fix(rpc): override mainnet RPC to resolve CORS errors on eth.merkle.io

[Atharva0506]

Addressed Issues:

Fixes #170

Screenshots/Recordings:

Before:
The browser console was cluttered with persistent CORS errors when the application attempted to connect to Mainnet via Wagmi's default RPC endpoint (eth.merkle.io).

After:
The console is now clean on initial load, and Wagmi connects successfully to the Mainnet network without failing preflight requests or throwing ERR_FAILED logs.

Additional Notes:

• Root Cause: The default Wagmi Mainnet RPC endpoint (eth.merkle.io) actively blocks requests originating from our domain (https://chainvoice.stability.nexus) by omitting the required Access-Control-Allow-Origin header, which caused the browser's CORS policy to block the fetch requests.
• Solution: I overrode the Wagmi mainnet configuration in src/App.jsx to prepend a reliable, CORS-friendly public RPC (https://cloudflare-eth.com) to the list of rpcUrls.
• Impact: This clears up the console for easier debugging and slightly improves initial network connection performance since we are bypassing the blocked preflight requests. It maintains complete functionality as Wagmi still retains redundancy through its fallback nodes.

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Summary by CodeRabbit

• Bug Fixes
  • Improved Ethereum network connectivity by routing requests through more reliable RPC endpoints, which may reduce failed connections and improve app responsiveness.

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No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro

Run ID: c0132d53-2e21-419a-99c0-7760db54cab4

📥 Commits

Reviewing files that changed from the base of the PR and between c047352 and a4e1445.

📒 Files selected for processing (1)

• frontend/src/App.jsx

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Walkthrough

The frontend now defines a local Mainnet chain object in App.jsx that preserves wagmi chain data while prepending Cloudflare to the default HTTP RPC URL list.

Changes

Mainnet RPC override

Layer / File(s)	Summary
Local Mainnet chain object frontend/src/App.jsx	Aliases the wagmi Mainnet import and spreads it into a local mainnet constant with Cloudflare added to rpcUrls.default.http.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~5 minutes

Possibly related PRs

• StabilityNexus/Chainvoice#48: Also changes the frontend/src/App.jsx chain configuration path that determines which chain object is used by the app.

Suggested labels

Typescript Lang

Poem

A bunny hopped through RPC dew,
And Cloudflare clouds came into view.
Mainnet twitched with a gentler call,
Fewer console squeaks for one and all.
Hop hop! 🐰

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main change: overriding the mainnet RPC to address CORS errors.
Linked Issues check	✅ Passed	The change matches issue #170 by prepending a CORS-friendly RPC to Wagmi mainnet to stop eth.merkle.io failures.
Out of Scope Changes check	✅ Passed	The PR stays focused on the RPC override and does not introduce unrelated changes.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[rohans02]

Just two small nits (non-blocking):

• const mainnet = { ... } sits between imports (App.jsx:10–24), move it below the imports for readability.
• The public RPC override is no longer used by viem v2, so that block can be removed.

Otherwise, LGTM.