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### Dify version
Source checkout of main at `43af5082d3c4ab8a96067370d2f86f214e3c85ae`.
### Cloud or Self Hosted
Self Hosted (Source)
### Steps to reproduce
This was reproduced with the real `DifyLLMAdapterModel`, `DifyApiLLMClient`, and HTTPX streaming response machinery. The test transport supplies a tracked `httpx.AsyncByteStream` so closure can be observed deterministically.
1. Enter `adapter.request_stream(...)` and consume one event so the gateway response is open.
2. Leave the context without exhausting the stream, either by breaking, raising an exception, or cancelling the consuming task.
3. Check whether the gateway response body's `aclose` has been called when the context exits.
`request_stream` yields `DifyStreamedResponse` but does not close its provider generator on context exit. The provider's `async with http_client.stream(...)` is therefore left suspended until later generator finalization.
The regressions also cover natural EOF, a close failure without a primary error, and simultaneous consumer/close failures. This is a controlled HTTPX transport test rather than a live TCP server test.
### ✔️ Expected Behavior
Leaving the request_stream context deterministically closes the gateway response. An existing consumer or cancellation exception remains the primary exception; a standalone cleanup failure is propagated. Completed responses retain their usage accounting.
### ❌ Actual Behavior
An early exit leaves the gateway response open at the request_stream boundary. Cleanup is deferred to later generator finalization rather than tied to context exit.
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<!-- Answer -->
The code at that commit matches your report. `request_stream` creates the provider generator inline, yields the `DifyStreamedResponse`, and then calls `_record_usage`, with no `try/finally` and no close of the generator ([model.py](https://github.com/langgenius/dify/blob/43af5082d3c4ab8a96067370d2f86f214e3c85ae/dify-agent/src/dify_agent/adapters/llm/model.py#L169-L197)). The gateway response is opened inside that generator by `async with self.http_client.stream(...)` ([provider.py](https://github.com/langgenius/dify/blob/43af5082d3c4ab8a96067370d2f86f214e3c85ae/dify-agent/src/dify_agent/adapters/llm/provider.py#L129-L162)). If the consumer stops early, that `async with` stays suspended until the async generator is garbage-collected or finalized by the event loop, so nothing ties cleanup to leaving the context.
The unguarded `_record_usage` line after `yield` is also skipped when the body raises. That fits your expected behavior, where only completed responses keep their usage accounting.
A fix could look like this:
- Keep a reference to the `chunks` generator and wrap `yield response` in `try/finally`, calling `await chunks.aclose()` in the `finally` (for example via `contextlib.aclosing`). The `AsyncIterator` type on `DifyStreamedResponse.chunks` and `DifyLLMClient.iter_llm_result_chunks` has no `aclose`, so you would need to widen it to `AsyncGenerator` or cast.
- Record usage only on normal completion, after the close succeeds.
- If the body already raised (including `CancelledError`), catch and suppress any `aclose` failure so the original exception stays primary. If the body succeeded and `aclose` fails, let that error propagate.
`request()` consumes the stream to the end, so it has the same gap only if the consumer loop raises partway through. The same close guard is worth applying there.
I only read the source and did not run your regression tests.
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I reproduced the additional cleanup gap in regular `request()` from #43454. A valid Graphon URL multimodal chunk triggers a production response-mapping error while the provider generator is suspended, leaving the tracked HTTPX response body unclosed at the exception boundary.
A supplemental patch is prepared that closes the chunk generator in `finally` for regular requests as well. It preserves the original mapping error if cleanup also fails, attaches the cleanup failure as an exception note, and propagates a standalone cleanup error. Usage is recorded after successful completion and closure.
The model and API-provider modules have **30 passing tests** with this supplemental patch, including natural EOF, response-mapping failure, and simultaneous mapping/cleanup failure. The tests exercise HTTPX streaming with `MockTransport` and a tracked `AsyncByteStream`; live TCP behavior has not been tested. Targeted production-source type checks, the package's locked lint checker, formatting, and `git diff --check` pass.
Task cancellation and context-exit cleanup are covered by the existing stream tests. Explicit SDK `stream.cancel()` behavior remains a separate issue outside this supplemental patch.
The supplemental patch has been validated locally and is pending upload to #43454; these results describe the prepared patch, rather than the current published PR head.
I independently reproduced the early-exit leak on the source commit above with a tracked `httpx.AsyncByteStream`. I noticed PR #43454 has since been closed, but did not find a maintainer explanation on its timeline. Could a maintainer confirm whether this issue remains in scope for a follow-up contribution, and whether there is a specific concern the fix should address? If it is still open for contribution, I’d like to work on it and add a focused regression test.