Broken planes cannot fly; repair heals gradually (ISS-089)

- flyPlane 409s a broken plane (health <= 0) before any refuel math — fuel/cash untouched
- engine auto-chain skips chaining when a landing's wear breaks the plane (queue kept intact)
- finishRepairs heals along round(f x 100) each tick; flip to available at exactly 100 on gate pass
- repairPlane no longer jumps health to 100 — it starts the gradual heal
- REMOVED BROKEN_BURN_MULTIPLIER / conditionBurnMultiplier and all burn sites (unreachable now)
- OpenAPI + route comments reworded; unit tests reworked; e2e maintenance.spec.ts per issue
- v0.45.0

lib/db/schema.ts

@@ -27,7 +27,7 @@ export const planes = sqliteTable('planes', {
   // departureSimTime; on landing the engine auto-chains queue[0] if fuel covers it.
   queue: text('queue').notNull().default('[]'),
   // Structural health in [0, 100] (v0.39.0, ISS-069) — wears down by WEAR_PER_KM per km of
-  // landed legs; at 0 the plane is broken and burns BROKEN_BURN_MULTIPLIER × more fuel.
+  // landed legs; at 0 the plane is broken and cannot fly until repaired (v0.45.0, ISS-089).
   health: real('health').notNull().default(100),
   // Sim-clock epoch ms when an active repair finishes (v0.39.0, ISS-069) — set with status
   // 'repairing', cleared by the engine's flip-back pass; NULL = not in repair.

lib/game/actions.test.ts

@@ -10,7 +10,6 @@ import { haversineKm, initialBearingDeg } from '@/lib/geo';
 import { weatherFor } from '@/lib/weather';
 import { requiredFuelFor, windBurnFactor } from '@/lib/sim/movement';
 import {
-  BROKEN_BURN_MULTIPLIER,
   FUEL_DISCOUNT_PER_REP,
   FUEL_PRICE_PER_L,
   MAX_FUEL_DISCOUNT,
@@ -230,36 +229,28 @@ describe('flyPlane', () => {
     await expectActionError(flyPlane(inst, 'plane-starter', 'ZZZZ'), 400, /unknown airport/);
   });
 
-  it('uses the ×1.5 broken burn for the dispatch auto-top-up when health is 0 (v0.39.0, ISS-069)', async () => {
+  it('rejects a broken plane (health 0) with 409 and mutates nothing (v0.45.0, ISS-089)', async () => {
     const inst = await freshDb('fly-broken.db'); // EDDF → LEMD
-    const fc = await loadAirportsGeoJson();
-    const from = fc.features.find((f) => f.properties.icao === HUB_ICAO)!.properties;
-    const to = fc.features.find((f) => f.properties.icao === 'LEMD')!.properties;
-    const km = haversineKm(from.lat, from.lon, to.lat, to.lon);
-    const type = PLANE_TYPES.atr72;
-    const w = weatherFor(HUB_ICAO);
-    const f = windBurnFactor(w.windKt, w.windDirDeg, initialBearingDeg(from.lat, from.lon, to.lat, to.lon));
-    // The tank holds EXACTLY the healthy requirement — a broken plane's 150% top-up target is higher.
-    const healthyRequired = requiredFuelFor(type.burnPerKm * f, type.emptyWeightKg, type.maxFuel, km);
-    await inst.db.update(schema.planes)
-      .set({ health: 0, fuel: healthyRequired })
-      .where(eq(schema.planes.id, 'plane-starter'));
+    const fuelBefore = PLANE_TYPES.atr72.maxFuel; // seeded full tank
+    await inst.db.update(schema.planes).set({ health: 0 }).where(eq(schema.planes.id, 'plane-starter'));
+    const cashBefore = (await inst.db.select().from(schema.account))[0].cash;
 
-    await flyPlane(inst, 'plane-starter', 'LEMD'); // auto-refuel covers the extra burn — no 409
+    await expectActionError(flyPlane(inst, 'plane-starter', 'LEMD'), 409, /broken \(health 0\)/);
+
+    const plane = (await inst.db.select().from(schema.planes))[0];
+    expect(plane.status).toBe('available'); // still grounded…
+    expect(plane.fuel).toBe(fuelBefore); // …no auto-refuel ran — the tank is untouched…
+    expect((await inst.db.select().from(schema.account))[0].cash).toBe(cashBefore); // …and no cash left the account
+  });
+
+  it('still flies a worn-but-not-broken plane (health > 0) with plain burn', async () => {
+    const inst = await freshDb('fly-worn.db'); // EDDF → LEMD
+    await inst.db.update(schema.planes).set({ health: 1 }).where(eq(schema.planes.id, 'plane-starter'));
+
+    await flyPlane(inst, 'plane-starter', 'LEMD'); // no 409 — worn is not broken
 
-    const brokenRequired = requiredFuelFor(type.burnPerKm * f * BROKEN_BURN_MULTIPLIER, type.emptyWeightKg, type.maxFuel, km);
-    expect(brokenRequired).toBeGreaterThan(healthyRequired); // sanity: the multiplier genuinely raises the requirement
     const plane = (await inst.db.select().from(schema.planes))[0];
     expect(plane.status).toBe('flying');
-    expect(plane.fuel).toBeCloseTo(Math.min(type.maxFuel, Math.max(healthyRequired, brokenRequired * 1.5)), 6); // topped up for the BROKEN burn…
-
-    // …while the same tank at full health tops up to the LOWER healthy target — the multiplier is what raised it.
-    const inst2 = await freshDb('fly-broken-healthy.db');
-    await inst2.db.update(schema.planes).set({ fuel: healthyRequired }).where(eq(schema.planes.id, 'plane-starter'));
-    await flyPlane(inst2, 'plane-starter', 'LEMD'); // must not throw
-    const plane2 = (await inst2.db.select().from(schema.planes))[0];
-    expect(plane2.fuel).toBeCloseTo(Math.min(type.maxFuel, Math.max(healthyRequired, healthyRequired * 1.5)), 6);
-    expect(plane.fuel).toBeGreaterThan(plane2.fuel); // the broken plane genuinely got more fuel
   });
 
   // --- Auto-refuel on dispatch (ISS-082, v0.42.0) ---
@@ -691,8 +682,8 @@ describe('sellPlane', () => {
   });
 });
 
-describe('repairPlane (v0.39.0, ISS-069)', () => {
-  it('charges exactly REPAIR_COST, restores health to 100 and grounds the plane for REPAIR_DURATION_MS', async () => {
+describe('repairPlane (v0.39.0, ISS-069; gradual since v0.45.0, ISS-089)', () => {
+  it('charges exactly REPAIR_COST and grounds the plane for REPAIR_DURATION_MS without touching health yet', async () => {
     const inst = await freshDb('repair-ok.db');
     await inst.db.update(schema.planes).set({ health: 42 }).where(eq(schema.planes.id, 'plane-starter'));
     const cashBefore = (await inst.db.select().from(schema.account))[0].cash;
@@ -702,7 +693,7 @@ describe('repairPlane (v0.39.0, ISS-069)', () => {
     expect(cost).toBe(REPAIR_COST);
     const plane = (await inst.db.select().from(schema.planes))[0];
     expect(plane.status).toBe('repairing');
-    expect(plane.health).toBe(100); // restored to full…
+    expect(plane.health).toBe(42); // NOT restored yet — the engine's finishRepairs pass heals it gradually…
     expect(plane.repairUntilSimTime).toBe(T0 + REPAIR_DURATION_MS); // …with the gate set from the seeded clock (no tick in direct calls)
     const account = (await inst.db.select().from(schema.account))[0];
     expect(account.cash).toBeCloseTo(cashBefore - REPAIR_COST, 6);

lib/game/actions.ts

@@ -9,7 +9,6 @@ import { requiredFuelFor, windBurnFactor } from '@/lib/sim/movement';
 import { runAction } from '@/lib/sim/engine';
 import { getStateSnapshot, parseIcaoQueue } from './state';
 import {
-  conditionBurnMultiplier,
   FUEL_DISCOUNT_PER_REP,
   FUEL_PRICE_PER_L,
   MAX_FUEL_DISCOUNT,
@@ -106,7 +105,8 @@ export async function loadPackage(inst: GameDb, packageId: string, planeId: stri
 // dispatch AUTO-refuels first — the tank is topped up to min(maxFuel, max(fuel, 1.5 × required))
 // at FUEL_PRICE_PER_L per liter minus the rep-scaled discount, deducted from cash; a leg that
 // doesn't fit even a full tank still 409s (insufficient fuel), and an unaffordable top-up 409s
-// with nothing mutated.
+// with nothing mutated. v0.45.0 (ISS-089): a broken plane (health ≤ 0) cannot fly at all — it
+// 409s before any refuel math, so fuel and cash stay untouched.
 export async function flyPlane(inst: GameDb, planeId: string, destIcao: string): Promise<void> {
   const planeRows = await inst.db.select().from(schema.planes).where(eq(schema.planes.id, planeId));
   const plane = planeRows[0];
@@ -114,6 +114,9 @@ export async function flyPlane(inst: GameDb, planeId: string, destIcao: string):
   if (plane.status !== 'available') {
     throw new GameActionError(409, `plane is ${plane.status}, only grounded planes can fly`);
   }
+  if (plane.health <= 0) {
+    throw new GameActionError(409, 'the plane is broken (health 0) — repair it first');
+  }
 
   const fc = await loadAirportsGeoJson();
   const destFeature = fc.features.find((f) => f.properties.icao === destIcao);
@@ -125,9 +128,8 @@ export async function flyPlane(inst: GameDb, planeId: string, destIcao: string):
   const distanceKm = haversineKm(origin.lat, origin.lon, destFeature.properties.lat, destFeature.properties.lon);
   // Weighted burn model (v0.16.0): the leg needs enough fuel to cover it arriving empty; wind-
   // adjusted (v0.36.0) by departure weather vs route heading — every call site uses this same factor.
-  // v0.39.0 (ISS-069): a broken plane (health ≤ 0) burns BROKEN_BURN_MULTIPLIER × more per km.
   const w = weatherFor(plane.locationIcao);
-  const burnPerKm = type.burnPerKm * windBurnFactor(w.windKt, w.windDirDeg, initialBearingDeg(origin.lat, origin.lon, destFeature.properties.lat, destFeature.properties.lon)) * conditionBurnMultiplier(plane.health);
+  const burnPerKm = type.burnPerKm * windBurnFactor(w.windKt, w.windDirDeg, initialBearingDeg(origin.lat, origin.lon, destFeature.properties.lat, destFeature.properties.lon));
   const requiredL = requiredFuelFor(burnPerKm, type.emptyWeightKg, type.maxFuel, distanceKm);
 
   // ISS-082 (v0.42.0): dispatch auto-refuels — top up to 150% of the requirement (capped at tank
@@ -355,10 +357,12 @@ export async function sellPlane(inst: GameDb, planeId: string): Promise<{ payout
 
 // --- Repair (POST /api/planes/:planeId/repair) — v0.39.0 (ISS-069) ---
 
-// Restore a worn-out plane to full health for the flat REPAIR_COST; it is grounded in 'repairing'
-// status until sim.clockMs + REPAIR_DURATION_MS, when the engine's tick flips it back to
-// 'available'. Only GROUNDED planes can be repaired (409 otherwise); an already-full-health
-// repair is a free no-op. 404 unknown plane; 409 not grounded / insufficient funds.
+// Ground a worn-out plane in 'repairing' status for the flat REPAIR_COST (v0.39.0, ISS-069).
+// Since v0.45.0 (ISS-089) the repair is GRADUAL: health stays where it is and climbs back to 100
+// over REPAIR_DURATION_MS of sim time — the engine's finishRepairs pass applies the curve each tick
+// and flips the plane to 'available' exactly when it reaches full health (the gate). Only GROUNDED
+// planes can be repaired (409 otherwise); an already-full-health repair is a free no-op. 404 unknown
+// plane; 409 not grounded / insufficient funds.
 export async function repairPlane(inst: GameDb, planeId: string): Promise<{ cost: number }> {
   const rows = await inst.db.select().from(schema.planes).where(eq(schema.planes.id, planeId));
   const plane = rows[0];
@@ -377,8 +381,9 @@ export async function repairPlane(inst: GameDb, planeId: string): Promise<{ cost
     throw new GameActionError(409, `insufficient funds: repair costs ${REPAIR_COST}, you have ${Math.round(account.cash)}`);
   }
 
+  // Health is NOT set here — the engine's finishRepairs pass heals it gradually along the gate.
   await inst.db.update(schema.planes)
-    .set({ health: 100, status: 'repairing', repairUntilSimTime: sim.clockMs + REPAIR_DURATION_MS })
+    .set({ status: 'repairing', repairUntilSimTime: sim.clockMs + REPAIR_DURATION_MS })
     .where(eq(schema.planes.id, planeId));
   await inst.db.update(schema.account).set({ cash: Math.round((account.cash - REPAIR_COST) * 100) / 100 });
   await persist(inst);

lib/game/catalog.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, it } from 'vitest';
-import { BROKEN_BURN_MULTIPLIER, conditionBurnMultiplier, FUEL_DISCOUNT_PER_REP, MAX_FUEL_DISCOUNT, MAX_PLANE_DISCOUNT, PLANE_DISCOUNT_PER_REP, PLANE_TYPES, repRate, STARTER_MODEL } from './catalog';
+import { FUEL_DISCOUNT_PER_REP, MAX_FUEL_DISCOUNT, MAX_PLANE_DISCOUNT, PLANE_DISCOUNT_PER_REP, PLANE_TYPES, repRate, STARTER_MODEL } from './catalog';
 import { STARTING_REPUTATION } from './seed';
 
 // v0.28.0 (ISS-047) — catalog sanity: the progression ladder must stay well-formed as types are added.
@@ -43,21 +43,3 @@ describe('repRate', () => {
     expect(repRate(1_000_000, FUEL_DISCOUNT_PER_REP, MAX_FUEL_DISCOUNT)).toBe(MAX_FUEL_DISCOUNT);
   });
 });
-
-// v0.39.0 (ISS-069) — the broken-state burn factor: ×BROKEN_BURN_MULTIPLIER at/below zero health, exactly 1 above it.
-describe('conditionBurnMultiplier', () => {
-  it('is exactly 1 for any positive health', () => {
-    expect(conditionBurnMultiplier(100)).toBe(1);
-    expect(conditionBurnMultiplier(42)).toBe(1);
-    expect(conditionBurnMultiplier(0.5)).toBe(1); // worn but not broken
-  });
-
-  it('is exactly BROKEN_BURN_MULTIPLIER at and below zero health', () => {
-    expect(conditionBurnMultiplier(0)).toBe(BROKEN_BURN_MULTIPLIER);
-    expect(conditionBurnMultiplier(-3)).toBe(BROKEN_BURN_MULTIPLIER); // defensive — wear clamps at 0, but the gate is <= 0
-  });
-
-  it('pins the broken multiplier at ×1.5', () => {
-    expect(BROKEN_BURN_MULTIPLIER).toBe(1.5);
-  });
-});

lib/game/catalog.ts

@@ -128,15 +128,6 @@ export const MAX_FUEL_DISCOUNT = 0.2;
 // ponytail: balance-tunable — health lost per km of landed legs (~130 mid-range EDDF↔LEMD hops to break from full; 1/10× slower since v0.43.0, ISS-085).
 export const WEAR_PER_KM = 0.0005;
 
-// ponytail: balance-tunable — burn multiplier for a broken plane (health ≤ 0): it still flies, just thirsty.
-export const BROKEN_BURN_MULTIPLIER = 1.5;
-
-// Broken-state burn factor for one plane's health — the third multiplicative term alongside wind at every
-// per-plane burn site (flyPlane dispatch top-up + backstop, engine landed fuel + auto-chain, live display).
-export function conditionBurnMultiplier(health: number): number {
-  return health <= 0 ? BROKEN_BURN_MULTIPLIER : 1;
-}
-
 // ponytail: balance-tunable — flat repair cost in € (per-type if balance demands it).
 export const REPAIR_COST = 1_500;
 // ponytail: balance-tunable — how long a repair grounds the plane, sim ms (3 game days).

lib/game/state.ts

@@ -3,7 +3,7 @@ import { haversineKm, initialBearingDeg } from '@/lib/geo';
 import { weatherFor } from '@/lib/weather';
 import { getGameDb } from '@/lib/db/client';
 import * as schema from '@/lib/db/schema';
-import { conditionBurnMultiplier, catalogEntries, FUEL_PRICE_PER_L, PLANE_TYPES, SELL_FRACTION, type CatalogEntry } from './catalog';
+import { catalogEntries, FUEL_PRICE_PER_L, PLANE_TYPES, SELL_FRACTION, type CatalogEntry } from './catalog';
 import { fuelAtWeighted, progressAt, positionAt, windBurnFactor } from '@/lib/sim/movement';
 
 // Read-only game-state snapshot for client polling (GET /api/state).
@@ -30,7 +30,8 @@ export interface PlaneState {
   // leg is destIcao. The engine auto-chains queue[0] on landing when fuel covers it.
   queue: string[];
   // Structural health in [0, 100] (v0.39.0, ISS-069) — wears down with distance flown; at 0 the
-  // plane is broken and burns BROKEN_BURN_MULTIPLIER × more fuel until repaired.
+  // plane is broken and cannot fly until repaired (v0.45.0, ISS-089). While 'repairing' this is
+  // also the repair progress: it climbs back to 100 over REPAIR_DURATION_MS of sim time.
   health: number;
   // Sim-clock epoch ms when an active repair finishes (v0.39.0, ISS-069); null when not in repair.
   repairUntilSimTime: number | null;
@@ -113,12 +114,10 @@ export async function getStateSnapshot(): Promise<StateSnapshot> {
     const pos = positionAt(from.lat, from.lon, to.lat, to.lon, progress);
     // Wind-adjusted burn (v0.36.0) — weather is a pure function of the departure ICAO, so this
     // recomputes exactly the factor the engine used for the leg; no stored state needed.
-    // v0.39.0 (ISS-069): broken planes burn BROKEN_BURN_MULTIPLIER × more — p.health is frozen at
-    // departure (wear lands only), so this stays bit-consistent with the engine's landed fuel.
     const w = weatherFor(p.locationIcao);
     return { ...pos, fuel: fuelAtWeighted(
       p.fuel,
-      type.burnPerKm * windBurnFactor(w.windKt, w.windDirDeg, initialBearingDeg(from.lat, from.lon, to.lat, to.lon)) * conditionBurnMultiplier(p.health),
+      type.burnPerKm * windBurnFactor(w.windKt, w.windDirDeg, initialBearingDeg(from.lat, from.lon, to.lat, to.lon)),
       type.emptyWeightKg,
       type.maxFuel,
       distanceKm,

lib/openapi.ts

@@ -223,7 +223,7 @@ export const openApiSpec = {
           },
           409: {
             description:
-              'Plane not grounded, or the leg does not fit even a FULL tank (v0.16.0 weight-proportional burn — the fuel required to cover the great-circle distance arriving empty; dispatch auto-refuels up to min(maxFuel, max(fuel, 1.5 × required)) first, ISS-082), or cash is insufficient for that top-up',
+              'Plane not grounded, plane broken (health ≤ 0 — repair it first, v0.45.0), or the leg does not fit even a FULL tank (v0.16.0 weight-proportional burn — the fuel required to cover the great-circle distance arriving empty; dispatch auto-refuels up to min(maxFuel, max(fuel, 1.5 × required)) first, ISS-082), or cash is insufficient for that top-up',
             content: { 'application/json': { schema: { $ref: '#/components/schemas/Error' } } },
           },
         },
@@ -233,7 +233,7 @@ export const openApiSpec = {
       post: {
         summary: 'Queue a flight leg for a plane',
         description:
-          'Append a NOT-yet-started leg to the plane\'s flight queue (v0.25.0, ISS-043). Works whether the plane is grounded or flying — you can pre-build a route; the active leg still starts via /fly and nothing auto-starts here. On landing, the engine auto-chains the first queued leg when fuel covers it — with a short tank it auto-refuels to 150% of the requirement (capped at tank capacity) when cash allows (ISS-082); only an unaffordable top-up grounds the plane with the queue kept intact for a later dispatch.',
+          'Append a NOT-yet-started leg to the plane\'s flight queue (v0.25.0, ISS-043). Works whether the plane is grounded or flying — you can pre-build a route; the active leg still starts via /fly and nothing auto-starts here. On landing, the engine auto-chains the first queued leg when fuel covers it and the plane is not broken by the landing\'s wear (v0.45.0) — with a short tank it auto-refuels to 150% of the requirement (capped at tank capacity) when cash allows (ISS-082); only an unaffordable top-up (or a broken plane) grounds the plane with the queue kept intact for a later dispatch.',
         operationId: 'queueLeg',
         parameters: [
           { name: 'planeId', in: 'path', required: true, schema: { type: 'string' } },
@@ -370,14 +370,14 @@ export const openApiSpec = {
       post: {
         summary: 'Repair a grounded plane',
         description:
-          'Restore a worn-out plane to full health for the flat repair cost (v0.39.0, ISS-069): the plane is grounded in "repairing" status until 3 sim days pass, when the engine\'s tick flips it back to "available". While repairing it cannot load, fly or be sold; a broken plane (health ≤ 0) still flies but burns 50% more fuel. A full-health repair is a free no-op (cost 0). No body.',
+          'Ground a worn-out plane in "repairing" status for the flat repair cost (v0.39.0, ISS-069): its health climbs back to 100 over 3 sim days — the engine\'s tick applies the curve each tick and flips it back to "available" exactly when full health is reached (v0.45.0, ISS-089). While repairing it cannot load, fly or be sold; a broken plane (health ≤ 0) cannot fly at all until repaired. A full-health repair is a free no-op (cost 0). No body.',
         operationId: 'repairPlane',
         parameters: [
           { name: 'planeId', in: 'path', required: true, schema: { type: 'string' } },
         ],
         responses: {
           200: {
-            description: 'Repair started (or free no-op) — full state snapshot (health 100, status "repairing" with the gate set, cash reduced by the flat cost)',
+            description: 'Repair started (or free no-op) — full state snapshot (status "repairing" with the gate set, health unchanged until the engine\'s tick heals it back to 100 over the duration, cash reduced by the flat cost)',
             content: { 'application/json': { schema: { $ref: '#/components/schemas/StateSnapshot' } } },
           },
           404: {
@@ -594,7 +594,7 @@ export const openApiSpec = {
           health: {
             type: 'number',
             description:
-              'Structural health in [0, 100] (v0.39.0) — wears down by a fixed amount per km of landed legs; at 0 the plane is broken and burns 50% more fuel until repaired.',
+              'Structural health in [0, 100] (v0.39.0) — wears down by a fixed amount per km of landed legs; at 0 the plane is broken and cannot fly until repaired (v0.45.0). While "repairing" this doubles as repair progress: it climbs back to 100 over the repair duration.',
           },
           repairUntilSimTime: {
             type: ['integer', 'null'],

lib/sim/engine.test.ts

@@ -8,7 +8,7 @@ import * as schema from '@/lib/db/schema';
 import { loadAirportsGeoJson } from '@/lib/airports';
 import { haversineKm, initialBearingDeg } from '@/lib/geo';
 import { weatherFor } from '@/lib/weather';
-import { BROKEN_BURN_MULTIPLIER, conditionBurnMultiplier, FUEL_DISCOUNT_PER_REP, FUEL_PRICE_PER_L, MAX_FUEL_DISCOUNT, PLANE_TYPES, repRate, WEAR_PER_KM } from '@/lib/game/catalog';
+import { FUEL_DISCOUNT_PER_REP, FUEL_PRICE_PER_L, MAX_FUEL_DISCOUNT, PLANE_TYPES, REPAIR_DURATION_MS, repRate, WEAR_PER_KM } from '@/lib/game/catalog';
 import { SPECIALS } from '@/lib/game/specials';
 import { MARKET_TARGET_OPEN_PACKAGES, mulberry32 } from '@/lib/game/seed';
 import { arrivalTimeFor, fuelAtWeighted, requiredFuelFor, windBurnFactor } from './movement';
@@ -313,17 +313,16 @@ describe('deliverPackages (v0.12.0 arrival delivery)', () => {
     const clock = T0 + travelMs(km, type.speedKmh); // exactly at arrival
     expect(await deliverPackages(inst, clock)).toBe(1);
 
-    // Expected top-up from the SAME helpers the engine uses: landed fuel (≈ 0), post-wear health,
-    // wind-adjusted requirement for LEMD→EHAM, ×1.5 margin capped at tank capacity.
+    // Expected top-up from the SAME helpers the engine uses: landed fuel (≈ 0), wind-adjusted
+    // requirement for LEMD→EHAM, ×1.5 margin capped at tank capacity.
     const fc = await loadAirportsGeoJson();
     const nextP = fc.features.find((x) => x.properties.icao === 'EHAM')!.properties;
     const landedFuel = fuelAtWeighted(depFuel, type.burnPerKm * f, type.emptyWeightKg, type.maxFuel, km, 1);
     expect(landedFuel).toBeCloseTo(0, 6); // sanity: arrived empty — the top-up path is what ran
-    const newHealth = Math.max(0, 100 - WEAR_PER_KM * km);
     const wTo = weatherFor(TO); // the chained leg departs from the arrival airport
     const fNext = windBurnFactor(wTo.windKt, wTo.windDirDeg, initialBearingDeg(to.lat, to.lon, nextP.lat, nextP.lon));
     const nextRequiredL = requiredFuelFor(
-      type.burnPerKm * fNext * conditionBurnMultiplier(newHealth),
+      type.burnPerKm * fNext,
       type.emptyWeightKg,
       type.maxFuel,
       haversineKm(to.lat, to.lon, nextP.lat, nextP.lon),
@@ -381,7 +380,7 @@ describe('deliverPackages (v0.12.0 arrival delivery)', () => {
   });
 });
 
-describe('wear on landed legs + broken burn (v0.39.0, ISS-069)', () => {
+describe('wear on landed legs (v0.39.0, ISS-069)', () => {
   const FROM = 'EDDF';
   const TO = 'LEMD';
 
@@ -433,27 +432,22 @@ describe('wear on landed legs + broken burn (v0.39.0, ISS-069)', () => {
     expect(plane.health).toBe(0); // still clamped after the second leg
   });
 
-  it('a broken plane burns ×1.5 more fuel on the leg (landed fuel)', async () => {
-    const { inst, from, to, km, type } = await setupFlight('wear-broken.db');
-    await inst.db.update(schema.planes).set({ health: 0 }).where(eq(schema.planes.id, 'plane-starter'));
+  it('a plane that lands broken does NOT chain — grounded with the queue intact (v0.45.0, ISS-089)', async () => {
+    const { inst, km, type } = await setupFlight('wear-broken-nochain.db'); // full tank EDDF→LEMD
+    // Start below one leg's wear so this landing clamps health to 0 — a full-tank departure leaves
+    // enough fuel for the queued LEMD→EHAM hop (same precondition as chain-ok), so ONLY the broken
+    // guard can explain why it doesn't chain.
+    await inst.db.update(schema.planes)
+      .set({ health: WEAR_PER_KM * km / 2, queue: JSON.stringify(['EHAM']) })
+      .where(eq(schema.planes.id, 'plane-starter'));
 
     expect(await deliverPackages(inst, T0 + travelMs(km, type.speedKmh))).toBe(1);
 
-    const w = weatherFor(FROM);
-    const f = windBurnFactor(w.windKt, w.windDirDeg, initialBearingDeg(from.lat, from.lon, to.lat, to.lon));
     const plane = (await inst.db.select().from(schema.planes))[0];
-    // The ×1.5-adjusted closed form — the same factor livePlane() shows in flight…
-    expect(plane.fuel).toBeCloseTo(
-      fuelAtWeighted(type.maxFuel, type.burnPerKm * f * BROKEN_BURN_MULTIPLIER, type.emptyWeightKg, type.maxFuel, km, 1),
-      6,
-    );
-
-    // …and strictly less than the healthy control on the identical leg.
-    const control = await setupFlight('wear-broken-control.db');
-    expect(await deliverPackages(control.inst, T0 + travelMs(km, type.speedKmh))).toBe(1);
-    const healthy = (await control.inst.db.select().from(schema.planes))[0];
-    expect(healthy.fuel).toBeCloseTo(fuelAtWeighted(type.maxFuel, type.burnPerKm * f, type.emptyWeightKg, type.maxFuel, km, 1), 6);
-    expect(plane.fuel).toBeLessThan(healthy.fuel); // the broken plane genuinely burned more
+    expect(plane.health).toBe(0); // broken by this landing's wear…
+    expect(plane.status).toBe('available'); // …grounded — the chain was skipped despite enough fuel…
+    expect(plane.destIcao).toBeNull();
+    expect(JSON.parse(plane.queue)).toEqual(['EHAM']); // …queue kept intact for a later dispatch
   });
 });
 
@@ -487,6 +481,37 @@ describe('finishRepairs (v0.39.0, ISS-069)', () => {
     expect(plane.status).toBe('available');
     expect(plane.repairUntilSimTime ?? null).toBeNull();
   });
+
+  it('heals gradually along round(f × 100) while repairing; lands exactly on 100 + available at the gate (v0.45.0, ISS-089)', async () => {
+    const inst = await freshDb('repair-curve.db');
+    // Repair started at T0 with health 42 — the gate is what repairPlane stores: start + duration.
+    const gate = T0 + REPAIR_DURATION_MS;
+    await inst.db.update(schema.planes)
+      .set({ status: 'repairing', health: 42, repairUntilSimTime: gate })
+      .where(eq(schema.planes.id, 'plane-starter'));
+
+    // Mid-repair (f = 0.5): the curve (round(50)) is above the start value → health climbs to 50…
+    expect(await finishRepairs(inst, T0 + REPAIR_DURATION_MS / 2)).toBe(0); // …but no flip before the gate…
+    let plane = (await inst.db.select().from(schema.planes))[0];
+    expect(plane.status).toBe('repairing');
+    expect(plane.health).toBe(50);
+
+    // …and it never DROPS below the start value: at f = 0.2 the curve (20) is below 42, so health stays put.
+    const inst2 = await freshDb('repair-curve-floor.db');
+    await inst2.db.update(schema.planes)
+      .set({ status: 'repairing', health: 42, repairUntilSimTime: gate })
+      .where(eq(schema.planes.id, 'plane-starter'));
+    expect(await finishRepairs(inst2, T0 + REPAIR_DURATION_MS / 5)).toBe(0);
+    const plane2 = (await inst2.db.select().from(schema.planes))[0];
+    expect(plane2.health).toBe(42); // max(p.health, round(f × 100)) — the start value is the floor
+
+    // At the gate: exactly 100 and back in service.
+    expect(await finishRepairs(inst, gate)).toBe(1);
+    plane = (await inst.db.select().from(schema.planes))[0];
+    expect(plane.status).toBe('available');
+    expect(plane.health).toBe(100);
+    expect(plane.repairUntilSimTime ?? null).toBeNull();
+  });
 });
 
 describe('slow to 1× when a landing leaves any plane on the ground (ISS-057)', () => {

lib/sim/engine.ts

@@ -5,7 +5,7 @@ import * as schema from '@/lib/db/schema';
 import { loadAirportsGeoJson } from '@/lib/airports';
 import { haversineKm, initialBearingDeg } from '@/lib/geo';
 import { weatherFor } from '@/lib/weather';
-import { conditionBurnMultiplier, FUEL_DISCOUNT_PER_REP, FUEL_PRICE_PER_L, MAX_FUEL_DISCOUNT, PLANE_TYPES, repRate, WEAR_PER_KM } from '@/lib/game/catalog';
+import { FUEL_DISCOUNT_PER_REP, FUEL_PRICE_PER_L, MAX_FUEL_DISCOUNT, PLANE_TYPES, REPAIR_DURATION_MS, repRate, WEAR_PER_KM } from '@/lib/game/catalog';
 import { SPECIALS } from '@/lib/game/specials';
 import { parseIcaoQueue } from '@/lib/game/state';
 import {
@@ -130,18 +130,32 @@ export async function expirePackages(inst: GameDb, clockMs: number): Promise<num
   return n;
 }
 
-// Repairs whose gate has passed flip the plane back to 'available' and clear the gate
-// (v0.39.0, ISS-069) — same shape as expirePackages: one guarded pass over the rows,
-// `<=` inclusive at the clock. Returns the count flipped.
+// Repairs heal gradually (v0.45.0, ISS-089): while a plane is 'repairing', its health climbs along
+// round(f × 100), where f is the fraction of REPAIR_DURATION_MS elapsed since the repair started —
+// derived from the stored gate alone (start = gate − duration), so no schema change. The plane flips
+// back to 'available' exactly when it reaches full health, i.e. at the gate. Same shape as
+// expirePackages: one guarded pass over the rows. Returns the count flipped.
 export async function finishRepairs(inst: GameDb, clockMs: number): Promise<number> {
   const rows = await inst.db.select().from(schema.planes).where(eq(schema.planes.status, 'repairing'));
   let n = 0;
   for (const p of rows) {
-    if (p.repairUntilSimTime !== null && p.repairUntilSimTime <= clockMs) {
+    if (p.repairUntilSimTime === null) continue; // defensive — repairing always carries a gate
+    // ponytail: constant duration regardless of starting health — the curve is absolute (f × 100), so a
+    // plane at 90 heals in the same sim time as one at 5. Proportional duration would need storing the
+    // start health; add a column if balance wants it. The flip stays strictly at the gate (`<=` inclusive,
+    // as before) — round(f × 100) can hit 100 a hair early (f ≥ 0.995), which is cosmetic only: the plane
+    // is still 'repairing' and grounded until the gate passes.
+    const f = Math.min(1, Math.max(0, (clockMs - (p.repairUntilSimTime - REPAIR_DURATION_MS)) / REPAIR_DURATION_MS));
+    if (p.repairUntilSimTime <= clockMs) {
       await inst.db.update(schema.planes)
-        .set({ status: 'available', repairUntilSimTime: null })
+        .set({ status: 'available', health: 100, repairUntilSimTime: null })
         .where(eq(schema.planes.id, p.id));
       n++;
+    } else {
+      const newHealth = Math.min(100, Math.max(p.health, Math.round(f * 100)));
+      if (newHealth !== p.health) {
+        await inst.db.update(schema.planes).set({ health: newHealth }).where(eq(schema.planes.id, p.id));
+      }
     }
   }
   return n;
@@ -152,8 +166,9 @@ export async function finishRepairs(inst: GameDb, clockMs: number): Promise<numb
 // ones still inside their deadline are delivered (cash += reward + reputation
 // gain per package), 'expired' ones just unbind (no reward). Packages destined
 // elsewhere stay loaded on the plane for a later leg. Then (v0.25.0, ISS-043)
-// auto-chain: if the queue holds legs and fuel covers the first one, start it
-// immediately from the arrival airport; with a short tank, ISS-082 (v0.42.0) tops
+// auto-chain: if the queue holds legs, fuel covers the first one and the plane is not
+// broken by this landing's wear (v0.45.0, ISS-089), start it immediately from the arrival
+// airport; with a short tank, ISS-082 (v0.42.0) tops
 // up to 150% of the requirement (capped at tank capacity) when cash allows and
 // chains anyway — only an unaffordable top-up grounds the plane there with its
 // remaining fuel and the queue kept intact for a later dispatch.
@@ -183,12 +198,10 @@ export async function deliverPackages(inst: GameDb, clockMs: number): Promise<nu
 
     // Arrived: progress is exactly 1 here, so remaining fuel is the full-leg weighted burn —
     // wind-adjusted (v0.36.0) by departure weather vs route heading, same factor flyPlane used.
-    // v0.39.0 (ISS-069): broken planes (health ≤ 0 at DEPARTURE) burn BROKEN_BURN_MULTIPLIER × more —
-    // p.health is the pre-landing value, so this stays bit-consistent with livePlane()'s gauge.
     const w = weatherFor(p.locationIcao);
     const landedFuel = fuelAtWeighted(
       p.fuel,
-      type.burnPerKm * windBurnFactor(w.windKt, w.windDirDeg, initialBearingDeg(from.lat, from.lon, to.lat, to.lon)) * conditionBurnMultiplier(p.health),
+      type.burnPerKm * windBurnFactor(w.windKt, w.windDirDeg, initialBearingDeg(from.lat, from.lon, to.lat, to.lon)),
       type.emptyWeightKg,
       type.maxFuel,
       distanceKm,
@@ -225,20 +238,20 @@ export async function deliverPackages(inst: GameDb, clockMs: number): Promise<nu
     // (requiredFuelFor is independent of current load). ISS-082 (v0.42.0): manual refuel is gone,
     // so a short tank no longer strands the chain — when cash allows, top up to 150% of the
     // requirement (capped at tank capacity) and chain anyway; unaffordable → ground here with the
-    // queue kept intact. An unknown ICAO in the queue simply cannot chain either way.
+    // queue kept intact. An unknown ICAO in the queue simply cannot chain either way. v0.45.0
+    // (ISS-089): a plane that lands BROKEN (newHealth ≤ 0) never chains — it stays grounded with
+    // the queue intact until repaired, exactly like flyPlane's broken guard.
     const queue = parseIcaoQueue(p.queue);
     let chainedTo: string | null = null;
     let topUpFuel: number | null = null; // post-top-up fuel for the chained departure, when a top-up happened
-    if (queue.length > 0) {
+    if (queue.length > 0 && newHealth > 0) {
       const nextDest = queue[0];
       const next = byIcao.get(nextDest); // unknown ICAO in the queue → cannot chain
       if (next) {
-        // Wind-adjusted requirement for the NEXT leg — it departs from `to` (v0.36.0). v0.39.0 (ISS-069):
-        // the chained leg starts AFTER this landing's wear, so its burn uses newHealth — exactly what
-        // livePlane()/the next landing will compute for that flight.
+        // Wind-adjusted requirement for the NEXT leg — it departs from `to` (v0.36.0).
         const wNext = weatherFor(to.icao);
         const nextRequiredL = requiredFuelFor(
-          type.burnPerKm * windBurnFactor(wNext.windKt, wNext.windDirDeg, initialBearingDeg(to.lat, to.lon, next.lat, next.lon)) * conditionBurnMultiplier(newHealth),
+          type.burnPerKm * windBurnFactor(wNext.windKt, wNext.windDirDeg, initialBearingDeg(to.lat, to.lon, next.lat, next.lon)),
           type.emptyWeightKg,
           type.maxFuel,
           haversineKm(to.lat, to.lon, next.lat, next.lon),