feat: index RewardCallerSet reward caller delegation

[rickstaa]

Description

livepeer/protocol#648 lets an orchestrator nominate a single address it trusts to call reward() on its behalf, so the main wallet no longer has to stay unlocked every round. It adds one event, RewardCallerSet(address indexed transcoder, address indexed rewardCaller), which the subgraph did not index — so a delegation was invisible to the Explorer and an orchestrator had no way to confirm from indexed data that it took effect.

This adds:

• Transcoder.rewardCaller: String — nullable, null when unset, alongside serviceURI
• RewardCallerSetEvent — the standard Event shape, recording the literal 0x0 on unset so
  unset actions stay in history
• A rewardCallerSet handler, following the serviceURIUpdate / transcoderUpdate pattern

The upgrade is already live on Arbitrum One (target 0xbe197fc…Bd2, artifacts in livepeer/protocol#660), so these events can land today.

The Reward path is deliberately untouched

PR 648 refactored rewardWithHint into a private _rewardWithHint(_transcoder, ...) and switched every emit inside it from msg.sender to _transcoder. The Reward(indexed address,uint256) signature and semantics are unchanged, so both existing handlers — reward in bondingManager.ts and updatePollTallyOnReward on the PollTallyTemplate — stay correct without modification.

One behavioural consequence worth knowing, no code change: once delegation is in use, Transaction.from on a reward tx is the reward caller, not the orchestrator. Per-event attribution via RewardEvent.delegate remains authoritative. No caller field was added to RewardEvent — it would duplicate transaction.from, which is already reachable and is transaction-level rather than per-event.

ABI

The RewardCallerSet entry in abis/BondingManager.json was added by hand, copied from deployments/arbitrumMainnet/BondingManagerTarget.json in the protocol repo and diffed to confirm it matches byte-for-byte. This repo has no ABI sync mechanism, and the change was kept narrow rather than mixing a full resync into a feature PR.

Follow-up tracked in #252, which measures the current drift across all ABIs.

Verification

RewardCallerSet cannot be exercised by the local test suite — the livepeer/geth-with-livepeer-protocol:streamflow image predates setRewardCaller. Two real on-chain events serve as fixtures instead, covering both the set and unset branches on the same transcoder, in order:

Block	transcoder	rewardCaller
489361725	0x8Ad7BCac720DdCc23cfB0b57fb3c7Da02368E947	0x…dEaD (set)
489361734	0x8Ad7BCac720DdCc23cfB0b57fb3c7Da02368E947	0x0 (unset)

A correct implementation ends with rewardCaller: null and two RewardCallerSetEvent rows.

Checklist

• Ran yarn prepare and verified yarn codegen and yarn build succeed.
• (Optional) Validated locally with yarn deploy:local.
• Confirmed the Subgraph Studio preview link in the PR comment works and the subgraph syncs without errors.

[github-actions]

🚀 Subgraph Studio preview deployed

Item	Details
Version label	pr-253-0d309f6-30900501743
Query endpoint	https://api.studio.thegraph.com/query/31909/livepeer-ci/pr-253-0d309f6-30900501743

curl -H 'Content-Type: application/json' \
  -d '{"query":"{ protocol(id: \"0\") { inflation } }"}' \
  https://api.studio.thegraph.com/query/31909/livepeer-ci/pr-253-0d309f6-30900501743

[coderabbitai]

📝 Walkthrough

Walkthrough

Changes

Reward caller indexing

Layer / File(s)	Summary
Reward caller event contract abis/BondingManager.json, schema.graphql	Defines the RewardCallerSet ABI event, the nullable Transcoder.rewardCaller field, and the RewardCallerSetEvent entity.
Reward caller event handling src/mappings/bondingManager.ts	Handles reward-caller updates, clears the field for the zero address, persists transaction data, and creates the event entity.
Data source wiring and release metadata subgraph.template.yaml, package.json	Registers the event and handler, includes the event entity, and updates the package version to 1.4.0.

Estimated code review effort: 2 (Simple) | ~10 minutes

Sequence Diagram(s)

sequenceDiagram
  participant BondingManager
  participant rewardCallerSet
  participant Transcoder
  participant RewardCallerSetEvent
  BondingManager->>rewardCallerSet: Emit RewardCallerSet(transcoder, rewardCaller)
  rewardCallerSet->>Transcoder: Set or clear rewardCaller
  rewardCallerSet->>RewardCallerSetEvent: Store event metadata and caller address

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Suggested reviewers: copilot

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly identifies indexing for the RewardCallerSet reward-caller delegation event.
Description check	✅ Passed	The description explains the change, motivation, verification, dependencies, and checklist status; the issue field and preview confirmation remain incomplete.

✨ Finishing Touches 💡 1

📝 Generate docstrings 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/index-reward-caller-set

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[Copilot]

Pull request overview

Adds subgraph indexing support for BondingManager’s RewardCallerSet event so reward-caller delegation is visible in indexed data (including preserving unset actions in history).

Changes:

• Adds Transcoder.rewardCaller (nullable) and a new RewardCallerSetEvent entity to the GraphQL schema.
• Wires a rewardCallerSet mapping handler and registers the event/handler in the subgraph manifest template.
• Extends abis/BondingManager.json with the RewardCallerSet event fragment and bumps package version.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
subgraph.template.yaml	Registers RewardCallerSet event + handler and exposes RewardCallerSetEvent in the manifest entities list.
src/mappings/bondingManager.ts	Implements rewardCallerSet handler to update Transcoder.rewardCaller and persist RewardCallerSetEvent history rows.
schema.graphql	Adds the rewardCaller field to Transcoder and introduces the RewardCallerSetEvent entity type.
package.json	Bumps package version to 1.4.0.
abis/BondingManager.json	Adds the RewardCallerSet(address,address) event to enable codegen/handler wiring.

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[Copilot]

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated no new comments.