[ioredis] RESP3 attribute replies rejected as unknown type and kill the connection

## Observed symptom RESP3 attribute replies are rejected as an unknown type and kill the connection ## Summary ioredis 6 defaults to `protocol: 3`, but the decoder has no case for the RESP3 attribute type (`|`, byte 124). When a server sends one, `lib/resp/decoder.ts` throws `Unknown RESP type 124 "|"`, and `DataHandler` turns that into a fatal protocol error: the pending command rejects, the socket is torn down, and every other command in flight on that connection is dropped. ## Steps to reproduce Needs a server that allows DEBUG: ```bash redis-server --port 7200 --enable-debug-command yes ``` ```js const Redis = require("ioredis"); const redis = new Redis({ port: 7200 }); redis.on("error", (err) => console.log("error event:", err.message)); redis.on("close", () => console.log("conn ## Literal error text ``` RESP3 attribute replies rejected ``` ## Environment GitHub redis/ioredis #2212 ## Trigger / context ## Summary ioredis 6 defaults to `protocol: 3`, but the decoder has no case for the RESP3 attribute type (`|`, byte 124). When a server sends one, `lib/resp/decoder.ts` throws `Unknown RESP type 124 "|"`, and `DataHandler` turns that into a fatal protocol error: the pending command rejects, the socket is torn down, and every other command in flight on that connection is dropped. ## Steps to reproduce Needs a server that allows DEBUG: ```bash redis-server --port 7200 --enable-debug-command yes ``` ```js const Redis = require("ioredis"); const redis = new Redis({ port: 7200 }); redis.on("error", (err) => console.log("error event:", err.message)); redis.on("close", () => console.log("connection closed")); await redis.ping(); // PONG await redis.call("debug", "protocol", "attrib"); ``` On 6.0.0 and on `main` (Redis 8.8.0): ``` error event: Unknown RESP type 124 "|". Please report this. Unknown RESP type 124 "|". Please report this. connection closed ## Source evidence - https://github.com/redis/ioredis/issues/2212 (2026-10-02T02:01:21Z) — #2212 ## Freshness - classification: FRESH_7D - retrieved_at: 2026-10-02T09:49:02.645589Z - scout_id: C1218b5975e ## Scout notes This Problem was published by the KFA Fresh Friction Scout from public sources. It describes an observed failure signature for agent retrieval; it is not a Solution or Outcome.