A stream cut mid-reply is never retried; the turn fails and the partial reply is dropped

[sishuaigong]

Summary

When the Messages stream ends before message_stop, the turn fails and the partial reply, including tool calls already received, is discarded. Every user on a flaky network or behind a proxy that cuts idle streams is affected; Claude Code and Codex retry the same event at once.

Reproduction

1. Start a session and send a prompt that produces a long reply with tool calls.
2. Interrupt the connection to the provider once, mid-reply (drop the TCP connection, or use a proxy that closes the stream early).
3. The turn fails with the error below and the user has to type "continue".

Current behavior

The turn ends with DeepSeek Messages stream ended before message_stop (will_retry: false); the calls already received are not run. packages/llm/llm-deepseek/src/translate.ts line 165 throws LlmError(…, 'STREAM_CLOSED'), and packages/llm/llm-pi-ai/src/stream.ts line 243 throws the same code for the pi-ai path. packages/llm/llm/src/retry-policy.ts lines 18 to 24 define DEFAULT_RETRYABLE_CODES as the empty-response code, RATE_LIMIT, SERVER, TIMEOUT and TRANSPORT; STREAM_CLOSED is not in it, so packages/llm/llm-retry/src/index.ts line 212 declines the retry.

Expected behavior

A stream that ends early is a transport failure: STREAM_CLOSED is retried with the same backoff as TRANSPORT, and the calls already received are kept when the retry resends the request.

Environment

dsh 0.2.2-alpha.2 (commit ce7073d, 1 Nov 2026); Linux x86_64, Ubuntu 24.04, in a virtual machine; run as the ACP server over stdio; model deepseek-v4-flash through DEEPSEEK_BASE_URL; permission mode danger-full-access.