feat: position transfer — transfer ownership of an open position to another address

[abayomicornelius]

Summary

Allow a position holder to transfer their open position to another Stellar address. Useful for portfolio restructuring, OTC desk transfers, and DeFi composability.

Proposed Design

Add transfer_position(position_key: Bytes, new_owner: Address) to exchange_router.

• Requires auth from the current position owner
• Rewrites the position's owner field in data_store
• New owner can then manage (increase, decrease, close) the position
• Emits PositionTransferred { key, from, to }

Security Considerations

• New owner cannot refuse the transfer (push model) — document this UX risk
• Consider a pull model: new owner must accept within N ledgers
• Referral code attribution follows the position (not the new owner's code)

Acceptance Criteria

• Transfer updates owner in persistent storage
• New owner can execute decrease/close orders
• Old owner cannot access position after transfer
• Integration test: transfer, old owner decrease attempt reverts, new owner succeeds
• Pull-model variant discussed and a decision documented in the PR

Affected Contracts

exchange_router, order_handler, data_store

[Codekill33]

@Codekill33 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi! I’d like to work on this issue. I’ll implement transfer_position with proper ownership authorization, update the position owner in persistent storage, emit the PositionTransferred event, and ensure only the new owner can manage the position after transfer. I’ll also add integration tests covering successful transfer, old owner access revocation, new owner management, and document the pull-model alternative and rationale in the PR.

ETA: 5–7 hours.

Kindly assign this issue to me. Thank you!

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Codekill33 to this issue.

[Adamsonoladipupo]

@Adamsonoladipupo has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I would like to work on this issue because it align with my skill set.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Adamsonoladipupo to this issue.