`set_oracle` and `add_oracle`/`remove_oracle` are duplicate, conflicting APIs; `set_oracle` silently drops all existing oracles

[cybermax4200]

Labels: type: bug, type: api-design, difficulty: intermediate, area: reward-engine

Why this matters now

The README documents set_oracle as "Replace the entire oracle roster with a single oracle" and also lists it under the function table for reward-engine twice (both as an admin function and under the oracle management section). In the contract, set_oracle (verification.rs line ~149) overwrites Oracles with a single-element Vec, silently dropping every oracle added via add_oracle. A multi-oracle operator who calls set_oracle to rotate one oracle accidentally removes all others with no warning and no event. This is a liveness risk — if set_oracle is called by mistake in a production multi-oracle setup, all but one oracle lose their ability to submit proofs with no on-chain record of the removal.

Key Challenges

• set_oracle emits no OracleRemovedEvent for the oracles it silently drops; this is inconsistent with remove_oracle which always emits one.
• Two competing mental models exist: set_oracle (replace roster) vs add_oracle/remove_oracle (roster management). One must be canonical. The recommended fix is to either: (a) remove set_oracle and require callers to use add_oracle/remove_oracle, or (b) make set_oracle emit OracleRemovedEvent for every evicted oracle and OracleAddedEvent for the new one.
• The README lists set_oracle twice — the docs must be corrected to match whichever model is chosen.

Acceptance Criteria

• Either set_oracle is removed (breaking) and the docs updated, OR set_oracle emits OracleRemovedEvent for every oracle it evicts.
• A test test_set_oracle_evicts_existing_oracles_with_events asserts the eviction events fire.
• No oracle can be silently removed without an on-chain event record.
• README function table corrected (remove duplicate set_oracle entry).
• All existing oracle tests pass.

Relevant files / functions

File	Symbol
contracts/reward-engine/src/verification.rs	set_oracle, add_oracle, remove_oracle

Out of scope

• Multi-oracle consensus logic
• Changes to add_oracle / remove_oracle behaviour

[Delightech28]

I'd like to work on this

[felladaniel36-hash]

I'd like to claim this issue. I have reviewed the details and can begin working on a fix right away. Please assign it to me if it's still available. Thanks!

[ibochivincent-lang]

can i work on this?

[syed-ghufran-hassan]

Hi maintainer, for the set_oracle issue, which resolution do you prefer—remove it or keep it with full eviction events so I can proceed with the PR?

[grantfox-oss]

🦊 GrantFox — @Delightech28 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 #43)
2. Your PR will be reviewed by the ecotask-network maintainers

Good luck! Track your progress on GrantFox.