- new open-sse/utils/streamErrorPeek.js: bounded peek of the first bytes of a
200 stream; configured pattern match → 502 so account/combo fallback can run
before any byte reaches the client (streaming included). Re-emits RAW bytes
so split multi-byte UTF-8 sequences survive the peek (never re-encode
decoded text — TextDecoder flush corrupts a lone leading byte to U+FFFD).
- chatCore: run the peek after executor.execute when the provider has
streamErrorPatterns configured; chat.js passes the settings through.
- commandcode executor: same raw-bytes fix in peekForUpstreamError + regression
test that fails against the old flush-based re-encode.
Upstream emits AI SDK v5 {"type":"error"} events inside an HTTP 200 stream.
The translator turned them into fake success content ([CommandCode error: ...]
+ finish_reason stop), so account/model fallback never fired and logs showed
Status: success.
- translator: error events now emit an OpenAI-shaped error chunk (chunk.error)
instead of content; parseSSEToOpenAIResponse already detects chunk?.error
- executor: peek the first events before committing the response; an early
error event returns 502 so fallback runs before any byte reaches the client
