251606460 dropped each component's window hooks on unmount, but deleted them
unconditionally, and that is wrong as soon as two of the same component share a
page -- which research-map-plus-grid and the Big Picture composite both arrange.
B mounts and overwrites A's hooks; A unmounts and deletes them; B is still on
screen with its verify hooks gone. Not a leak, and not visible to a reader: the
cost lands on rega, as a hook reported missing on a map that is perfectly
healthy, which is a more expensive thing to chase than this is to write.
people-groups-grid already compared identity before releasing. research-map (4
hooks) and the dashboard map panel (3) did not, so the commit was uneven with
itself; gospel's d3597f3d1 settled on the same identity-checked pattern, and one
pattern across the fleet is what lets the check enforce it later.
Each hook is now held in a local as it is installed -- window.__x = _hookX = (…)
-- declared outside the block that assigns it, because a const in there is
invisible to onBeforeUnmount. The release compares before deleting, one key per
line, so the check can read both halves.
The check reports how many releases are identity-checked and enforces it under
STRICT_IDENTITY=1, which is off only because other owners have not adopted the
pattern yet. Flipping it later is a smaller change than re-deriving this.
Two things it taught me while I wrote it. Enforcement first flagged the grid,
which WAS identity-checked -- the comparison simply sat on the line above the
delete, and looking only at the delete's own line dictated formatting instead of
recognising correct code; the window now covers the lines leading up to it. And
the pattern is tested for BEHAVIOUR, not presence: two hooks installed in turn,
the first unmount must leave the second working, the second must leave nothing.
rega's heap snapshots (leak-722ac7789): Simple Research and All People Groups
mounted twice went 54.2 MB to 65.1 MB, with live Vue apps 6 to 8. Every unmounted
application was still there, one copy per mount, and the retainers were all the
same shape -- a window key set during setup and never cleared. The closure keeps
its component, the component keeps its shadow root, and a whole app survives its
own unmount. An element property dies with the element; a window key does not.
The named one was window.__doxaLogoOwner -> Map -> div.rm-map-canvas -> ShadowRoot
-> app, released only when the map's 'remove' event fires. That listener cannot be
the guarantee the global is cleared, because it only runs if remove() is reached;
it is a consequence of the guarantee, not the guarantee itself. useMapInstance now
drops the claim inside destroy(), before removing, so it goes even if remove()
throws part-way.
As for why remove() was never reached: research-map's unmount hook ran ten
teardown steps and called destroy() last, and two of those steps were unguarded
calls into other composables. A single throw anywhere above stranded the map, and
with it the app. I could not reproduce which step threw without a browser, so the
fix does not depend on knowing: each step is isolated and destroy() runs from a
finally, where nothing above it can skip it. Ordering teardown so the most
important step is last, behind nine chances to fail, was the real defect.
The globals themselves are released by the components that set them -- four verify
hooks in research-map, three in the dashboard map panel, the vocabulary hook in
the grid, which had no unmount hook at all. Released as SETS: __rdashPinAt was the
one the snapshot named, but __rdashMap holds the map and retains strictly more, so
clearing only the reported one would have looked fixed and leaked nearly as much.
The deletes are written one per line instead of looped over an array of names, so
that the check can read them. A release a checker cannot see is worth no more than
no release, the day someone removes three of the four.
The check flags only values that actually retain. A warn-once boolean latch and a
page-wide cache keyed off itself are deliberate and must not be reported, or it
becomes noise and gets switched off. It is NOT in gates:pre: 19 sites remain in
other owners' plugins, and this is a fleet pattern rather than one plugin's bug.
