add darwin to upgrades page

Author: isabellewei

src/content/docs/en/technology/overview/scroll-upgrades.mdx

@@ -19,6 +19,109 @@ The following contracts are used to initiate upgrades and execute upgrades after
 
 You can join our [Telegram channel for technical updates](https://t.me/scroll_tech_updates), which includes future upgrade announcements and on-chain operation events.
 
+## Darwin Upgrade
+
+### Overview
+
+This upgrade will reduce gas fees by 34% by using a single aggregated proof for multiple batches, eliminating the need to finalize each batch individually.
+
+- Darwin uses a new [V3 batch codec](https://github.com/scroll-tech/da-codec/tree/main/encoding/codecv3).
+- In addition to the previous notions of `chunk` and `batch`, we have introduced a new concept called `bundle`.
+    - `Chunk`: A unit of zkEVM proving, consisting of a list of L2 blocks.
+    - `Batch`: A collection of chunks encoded into one EIP-4844 blob, serving as the unit of Data Availability.
+    - `Bundle`: A series of batches that functions as the unit of finalization.
+    
+    The main difference compared to Curie is that Scroll will now finalize multiple batches using a single aggregated bundle proof.
+    
+- The on-chain bundle proof verifier uses a new public input layout.
+
+### Timeline
+
+- **Scroll Sepolia**
+	- Network Upgrade: August 14th, 2024
+- **Scroll Mainnet**
+	- Upgrade Initiation: August 5th, 2024
+	- Timelock Completion & Upgrade: August 21st, 2024
+
+### Technical Details
+
+#### Contract Changes
+
+*Note: Since the previous Curie upgrade, we have migrated the Scroll contracts to a new repo at [scroll-contracts](https://github.com/scroll-tech/scroll-contracts).*
+
+The code changes for this upgrade are implemented in [this PR](https://github.com/scroll-tech/scroll-contracts/pull/4). The key changes are as follows:
+
+- We have introduced a new `BatchHeaderV3Codec`.
+- We have changed how messages are processed in the `L1MessageQueue` contract. Prior to Darwin, we would process messages when a batch is finalized. After Darwin, most of this processing is moved to the commit step.
+- We have introduced a new public input format for bundle proofs. This is implemented in a new contract `IZkEvmVerifierV2`, which is in turn added to `MultipleVersionRollupVerifier`.
+- In the `ScrollChain` contract `version=3` batches will now be committed through a new function called `commitBatchWithBlobProof`. Bundles will be finalized using a new function called `finalizeBundleWithProof`.
+
+See the contract [release notes](https://github.com/scroll-tech/scroll-contracts/releases/tag/v1.0.0) for more information.
+
+#### Node Changes
+
+The new node version is `v5.6.0`. See the [release notes](https://github.com/scroll-tech/go-ethereum/releases/tag/scroll-v5.6.0) for more information.
+
+The main changes are:
+
+- Implementation of timestamp-based hard forks.
+- Processing V3 batch codec in rollup-verifier.
+
+#### zkEVM circuit changes
+
+The new version of zkevm circuits is `v0.12.0`. See [here](https://github.com/scroll-tech/zkevm-circuits/releases/tag/v0.12.0) for the release log.
+
+We have introduced a `RecursionCircuit` that will bundle multiple sequential batches by recursively aggregating the SNARKs from the `BatchCircuit` (previously `AggregationCircuit`). The previously 5 layer proving system is now 7 layers as we introduce:
+
+- 6th Layer (layer5): `RecursionCircuit` that recursively aggregates `BatchCircuit` SNARKs.
+- 7th Layer (layer6): `CompressionCircuit` that compresses the `RecursionCircuit` SNARK and produce an EVM-verifiable validity proof.
+
+The public input to the `BatchCircuit` is now context-aware of the “previous” `batch`, which allows us to implement the recursion scheme we adopted (described [here](https://scrollzkp.notion.site/Upgrade-4-Darwin-Documentation-05a3ecb59e9d4f288254701f8c888173) in-depth).
+
+#### Audits
+
+- TrailofBits: coming soon!
+
+### Compatibility
+
+#### Sequencer and Follower Nodes (l2geth)
+
+This upgrade does not alter the state transition function and is therefore backward-compatible. However, we strongly recommend node operators to upgrade to [v5.6.0](https://github.com/scroll-tech/go-ethereum/releases/tag/scroll-v5.6.0).
+
+#### Dapps and Indexers
+
+There are some major changes to how we commit and finalize batches after Darwin. 
+
+- Batches will be encoded using the new [V3 batch codec](https://github.com/scroll-tech/da-codec/tree/main/encoding/codecv3). This version adds two new fields:
+    1. `lastBlockTimestamp` (the timestamp of the last block in this batch).
+    2. `blobDataProof` (the KZG challenge point evaluation proof).
+    
+    This version removes `skippedL1MessageBitmap`. There will be no changes to how the blob data is encoded and compressed.
+- Batches will be committed using the `commitBatchWithBlobProof` function (instead of the previous `commitBatch`).
+    
+    New function signature:
+    
+    ```solidity
+    function commitBatchWithBlobProof(uint8 _version, bytes calldata _parentBatchHeader, bytes[] memory _chunks, bytes calldata _skippedL1MessageBitmap, bytes calldata _blobDataProof)
+    ```
+    
+- Batches will be finalized using the `finalizeBundleWithProof` function (instead of the previous `finalizeBatchWithProof4844`).
+    
+    New function signature:
+    
+    ```solidity
+    function finalizeBundleWithProof(bytes calldata _batchHeader, bytes32 _postStateRoot, bytes32 _withdrawRoot, bytes calldata _aggrProof)
+    ```
+    
+- The semantics of the `FinalizeBatch` event will change: It will now mean that all batches between the last finalized batch and the event’s `_batchIndex` have been finalized. The event’s stateRoot and withdrawRoot values belong to the last finalized batch in the bundle. Finalized roots for intermediate batches are no longer available.
+    
+    The semantics of the `CommitBatch` and `RevertBatch` events will not change.
+
+Recommendations:
+
+- Indexers that decode committed batch data should be adjusted to use the new codec and the new function signature.
+- Indexers that track batch finalization status should be adjusted to consider the new event semantics.
+
 ## Curie Upgrade
 
 ### Overview