implement game turn logic

game-server/internal/game/manager.go

@@ -23,6 +23,7 @@ var (
 	ErrUnexpectedState    = errors.New("unexpected state for placing ships")
 	ErrShipsAlreadyPlaced = errors.New("ships already placed")
 	ErrInvalidSlot        = errors.New("invalid slot index")
+	ErrNotYourTurn        = errors.New("not your turn")
 )
 
 // BoardSize is the width and height of the Sea Battle board.
@@ -99,9 +100,11 @@ type PlayerSlot struct {
 	lastState     int  // last state sent to this player, 0 if none
 	everConnected bool // true after the first successful join
 
-	ships       []protocol.Ship
-	board       Board
-	shipsPlaced bool
+	ships          []protocol.Ship
+	board          Board
+	shipsPlaced    bool
+	struck         [BoardSize][BoardSize]bool
+	shipsRemaining int
 }
 
 // Match is the state of a single game of sea battle.
@@ -156,6 +159,26 @@ func (m *Match) Board(slotIdx int) (Board, bool) {
 	return m.slots[slotIdx].board, m.slots[slotIdx].shipsPlaced
 }
 
+// Struck returns a copy of the struck grid for the player in slotIdx.
+func (m *Match) Struck(slotIdx int) ([BoardSize][BoardSize]bool, bool) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	if slotIdx < 0 || slotIdx >= len(m.slots) {
+		return [BoardSize][BoardSize]bool{}, false
+	}
+	return m.slots[slotIdx].struck, true
+}
+
+// ShipsRemaining returns the number of unsunk ships for the player in slotIdx.
+func (m *Match) ShipsRemaining(slotIdx int) int {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	if slotIdx < 0 || slotIdx >= len(m.slots) {
+		return -1
+	}
+	return m.slots[slotIdx].shipsRemaining
+}
+
 func (m *Match) slotIndex(userID int64) int {
 	switch userID {
 	case m.playerIDs[0]:
@@ -395,11 +418,119 @@ func (m *Manager) PlaceShips(ctx context.Context, match *Match, slotIdx int, shi
 	copy(slot.ships, ships)
 	slot.board = NewBoard(ships)
 	slot.shipsPlaced = true
+	slot.shipsRemaining = len(ships)
+	slot.struck = [BoardSize][BoardSize]bool{}
 
 	m.setStateLocked(ctx, match, nextState)
 	return nil
 }
 
+// Fire processes a shot from the player at slotIdx towards opponent's board (1 - slotIdx).
+// If the player does not have the right of turn, the message is ignored and ErrNotYourTurn is returned.
+// If the position is out of bounds or already struck, FireResultInvalidPosition is sent to the shooter.
+// Otherwise:
+// - Miss: marks cell as struck, sends FireResultMiss to shooter, turn passes to opponent.
+// - Hit: marks cell as struck, sends FireResultHit to shooter, turn does not pass.
+// - Sunk: marks ship and all surrounding cells (including diagonals) as struck, sends FireResultSunk to shooter.
+//   If all opponent ships are destroyed, match finishes: END messages (victory/defeat) are sent to both players,
+//   and connections are closed immediately.
+//   Otherwise, turn does not pass.
+func (m *Manager) Fire(ctx context.Context, match *Match, slotIdx int, x, y int) (int, error) {
+	res, won, matchID, err := m.fireLocked(ctx, match, slotIdx, x, y)
+	if won {
+		// TODO: Report match result to main-server once endpoint is ready.
+		m.finishGame(matchID, slotIdx)
+	}
+	return res, err
+}
+
+func (m *Manager) fireLocked(ctx context.Context, match *Match, slotIdx int, x, y int) (res int, won bool, matchID string, err error) {
+	match.mu.Lock()
+	defer match.mu.Unlock()
+
+	if match.ended {
+		return 0, false, "", ErrMatchFinished
+	}
+	if !match.started {
+		return 0, false, "", ErrMatchNotStarted
+	}
+	if slotIdx < 0 || slotIdx >= len(match.slots) {
+		return 0, false, "", ErrInvalidSlot
+	}
+
+	var isTurn bool
+	switch match.state {
+	case StatePlayer1Turn:
+		isTurn = (slotIdx == 0)
+	case StatePlayer2Turn:
+		isTurn = (slotIdx == 1)
+	}
+	if !isTurn {
+		return 0, false, "", ErrNotYourTurn
+	}
+
+	shooter := match.slots[slotIdx]
+	target := match.slots[1-slotIdx]
+
+	if x < 0 || x >= BoardSize || y < 0 || y >= BoardSize || target.struck[y][x] {
+		m.queueFireResultLocked(ctx, shooter, protocol.FireResultInvalidPosition)
+		return protocol.FireResultInvalidPosition, false, "", nil
+	}
+
+	shipID := target.board[y][x]
+	if shipID == 0 {
+		target.struck[y][x] = true
+		m.queueFireResultLocked(ctx, shooter, protocol.FireResultMiss)
+
+		var nextState int
+		if slotIdx == 0 {
+			nextState = StatePlayer2Turn
+		} else {
+			nextState = StatePlayer1Turn
+		}
+		m.setStateLocked(ctx, match, nextState)
+		return protocol.FireResultMiss, false, "", nil
+	}
+
+	target.struck[y][x] = true
+	shipIdx := int(shipID - 1)
+	ship := target.ships[shipIdx]
+
+	sunk := true
+	for _, c := range ship.Cells() {
+		if !target.struck[c.Y][c.X] {
+			sunk = false
+			break
+		}
+	}
+
+	if !sunk {
+		m.queueFireResultLocked(ctx, shooter, protocol.FireResultHit)
+		return protocol.FireResultHit, false, "", nil
+	}
+
+	for _, c := range ship.Cells() {
+		for dy := -1; dy <= 1; dy++ {
+			for dx := -1; dx <= 1; dx++ {
+				nx, ny := c.X+dx, c.Y+dy
+				if nx >= 0 && nx < BoardSize && ny >= 0 && ny < BoardSize {
+					target.struck[ny][nx] = true
+				}
+			}
+		}
+	}
+	target.shipsRemaining--
+
+	m.queueFireResultLocked(ctx, shooter, protocol.FireResultSunk)
+
+	if target.shipsRemaining == 0 {
+		match.state = 0
+		return protocol.FireResultSunk, true, match.ID, nil
+	}
+
+	return protocol.FireResultSunk, false, "", nil
+}
+
 // SetState moves the match into a new server-side state and notifies both players.
 func (m *Manager) SetState(ctx context.Context, match *Match, state int) {
 	match.mu.Lock()
@@ -433,6 +564,18 @@ func (m *Manager) queueStateLocked(ctx context.Context, slot *PlayerSlot, state
 	}
 }
 
+// queueFireResultLocked appends a FIRE_RESULT message to the player's unacknowledged
+// queue and sends it right away if the player is connected.
+// match.mu must be held.
+func (m *Manager) queueFireResultLocked(ctx context.Context, slot *PlayerSlot, result int) {
+	slot.seq++
+	data := protocol.BuildFireResult(slot.seq, result)
+	slot.unacked = append(slot.unacked, queuedMessage{seq: slot.seq, data: data})
+	if slot.conn != nil {
+		_ = slot.conn.Send(ctx, data)
+	}
+}
+
 // replayLocked re-sends everything the connected player has not
 // acknowledged yet; if there is nothing pending, the current state is sent
 // anew so a reconnected client can catch up.
@@ -483,10 +626,25 @@ func (m *Manager) onJoinTimeout(matchID string) {
 	m.finishMatchLocked(match, protocol.EndCodeJoinTimeout, "join timeout exceeded")
 }
 
+type playerEnd struct {
+	code   int
+	reason string
+}
+
 // finishMatchLocked tears down a match, removes it from m.matches, records it in m.finished,
-// and sends END notifications to connected players. Both m.mu and match.mu must be held
+// and sends identical END notifications to all players. Both m.mu and match.mu must be held
 // upon entry; both are unlocked by this function.
 func (m *Manager) finishMatchLocked(match *Match, code int, reason string) {
+	m.finishMatchWithEndsLocked(match, [2]playerEnd{
+		{code: code, reason: reason},
+		{code: code, reason: reason},
+	})
+}
+
+// finishMatchWithEndsLocked tears down a match, removes it from m.matches, records it in m.finished,
+// and sends per-player END notifications to connected players. Both m.mu and match.mu must be held
+// upon entry; both are unlocked by this function.
+func (m *Manager) finishMatchWithEndsLocked(match *Match, endsPerSlot [2]playerEnd) {
 	match.ended = true
 	if match.joinTimer != nil {
 		match.joinTimer.Stop()
@@ -499,9 +657,10 @@ func (m *Manager) finishMatchLocked(match *Match, code int, reason string) {
 		data []byte
 	}
 	var notify []notification
-	for _, slot := range match.slots {
+	for i, slot := range match.slots {
 		slot.seq++
-		data := protocol.BuildEnd(slot.seq, code, reason)
+		end := endsPerSlot[i]
+		data := protocol.BuildEnd(slot.seq, end.code, end.reason)
 		slot.unacked = append(slot.unacked, queuedMessage{seq: slot.seq, data: data})
 		ends[slot.UserID] = data
 		if slot.conn != nil {
@@ -529,8 +688,43 @@ func (m *Manager) finishMatchLocked(match *Match, code int, reason string) {
 	// Network I/O happens outside of any lock.
 	for _, n := range notify {
 		_ = n.conn.Send(context.Background(), n.data)
-		_ = n.conn.Close(protocol.CloseCodeNormal, "match ended")
 	}
+	var wg sync.WaitGroup
+	for _, n := range notify {
+		wg.Add(1)
+		go func(c Sender) {
+			defer wg.Done()
+			_ = c.Close(protocol.CloseCodeNormal, "match ended")
+		}(n.conn)
+	}
+	wg.Wait()
+}
+
+// finishGame completes a match due to all opponent ships being sunk.
+// winnerSlot is the slot index of the winning player (0 or 1).
+func (m *Manager) finishGame(matchID string, winnerSlot int) {
+	m.mu.Lock()
+	match, ok := m.matches[matchID]
+	if !ok {
+		m.mu.Unlock()
+		return
+	}
+	match.mu.Lock()
+	if match.ended {
+		match.mu.Unlock()
+		m.mu.Unlock()
+		return
+	}
+
+	endsPerSlot := [2]playerEnd{
+		{code: protocol.EndCodeVictory, reason: "victory"},
+		{code: protocol.EndCodeDefeat, reason: "defeat"},
+	}
+	if winnerSlot == 1 {
+		endsPerSlot[0], endsPerSlot[1] = endsPerSlot[1], endsPerSlot[0]
+	}
+
+	m.finishMatchWithEndsLocked(match, endsPerSlot)
 }
 
 // Shutdown closes all active player connections across all matches with code 1001 (going away)

game-server/internal/game/manager_test.go

@@ -644,3 +644,343 @@ func TestPlaceShipsBeforeMatchStarts(t *testing.T) {
 		t.Fatalf("got err = %v, want ErrMatchNotStarted", err)
 	}
 }
+
+func setupStartedGame(t *testing.T) (*Manager, *Match, *fakeConn, *fakeConn) {
+	t.Helper()
+	m := NewManager(time.Minute)
+	gc := claims(time.Now().Add(time.Hour))
+	c1, c2 := &fakeConn{}, &fakeConn{}
+
+	match, _, err := m.Join(context.Background(), c1, gc, gc.Player1ID)
+	if err != nil {
+		t.Fatalf("join p1: %v", err)
+	}
+	if _, _, err := m.Join(context.Background(), c2, gc, gc.Player2ID); err != nil {
+		t.Fatalf("join p2: %v", err)
+	}
+
+	ships := validTestShips()
+	if err := m.PlaceShips(context.Background(), match, 0, ships); err != nil {
+		t.Fatalf("p1 place ships: %v", err)
+	}
+	if err := m.PlaceShips(context.Background(), match, 1, ships); err != nil {
+		t.Fatalf("p2 place ships: %v", err)
+	}
+	if match.State() != StatePlayer1Turn {
+		t.Fatalf("state = %d, want StatePlayer1Turn", match.State())
+	}
+	return m, match, c1, c2
+}
+
+func TestFireMissTransitionsTurn(t *testing.T) {
+	m, match, c1, c2 := setupStartedGame(t)
+
+	// In validTestShips, cell (9, 9) has no ships.
+	res, err := m.Fire(context.Background(), match, 0, 9, 9)
+	if err != nil {
+		t.Fatalf("Fire: %v", err)
+	}
+	if res != protocol.FireResultMiss {
+		t.Fatalf("res = %d, want FireResultMiss", res)
+	}
+
+	// Shooter receives FIRE_RESULT with miss (1)
+	c1Msgs := c1.messages()
+	// c1 got: [STATE 1], [STATE 3], [STATE 4], [FIRE_RESULT 1], [STATE 5]
+	fireMsg := parseMsg(t, c1Msgs[len(c1Msgs)-2])
+	if fireMsg[0] != float64(protocol.OpFireResult) || fireMsg[2] != float64(protocol.FireResultMiss) {
+		t.Fatalf("unexpected fireMsg: %v", fireMsg)
+	}
+
+	// Turn transitions to Player 2
+	if match.State() != StatePlayer2Turn {
+		t.Fatalf("state = %d, want StatePlayer2Turn", match.State())
+	}
+
+	c1Last := parseMsg(t, c1Msgs[len(c1Msgs)-1])
+	if c1Last[0] != float64(protocol.OpState) || c1Last[2] != float64(protocol.StateWaitOpponentTurn) {
+		t.Fatalf("c1 last state = %v, want StateWaitOpponentTurn", c1Last)
+	}
+
+	c2Msgs := c2.messages()
+	c2Last := parseMsg(t, c2Msgs[len(c2Msgs)-1])
+	if c2Last[0] != float64(protocol.OpState) || c2Last[2] != float64(protocol.StateYourTurn) {
+		t.Fatalf("c2 last state = %v, want StateYourTurn", c2Last)
+	}
+
+	// Target board cell (9, 9) marked struck
+	struck, ok := match.Struck(1)
+	if !ok || !struck[9][9] {
+		t.Fatalf("expected p2 cell (9, 9) to be struck")
+	}
+}
+
+func TestFireHitKeepsTurn(t *testing.T) {
+	m, match, c1, c2 := setupStartedGame(t)
+
+	// Ship 9 is 4 cells horizontally at (0, 0), (1, 0), (2, 0), (3, 0)
+	res, err := m.Fire(context.Background(), match, 0, 0, 0)
+	if err != nil {
+		t.Fatalf("Fire: %v", err)
+	}
+	if res != protocol.FireResultHit {
+		t.Fatalf("res = %d, want FireResultHit", res)
+	}
+
+	c1Msgs := c1.messages()
+	fireMsg := parseMsg(t, c1Msgs[len(c1Msgs)-1])
+	if fireMsg[0] != float64(protocol.OpFireResult) || fireMsg[2] != float64(protocol.FireResultHit) {
+		t.Fatalf("unexpected fireMsg: %v", fireMsg)
+	}
+
+	// Turn stays with Player 1
+	if match.State() != StatePlayer1Turn {
+		t.Fatalf("state = %d, want StatePlayer1Turn", match.State())
+	}
+
+	// Player 2 should not have received any new messages
+	c2Msgs := c2.messages()
+	// c2 messages before: [STATE 1], [STATE 2], [STATE 5]
+	if len(c2Msgs) != 3 {
+		t.Fatalf("p2 received unexpected message: %d messages", len(c2Msgs))
+	}
+}
+
+func TestFireSunkMarksSurroundings(t *testing.T) {
+	m, match, c1, _ := setupStartedGame(t)
+
+	// Ship 0 is 1 cell at (9, 4)
+	res, err := m.Fire(context.Background(), match, 0, 9, 4)
+	if err != nil {
+		t.Fatalf("Fire: %v", err)
+	}
+	if res != protocol.FireResultSunk {
+		t.Fatalf("res = %d, want FireResultSunk", res)
+	}
+
+	c1Msgs := c1.messages()
+	fireMsg := parseMsg(t, c1Msgs[len(c1Msgs)-1])
+	if fireMsg[0] != float64(protocol.OpFireResult) || fireMsg[2] != float64(protocol.FireResultSunk) {
+		t.Fatalf("unexpected fireMsg: %v", fireMsg)
+	}
+
+	if match.ShipsRemaining(1) != 9 {
+		t.Fatalf("shipsRemaining = %d, want 9", match.ShipsRemaining(1))
+	}
+
+	// Check that (9, 4) and surrounding cells (8,3), (8,4), (8,5), (9,3), (9,5) are struck
+	struck, _ := match.Struck(1)
+	expectedCells := [][2]int{
+		{9, 4},
+		{8, 3}, {8, 4}, {8, 5},
+		{9, 3}, {9, 5},
+	}
+	for _, pt := range expectedCells {
+		if !struck[pt[1]][pt[0]] {
+			t.Fatalf("expected cell (%d, %d) to be struck", pt[0], pt[1])
+		}
+	}
+
+	// Turn stays with Player 1 because hit/sunk does not pass turn unless game over
+	if match.State() != StatePlayer1Turn {
+		t.Fatalf("state = %d, want StatePlayer1Turn", match.State())
+	}
+}
+
+func TestFireInvalidPosition(t *testing.T) {
+	m, match, c1, _ := setupStartedGame(t)
+
+	t.Run("out of bounds negative", func(t *testing.T) {
+		res, err := m.Fire(context.Background(), match, 0, -1, 5)
+		if err != nil {
+			t.Fatalf("Fire: %v", err)
+		}
+		if res != protocol.FireResultInvalidPosition {
+			t.Fatalf("res = %d, want FireResultInvalidPosition", res)
+		}
+		msgs := c1.messages()
+		msg := parseMsg(t, msgs[len(msgs)-1])
+		if msg[0] != float64(protocol.OpFireResult) || msg[2] != float64(protocol.FireResultInvalidPosition) {
+			t.Fatalf("unexpected msg: %v", msg)
+		}
+	})
+
+	t.Run("out of bounds over 9", func(t *testing.T) {
+		res, err := m.Fire(context.Background(), match, 0, 10, 0)
+		if err != nil {
+			t.Fatalf("Fire: %v", err)
+		}
+		if res != protocol.FireResultInvalidPosition {
+			t.Fatalf("res = %d, want FireResultInvalidPosition", res)
+		}
+	})
+
+	t.Run("already struck cell", func(t *testing.T) {
+		// First shoot (9, 4) - sinks single ship
+		res, err := m.Fire(context.Background(), match, 0, 9, 4)
+		if err != nil || res != protocol.FireResultSunk {
+			t.Fatalf("initial fire: res=%d, err=%v", res, err)
+		}
+
+		// Shooting (9, 4) again returns InvalidPosition
+		res, err = m.Fire(context.Background(), match, 0, 9, 4)
+		if err != nil {
+			t.Fatalf("repeat fire: %v", err)
+		}
+		if res != protocol.FireResultInvalidPosition {
+			t.Fatalf("res = %d, want FireResultInvalidPosition", res)
+		}
+
+		// Shooting diagonal neighbor (8, 5) which was marked struck due to sunk ship also returns InvalidPosition
+		res, err = m.Fire(context.Background(), match, 0, 8, 5)
+		if err != nil {
+			t.Fatalf("halo fire: %v", err)
+		}
+		if res != protocol.FireResultInvalidPosition {
+			t.Fatalf("res = %d, want FireResultInvalidPosition", res)
+		}
+	})
+}
+
+func TestFireIgnoredWhenNotYourTurn(t *testing.T) {
+	m, match, c1, c2 := setupStartedGame(t)
+
+	// It's player 1's turn, player 2 tries to shoot
+	c2CountBefore := len(c2.messages())
+	res, err := m.Fire(context.Background(), match, 1, 0, 0)
+	if err != ErrNotYourTurn {
+		t.Fatalf("p2 fire: got err = %v, want ErrNotYourTurn", err)
+	}
+	if res != 0 {
+		t.Fatalf("res = %d, want 0", res)
+	}
+	if len(c2.messages()) != c2CountBefore {
+		t.Fatal("expected no messages sent to p2 on ignored fire")
+	}
+
+	// Match state unchanged
+	if match.State() != StatePlayer1Turn {
+		t.Fatalf("state = %d, want StatePlayer1Turn", match.State())
+	}
+	_ = c1
+}
+
+func TestFireWinCondition(t *testing.T) {
+	m, match, c1, c2 := setupStartedGame(t)
+	gc := claims(time.Now().Add(time.Hour))
+
+	// Player 1 destroys all 10 ships of Player 2
+	ships := validTestShips()
+	for i, ship := range ships {
+		cells := ship.Cells()
+		for j, c := range cells {
+			res, err := m.Fire(context.Background(), match, 0, c.X, c.Y)
+			if err != nil {
+				t.Fatalf("ship %d cell %d fire: %v", i, j, err)
+			}
+			if j < len(cells)-1 {
+				if res != protocol.FireResultHit {
+					t.Fatalf("ship %d cell %d: res = %d, want Hit", i, j, res)
+				}
+			} else {
+				if res != protocol.FireResultSunk {
+					t.Fatalf("ship %d cell %d: res = %d, want Sunk", i, j, res)
+				}
+			}
+		}
+	}
+
+	// Match should be removed from m.matches (preventing memory leak)
+	if m.GetMatch(match.ID) != nil {
+		t.Fatal("expected match to be removed from m.matches")
+	}
+
+	// Check END messages sent to both players
+	c1Msgs := c1.messages()
+	// c1 receives FIRE_RESULT (sunk) followed by END (victory)
+	c1End := parseMsg(t, c1Msgs[len(c1Msgs)-1])
+	if c1End[0] != float64(protocol.OpEnd) || c1End[2] != float64(protocol.EndCodeVictory) || c1End[3] != "victory" {
+		t.Fatalf("p1 got %v, want END with EndCodeVictory (1) 'victory'", c1End)
+	}
+
+	c2Msgs := c2.messages()
+	c2End := parseMsg(t, c2Msgs[len(c2Msgs)-1])
+	if c2End[0] != float64(protocol.OpEnd) || c2End[2] != float64(protocol.EndCodeDefeat) || c2End[3] != "defeat" {
+		t.Fatalf("p2 got %v, want END with EndCodeDefeat (2) 'defeat'", c2End)
+	}
+
+	// Connections must be closed immediately with CloseCodeNormal
+	if closed, code := c1.isClosed(); !closed || code != protocol.CloseCodeNormal {
+		t.Fatalf("c1 closed=%v code=%d, want closed with %d", closed, code, protocol.CloseCodeNormal)
+	}
+	if closed, code := c2.isClosed(); !closed || code != protocol.CloseCodeNormal {
+		t.Fatalf("c2 closed=%v code=%d, want closed with %d", closed, code, protocol.CloseCodeNormal)
+	}
+
+	// Late reconnects get the respective END messages replayed
+	c1Rejoin := &fakeConn{}
+	_, _, err := m.Join(context.Background(), c1Rejoin, gc, gc.Player1ID)
+	if err != ErrMatchFinished {
+		t.Fatalf("rejoin p1: got err = %v, want ErrMatchFinished", err)
+	}
+	msgs := c1Rejoin.messages()
+	if len(msgs) != 1 {
+		t.Fatalf("p1 got %d replay messages, want 1", len(msgs))
+	}
+	if v := parseMsg(t, msgs[0]); v[0] != float64(protocol.OpEnd) || v[2] != float64(protocol.EndCodeVictory) {
+		t.Fatalf("p1 replayed msg = %v, want END victory", v)
+	}
+
+	c2Rejoin := &fakeConn{}
+	_, _, err = m.Join(context.Background(), c2Rejoin, gc, gc.Player2ID)
+	if err != ErrMatchFinished {
+		t.Fatalf("rejoin p2: got err = %v, want ErrMatchFinished", err)
+	}
+	msgs = c2Rejoin.messages()
+	if len(msgs) != 1 {
+		t.Fatalf("p2 got %d replay messages, want 1", len(msgs))
+	}
+	if v := parseMsg(t, msgs[0]); v[0] != float64(protocol.OpEnd) || v[2] != float64(protocol.EndCodeDefeat) {
+		t.Fatalf("p2 replayed msg = %v, want END defeat", v)
+	}
+}
+
+func TestFireAckAndReplay(t *testing.T) {
+	m, match, _, _ := setupStartedGame(t)
+
+	// In setupStartedGame, c1 received 3 STATE messages (seq 1, 2, 3)
+	// Player 1 fires: generates FIRE_RESULT with seq 4
+	res, err := m.Fire(context.Background(), match, 0, 0, 0)
+	if err != nil || res != protocol.FireResultHit {
+		t.Fatalf("fire: res=%d, err=%v", res, err)
+	}
+
+	// Ack seq 4
+	if err := m.Ack(match, 0, 4); err != nil {
+		t.Fatalf("ack: %v", err)
+	}
+
+	// Player 1 fires again at (1, 0): generates FIRE_RESULT with seq 5
+	res, err = m.Fire(context.Background(), match, 0, 1, 0)
+	if err != nil || res != protocol.FireResultHit {
+		t.Fatalf("fire 2: res=%d, err=%v", res, err)
+	}
+
+	// Reconnect player 1 without ACKing seq 5
+	fresh := &fakeConn{}
+	gc := claims(time.Now().Add(time.Hour))
+	if _, _, err := m.Join(context.Background(), fresh, gc, gc.Player1ID); err != nil {
+		t.Fatalf("rejoin: %v", err)
+	}
+
+	freshMsgs := fresh.messages()
+	if len(freshMsgs) != 1 {
+		t.Fatalf("rejoined player got %d messages, want 1", len(freshMsgs))
+	}
+	v := parseMsg(t, freshMsgs[0])
+	// Should be replayed FIRE_RESULT [7, 5, 2]
+	if v[0] != float64(protocol.OpFireResult) || v[1] != float64(5) || v[2] != float64(protocol.FireResultHit) {
+		t.Fatalf("replayed msg = %v, want [7, 5, 2]", v)
+	}
+}
+