fix(proxy): handle client-aborted streaming requests

[bnema]

Summary

• Treat client-canceled reverse proxy requests as client disconnects instead of upstream failures.
• Preserve real upstream failures as 503 responses while returning 499 for canceled proxy requests.
• Let http.ErrAbortHandler panics escape Gordon panic recovery so Go suppresses benign streaming abort logs.

Test Plan

• go test ./internal/adapters/in/http/proxy ./internal/adapters/in/http/middleware
• go test ./...
• golangci-lint run ./...
• go vet ./...

Summary by CodeRabbit

Release Notes

• Bug Fixes
  • Improved handling of aborted reverse proxy requests to prevent incorrect error logging and 500 responses.
  • Added client disconnection detection for proxied requests, responding with appropriate status code instead of treating as service failure.

[coderabbitai]

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: c54942b0-3f3e-4335-9052-2805cfc527b4

📥 Commits

Reviewing files that changed from the base of the PR and between afb5326 and 8823050.

📒 Files selected for processing (4)

• internal/adapters/in/http/middleware/logging.go
• internal/adapters/in/http/middleware/logging_test.go
• internal/adapters/in/http/proxy/forwarder.go
• internal/adapters/in/http/proxy/forwarder_test.go

📝 Walkthrough

Walkthrough

The PR improves HTTP error handling across middleware and proxy layers. The middleware now correctly re-panics http.ErrAbortHandler instead of converting it to a 500 response. The proxy detects client disconnection/cancellation errors and returns a 499 status instead of treating them as upstream failures.

Changes

Client Abort and Disconnect Handling

Layer / File(s)	Summary
Middleware panic recovery for handler abort internal/adapters/in/http/middleware/logging.go, internal/adapters/in/http/middleware/logging_test.go	PanicRecovery adds detection of http.ErrAbortHandler panics via isAbortHandlerPanic helper and re-panics the abort handler instead of logging and converting to 500; test verifies re-panic behavior.
Proxy client disconnect detection and 499 response internal/adapters/in/http/proxy/forwarder.go, internal/adapters/in/http/proxy/forwarder_test.go	Both forwardToTarget and forwardToRegistry error handlers now detect client cancellation/abort via isClientDisconnectError helper and return HTTP 499 status; request overflow detection refactored to errors.AsType; test stubs transport to return context.Canceled and verifies 499 response.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Poem

🐰 A client that fled or panics mid-stream,
No longer becomes the middleware's dream;
Now 499 shines where errors once loomed,
And abort handlers hop free from their gloom! ✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 20.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title "fix(proxy): handle client-aborted streaming requests" accurately summarizes the main change: handling client-aborted requests in the proxy layer with appropriate status codes and panic recovery.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/sse-client-abort-proxy-errors

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[Copilot]

Pull request overview

This PR improves reverse-proxy handling of client-aborted streaming requests by distinguishing client cancellations from true upstream failures, and by letting http.ErrAbortHandler panics propagate so Go’s HTTP server suppresses benign abort logging.

Changes:

• Map proxy errors caused by request cancellation (context.Canceled) to HTTP 499 (Client Closed Request) instead of returning 503.
• Preserve 503 responses for genuine upstream/proxy failures while downgrading cancellation logging to debug level.
• Update panic recovery middleware to rethrow http.ErrAbortHandler, with new tests covering both behaviors.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
internal/adapters/in/http/proxy/forwarder.go	Returns 499 for canceled proxy requests and adjusts error classification/logging.
internal/adapters/in/http/proxy/forwarder_test.go	Adds a unit test asserting 499 is returned on context.Canceled from the transport.
internal/adapters/in/http/middleware/logging.go	Updates panic recovery to rethrow http.ErrAbortHandler so Go suppresses abort logs.
internal/adapters/in/http/middleware/logging_test.go	Adds coverage ensuring http.ErrAbortHandler panics are rethrown (not converted to 500).

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