docs: v6.6.3 catch-up

node/node-types.mdx

@@ -21,7 +21,7 @@ Seid uses the following TCP ports. Toggle their settings to match your environme
 - `26657`: The default port for the RPC interface. Because this port is used for querying and sending transactions, it must be open for serving queries from `seid`.
 - `1317`: The default port for interacting with the Seid API server for HTTP RESTful requests. This allows applications and services to interact with the `seid` instance through RPC.
 - `9090`: The default port for gRPC communication. This is used for high-performance communication with the node.
-- `8545`: The default port for EVM HTTP RPC. This port is used for Ethereum JSON-RPC calls and must be open if you want to interact with EVM-compatible applications.
+- `8545`: The default port for EVM HTTP RPC. This port is used for Ethereum JSON-RPC calls and must be open if you want to interact with EVM-compatible applications. The [`frozen-rpc-router`](/node/technical-reference#frozen-rpc-router) binary also listens on `127.0.0.1:8545` by default, so when you run the router on the same host as a live node, move one of them to a different port. The linked example keeps the router on `8545` and moves the two co-located nodes to `9545` and `9546`.
 - `8546`: The default port for EVM WebSocket RPC. This port provides real-time communication for EVM applications that require WebSocket connections.
 - `26660`: The default port for interacting with the Prometheus database, which can be used to monitor the environment. In the default configuration, this port is not open.
 

node/technical-reference.mdx

@@ -37,6 +37,91 @@ seid tendermint show-validator
 seid query node info
 ```
 
+#### Freeze mode (`--freeze-height`)
+
+As of v6.6.3, the `--freeze-height` start flag (and the corresponding `freeze-height` field in `app.toml`) puts a full node into read-only freeze mode at a specified block height. Freeze mode exists for historical RPC nodes. A node frozen at an upgrade height keeps running the pre-upgrade binary and keeps serving the state that binary produced, instead of shutting down at the boundary or executing the upgrade block with code that no longer matches that state. Query RPC remains available so the node can continue serving reads, but write and network paths are disabled from startup:
+
+- Transaction and evidence submission is rejected. The `BroadcastTx`, `BroadcastTxAsync`, `BroadcastTxSync`, `BroadcastTxCommit`, and `BroadcastEvidence` RPC calls all return `ErrReadOnly` (`RPC writes are disabled in freeze mode`). The EVM endpoint submits transactions through the same path, so `eth_sendRawTransaction` fails with the same error.
+- Mempool gossip is disabled — the mempool reactor is not started and the mempool p2p channel is not advertised to peers.
+- State sync is disabled. If it is enabled in `config.toml`, the node logs a notice and falls back to block sync.
+
+Block sync and consensus stop before executing the configured height and will not advance beyond it.
+
+The node must not have reached the freeze height yet. If the application, block store, or state store height is already at or above `freeze-height`, startup fails with `<source> height <n> has already reached freeze height <h>`. To build a frozen node, start from a data directory that is below the freeze height (a fresh sync from genesis, or a [snapshot](/node/snapshot) taken below that height) and let block sync stop at the boundary.
+
+```bash
+# Start a full node in read-only freeze mode at a given block height
+seid start --freeze-height <height>
+```
+
+The same behavior can be configured persistently via the `freeze-height` field. `freeze-height` is the first block height a full node must not execute; a value of `0` disables freeze mode. The key is a top-level entry in `app.toml`, in the base configuration next to `halt-height`, and does not belong under any `[section]` header. See the generated [default `app.toml`](/node/node-operators#default-configurations) for the field in context.
+
+```toml
+# app.toml — top-level key in the base configuration (next to halt-height), not under any [section]
+freeze-height = 0
+```
+
+<Warning>
+  Freeze mode is only supported for full nodes. Setting a non-zero `freeze-height` in validator or seed mode is rejected at startup with an error (`freeze height is not supported in <mode> mode`). `freeze-height` also cannot be combined with `halt-height`, `halt-time`, or the `--grpc-only` start flag; each combination is rejected at startup.
+</Warning>
+
+### Frozen RPC router
+
+The `frozen-rpc-router` binary, available as of v6.6.3, is a companion to freeze mode. It exposes a single HTTP EVM JSON-RPC endpoint that transparently proxies requests to a live node and one or more freeze-height-frozen nodes, routing each request to the correct backend based on the block height it references. This lets a set of archival nodes — each frozen at a different upgrade height and running the binary that was live for its interval — collectively serve historical state through one endpoint.
+
+Because a freeze height is an exclusive boundary, a node started with `--freeze-height 100` serves blocks through height 99. The router therefore sends height 99 to that node and height 100 to the next configured interval (or to the live node when no frozen interval covers it).
+
+The router is a standalone binary in the `sei-chain` repository. It is not part of `seid` and is not installed by `make install`, so build it from a source checkout with the `build-frozen-rpc-router` target, which writes the binary to `./build/frozen-rpc-router`:
+
+```bash
+git clone https://github.com/sei-protocol/sei-chain.git
+cd sei-chain
+git checkout <version-tag>  # v6.6.3 or later
+make build-frozen-rpc-router
+```
+
+```bash
+# Route between a live node and two frozen nodes. The router takes the default EVM
+# HTTP RPC port (8545), so the live node and the frozen node that share this host
+# have been moved to 9545 and 9546. The frozen node on 10.0.0.12 runs on its own
+# host and keeps the default port.
+./build/frozen-rpc-router \
+  --listen-address 127.0.0.1:8545 \
+  --live-node localhost:9545 \
+  --frozen-node 1000000=localhost:9546 \
+  --frozen-node 2000000=10.0.0.12:8545
+```
+
+<Warning>
+  The router has no authentication of its own: anyone who can reach its listen address can query every backend behind it. The example binds to `127.0.0.1` so that only local clients can connect. If you bind to a public interface (for example `--listen-address 0.0.0.0:8545`), put the router behind a firewall or reverse proxy, as you would for a node's own EVM RPC port.
+</Warning>
+
+The binary accepts the following flags:
+
+- `--listen-address` — address on which the router listens (default `127.0.0.1:8545`).
+- `--live-node` — HTTP RPC address of the live node (required).
+- `--frozen-node` — a `freeze-height=ip:port` pair; repeat once per frozen node. Bare `host:port` addresses and `http://` or `https://` URLs are all accepted. Frozen nodes may be listed in any order, but each freeze height must be positive and unique.
+- `--max-request-body-bytes` — maximum JSON-RPC request body size in bytes (default `5242880`, which is 5 MiB). Must be positive. Larger requests are rejected with HTTP `413`.
+- `--max-block-reference-depth` — maximum nested block reference depth (default `16`); bounds how deeply nested `blockNumber` object references are parsed when resolving a request's block parameter. Must be positive.
+- `--batch-request-limit` — maximum number of calls in a JSON-RPC batch (default `1000`). Must be positive. A batch exceeding this limit is rejected with JSON-RPC error `-32600` (`batch too large`).
+- `--write-timeout` — maximum duration for writing an HTTP response (default `30s`). Must be positive.
+- `--shutdown-timeout` — graceful shutdown timeout (default `10s`). Must be positive.
+
+#### Routing rules
+
+Only JSON-RPC `POST` requests are inspected and routed. Every other request, including WebSocket upgrade requests, is passed straight through to the `--live-node` address without inspection. Because that address is the live node's HTTP RPC endpoint, which does not accept WebSocket upgrades, clients that need subscriptions should connect directly to the live node's WebSocket port (`8546` by default) rather than through the router.
+
+- `eth_*` and `debug_*` methods that take an explicit block number or the `earliest` tag (for example `eth_getBlockByNumber`, `eth_getBalance`, `eth_call`, `eth_getStorageAt`, `debug_traceBlockByNumber`) are routed to the interval that contains that height. `earliest` resolves to height 0.
+- `eth_getLogs` and `eth_feeHistory` are routed only when their entire block range falls within a single interval. The range is explicit for `eth_getLogs`; for `eth_feeHistory` it is derived from `blockCount` and `newestBlock` (`newestBlock - blockCount + 1` through `newestBlock`, clamped at `0`). A range that crosses an interval boundary is rejected with JSON-RPC error `-32000` (`block ranges spanning multiple frozen-node intervals are not supported`).
+- An `eth_getLogs` filter that sets `fromBlock` but omits `toBlock` is treated as ending at `latest`, so it is rejected with the same `-32000` error whenever `fromBlock` is inside a frozen interval. Set `toBlock` explicitly to stay within one interval. The reverse works: a filter that sets only `toBlock` is routed to the interval that contains `toBlock`.
+- Latest-style block tags (`latest`, `pending`, `safe`, `finalized`), requests referencing a block by hash, methods without a block parameter, and stateful filter methods are all forwarded to the live node.
+- Batch requests are split so each call reaches its correct backend, then reassembled into a single response.
+- Calls whose backend cannot be reached return JSON-RPC error `-32001` (`upstream request failed`).
+
+#### Route header
+
+Responses proxied to a single backend carry a `Sei-RPC-Route` header identifying which backend served them: `frozen:<height>` for the frozen node at that freeze height, or `live` for the live node. A batch split across multiple backends returns `mixed`. Errors generated by the router itself (oversized or malformed requests, batches over the limit, block ranges spanning intervals, unreachable backends) and non-`POST` traffic passed through to the live node do not carry the header.
+
 ### seidb Tooling Commands
 
 The `seidb` binary provides low-level tooling for inspecting and maintaining a node's on-disk state.
@@ -232,6 +317,10 @@ The app.toml file controls application-specific settings:
 # Minimum gas prices for transaction acceptance
 minimum-gas-prices = "0.02usei"
 
+# First block height a full node must not execute (read-only freeze mode).
+# 0 disables freeze mode. Full nodes only; see "Freeze mode" above.
+freeze-height = 0
+
 # API configuration
 [api]
 enable = true