implement ships depart in waves

src/lib/sim/Ship.h

@@ -62,6 +62,11 @@ struct HomeReturn
     QVector2D homePos;
 };
 
+struct RallyBehavior
+{
+    QVector2D rallyPoint;
+};
+
 // ---------------------------------------------------------------------------
 // Ship
 // ---------------------------------------------------------------------------
@@ -86,6 +91,7 @@ struct Ship
     std::optional<ScrapCollector> scrapCollector;
     std::optional<RepairBehavior> repairBehavior;
     std::optional<HomeReturn>     homeReturn;
+    std::optional<RallyBehavior>  rallyBehavior;
 
     // Cleared at the start of the behavior step each tick; the highest-priority
     // write from behavior systems wins (architecture.md §Movement Arbitration).

src/lib/sim/ShipSystem.cpp

@@ -64,6 +64,11 @@ EntityId ShipSystem::spawn(const std::string& schematicId, int level, QVector2D
         ThreatResponse tr;
         tr.engagementRange = w.range;
         ship.threatResponse = tr;
+
+        if (!isEnemy)
+        {
+            ship.rallyBehavior = RallyBehavior{m_rallyPoint};
+        }
     }
 
     if (def->salvage)
@@ -271,11 +276,18 @@ void ShipSystem::tickThreatResponse(const BuildingSystem& buildings)
             }
             else
             {
-                // No target: patrol rightward (aggressive).
+                // No target: gather at rally point or patrol rightward once departed.
                 if (3 > s.intent.priority)
                 {
-                    s.intent = MovementIntent{3, QVector2D(s.position.x() + 1000.0f,
-                                                           s.position.y())};
+                    if (s.rallyBehavior)
+                    {
+                        s.intent = MovementIntent{3, s.rallyBehavior->rallyPoint};
+                    }
+                    else
+                    {
+                        s.intent = MovementIntent{3, QVector2D(s.position.x() + 1000.0f,
+                                                               s.position.y())};
+                    }
                 }
             }
         }
@@ -636,6 +648,26 @@ void ShipSystem::tickScrapCollector(ScrapSystem& scraps, const BuildingSystem& b
     }
 }
 
+// ---------------------------------------------------------------------------
+// Rally point management (REQ-SHP-RALLY)
+// ---------------------------------------------------------------------------
+
+void ShipSystem::setRallyPoint(QVector2D point)
+{
+    m_rallyPoint = point;
+}
+
+void ShipSystem::triggerRallyDeparture()
+{
+    for (Ship& s : m_ships)
+    {
+        if (!s.isEnemy)
+        {
+            s.rallyBehavior = std::nullopt;
+        }
+    }
+}
+
 // ---------------------------------------------------------------------------
 // tickMovement  (tick-order step 10)
 // ---------------------------------------------------------------------------

src/lib/sim/ShipSystem.h

@@ -47,6 +47,12 @@ public:
     // -- Movement (tick-order step 10) ---------------------------------------
     void tickMovement();
 
+    // Set the rally point that newly spawned player combat ships will loiter at.
+    void setRallyPoint(QVector2D point);
+
+    // Release all gathered player combat ships to advance toward the enemy.
+    void triggerRallyDeparture();
+
     // Reduce ship HP by amount. Does not remove the ship; step 9 handles death.
     // Returns false if ship not found.
     bool damageShip(EntityId id, float amount);
@@ -66,4 +72,5 @@ private:
     const GameConfig&         m_config;
     std::function<EntityId()> m_allocateId;
     std::vector<Ship>         m_ships;
+    QVector2D                 m_rallyPoint;
 };

src/lib/sim/Simulation.cpp

@@ -13,6 +13,7 @@ Simulation::Simulation(GameConfig config, unsigned int seed)
     : m_config(std::move(config))
     , m_rng(seed)
     , m_currentTick(0)
+    , m_nextDepartureTick(secondsToTicks(m_config.world.departureIntervalSeconds))
     , m_nextId(1)
     , m_buildingBlocksStock(m_config.world.startingBuildingBlocks)
     , m_gameOver(false)
@@ -73,6 +74,7 @@ void Simulation::reset(unsigned int seed)
 {
     m_rng.seed(seed);
     m_currentTick              = 0;
+    m_nextDepartureTick        = secondsToTicks(m_config.world.departureIntervalSeconds);
     m_nextId                   = 1;
     m_buildingBlocksStock      = m_config.world.startingBuildingBlocks;
     m_gameOver                 = false;
@@ -139,6 +141,14 @@ void Simulation::tick()
     m_beltSystem.tick();                                 // step 6
 
     // Step 7: ship behavior systems (movement arbitration via intent priority)
+
+    // Departure timer: release gathered combat ships on a fixed interval (REQ-SHP-RALLY).
+    if (m_currentTick >= m_nextDepartureTick)
+    {
+        m_shipSystem->triggerRallyDeparture();
+        m_nextDepartureTick += secondsToTicks(m_config.world.departureIntervalSeconds);
+    }
+
     m_shipSystem->clearMovementIntents();
     m_shipSystem->tickHomeReturn();                          // priority 4
     m_shipSystem->tickThreatResponse(*m_buildingSystem);     // priority 3
@@ -217,6 +227,11 @@ void Simulation::placeInitialStructures()
         QPoint(psAnchorX, ps2Y), Rotation::East, psHp, psHp);
     m_buildingSystem->initStationWeapon(m_playerStation2Id, psWeapon);
 
+    // Rally point: center of the player defence stations' X column, world vertical midpoint.
+    const float rallyX = static_cast<float>(psAnchorX) + psParsed.footprint.width() / 2.0f;
+    const float rallyY = static_cast<float>(m_config.world.heightTiles) / 2.0f;
+    m_shipSystem->setRallyPoint(QVector2D(rallyX, rallyY));
+
     // Enemy defence stations — generation 0 (initial set).
     placeEnemyStationSet(0);
 }

src/lib/sim/Simulation.h

@@ -92,6 +92,7 @@ private:
     std::mt19937 m_rng;
 
     Tick     m_currentTick;
+    Tick     m_nextDepartureTick;
     EntityId m_nextId;
     int      m_buildingBlocksStock;
     bool     m_gameOver = false;