From b7a069069db18c937348935db6bc5f871d36e45c Mon Sep 17 00:00:00 2001
From: m3ultra <m3ultra@m3ultra.local>
Date: Sat, 18 Jul 2026 19:03:36 +1000
Subject: [PATCH] =?UTF-8?q?debris:=20delete=20the=20dead=20sail.nodes=20se?=
 =?UTF-8?q?am=20=E2=80=94=20sail.=5FapplyDebris=20is=20the=20one=20contact?=
 =?UTF-8?q?=20model?=
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The SPRINT2-era duck-typed path (if sail.nodes → applyToSail) has been
dead since decision 5 chose option b, and was a double-apply waiting for
the day anyone exposed .nodes. The sail key on step()'s world arg is
accepted and ignored, documented.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 web/world/js/debris.js | 41 +++++++----------------------------------
 1 file changed, 7 insertions(+), 34 deletions(-)

diff --git a/web/world/js/debris.js b/web/world/js/debris.js
index 7fccd11..3c24fbd 100644
--- a/web/world/js/debris.js
+++ b/web/world/js/debris.js
@@ -182,7 +182,8 @@ export function createDebris(o = {}) {
     /**
      * @param {number} dt fixed step
      * @param {number} t  storm time
-     * @param {object} [world] {player, sail} — both optional, both duck-typed
+     * @param {object} [world] {player} — optional, duck-typed. (A `sail` key is
+     *   accepted and ignored: debris-vs-sail is sail.js's `_applyDebris`.)
      */
     step(dt, t, world = {}) {
       // storm JSON drives the spawns; poll the window so nothing is missed
@@ -194,7 +195,6 @@ export function createDebris(o = {}) {
       }
 
       const player = world.player;
-      const sail = world.sail;
 
       for (let i = pieces.length - 1; i >= 0; i--) {
         const p = pieces[i];
@@ -269,10 +269,11 @@ export function createDebris(o = {}) {
           }
         }
 
-        // --- sphere vs sail nodes: impulse ---
-        // Duck-typed: lights up the moment Lane B exposes nodes, silent until
-        // then. See THREADS — B owns sail.js, so this is the seam we agreed on.
-        if (sail && sail.nodes) applyToSail(p, sail);
+        // debris-vs-sail lives in sail.js (`_applyDebris` reads `debris.pieces`
+        // each step — SPRINT2 decision 5, option b). The old duck-typed seam
+        // here (`if (sail.nodes) applyToSail(...)`) is deleted, not dormant:
+        // had Lane B ever exposed `.nodes`, every hit would have been applied
+        // TWICE through two different contact models.
 
         if (p.y < groundAt(p.x, p.z) - 5 || Math.abs(p.x) > bounds.x || Math.abs(p.z) > bounds.z) {
           despawn(p);
@@ -292,33 +293,5 @@ export function createDebris(o = {}) {
     },
   };
 
-  /**
-   * Shove any cloth node the piece is intersecting, and lose some of the piece's
-   * own momentum doing it. Expects sail.nodes: [{x,y,z,px,py,pz}] (verlet, so we
-   * move position and let the integrator turn it into velocity).
-   */
-  function applyToSail(p, sail) {
-    const nodes = sail.nodes;
-    const reach = p.r + 0.15;
-    const reachSq = reach * reach;
-    let hits = 0;
-    for (let i = 0; i < nodes.length; i++) {
-      const n = nodes[i];
-      const dx = n.x - p.x, dy = n.y - p.y, dz = n.z - p.z;
-      const dsq = dx * dx + dy * dy + dz * dz;
-      if (dsq > reachSq || dsq < 1e-9) continue;
-      const d = Math.sqrt(dsq);
-      // push the node out to the sphere surface along the contact normal
-      const push = (reach - d) / d;
-      n.x += dx * push; n.y += dy * push; n.z += dz * push;
-      hits++;
-    }
-    if (hits) {
-      const drag = Math.min(0.5, (hits * p.mass) / 400);
-      p.vx *= 1 - drag; p.vy *= 1 - drag; p.vz *= 1 - drag;
-      if (sail.onDebrisHit) sail.onDebrisHit(p, hits);
-    }
-  }
-
   return debris;
 }