[CRITICAL] `get_rank` returns 0 for any player outside the top-50 — misleading and inconsistent

[grantfox-oss]

Summary

leaderboard/src/lib.rs get_rank returns 0 for any address not in the top-50 list. A return value of 0 is indistinguishable from "rank 0" (the first position), making it impossible to tell whether a player is ranked first or not ranked at all.

Impact

• UIs and off-chain indexers cannot distinguish "ranked Systemic accounting & state-invariant violation across prediction_market ↔ referral_registry ↔ leaderboard — fee theft, leaderboard displacement, and unbounded inflation #1" from "unranked".
• Sorting a list that mixes ranked and unranked players places unranked players at the top.
• The sentinel violates the contract's own convention (see UNRANKED_RANK constant, line 17), which reserves values > MAX_TOP_PLAYERS for unranked players.

Fix

Return UNRANKED_RANK (51) for any player not in the top-50, ensuring rank > MAX_TOP_PLAYERS is the sole marker for "not ranked".

Reproduction

1. Query get_rank for an address that has never played.
2. Observe the return value 0.
3. Compare with get_top_players()[0] — the first entry has rank 1, so 0 appears to be ahead of rank 1.

[Meet-hybrid]

I’d like to work on this issue. I have experience with backend development, testing, Git, and working with APIs and data models. I’ve reviewed the issue and understand the inconsistency with the existing "UNRANKED_RANK" convention. I can update "get_rank" to return the correct sentinel value for unranked players and add regression tests to ensure ranked and unranked cases are handled correctly.

[grantfox-oss]

🦊 GrantFox — @Meet-hybrid has been assigned to this issue as part of the Third Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #159)
2. Your PR will be reviewed by the SPulse-Org maintainers

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