chore(release): 4.4.9 [skip ci]

## [4.4.9](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.4.8...v4.4.9) (2025-10-17)

### Bug Fixes

* **complement-race:** reduce initial momentum from 50 to 10 to prevent train sailing past first station ([5f146b0](5f146b0daf))

CHANGELOG.md

@@ -1,3 +1,31 @@
+## [4.4.9](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.4.8...v4.4.9) (2025-10-17)
+
+
+### Bug Fixes
+
+* **complement-race:** reduce initial momentum from 50 to 10 to prevent train sailing past first station ([5f146b0](https://github.com/antialias/soroban-abacus-flashcards/commit/5f146b0daf74d54e1c7b9a57d3a2f37e73849ff2))
+
+## [4.4.8](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.4.7...v4.4.8) (2025-10-17)
+
+
+### Bug Fixes
+
+* **complement-race:** implement client-side momentum with continuous decay for smooth train movement ([ea19ff9](https://github.com/antialias/soroban-abacus-flashcards/commit/ea19ff918bc70ad3eb0339e18dbd32195f34816e))
+
+## [4.4.7](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.4.6...v4.4.7) (2025-10-17)
+
+
+### Bug Fixes
+
+* **complement-race:** add missing useRef import ([d43829a](https://github.com/antialias/soroban-abacus-flashcards/commit/d43829ad48f7ee879a46879f5e6ac1256db1f564))
+
+## [4.4.6](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.4.5...v4.4.6) (2025-10-17)
+
+
+### Bug Fixes
+
+* **complement-race:** restore smooth train movement with client-side game loop ([46a80cb](https://github.com/antialias/soroban-abacus-flashcards/commit/46a80cbcc8ec39224d4edaf540da25611d48fbdd))
+
 ## [4.4.5](https://github.com/antialias/soroban-abacus-flashcards/compare/v4.4.4...v4.4.5) (2025-10-17)
 
 

apps/web/src/app/arcade/complement-race/components/GameDisplay.tsx

@@ -5,7 +5,6 @@ import { useComplementRace } from '@/arcade-games/complement-race/Provider'
 import { useAdaptiveDifficulty } from '../hooks/useAdaptiveDifficulty'
 import { useAIRacers } from '../hooks/useAIRacers'
 import { useSoundEffects } from '../hooks/useSoundEffects'
-import { useSteamJourney } from '../hooks/useSteamJourney'
 import { generatePassengers } from '../lib/passengerGenerator'
 import { AbacusTarget } from './AbacusTarget'
 import { CircularTrack } from './RaceTrack/CircularTrack'
@@ -16,10 +15,9 @@ import { RouteCelebration } from './RouteCelebration'
 type FeedbackAnimation = 'correct' | 'incorrect' | null
 
 export function GameDisplay() {
-  const { state, dispatch } = useComplementRace()
+  const { state, dispatch, boostMomentum } = useComplementRace()
   useAIRacers() // Activate AI racer updates (not used in sprint mode)
   const { trackPerformance, getAdaptiveFeedbackMessage } = useAdaptiveDifficulty()
-  const { boostMomentum } = useSteamJourney()
   const { playSound } = useSoundEffects()
   const [feedbackAnimation, setFeedbackAnimation] = useState<FeedbackAnimation>(null)
 
@@ -109,7 +107,7 @@ export function GameDisplay() {
 
               // Boost momentum for sprint mode
               if (state.style === 'sprint') {
-                boostMomentum()
+                boostMomentum(true)
 
                 // Play train whistle for milestones in sprint mode (line 13222-13235)
                 if (newStreak >= 5 && newStreak % 3 === 0) {
@@ -144,6 +142,11 @@ export function GameDisplay() {
               // Play incorrect sound (from web_generator.py line 11589)
               playSound('incorrect')
 
+              // Reduce momentum for sprint mode
+              if (state.style === 'sprint') {
+                boostMomentum(false)
+              }
+
               // Show adaptive feedback
               const feedback = getAdaptiveFeedbackMessage(pairKey, false, responseTime)
               if (feedback) {

apps/web/src/arcade-games/complement-race/Provider.tsx

@@ -11,6 +11,7 @@ import {
   useContext,
   useEffect,
   useMemo,
+  useRef,
   useState,
   type ReactNode,
 } from 'react'
@@ -110,6 +111,7 @@ interface ComplementRaceContextValue {
   setConfig: (field: keyof ComplementRaceConfig, value: unknown) => void
   clearError: () => void
   exitSession: () => void
+  boostMomentum: (correct: boolean) => void // Client-side momentum boost/reduce
 }
 
 const ComplementRaceContext = createContext<ComplementRaceContextValue | null>(null)
@@ -251,6 +253,29 @@ export function ComplementRaceProvider({ children }: { children: ReactNode }) {
   // Debug logging ref (track last logged values)
   const lastLogRef = useState({ key: '', count: 0 })[0]
 
+  // Client-side game state (NOT synced to server - purely visual/gameplay)
+  const [clientMomentum, setClientMomentum] = useState(10) // Start at 10 for gentle push
+  const [clientPosition, setClientPosition] = useState(0)
+  const [clientPressure, setClientPressure] = useState(0)
+  const lastUpdateRef = useRef(Date.now())
+  const gameStartTimeRef = useRef(0)
+
+  // Decay rates based on skill level (momentum lost per second)
+  const MOMENTUM_DECAY_RATES = {
+    preschool: 2.0,
+    kindergarten: 3.5,
+    relaxed: 5.0,
+    slow: 7.0,
+    normal: 9.0,
+    fast: 11.0,
+    expert: 13.0,
+  }
+
+  const MOMENTUM_GAIN_PER_CORRECT = 15
+  const MOMENTUM_LOSS_PER_WRONG = 10
+  const SPEED_MULTIPLIER = 0.15 // momentum * 0.15 = % per second
+  const UPDATE_INTERVAL = 50 // 50ms = ~20fps
+
   // Transform multiplayer state to look like single-player state
   const compatibleState = useMemo((): CompatibleGameState => {
     const localPlayer = localPlayerId ? multiplayerState.players[localPlayerId] : null
@@ -314,10 +339,10 @@ export function ComplementRaceProvider({ children }: { children: ReactNode }) {
         previousPosition: ai.position,
       })),
 
-      // Sprint mode specific
-      momentum: localPlayer?.momentum || 0,
-      trainPosition: localPlayer?.position || 0,
-      pressure: localPlayer?.pressure || 0, // Use actual pressure from server (has decay)
+      // Sprint mode specific (all client-side for smooth movement)
+      momentum: clientMomentum, // Client-only state with continuous decay
+      trainPosition: clientPosition, // Client-calculated from momentum
+      pressure: clientPressure, // Client-calculated from momentum (0-150 PSI)
       elapsedTime: multiplayerState.gameStartTime ? Date.now() - multiplayerState.gameStartTime : 0,
       lastCorrectAnswerTime: localPlayer?.lastAnswerTime || Date.now(),
       currentRoute: multiplayerState.currentRoute,
@@ -339,7 +364,80 @@ export function ComplementRaceProvider({ children }: { children: ReactNode }) {
       adaptiveFeedback: localUIState.adaptiveFeedback,
       difficultyTracker: localUIState.difficultyTracker,
     }
-  }, [multiplayerState, localPlayerId, localUIState])
+  }, [multiplayerState, localPlayerId, localUIState, clientPosition, clientPressure])
+
+  // Initialize game start time when game becomes active
+  useEffect(() => {
+    if (compatibleState.isGameActive && compatibleState.style === 'sprint') {
+      if (gameStartTimeRef.current === 0) {
+        gameStartTimeRef.current = Date.now()
+        lastUpdateRef.current = Date.now()
+        // Reset client state for new game
+        setClientMomentum(10) // Start with gentle push
+        setClientPosition(0)
+        setClientPressure((10 / 100) * 150) // Initial pressure from starting momentum
+      }
+    } else {
+      // Reset when game ends
+      gameStartTimeRef.current = 0
+    }
+  }, [compatibleState.isGameActive, compatibleState.style])
+
+  // Main client-side game loop: momentum decay and position calculation
+  useEffect(() => {
+    if (!compatibleState.isGameActive || compatibleState.style !== 'sprint') return
+
+    const interval = setInterval(() => {
+      const now = Date.now()
+      const deltaTime = now - lastUpdateRef.current
+      lastUpdateRef.current = now
+
+      // Get decay rate based on skill level
+      const decayRate =
+        MOMENTUM_DECAY_RATES[compatibleState.timeoutSetting as keyof typeof MOMENTUM_DECAY_RATES] ||
+        MOMENTUM_DECAY_RATES.normal
+
+      setClientMomentum((prevMomentum) => {
+        // Calculate momentum decay for this frame
+        const momentumLoss = (decayRate * deltaTime) / 1000
+
+        // Update momentum (don't go below 0)
+        const newMomentum = Math.max(0, prevMomentum - momentumLoss)
+
+        // Calculate speed from momentum (% per second)
+        const speed = newMomentum * SPEED_MULTIPLIER
+
+        // Update position (accumulate, never go backward)
+        const positionDelta = (speed * deltaTime) / 1000
+        setClientPosition((prev) => prev + positionDelta)
+
+        // Calculate pressure (0-150 PSI)
+        const pressure = Math.min(150, (newMomentum / 100) * 150)
+        setClientPressure(pressure)
+
+        return newMomentum
+      })
+    }, UPDATE_INTERVAL)
+
+    return () => clearInterval(interval)
+  }, [
+    compatibleState.isGameActive,
+    compatibleState.style,
+    compatibleState.timeoutSetting,
+    MOMENTUM_DECAY_RATES,
+    SPEED_MULTIPLIER,
+    UPDATE_INTERVAL,
+  ])
+
+  // Reset client position when route changes
+  useEffect(() => {
+    const currentRoute = multiplayerState.currentRoute
+    // When route changes, reset position and give starting momentum
+    if (currentRoute > 1 && compatibleState.style === 'sprint') {
+      setClientPosition(0)
+      setClientMomentum(10) // Reset to starting momentum (gentle push)
+    }
+  }, [multiplayerState.currentRoute, compatibleState.style])
 
   // Debug logging: only log on answer submission or significant events
   useEffect(() => {
@@ -634,6 +732,22 @@ export function ComplementRaceProvider({ children }: { children: ReactNode }) {
     ]
   )
 
+  // Client-side momentum boost/reduce (sprint mode only)
+  const boostMomentum = useCallback(
+    (correct: boolean) => {
+      if (compatibleState.style !== 'sprint') return
+
+      setClientMomentum((prevMomentum) => {
+        if (correct) {
+          return Math.min(100, prevMomentum + MOMENTUM_GAIN_PER_CORRECT)
+        } else {
+          return Math.max(0, prevMomentum - MOMENTUM_LOSS_PER_WRONG)
+        }
+      })
+    },
+    [compatibleState.style, MOMENTUM_GAIN_PER_CORRECT, MOMENTUM_LOSS_PER_WRONG]
+  )
+
   const contextValue: ComplementRaceContextValue = {
     state: compatibleState, // Use transformed state
     dispatch,
@@ -649,6 +763,7 @@ export function ComplementRaceProvider({ children }: { children: ReactNode }) {
     setConfig,
     clearError,
     exitSession,
+    boostMomentum, // Client-side momentum control
   }
 
   return (

apps/web/src/arcade-games/complement-race/Validator.ts

@@ -168,9 +168,7 @@ export class ComplementRaceValidator
         bestStreak: 0,
         correctAnswers: 0,
         totalQuestions: 0,
-        position: 0,
-        momentum: 50, // Start with some momentum in sprint mode
-        pressure: 60, // Start with initial pressure
+        position: 0, // Only used for practice/survival; sprint mode is client-side
         isReady: false,
         isActive: true,
         currentAnswer: null,
@@ -318,25 +316,9 @@ export class ComplementRaceValidator
         updatedPlayer.position = Math.min(100, player.position + 100 / state.config.raceGoal)
       }
     } else if (state.config.style === 'sprint') {
-      // Sprint: Update momentum, pressure, AND position
-      if (correct) {
-        updatedPlayer.momentum = Math.min(100, player.momentum + 15)
-        // Add pressure on correct answer (add steam to boiler)
-        updatedPlayer.pressure = Math.min(100, player.pressure + 20)
-      } else {
-        updatedPlayer.momentum = Math.max(0, player.momentum - 10)
-        // Less pressure added on wrong answer
-        updatedPlayer.pressure = Math.min(100, player.pressure + 5)
-      }
-
-      // Pressure decay: Every answer causes some steam to escape
-      // Decay rate: 8 points per answer (pressure naturally decreases over time)
-      updatedPlayer.pressure = Math.max(0, updatedPlayer.pressure - 8)
-
-      // Move train based on momentum (momentum/20 = position change per answer)
-      // Higher momentum = faster movement
-      const moveDistance = updatedPlayer.momentum / 20
-      updatedPlayer.position = Math.min(100, player.position + moveDistance)
+      // Sprint: All momentum/position handled client-side for smooth 20fps movement
+      // Server only tracks scoring, passengers, and game progression
+      // No server-side position updates needed
     } else if (state.config.style === 'survival') {
       // Survival: Always move forward, speed based on accuracy
       const moveDistance = correct ? 5 : 2
@@ -536,14 +518,12 @@ export class ComplementRaceValidator
       return { valid: false, error: 'Routes only available in sprint mode' }
     }
 
-    // Reset all player positions to 0 for new route
+    // Reset all player positions to 0 for new route (client handles momentum reset)
     const resetPlayers: Record<string, PlayerState> = {}
     for (const [playerId, player] of Object.entries(state.players)) {
       resetPlayers[playerId] = {
         ...player,
-        position: 0,
-        momentum: 50, // Reset momentum to starting value
-        pressure: 60, // Reset pressure to starting value
+        position: 0, // Server position not used in sprint; client will reset
         passengers: [], // Clear any remaining passengers
       }
     }

apps/web/src/arcade-games/complement-race/types.ts

@@ -61,9 +61,7 @@ export interface PlayerState {
   totalQuestions: number
 
   // Position & Progress
-  position: number // 0-100% for practice/sprint, lap count for survival
-  momentum: number // 0-100 (sprint mode only)
-  pressure: number // 0-100 (sprint mode only, decays over time)
+  position: number // 0-100% for practice/survival only (sprint mode: client-side)
 
   // Current state
   isReady: boolean

package.json

@@ -1,6 +1,6 @@
 {
   "name": "soroban-monorepo",
-  "version": "4.4.5",
+  "version": "4.4.9",
   "private": true,
   "description": "Beautiful Soroban Flashcard Generator - Monorepo",
   "workspaces": [