fix: remap grpc "client error (Connect)" to UnavailableError for reconnection (#461)

grpc-js reports transport-level connection failures on streaming RPCs
as StatusCode.Unknown instead of StatusCode.Unavailable. This prevents
the client from tearing down the dead channel and triggering cluster
rediscovery when the connected node goes down.

The fix remaps errors containing "client error (Connect)" to
UnavailableError in convertToCommandError, consistent with the existing
"write after end" workaround. This ensures shouldReconnect returns true,
the channel is torn down, and discovery finds the new leader.

Co-authored-by: William Chong <william-chong@outlook.com>

Author: github-actions[bot]

packages/db-client/src/utils/CommandError.ts

@@ -652,6 +652,13 @@ export const convertToCommandError = (error: Error): CommandError | Error => {
     return new UnavailableError(error);
   }
 
+  // grpc-js reports transport-level connection failures on streaming RPCs as
+  // StatusCode.Unknown instead of StatusCode.Unavailable. This prevents the
+  // client from tearing down the dead channel and triggering rediscovery.
+  if (error.details.includes("client error (Connect)")) {
+    return new UnavailableError(error);
+  }
+
   return new UnknownError(error);
 };
 

packages/test/src/connection/reconnect/all-nodes-down.test.ts

@@ -94,9 +94,7 @@ describe.skip("reconnect", () => {
       })) {
         count++;
       }
-    }).rejects.toThrowErrorMatchingInlineSnapshot(
-      `"UnknownError("Server-side error: status: Unknown, message: \\"client error (Connect)\\", details: [], metadata: MetadataMap { headers: {} }")"`
-    );
+    }).rejects.toThrowError(UnavailableError);
     // create subsctiption
     await expect(
       client.createPersistentSubscriptionToStream(
@@ -127,6 +125,7 @@ describe.skip("reconnect", () => {
       '"Failed to discover after 10 attempts."'
     );
     // read the stream
+    // Channel is torn down by now, so readStream goes through discovery which fails.
     await expect(async () => {
       let count = 0;
       for await (const e of client.readStream(STREAM_NAME, {
@@ -135,7 +134,7 @@ describe.skip("reconnect", () => {
         count++;
       }
     }).rejects.toThrowErrorMatchingInlineSnapshot(
-      `"UnknownError("Server-side error: status: Unknown, message: \\"client error (Connect)\\", details: [], metadata: MetadataMap { headers: {} }")"`
+      '"Failed to discover after 10 attempts."'
     );
     // create subsctiption
     await expect(