feat: add Zenith strategy and move latency tracing

- Register Zenith 1.1 with balanced duel verdicts and forced-outcome overrides.
- Prioritize permanent-trail space in Constrictor and health-aware hazard routes.
- Deduct executor queue delays and return fallback directions on move timeouts.
- Correlate response headers, replay timings, and sampled structured trace logs.
- Move shared metrics publication off the response path without losing local counts.
- Allow configurable tournament opponents and add a psql helper recipe.
- Preserve empty latency values through compact replay encoding and migration.
- Update Arena game links and use default assets for missing customizations.
- Cover strategy, HTTP lifecycle, tracing, replay codecs, and dashboard behavior.
- Validate with 260 passing Python tests, 4 skips, and 2 passing JavaScript tests.

tests/snakes/test_ZenithBattleSnake_ClaudeOpus5_5.py

@@ -0,0 +1,84 @@
+import unittest
+from time import perf_counter
+
+from snakes import SnakeBuilder, get_snake_version
+from snakes.strategies.prism import PrismBattleSnake_GPT_5_6_Sol
+from snakes.strategies.zenith import ZenithBattleSnake_ClaudeOpus5_5
+
+LOSS = -100_000.0
+WIN = 100_000.0
+
+class TestZenithRegistration(unittest.TestCase):
+
+  def test_api_name_and_version_are_exposed(self):
+    snake = ZenithBattleSnake_ClaudeOpus5_5()
+
+    self.assertEqual(snake.name, "ZenithBattleSnake")
+    self.assertEqual(snake.version, "1.1.0")
+    self.assertEqual(get_snake_version("ZenithBattleSnake_ClaudeOpus5_5"), "1.1.0")
+    self.assertIsInstance(snake, PrismBattleSnake_GPT_5_6_Sol)
+    self.assertIsInstance(
+      SnakeBuilder.build("ZenithBattleSnake_ClaudeOpus5_5"),
+      ZenithBattleSnake_ClaudeOpus5_5,
+    )
+
+class TestZenithVerdicts(unittest.TestCase):
+
+  def test_proven_loss_is_vetoed_for_best_surviving_heuristic(self):
+    scores = {"up": 300.0, "left": 120.0, "right": 90.0}
+    verdicts = {"up": (LOSS, 3), "left": (-40.0, 3), "right": (25.0, 3)}
+
+    self.assertEqual(ZenithBattleSnake_ClaudeOpus5_5._apply_verdicts("up", scores, verdicts), "left")
+
+  def test_proven_win_overrides_heuristic(self):
+    scores = {"up": 300.0, "left": 120.0}
+    verdicts = {"up": (15.0, 2), "left": (WIN, 2)}
+
+    self.assertEqual(ZenithBattleSnake_ClaudeOpus5_5._apply_verdicts("up", scores, verdicts), "left")
+
+  def test_keeps_choice_when_every_move_loses(self):
+    scores = {"up": 300.0, "left": 120.0}
+    verdicts = {"up": (LOSS, 2), "left": (LOSS - 1, 2)}
+
+    self.assertEqual(ZenithBattleSnake_ClaudeOpus5_5._apply_verdicts("up", scores, verdicts), "up")
+
+  def test_keeps_choice_without_verdict(self):
+    scores = {"up": 300.0, "left": 120.0}
+    self.assertEqual(ZenithBattleSnake_ClaudeOpus5_5._apply_verdicts("up", scores, {}), "up")
+
+  def test_verdict_search_resolves_every_candidate(self):
+    snake = ZenithBattleSnake_ClaudeOpus5_5()
+    # Longer enemy can also reach (2, 5): stepping there loses the head-to-head.
+    my_body = [{"x": 1, "y": 5}, {"x": 0, "y": 5}]
+    enemy = {"body": [{"x": 3, "y": 5}, {"x": 4, "y": 5}, {"x": 5, "y": 5}], "health": 100}
+    safe_moves = {"up": {"x": 1, "y": 6}, "right": {"x": 2, "y": 5}}
+
+    verdicts = snake._duel_verdicts(
+      safe_moves=safe_moves, my_body=my_body, enemy=enemy, my_health=100,
+      food_set=set(), hazard_set=set(), hazard_damage=15, hazard_count={},
+      previous_hazard_set=set(), width=11, height=11,
+      deadline=perf_counter() + 1.0,
+    )
+
+    self.assertEqual(set(verdicts), {"up", "right"})
+    self.assertLessEqual(verdicts["right"][0], LOSS / 2)
+    self.assertGreater(verdicts["up"][0], LOSS / 2)
+    self.assertEqual(
+      snake._apply_verdicts("right", {"right": 50.0, "up": 10.0}, verdicts), "up",
+    )
+
+  def test_verdict_search_stops_when_out_of_time(self):
+    snake = ZenithBattleSnake_ClaudeOpus5_5()
+
+    verdicts = snake._duel_verdicts(
+      safe_moves={"up": {"x": 0, "y": 2}}, my_body=[{"x": 0, "y": 1}],
+      enemy={"body": [{"x": 4, "y": 4}]}, my_health=100,
+      food_set=set(), hazard_set=set(), hazard_damage=15, hazard_count={},
+      previous_hazard_set=set(), width=5, height=5,
+      deadline=perf_counter() - 0.001,
+    )
+
+    self.assertEqual(verdicts, {})
+
+if __name__ == "__main__":
+  unittest.main()

tests/snakes/test_ZenithSurvival.py

@@ -0,0 +1,44 @@
+import unittest
+from time import perf_counter
+
+from snakes.engine.health_routes import health_route_cost
+from snakes.engine.bitboard import BitBoard
+from snakes.engine.survival_search import CompactSurvivalSearch
+from server.services.move_safety import fallback_move, run_budgeted_move
+from unittest.mock import Mock
+
+class TestSurvivalCorrections(unittest.TestCase):
+  def test_food_resets_health_before_elimination(self):
+    self.assertEqual(health_route_cost((0, 0), {(1, 0)}, {(1, 0)}, {}, 14, set(), 2, 1), 0)
+
+  def test_food_does_not_make_body_passable(self):
+    self.assertIsNone(health_route_cost((0, 0), {(1, 0)}, set(), {}, 14, {(1, 0)}, 2, 1))
+
+  def test_hazard_escape_charges_every_step(self):
+    self.assertEqual(health_route_cost((0, 0), set(), {(0, 0), (1, 0)}, {}, 14, set(), 3, 1, refuge=True), 16)
+
+  def test_long_constrictor_can_survive_in_small_free_region(self):
+    bb = BitBoard(5, 2)
+    body = (0, 5, 6, 7, 8, 9)
+    search = CompactSurvivalSearch(bb, set(), True, None, 2)
+    self.assertGreater(search._evaluate(body, ()), search.DEATH)
+    standard = CompactSurvivalSearch(bb, set(), False, None, 2)
+    self.assertEqual(standard._evaluate(body, ()), standard.DEATH)
+
+  def test_expired_queued_job_never_starts_strategy(self):
+    board = Mock(timeout=500)
+    self.assertEqual(run_budgeted_move(board, perf_counter()-1, 'left'), 'left')
+    board.snake_neat_make_a_move.assert_not_called()
+
+  def test_worker_deducts_queue_time_and_restores_timeout(self):
+    board = Mock(timeout=500)
+    observed = []
+    board.snake_neat_make_a_move.side_effect = lambda: observed.append(board.timeout) or 'right'
+    self.assertEqual(run_budgeted_move(board, perf_counter()+0.2, 'left'), 'right')
+    self.assertLessEqual(observed[0], 200)
+    self.assertEqual(board.timeout, 500)
+
+  def test_fallback_avoids_body_and_wall(self):
+    mine = {'id':'me','head':{'x':0,'y':0},'body':[{'x':0,'y':0},{'x':1,'y':0}]}
+    state = {'you':mine,'board':{'width':3,'height':3,'snakes':[mine]}}
+    self.assertEqual(fallback_move(state), 'up')