No event emitted when `transfer_admin` succeeds in any contract; admin handover is silent on-chain

[cybermax4200]

Labels: type: bug, type: observability, difficulty: intermediate, area: eco-token, area: task-registry, area: reward-engine

Why this matters now

Phase 4 backend integration requires the off-chain indexer to track admin changes for governance auditing. A silent admin transfer is indistinguishable from no transfer at all — a compromised admin could rotate the role and the backend would never know. This is a finding every security auditor will raise.

Problem / What

transfer_admin is implemented in all three contracts (eco-token/src/token.rs, task-registry/src/registry.rs, reward-engine/src/verification.rs) and is tested, but none of them emit a contract event. Every other privileged operation in these contracts (mint, burn, transfer, task creation, sponsor changes, oracle changes) emits a typed #[contractevent] struct. Admin transfer is the only governance-critical operation that is silent.

Key Challenges

• Define a consistent AdminTransferredEvent { previous_admin: Address, new_admin: Address } struct (with previous_admin as a topic) in each contract.
• The event must be emitted after the storage write (not before), so it reflects committed state.
• All three contracts need the same change applied consistently.

Acceptance Criteria

• AdminTransferredEvent { previous_admin, new_admin } is defined and emitted in transfer_admin in all three contracts.
• previous_admin is a #[topic] field so indexers can filter by outgoing admin address.
• Tests in each contract assert the event is emitted with correct fields after a successful transfer_admin call.
• No event is emitted on a failed (panicking) call.
• All existing tests pass.

Relevant files / functions

File	Symbol
contracts/eco-token/src/token.rs	transfer_admin
contracts/task-registry/src/registry.rs	transfer_admin
contracts/reward-engine/src/verification.rs	transfer_admin

Out of scope

• Adding events to other admin-only operations (covered separately)
• Changes to existing event structs

[Bidex-cmyk]

Motivation & Experience Application

I would like to take on issue #55 to implement on-chain AdminTransferredEvent emissions across all three contracts in ecotask-network / EcoTask-contract. I have strong experience developing and testing Soroban Rust smart contracts on Stellar, focusing on event indexing, state storage, and contract security auditing standards.

Here is my planned execution strategy:

Typed Event Definition (AdminTransferredEvent):

Define a consistent #[contractevent] struct AdminTransferredEvent { #[topic] previous_admin: Address, new_admin: Address } across eco-token, task-registry, and reward-engine.

Ensure previous_admin is decorated with #[topic] so off-chain indexers can filter by outgoing admin address.

Post-State Event Emission Logic:

Update transfer_admin across contracts/eco-token/src/token.rs, contracts/task-registry/src/registry.rs, and contracts/reward-engine/src/verification.rs.

Read the current admin address before state modification, perform the storage write to record the new admin, and emit AdminTransferredEvent via env.events().publish() after state commit.

Comprehensive Unit Testing:

Add test cases in each contract test suite validating that transfer_admin emits AdminTransferredEvent with the expected topic and payload fields.

Verify that failing calls (e.g., unauthorized callers) panic and emit zero events.

Ensure all existing contract test suites pass without regression.

[GiftedGiftB]

I can get this work done in less than 24 hours.

[grantfox-oss]

🦊 GrantFox — @baedboibidex-cmyk 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 #55)
2. Your PR will be reviewed by the ecotask-network maintainers

Good luck! Track your progress on GrantFox.