Build LP reward contract for liquidity providers on key pairs

[Chucks1093]

Summary

Implement a liquidity provider reward contract that distributes a share of trading fees to wallets that provide liquidity for key pairs, proportional to their liquidity contribution.

Scope

• add_liquidity(key_id, amount) — locks tokens as liquidity and records LP share
• remove_liquidity(lp_id) — returns tokens plus accrued fee rewards
• claim_lp_rewards(lp_id) — claims rewards without removing liquidity
• get_lp_position(lp_id) — returns contribution, share, and pending rewards
• LPAdded and LPRewardClaimed events emitted

Acceptance Criteria

• LP share computed proportionally from total liquidity pool
• Rewards accrue correctly proportional to share and trading volume
• remove_liquidity returns correct principal plus rewards
• claim_lp_rewards transfers correct pending amount
• get_lp_position returns accurate values at any point

ETA

24 hours

[DevScoopee]

@DevScoopee has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

I fully understand what needs to be done and can deliver. Kindly assign

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[CathyZaks]

@CathyZaks has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

Please assign to me. I can fix it

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Congratulations, @CathyZaks! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on September 30, 2026.

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This issue has been completed by @CathyZaks as part of the Stellar Wave Program's 9th Wave 🥳

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