#107 Monitor STDERR and refactor StdioClientTransport to use flows
#442
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StdioClientTransport to use flowsStdioClientTransport to use flows
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…ndling, and support for optional error stream. Update dependencies in `libs.versions.toml`.
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Replaced a boolean ` processStdError ` callback with `classifyStderr` that returns a `StderrSeverity` enum (FATAL, WARNING, INFO, DEBUG, IGNORE). This allows fine-grained control over stderr message handling: FATAL terminates the transport, while other levels log at appropriate levels or discard messages. Updated KDoc with comprehensive documentation and usage examples.
Enhance `StdioClientTransportTest` with clean shutdown validation, error handling, and added assertions. Extend timeout for stability.
…p test suites, and avoid stack trace truncation.
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nerzhulart
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Dec 3, 2025
…ifyStderr` to DEBUG
nerzhulart
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e5l
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Dec 4, 2025
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lgtm, please check minor comments
| transport.onError { errorCalled = true } | ||
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| transport.start() | ||
| delay(100.milliseconds) |
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runTest is using virtual time, please make sure the delay is used to skip virtual time and not real
| } catch (e: McpException) { | ||
| logger.debug(e) { "Error while sending message: ${e.message}" } | ||
| throw e | ||
| } catch (e: Exception) { |
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I would also handle CancellationException (and add a test);
Exception -> Throwable
| handleJSONRPCMessage(event.message) | ||
| } | ||
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| is Event.StderrEvent -> { |
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consider extracting error handling to a separate method (for readability)
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# Better exception handling in StdioClientTransport Refactor `McpException` for improved handling with convenience constructors and enhanced exception wrapping logic in `StdioClientTransport`. Update tests to use `kotest` matchers and add JUnit parameterized tests for exception handling. ## Motivation and Context #442 follow up ## How Has This Been Tested? <!-- Have you tested this in a real application? Which scenarios were tested? --> ## Breaking Changes <!-- Will users need to update their code or configurations? --> ## Types of changes <!-- What types of changes does your code introduce? Put an `x` in all the boxes that apply: --> - [x] Bug fix (non-breaking change which fixes an issue) - [ ] New feature (non-breaking change which adds functionality) - [ ] Breaking change (fix or feature that would cause existing functionality to change) - [ ] Documentation update ## Checklist <!-- Go over all the following points, and put an `x` in all the boxes that apply. --> - [ ] I have read the [MCP Documentation](https://modelcontextprotocol.io) - [ ] My code follows the repository's style guidelines - [ ] New and existing tests pass locally - [ ] I have added appropriate error handling - [ ] I have added or updated documentation as needed ## Additional context <!-- Add any other context, implementation notes, or design decisions -->
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Refactor
StdioClientTransportto monitor STDERRStdioClientTransportclass has been enhanced to monitor the standard error (stderr) stream, enabling the detection of fatal errors that should terminate the connection.using coroutine flows and channels
StderrSeverityenum (FATAL,WARNING,INFO,DEBUG,IGNORE)classification for flexible error handling
and in-memory streams
Motivation and Context
Fix for #107
How Has This Been Tested?
Regression tests, integration test added
Breaking Changes
Types of changes
Checklist
Additional context