In February 2026, Coinbase announced what amounted to a quiet bombshell: Base is moving away from the OP Stack toward an in-house "unified codebase."
I caught the news right as I was prepping a contract deployment. My entire stack — chain IDs, RPC endpoints, Foundry configs, wagmi imports — had been built for the OP Stack. My first thought wasn't "this is a crisis," but it was: is my documentation about to become obsolete at the exact moment I hit deploy?
I went down the rabbit hole. Here's what's actually changing.
What the migration actually is (and isn't)
The new system is the unified stack, currently living in github.com/base/base.
Don't let the "in-house codebase" framing spook you. This isn't a VM overhaul or a sudden pivot to ZK (yet). It's an infrastructure consolidation — pulling components previously scattered across different repositories into a single Base-managed binary, built on open-sourced components including Reth, the Rust Ethereum execution client.
Status as of now: v0.6.0 shipped March 27, 2026, and the repo has over 3,000 commits. We're well past announcement territory. The full mainnet cutover is expected "in the coming months," per the blog. Base Sepolia and mainnet RPCs are unaffected throughout.
One data point on the Superchain side: DL News reports that revenue sharing with the Optimism Collective is expected to end as part of this move, citing an Optimism spokesperson. The OP token fell roughly 4% on the day of the announcement, with further declines over the following days. Whether the Superchain model survives that departure is a debate for another day; the price move is just a signal of how it was read.
Building on Base this week? Change nothing.
I cross-referenced the Base Engineering Blog with current tooling and repo activity. No changes have been announced to developer-facing tooling, and everything continues to work as-is:
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Solidity:
pragma solidity 0.8.24— still correct. No EVM or compiler changes. -
Foundry: Business as usual.
forge script --verifystill targets Basescan. Base has explicitly committed to "continue contributing to Foundry." -
RPCs:
https://mainnet.base.organdhttps://sepolia.base.org— no changes. Base's stated commitment: "All RPCs, including those in the optimism namespace, will continue to be fully supported." -
Frontend:
import { base, baseSepolia } from 'wagmi/chains'— unchanged. Chain IDs 8453 (mainnet) and 84532 (Sepolia) do not change mid-chain. Base commits to "continue contributing to Wagmi." -
viem, EIP-1559,
block.timestamp— no changes announced.
The Research Agent ran the verification in minutes; the conclusion took three seconds to read. Nothing you interact with as a developer has changed.
Two threads to watch
Two items stayed on my radar after the verification pass.
1. The proof system upgrade. Base has had fault proofs live since October 2024, using the Cannon optimistic system — permissionless challengers, 3.5-day dispute window. Base reached Stage 1 decentralization in April 2025. The unified stack roadmap points toward Base V1: a planned swap from optimistic to TEE/ZK proofs for faster finality. No launch date yet. This is an upgrade to a functioning system, not a gap being closed — but worth watching when the spec arrives.
2. The exit mechanics. Two paths currently protect you from sequencer failure. Withdrawal finalization has a 7-day challenge window. If the sequencer goes offline entirely, you can force transaction inclusion via L1 — L2Beat documents up to a 12-hour delay on that path. Both are confirmed compatible during the current transition. How they change post-Base V1 is not publicly specified — a genuine documentation gap to revisit once the spec is out.
I checked what I needed to before building. The tools work as expected. Two threads to revisit when Base V1 ships — the proof system upgrade and the exit mechanics spec. The build went ahead on the same configuration the research documented. The Week 1 retrospective covers how it went.
Scoring methodology for the series
Live Proof Of Support deployment can be found at proof-of-support.pages.dev
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