs, and a caller census at the PR head shows nothing referenced them.
• Pointer tear-out, re-entry and the native title-bar drop are unchanged: the kept DragDrop.spec arms, the unit suite, and the Workstation and dashboard e2e folders are green at their dev baseline.
• file-size-baseline.json follows the shrink.

Out of Scope

• Any behaviour change.
• The worker-side dock (#19538).
• The native title-bar park (worker-side, kept).
• The class shape of the dock collaborators (#19540).

Related

• #19538: removes the last callers; this ticket is blocked by its merge, because on dev NativeVesselTransaction still calls resumeWindowDrag.
• #19540: class conversion of the Dock window collaborators; touches no file of this ticket.
• #19533: the decision.

Sweeps

• Live latest-open sweep: the latest 20 open issues at 2026-10-10T03:27Z, plus gh search issues --owner neomjs for parkWindowDrag and "orphan recovery DragDrop". Only closed predecessors came up (#19278, #19288, #19186, #19533).
• A2A sweep: the latest 30 messages, all read states; no claim on this surface.
• Memory Core: no prior decision on retiring it.
• Own assignments: #19538 and #19540 are adjacent; neither covers the addon.

Origin Session ID: fcc49158-63cf-4317-a407-741c5e5e3d8c

Retrieval Hint: "DragDrop addon parkWindowDrag orphan recovery retired after the pointer park"