[Constitutional] AIP ArbOS 51: Activate ArbOS 51 (Dia) and Gas Pricing Updates

# [Constitutional] AIP ArbOS 51: Activate ArbOS 51 (Dia) and Gas Pricing Updates ## Abstract This AIP proposes the activation of **ArbOS 50: Dia** on Arbitrum One and Arbitrum Nova, as well as increases to the gas target and minimum L2 base fee, alongside updates to the L2 pricing algorithm. This on-chain vote bundles the following two temperature-check proposals: - **AIP: ArbOS 50 Version 50 Dia** — integrating relevant Fusaka EIPs, introducing `MaxTxGasLimit` for full block utilization, updating Nitro’s STF to instrument gas by resource type, enabling native token mint/burn (disabled on One/Nova), and applying bug fixes. - **AIP: Raise the gas target, update the pricing algorithm, and raise the L2 min base fee** These two proposals will ship together as a single integrated release designated **ArbOS 51**, replacing the originally planned standalone activation of ArbOS 50. Because the ArbitrumDAO has signaled approval for both AIPs in prior Snapshot temperature checks, this on-chain vote bundles both for activation on Arbitrum One and Arbitrum Nova. Refer to the forum posts for each AIP for detailed context. ArbOS 51 builds on **ArbOS 40 Callisto** and will ship as a mandatory Nitro release plus new rollup contract versions for Arbitrum One and Nova, pending DAO approval. The proposal increments the ArbOS version to `5x` (from the planned `4x`) for technical reasons improving Orbit chain customization—explained [here](#). This proposal applies **only to Arbitrum One and Nova**, which fall under ArbitrumDAO governance. ArbOS upgrades are analogous to hard forks—read more [here](#). --- ## Changes Included ### Activation of ArbOS 50 Dia ArbOS 50 Dia provides full Fusaka compatibility and introduces native improvements. Details are in the [original forum post](#). Key components include: - **EIPs** - EIP-7951 — Precompile for secp256r1 curve - EIP-7825 — Transaction Gas Limit Cap - EIP-7642 — `eth/69` history expiry and simpler receipts - EIP-7939 — CLZ opcode - EIP-7823 — Upper bounds for MODEXP - EIP-7883 — ModExp gas cost increase - EIP-7910 — `eth_config` JSON-RPC - Enable EIP-2537 — Precompile for BLS12-381 ops - **Effective Block Gas Limit** - Introduces a MaxTxGasLimit of **32M gas** - Total effective block gas limit becomes **64M gas** - No change to overall GasTarget; only distribution changes - **STF Instrumentation for Multidimensional Gas Accounting** Tracks consumption across: - computation - storage growth - storage reads - history growth - calldata Background resources: - Arbitrum explainer blog on multidimensional gas (link) - Vitalik’s post on multidimensional gas pricing (link) - **Native Token Mint/Burn (disabled for One & Nova)** Supports Orbit chains; details [here](#). - **Bug Fixes** - Standardized computation for compressed batch calldata gas - Fix for EIP-7702 delegation divergence - Fix for Stylus-related divergence on Arbitrum Sepolia — incident details [here](#) - **Fusaka EIPs *not* included** (Rationale in the [forum post](#)) - EIP-7594, EIP-7918, EIP-7892 — blob market not supported - EIP-7917 — no beacon chain / P2P layer - EIP-7934 — Arbitrum does not propagate blocks between nodes - EIP-7935 — Arbitrum block constraints differ from Ethereum’s --- ### Raising Gas Target, Increasing Min L2 Base Fee & Pricing Algorithm Improvements This proposal incorporates the AIP to improve pricing mechanics for Arbitrum One and Nova, reducing L2 gas price spikes during demand surges. Changes include: - Replacing the single gas target & single adjustment window - Introducing **multiple, higher gas targets** measured over multiple adjustment windows - Raising the long-term effective gas target (currently 7 Mgas/s; new cap 100 Mgas/s) - Granting Offchain Labs (as an Arbitrum Aligned Entity) permission to adjust parameters gradually - Increasing minimum L2 base fee from **0.01 gwei → 0.02 gwei** Full rationale and supporting data: [original AIP](#) --- ## Implementation Details All changes ship via: 1. **Nitro node version upgrade** 2. **Rollup contract upgrade** on Arbitrum One & Nova If passed, the payload executes on-chain, updating: - rollup contract code - WASM module root - scheduling the ArbOS upgrade Assumes node operators update to a Nitro version supporting ArbOS 51. --- ## Audit Reports Trail of Bits completed a third-party audit. Reports: **https://docs.arbitrum.io/audit-reports** --- ## Proposal Payload Activation Date If passed, **ArbOS 51 activates at 17:00:00 UTC on Thursday, January 8, 2026**, the final step in executing a Constitutional AIP (process described [here](#)). This date ensures availability of Arbitrum Foundation, Offchain Labs, and Security Council personnel. --- ## Verifying ArbOS 51 Code Difference **[Click here](#)** --- ## Implementation Steps - **[Completed] Forum Proposals & Snapshot Votes** - Posted on the ArbitrumDAO Forums: [here](#) and [here](#) - Passed temperature checks: [here](#) and [here](#) - **[Completed] Engineering Work** Implemented and tested in Nitro; rollup contract updates via `nitro-contracts 3.1.0` & `3.1.1`. - **[Completed] Trail of Bits Security Audit** Publication: https://docs.arbitrum.io/audit-reports - **[Completed] Release Candidate** Nitro v3.9.3: - Docker: `offchainlabs/nitro-node:v3.9.3-8bc5554` - Release notes: https://github.com/OffchainLabs/nitro/releases/tag/v3.9.3 Supports ArbOS 51; final recommended version will be announced post-vote. - **[Completed] Arbitrum Sepolia Testnet Deployment** - ArbOS 50 Dia activated: **Nov 20, 2025** - ArbOS 51 activated: **Dec 1, 2025** - **[This Post] On-chain Vote** Formal Tally vote to determine activation on Arbitrum One & Nova. - **[Next] Upgrade Execution** If passed, ArbOS 51 activates **17:00 UTC, Jan 8, 2026**. ---