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- Return raw Response from createChatCompletions instead of parsing SSE in the service layer, allowing handlers to pipe streams directly - Pipe OpenAI-compatible streams through a monitoring TransformStream for TTFT and throughput logging without re-serializing - Anthropic /messages handler now parses SSE at the handler level where it needs to translate events - Normalize max_completion_tokens to max_tokens for upstream compat - Set Bun idleTimeout to 0 to prevent premature SSE connection kills (default 10s was dropping long-running LLM streams) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
laizhengbao
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Two fixes in the chat completions handler: 1. Clients that send the newer `max_completion_tokens` parameter (instead of legacy `max_tokens`) receive a 400 from the Copilot API: `max_tokens and max_completion_tokens cannot both be set`. The handler injects its own `max_tokens` whenever the legacy field is unset, and upstream rejects requests carrying both parameters. Injection is now skipped when either parameter is present, and the payload type gains an optional `max_completion_tokens` field so the value is forwarded upstream as intended. Related: ericc-ch#220 addresses the same interop by normalizing `max_completion_tokens` into `max_tokens` instead; this commit takes the passthrough approach. Happy to drop this half if ericc-ch#220 lands first. 2. GitHub's /models endpoint lists some entries WITHOUT a `capabilities` object (observed: `gpt-41-copilot`, `trajectory-compaction`). Requesting one crashed the proxy with a 500: `undefined is not an object (evaluating 'selectedModel?.capabilities.limits.max_output_tokens')`. `Model.capabilities` is now optional to mirror the real API, and both the handler and the tokenizer lookup guard against its absence. Tested against a live Copilot endpoint (individual plan): - `max_completion_tokens`-only request -> 200 (previously 500) - capability-less model without max_tokens -> clean upstream error, no crash - plain request without either parameter -> `max_tokens` still injected - streaming requests unaffected
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Summary
ResponsefromcreateChatCompletionsinstead of parsing SSE in the service layer, allowing the OpenAI-compatible handler to pipe streams directly viaTransformStream(avoids re-serialization overhead and buffering issues)/messageshandler now parses SSE at the handler level where event translation is neededmax_completion_tokenstomax_tokensfor upstream compatibility (some clients send the newer OpenAI field which Copilot doesn't accept)idleTimeout: 0to prevent premature SSE connection kills (default 10s was dropping long-running LLM streams)Test plan
/messagesstreaming translation still works🤖 Generated with Claude Code