update: add arbos51 notice and update arbos51 description

Author: zk-Lumi

docs/notices/arbos51-arbmainnet-upgrade-notice.mdx

@@ -0,0 +1,21 @@
+---
+title: 'ArbOS 51 activation on Arbitrum One & Arbitrum Nova'
+description: Upgrade notices for ArbOS 51 activation on Arbitrum One & Arbitrum Nova
+user_story: As an Arbitrum chain owner or node operator, I want to configure my chain/nodes to run on Arbitrum One & Arbitrum Nova.
+content_type: notice
+---
+
+On Thursday, January 8, 2025 at 17:00 UTC, [ArbOS 51 "Dia"](docs/run-arbitrum-node/arbos-releases/arbos51.mdx) will activate on the Arbitrum One & Arbitrum Nova chains.
+
+:::warning Action required
+
+Arbitrum One & Arbitrum Nova node operators **must upgrade** to Nitro **`v3.9.3`** or newer ahead of this activation to continue syncing the chain.
+
+- **Docker image:** `offchainlabs/nitro-node:v3.9.3-8bc5554`
+- **Release notes:** https://github.com/OffchainLabs/nitro/releases/tag/v3.9.3
+
+:::
+
+### **Context**
+
+[ArbOS 51 "Dia"](docs/run-arbitrum-node/arbos-releases/arbos51.mdx) builds upon [ArbOS 40 "Callisto"](docs/run-arbitrum-node/arbos-releases/arbos40.mdx) with support for the relevant EVM changes that are a part of Ethereum's [Fusaka upgrade](https://ethereum.org/en/roadmap/fusaka/), as well as additional improvements to the gas pricing algorithm, a change to the min L2 base fee, MaxTxGasLimit allowing full block utilization, changes to instrument Nitro’s State Transition Function (STF) to price gas based on specific resource usage, native token mint/burn capabilities, and a few bug fixes.

docs/notices/arbos51-arbsepolia-upgrade-notice.mdx

@@ -5,7 +5,7 @@ user_story: As an Arbitrum chain owner or node operator, I want to configure my
 content_type: notice
 ---
 
-On Monday, December 1, 2025 at 17:00 UTC, ArbOS 51 will activate on the Arbitrum Sepolia chain.
+On Monday, December 1, 2025 at 17:00 UTC, [ArbOS 51 "Dia"](docs/run-arbitrum-node/arbos-releases/arbos51.mdx) will activate on the Arbitrum Sepolia chain.
 
 :::warning Action required
 
@@ -18,6 +18,6 @@ Arbitrum Sepolia node operators **must upgrade** to Nitro **`v3.9.3`** ahead of
 
 ### **Context**
 
-ArbOS 51 is a follow-up to ArbOS 50 that fixes issues with the Pricing Framework. ArbOS 50 was previously activated on Sepolia, but the Gas Target & Pricing Framework changes remained disabled pending this fix. ArbOS 51 now completes that work.
+[ArbOS 51](docs/run-arbitrum-node/arbos-releases/arbos51.mdx) is a follow-up to ArbOS 50 that fixes issues with the Pricing Framework. ArbOS 50 was previously activated on Sepolia, but the Gas Target & Pricing Framework changes remained disabled pending this fix. ArbOS 51 now completes that work.
 
-Upstream governance items (ArbOS 50 + Gas Target & Pricing Framework) are being bundled into a single on-chain vote. Both components have passed Snapshot temperature checks, with the Tally vote expected to open on or around **December 4, 2025**.
+Upstream governance items ([ArbOS 50](https://snapshot.box/#/s:arbitrumfoundation.eth/proposal/0x33754da4006d0ef38666ec5d5e85fd0966a891a594ab9dc21f23beedea2d330b) + [Gas Target & Pricing Framework](https://snapshot.box/#/s:arbitrumfoundation.eth/proposal/0x4a96a91d162975de0d402b83ca8b8a24e808ca357150120fc0d44ae0bf1cc4a5)) are being bundled into a single on-chain vote. Both components have passed Snapshot temperature checks, with the Tally vote expected to open on or around **December 4, 2025**.

docs/notices/fusaka-upgrade-notice.mdx

@@ -25,7 +25,7 @@ The following dates are relevant for Arbitrum chain operators.
 | ---------------------------------------- | ------------------------------------------------------------------------------------------ | ---------------------------------------------------------------------------------------------- |
 | `Nov 20th 2025, 17:00:00 UTC`            | Arbitrum Sepolia upgrade to ArbOS 50                                                       | Node operators for Arbitrum Sepolia                                                            |
 | `Dec 1st 2025, 17:00:00 UTC`             | Arbitrum Sepolia upgrade to [ArbOS 51](docs/run-arbitrum-node/arbos-releases/arbos51.mdx)  | Node operators for Arbitrum Sepolia                                                            |
-| `Jan 8th, 2026, 17:00:00 UTC (proposed)` | Arbitrum One/Nova upgrade to [ArbOS 51](docs/run-arbitrum-node/arbos-releases/arbos51.mdx) | Node operators for Arbitrum One/Nova                                                           |
+| `Jan 8th, 2026, 17:00:00 UTC`            | Arbitrum One/Nova upgrade to [ArbOS 51](docs/run-arbitrum-node/arbos-releases/arbos51.mdx) | Node operators for Arbitrum One/Nova                                                           |
 | `Oct 14th 2025, 07:36:00 UTC`            | Ethereum Sepolia Fusaka hard fork                                                          | Node operators for Arbitrum chains settling on Ethereum Sepolia (Orbit L2s, Arbitrum Sepolia)  |
 | `Dec 3rd 2025, 21:49:11 UTC`             | Ethereum Mainnet Fusaka hard fork                                                          | Node operators for Arbitrum chains settling on Ethereum Mainnet (Orbit L2s, Arbitrum One/Nova) |
 

docs/run-arbitrum-node/arbos-releases/arbos51.mdx

@@ -41,7 +41,7 @@ As a refresher, ArbOS upgrades get treated as Arbitrum's equivalent of a hard fo
 
 ### High-level description of ArbOS 51 changes
 
-ArbOS 51 Dia is an upgrade to support the relevant EVM changes that are a part of Ethereum's [Fusaka upgrade](https://ethereum.org/en/roadmap/fusaka/). Ethereum's mainnet upgrade to Fusaka was completed on [December 3, 2025 at epoch `411392`](https://notes.ethereum.org/@bbusa/fusaka-bpo-timeline). As a result, the majority of the ArbOS-specific changes revolve around implementing the relevant [Fusaka EIPs](https://eips.ethereum.org/EIPS/eip-7607) on <a data-quicklook-from="arbitrum-chains">Arbitrum Chains</a>.
+ArbOS 51 Dia is an upgrade for <a data-quicklook-from="arbitrum-chains">Arbitrum Chains</a> to support the relevant EVM changes that are a part of Ethereum's [Fusaka upgrade](https://ethereum.org/en/roadmap/fusaka/), as well as additional improvements to the gas pricing algorithm, MaxTxGasLimit allowing full block utilization, changes to instrument gas based on specific resource usage, native token mint/burn capabilities, and a few bug fixes. Ethereum's mainnet upgrade to Fusaka was completed on [December 3, 2025 at epoch `411392`](https://notes.ethereum.org/@bbusa/fusaka-bpo-timeline).
 
 Here's the list of all changes included in ArbOS 51 Dia:
 

sidebars.js

@@ -97,7 +97,7 @@ const sidebars = {
     {
       type: 'link',
       label: 'Notices',
-      href: '/notices/arbos51-arbsepolia-upgrade-notice',
+      href: '/notices/arbos51-arbmainnet-upgrade-notice',
     },
     {
       type: 'doc',
@@ -1528,14 +1528,19 @@ const sidebars = {
   noticeSidebar: [
     {
       type: 'doc',
-      id: 'notices/fusaka-upgrade-notice',
-      label: 'Upgrade for the Fusaka transition',
+      id: 'notices/arbos51-arbmainnet-upgrade-notice',
+      label: 'Upgrade for ArbOS 51 on Arbitrum One & Nova',
     },
     {
       type: 'doc',
       id: 'notices/arbos51-arbsepolia-upgrade-notice',
       label: 'Upgrade for ArbOS 51 on ArbSepolia',
     },
+    {
+      type: 'doc',
+      id: 'notices/fusaka-upgrade-notice',
+      label: 'Upgrade for the Fusaka transition',
+    },
   ],
 };
 

vercel.json

@@ -1486,9 +1486,14 @@
       "destination": "/build-decentralized-apps/reference/node-providers",
       "permanent": false
     },
+    {
+      "source": "/(notices/arbos-51/?)",
+      "destination": "/notices/arbos51-arbmainnet-upgrade-notice",
+      "permanent": false
+    },
     {
       "source": "/(notices/arbos-50/?)",
-      "destination": "/notices/arbos51-arbsepolia-upgrade-notice",
+      "destination": "/notices/arbos51-arbmainnet-upgrade-notice",
       "permanent": false
     },
     {