feat: runnable code & sandbox embeds for EVM examples

[alexander-sei]

What is the purpose of the change?

Adds new interactive content — runnable code on the EVM example pages. This closes the biggest gap from the Sei-vs-Solana docs review (roadmap P0.2, "make code runnable"): Sei's examples were copy-paste only, while Solana lets developers run code in the browser.

Describe the changes to the documentation

Two new self-contained Mintlify snippets, wired into five existing EVM example pages. Target audience: EVM developers evaluating or building on Sei who want to try calls and deploy contracts without leaving the docs.

snippets/run-snippet.jsx — Tier 1: read-only "Run" buttons

• Click-to-run read-only JSON-RPC issued straight from the browser to Sei's public RPC. Sei's endpoints send access-control-allow-origin: *, so no proxy is needed. Hex results auto-decode to decimal; copy + request-timing included.
• Added as "Try It Live" on the viem and ethers quickstarts (eth_blockNumber, eth_chainId, eth_getBalance).

snippets/sandbox-embed.jsx — Tier 2 & 3: click-to-load editor embeds

• Tier 2 (CodeSandbox) — editable, anonymously-runnable viem/ethers TypeScript reading Sei testnet, on the viem and ethers quickstarts.
• Tier 3 (Remix IDE) — compile + deploy Solidity to Sei testnet from the browser, on deploy-verify (Counter), erc20 (OpenZeppelin ERC-20), and erc721 (OpenZeppelin ERC-721), each paired with the existing AddSeiButton for adding Sei testnet to a wallet.
• The iframe src is deferred until the reader clicks, so pages pay nothing on load.

Notes

• Verified locally via mint dev + headless Chrome: all five pages return HTTP 200, every component mounts, zero page errors, iframes deferred. Tier 1 click→fetch→decode confirmed live against mainnet; Tier 2 confirmed to execute anonymously in an incognito context (real testnet RPC calls); Tier 3 Remix confirmed to load the preloaded contract and frame inside Mintlify with no CSP/X-Frame refusal.
• Mintlify constraints respected: no npm imports, named exports, all declarations inside the component. Surfaces use theme-agnostic translucent inline styles because Mintlify doesn't apply dark:bg-* / dark:border-* to custom-snippet container <div>s (only dark:text-* works).
• Follow-ups (not in this PR): the two CodeSandbox sandboxes (cgtx45, qs82lw) were created anonymously via the Define API and should be re-created under a Sei-owned CodeSandbox account for durability/branding. Tier-2 for the python quickstart (web3.py can't run in CodeSandbox's JS-only browser bundler) and a multicall example were intentionally deferred.

🤖 Generated with Claude Code

[mintlify]

Preview deployment for your docs. Learn more about Mintlify Previews.

Project	Status	Preview	Updated (UTC)
sei-docs	🟢 Ready	View Preview	Jun 20, 2026, 11:58 AM

💡 Tip: Enable Workflows to automatically generate PRs for you.

[cursor]

PR Summary

Low Risk
Documentation and client-side read-only RPC plus third-party iframe embeds only; no backend, auth, or on-chain logic changes in this repo.

Overview
Adds browser-runnable EVM example flows so readers can try Sei without only copy-pasting code.

Two new Mintlify snippets drive the UX: RunSnippet posts read-only JSON-RPC to Sei’s public RPC from the page (with timing, copy, and hex→decimal decode), and SandboxEmbed lazy-loads CodeSandbox or Remix iframes only after a click so initial page load stays light.

viem and ethers quickstarts gain Try It Live RPC buttons plus Edit and run CodeSandbox embeds. deploy-verify, erc20, and erc721 gain Remix sections with preloaded contracts (Counter, OpenZeppelin DemoToken / DemoNFT), wallet setup via existing AddSeiButton, and deploy instructions for Sei testnet.

^{Reviewed by Cursor Bugbot for commit aeaec89. Bugbot is set up for automated code reviews on this repo. Configure here.}