The stroke width is anchored to kFit (screen px at fit zoom — the
camera persists across searches), but the blur radius was anchored to
cell, which scales with the FILTERED world span: a tight search shrank
cell, and the blur's screen reach (blur*cell*kFit) collapsed with it
while the stroke stayed put — the blur visibly went away for
close-together matches and the knob did nothing (verified: blur 6 and
blur 10 produced identical output under a tight search). The blur now
uses the stroke's anchoring: its world reach is blur*cellRef, cellRef
being the full-graph cell from worldBBox (the same bbox kFit comes
from) — span-independent, and with nothing filtered cell == cellRef
so the unfiltered look is unchanged.
The cell also gains a floor: a single matching node (span 0) zeroed
the cell and blew the bitmap dims to Infinity, throwing the reported
getImageData TypeError. The floor is the padded rect's own reach, so
dims stay finite however tight the search (and the old bitmap
ballooning — ~1040px bitmap for a 3-node search — is gone too).