fix: add multicall batching to viem client

[sevenzing]

closes #2237

Summary

Enabling multicall batchin in viem: https://viem.sh/docs/clients/public#batchmulticall-optional

Why

Viem doesnt support eth_call batching by default!

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Testing

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Notes for Reviewer (Optional)

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Pre-Review Checklist (Blocking)

• This PR does not introduce significant changes and is low-risk to review quickly.
• Relevant changesets are included (or are not required)

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⚠️ No Changeset found

Latest commit: eb82213

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Project	Deployment	Actions	Updated (UTC)
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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: 7970e180-f76b-4ce7-a799-fc45915f5ddc

📥 Commits

Reviewing files that changed from the base of the PR and between 10c2583 and eb82213.

📒 Files selected for processing (2)

• apps/ensapi/src/di.ts
• apps/ensapi/src/lib/public-client.ts

📝 Walkthrough

Walkthrough

A new utility module buildPublicClient encapsulates public client creation with configured multicall batch size and fallback HTTP transports. The DI setup is refactored to use this shared builder instead of constructing the client inline, reducing duplication and improving maintainability.

Changes

Public client builder extraction and DI integration

Layer / File(s)	Summary
Public client builder utility apps/ensapi/src/lib/public-client.ts	New buildPublicClient function creates a viem PublicClient for the ENS root chain with multicall batch size 2048 and a fallback HTTP transport from provided RPC URLs.
DI integration of public client builder apps/ensapi/src/di.ts	The rootChainPublicClient getter calls buildPublicClient instead of constructing the client inline. viem imports simplified to type-only PublicClient, and a new import for buildPublicClient is added.

🎯 2 (Simple) | ⏱️ ~10 minutes

🐰 A client builder hops into the warren,
No more inline magic in the DI chain—
Shared and reusable, clean and bright,
The public client finds its rightful home,
Where configurations bloom in autumn light. 🌙

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.
Description check	⚠️ Warning	The PR description is largely incomplete. Critical sections like Testing and Notes for Reviewer contain only placeholder text, and the Pre-Review Checklist items are left unchecked despite being marked as blocking.	Complete the Testing section with concrete test steps or explanation of why testing was not performed. Address the blocking Pre-Review Checklist items by checking them or providing reasoning. Add any relevant notes for reviewers in the designated section.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main change: adding multicall batching to the viem client, which is the core objective of the PR.
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.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch ll/fixing-batch-multicall

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[greptile-apps]

Greptile Summary

Enables viem multicall batching on the ENS root chain PublicClient by extracting client construction into a dedicated buildRootChainPublicClient helper. The new client also now explicitly sets the chain (via getENSRootChain(namespace)), which was missing before and is required for viem to resolve the correct multicall3 contract address.

• public-client.ts: New helper wraps createPublicClient with batch.multicall enabled (batchSize: 2048 bytes) and a fallback transport over all configured HTTP RPCs.
• di.ts: rootChainPublicClient getter delegates to the new helper, passing rootChainRpcConfig and namespace; unneeded viem imports are cleaned up.

Confidence Score: 5/5

Safe to merge — the change is a focused, additive configuration tweak with a clean extraction refactor.

The diff is small and self-contained: multicall batching is opt-in at the viem client level and degrades gracefully (viem falls back to individual calls if the multicall contract isn't available). The new explicit chain setting is a correctness improvement needed for viem to locate the right multicall3 contract. No logic paths are altered in di.ts beyond delegating to the new helper.

No files require special attention.

Important Files Changed

Filename	Overview
apps/ensapi/src/lib/public-client.ts	New helper that creates the ENS root chain PublicClient with multicall batching (batchSize 2048) and an explicit chain config derived from the namespace.
apps/ensapi/src/di.ts	Refactored rootChainPublicClient getter to delegate to buildRootChainPublicClient; removes inline viem imports no longer needed here.

Sequence Diagram

sequenceDiagram
    participant DI as EnsApiDiContainer
    participant Builder as buildRootChainPublicClient
    participant Viem as viem PublicClient
    participant MC as Multicall3 Contract (on-chain)
    participant RPC as Fallback HTTP RPCs

    DI->>Builder: buildRootChainPublicClient(rootChainRpcConfig, namespace)
    Builder->>Viem: "createPublicClient({ chain, batch.multicall, transport: fallback([...]) })"
    Viem-->>DI: PublicClient instance

    note over Viem,MC: On contract reads
    DI->>Viem: readContract / call (N calls in same tick)
    Viem->>MC: aggregate3 batch (≤2048 bytes calldata)
    MC-->>RPC: single eth_call
    RPC-->>MC: aggregated results
    MC-->>Viem: decoded results[]
    Viem-->>DI: results

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[sevenzing]

@greptile review