Keep abis/*.json in sync with livepeer/protocol deployment artifacts

Problem

abis/*.json are hand-committed with no sync mechanism. There is no script, CI step, or documented
process that pulls them from livepeer/protocol, so they
drift silently from the deployed contracts and only get touched when someone notices something
missing.

abis/BondingManager.json last saw a real update in 6d5228b (2022). Adding reward-caller
indexing required hand-copying a single event fragment out of
deployments/arbitrumMainnet/BondingManagerTarget.json into it. That worked, but it is not a
process — the next person has to know to do the same thing.

This matters because a missing event in the ABI is invisible: graph codegen simply never emits the
event class, so the event cannot be wired up and nothing warns you.

Current drift

Measured on 2026-08-03 against livepeer/protocol deployments/arbitrumMainnet/*.json, comparing
event and function signature sets:

Better than feared — only two files are actually stale, and the missing TreasuryReward is the one
real indexing gap.

Not covered by livepeer/protocol/deployments/arbitrumMainnet, so they need a different source or
an explicit opt-out:

• L2Migrator — lives in livepeer/arbitrum-lpt-bridge
• LivepeerToken — no artifact in that deployments dir
• Poll — deployed per-poll by PollCreator, so there is no static deployment artifact
• UniswapV3Pool — third-party, correctly pinned by hand

Proposal

1. Add a sync script (e.g. yarn sync:abis) that pulls .abi from the protocol repo's
   deployments/arbitrumMainnet/*.json for each mapped contract, writing prettier-formatted output
   to abis/. Contracts with no upstream artifact get an explicit allowlist entry documenting why.
2. Add a CI drift check that fails, or at least warns, when a committed ABI diverges from upstream —
   that is what turns this from a one-off cleanup into something that stays fixed.
3. As part of (1), resync BondingManager and PollCreator. Verified safe: no function any
   mapping calls is lost, so no .bind() call breaks. The only removals are the unwired legacy
   WithdrawFees(address) overload and the nonexistent PollCreator.token().

Note that resyncing BondingManager adds the TreasuryReward event to the ABI but does not
index it — wiring a handler for treasury rewards is separate work and deserves its own issue.

Context

Split out of the reward-caller indexing work, which deliberately kept the ABI change narrow (one
event, copied verbatim from the canonical artifact and diffed to confirm it matched byte-for-byte)
rather than mixing a full resync into a feature PR.

Start with the committed abis/.json files and compare them with livepeer/protocol deployments/arbitrumMainnet/.json, using the contract mapping and exclusions described in the issue. Check the existing package scripts and CI configuration before adding the proposed yarn sync:abis command and drift check. Done means BondingManager and PollCreator are resynced, uncovered contracts have documented allowlist entries, and CI detects future divergence.