Deprecate Tendermint 0.34 client (#1891)

Author: webmaster128

CHANGELOG.md

@@ -68,6 +68,11 @@ and this project adheres to
   If you are using any of those methods, please comment at
   https://github.com/cosmos/cosmjs/issues/1796.
 
+- @cosmjs/tendermint-rpc: Deprecate the Tendermint/CometBFT 0.34 client
+  (`isTendermint34Client`/`Tendermint34Client` as well as all related types).
+  This will be removed in the next version of CosmJS:
+  https://github.com/cosmos/cosmjs/issues/1866
+
 ## [0.36.2] - 2025-10-24
 
 ### Fixed

packages/tendermint-rpc/src/tendermint34/tendermint34client.ts

@@ -19,6 +19,10 @@ type Encoder<T extends requests.Request> = (req: T) => JsonRpcRequest;
 // Decoder is a generic that matches all methods of Responses
 type Decoder<T extends responses.Response> = (res: JsonRpcSuccessResponse) => T;
 
+/**
+ * @deprecated Support for Tendermint/CometBFT 0.34 will be removed in the next version of CosmJS
+ *             (https://github.com/cosmos/cosmjs/issues/1866)
+ */
 export class Tendermint34Client {
   /**
    * Creates a new Tendermint client for the given endpoint.

packages/tendermint-rpc/src/tendermintclient.ts

@@ -14,6 +14,10 @@ export type TendermintClient = Tendermint34Client | Tendermint37Client;
 /** A CometClient is either a Tendermint34Client, Tendermint37Client Comet38Client or a Comet1Client */
 export type CometClient = Tendermint34Client | Tendermint37Client | Comet38Client | Comet1Client;
 
+/**
+ * @deprecated Support for Tendermint/CometBFT 0.34 will be removed in the next version of CosmJS
+ *             (https://github.com/cosmos/cosmjs/issues/1866)
+ */
 export function isTendermint34Client(client: CometClient): client is Tendermint34Client {
   return client instanceof Tendermint34Client;
 }