Decision 4 — conform to Lane D's call sites rather than the reverse (D
landed first and duck-typed them): repair(i), trim(i, delta) and
cornerPos(i). repair takes no hardware argument because prep sells
exactly one kind of spare, so it re-rigs at shackle grade — an upgrade
on a blown carabiner, a downgrade on a blown rated shackle, which is the
prototype's behaviour and a real choice about which corner you run to.
cornerPos returns a fresh vector at the live node, so a blown corner's
prompt chases the flogging corner instead of sitting on a dead anchor
(measured: 13 m off). All three are contract entries now, not PROPOSED
comments, so the merge tripwire enforces the seam.
Decision 5 — sail.step() takes an optional debris and applies sphere-vs-
cloth impulses. The exchange is symmetric: every newton-second the cloth
takes out of a crate, the crate loses. Asserted, and it conserves to
0.000% on an interior hit. Pinned corners are the deliberate exception —
invMass 0 means a crate off a corner dumps its momentum into the house,
which is correct, the anchor is bolted to a wall.
Note this leaves debris.js's applyToSail dead: it guards on `sail.nodes`,
which never existed on the rig — the cloth stores Float64Arrays. So the
debris-vs-sail impulse has been silently doing nothing in the assembled
game. Decision 5 puts it on this side; flagged for Lane C in THREADS.
The contact radius is swept by the piece's travel because main.js steps
the sail before the debris (so piece positions are a frame stale) and a
0.3 m crate at 25 m/s covers 0.42 m per frame — enough to pass clean
between cloth nodes.
Also: coverageOver() rays now start at heightAt(x,z) rather than y=0.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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