CLAUDE: Add HBP (Hit By Pitch) handler to PlayResolver

Fixed missing PlayOutcome.HIT_BY_PITCH handling in resolve_outcome().
HBP was being submitted via WebSocket but rejected with error:
"Unhandled outcome: PlayOutcome.HIT_BY_PITCH"

Changes:
- Added HBP case to play_resolver.py (lines 430-446)
- HBP uses same forced runner advancement logic as WALK
- HBP is NOT classified as is_walk=True (correct for stats)
- Added 2 unit tests: test_hit_by_pitch, test_hit_by_pitch_bases_loaded

Test results: 981/981 passing (100%)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

backend/app/core/play_resolver.py

@@ -427,6 +427,24 @@ class PlayResolver:
                 is_walk=True,
             )
 
+        if outcome == PlayOutcome.HIT_BY_PITCH:
+            # HBP - identical to walk: batter to first, runners advance if forced
+            runners_advanced = self._advance_on_walk(state)
+            runs_scored = sum(
+                1 for (from_base, to_base) in runners_advanced if to_base == 4
+            )
+
+            return PlayResult(
+                outcome=outcome,
+                outs_recorded=0,
+                runs_scored=runs_scored,
+                batter_result=1,
+                runners_advanced=runners_advanced,
+                description="Hit by pitch",
+                ab_roll=ab_roll,
+                # Note: HBP is NOT classified as a walk for statistics purposes
+            )
+
         # ==================== Singles ====================
         if outcome == PlayOutcome.SINGLE_1:
             # Single with standard advancement

backend/tests/unit/core/test_play_resolver.py

@@ -148,6 +148,71 @@ class TestResolveOutcome:
         assert result.runs_scored == 1  # Runner on 3rd forced home
         assert (3, 4) in result.runners_advanced
 
+    def test_hit_by_pitch(self):
+        """
+        Test HBP (Hit By Pitch) resolution.
+
+        HBP works identically to walk for runner advancement, but is NOT
+        classified as a walk for baseball statistics purposes.
+        """
+        resolver = PlayResolver(league_id="sba", auto_mode=False)
+        state = GameState(
+            game_id=uuid4(),
+            league_id="sba",
+            home_team_id=1,
+            away_team_id=2,
+            current_batter=LineupPlayerState(lineup_id=1, card_id=100, position="CF", batting_order=1)
+        )
+        ab_roll = create_mock_ab_roll(state.game_id)
+
+        result = resolver.resolve_outcome(
+            outcome=PlayOutcome.HIT_BY_PITCH,
+            hit_location=None,
+            state=state,
+            defensive_decision=DefensiveDecision(),
+            offensive_decision=OffensiveDecision(),
+            ab_roll=ab_roll
+        )
+
+        assert result.outcome == PlayOutcome.HIT_BY_PITCH
+        assert result.outs_recorded == 0
+        assert result.runs_scored == 0
+        assert result.batter_result == 1  # Batter to first
+        assert result.is_walk is False  # HBP is NOT classified as walk
+        assert result.is_hit is False
+        assert result.description == "Hit by pitch"
+
+    def test_hit_by_pitch_bases_loaded(self):
+        """
+        Test HBP with bases loaded forces run home.
+
+        Same forced runner advancement logic as walk.
+        """
+        resolver = PlayResolver(league_id="sba", auto_mode=False)
+        state = GameState(
+            game_id=uuid4(),
+            league_id="sba",
+            home_team_id=1,
+            away_team_id=2,
+            current_batter=LineupPlayerState(lineup_id=1, card_id=100, position="CF", batting_order=1),
+            on_first=LineupPlayerState(lineup_id=2, card_id=101, position="CF", batting_order=2),
+            on_second=LineupPlayerState(lineup_id=3, card_id=102, position="RF", batting_order=3),
+            on_third=LineupPlayerState(lineup_id=4, card_id=103, position="SS", batting_order=4)
+        )
+        ab_roll = create_mock_ab_roll(state.game_id)
+
+        result = resolver.resolve_outcome(
+            outcome=PlayOutcome.HIT_BY_PITCH,
+            hit_location=None,
+            state=state,
+            defensive_decision=DefensiveDecision(),
+            offensive_decision=OffensiveDecision(),
+            ab_roll=ab_roll
+        )
+
+        assert result.runs_scored == 1  # Runner on 3rd forced home
+        assert (3, 4) in result.runners_advanced
+
     def test_groundball_uses_runner_advancement(self):
         """Test that groundballs delegate to RunnerAdvancement"""
         resolver = PlayResolver(league_id="sba", auto_mode=False)