fix: compute clouds from planned route so destruction cannot leak (review)

src/sim/clouds.js

@@ -1,5 +1,6 @@
 import { VIS_BAND } from './constants.js';
 import { JIT_MIN, JIT_SPAN, DELAY_MULT, hazardProbs } from './npc.js';
+import { otherEnd } from './galaxy.js';
 
 export function totalMass(segs) {
   return segs.reduce((sum, s) => sum + s.w, 0);
@@ -12,14 +13,22 @@ export function totalMass(segs) {
 //   f0: progress if everything ran slowest (latest entry, slowest leg)
 // Weight ~ feasible track-days on that leg x survival probability, normalized.
 export function cloudFor(galaxy, plan, t) {
-  if (!plan || plan.legs.length === 0) return [];
+  if (!plan) return [];
+  // Walk the PLANNED route, not the resolved legs: a destroyed itinerary has
+  // truncated legs, and using them would leak the hidden outcome via the
+  // cloud's shape. Synthetic plans without routeLanes fall back to legs.
+  const laneIds = plan.routeLanes ?? plan.legs.map((l) => l.laneId);
+  if (laneIds.length === 0) return [];
   const e = t - plan.startTime;
   if (e <= 0) return [];
 
+  let sys = plan.startSys ?? (plan.legs.length > 0 ? plan.legs[0].fromSys : null);
+  if (sys == null) return [];
   let minStart = 0, maxStart = 0, survival = 1;
   const raw = [];
-  for (const leg of plan.legs) {
+  for (const laneId of laneIds) {
-    const lane = galaxy.lanes[leg.laneId];
+    const lane = galaxy.lanes[laneId];
+    const toSys = otherEnd(lane, sys);
     const minD = lane.days * JIT_MIN;
     const maxD = lane.days * (JIT_MIN + JIT_SPAN) * DELAY_MULT;
     // fastest possible progress: entered at minStart, moving at max speed
@@ -29,12 +38,13 @@ export function cloudFor(galaxy, plan, t) {
     const cf0 = Math.min(1, Math.max(0, f0));
     const cf1 = Math.min(1, Math.max(0, f1));
     if (cf1 > cf0) {
-      raw.push({ laneId: leg.laneId, fromSys: leg.fromSys, toSys: leg.toSys, f0: cf0, f1: cf1, w: (cf1 - cf0) * lane.days * survival });
+      raw.push({ laneId, fromSys: sys, toSys, f0: cf0, f1: cf1, w: (cf1 - cf0) * lane.days * survival });
     }
     const p = hazardProbs(lane.hazard);
     survival *= 1 - p.destroyed;
     minStart += minD;
     maxStart += maxD;
+    sys = toSys;
   }
   return normalize(raw);
 }
@@ -55,6 +65,7 @@ export function excludeVisibleBand(galaxy, segs, observedSystemId) {
     const bandLo = nearFrom ? 0 : 1 - VIS_BAND;
     const bandHi = nearFrom ? VIS_BAND : 1;
     const den = seg.f1 - seg.f0;
+    if (den <= 0) continue; // degenerate segment: drop rather than NaN-poison
     // keep the part below the band
     if (seg.f0 < bandLo) {
       const f1 = Math.min(seg.f1, bandLo);

src/sim/npc.js

@@ -97,6 +97,9 @@ export function planNpc(world, npc) {
   npc.plan = {
     id: planId, good: best.good, qty: best.qty,
     originPlanet: origin.id, destPlanet: best.dest.id,
+    // Planned route (public knowledge for clouds) — unlike legs, never
+    // truncated by a hidden 'destroyed' roll.
+    routeLanes: best.route.lanes, startSys: origin.systemId,
     startTime: t, ...itin,
   };
   npc.state = 'transit';

tests/clouds.test.js

@@ -73,4 +73,19 @@ describe('clouds', () => {
     expect(cloudFor(g, chainPlan(), 99)).toEqual([]);
     expect(cloudFor(g, { ...chainPlan(), legs: [] }, 1)).toEqual([]);
   });
+
+  it('a hidden destroyed outcome does not change the cloud shape', () => {
+    const g = chainGalaxy();
+    const intact = chainPlan();
+    intact.routeLanes = [0, 1, 2];
+    intact.startSys = 0;
+    const doomed = chainPlan();
+    doomed.routeLanes = [0, 1, 2];
+    doomed.startSys = 0;
+    doomed.finalOutcome = 'destroyed';
+    doomed.legs = doomed.legs.slice(0, 1); // itinerary truncated at the hidden destruction
+    for (const t of [1, 3, 4.5]) {
+      expect(JSON.stringify(cloudFor(g, doomed, t))).toBe(JSON.stringify(cloudFor(g, intact, t)));
+    }
+  });
 });