Make target dice sequence a ping-pong triangle wave

CLAUDE.md

@@ -314,7 +314,7 @@ This is implemented in `delayed_broadcast()` (`server/broadcast.py`) via an `asy
 1. Host clicks Start → `handle_start` calls `deal_round()` (10 fresh dice each), sets `started=True`
 2. Players roll; `apply_roll()` re-randomises unlocked dice and auto-locks any that match `target`
 3. First player to lock all 10 wins the round → `handle_roll` sets `round_over=True`, sends `round_won` privately and schedules a `delayed_broadcast`
-4. After `ROUND_WIN_DELAY` seconds, `delayed_broadcast` advances `target` (cycles 1→2→3→4→5→6→1), increments `round_num`, calls `deal_round()` again to clear per-round state
+4. After `ROUND_WIN_DELAY` seconds, `delayed_broadcast` advances `target` (a triangle wave over `round_num`: 1→2→3→4→5→6→5→4→3→2→1→2→…), increments `round_num`, calls `deal_round()` again to clear per-round state
 
 When `ENABLE_DRAND_ROLLING` is set (default **off** → local RNG), `handle_roll` derives the unlocked dice from the drand League-of-Entropy beacon (`server/drand.py`) instead of `random`, and records the `drand_round` on the roll — making every roll provably fair and replayable via `/api/game/{code}/verify` and `/api/verify/{code}/{pid}/{roll_count}`. `apply_roll()` stays pure: it takes an optional `dice_values` and otherwise randomises locally. See [`docs/ROLL_TRUST.md`](docs/ROLL_TRUST.md).
 

server/broadcast.py

@@ -6,7 +6,7 @@
 
 from . import db, db_places, fanout, gamestore, places, state
 from .config import DISCONNECT_GRACE, PAUSE_MAX, ROLL_ACK_TIMEOUT, ROUND_WIN_DELAY, log
-from .game import next_target, state_msg
+from .game import state_msg, target_for_round
 from .state import sessions
 from .telemetry import emit, metrics
 
@@ -52,7 +52,7 @@ async def advance_round(code: str) -> None:
     old_round = meta["round_num"]
     old_target = meta["target"]
     emit("round_ended", game_code=code, round_num=old_round, target=old_target)
-    new_target = next_target(old_target)
+    new_target = target_for_round(old_round + 1)
     await gamestore.advance_round(code, new_target)
     snap = await gamestore.snapshot(code)
     if snap is None:

server/game.py

@@ -42,9 +42,13 @@ def fresh_dice() -> list[int]:
     return [random.randint(1, 6) for _ in range(10)]
 
 
-def next_target(t: int) -> int:
-    # cycles 1 → 2 → 3 → 4 → 5 → 6 → 1 → …
-    return t % 6 + 1
+def target_for_round(round_num: int) -> int:
+    # Triangle wave over the 1-based round number: the target climbs 1→6 then
+    # descends 6→1 and back up, so it reads 1,2,3,4,5,6,5,4,3,2,1,2,3,4,5,6,…
+    # The value alone can't encode direction (target 3 could be rising or
+    # falling), so the round number — a monotonic counter — drives it instead.
+    m = (round_num - 1) % 10
+    return m + 1 if m <= 5 else 11 - m
 
 
 def apply_roll(player: dict, target: int, *, dice_values: list[int] | None = None) -> dict: