feat: implement protocol version negotiation (#502)
* feat: implement protocol version negotiation
Implement protocol version negotiation following the TypeScript SDK approach:
- Update LATEST_PROTOCOL_VERSION to 2025-06-18
- Add client-side validation of server protocol version
- Return UnsupportedProtocolVersionError for incompatible versions
- Add Mcp-Protocol-Version header support for HTTP transports
- Implement SetProtocolVersion method on HTTP connections
- Add comprehensive tests for protocol negotiation
This ensures both client and server agree on a mutually supported protocol
version, preventing compatibility issues.
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* fmt
* refactor: improve protocol negotiation implementation
- Move HTTP header constants to common location to avoid duplication
- Add errors.Is interface to UnsupportedProtocolVersionError for better Go error handling
- Add comprehensive edge case tests for empty and malformed protocol versions
- Ensure consistent header constant usage across client and server packages
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* fmt
* fix: include protocol version header in DELETE request for session termination
As per MCP specification, the MCP-Protocol-Version header must be included
on all subsequent requests to the MCP server, including DELETE requests
for terminating sessions.
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* fix: maintain backward compatibility for protocol version negotiation
When the server does not receive an MCP-Protocol-Version header,
it should assume protocol version 2025-03-26 for backward compatibility
as per the MCP specification.
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* test: update tests to reflect backward compatibility behavior
Tests now expect protocol version 2025-03-26 when no protocol version
is provided during initialization, as per MCP specification for
backward compatibility.
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feat(logging): add support for send log message notifications and imp…
…lemented the `SessionWithLogging` interface on `streamableHttpSession` (#484)
* feat(logging): add support for log message notifications
- Introduced `LoggingLevel.ShouldSendTo` for log level comparison
- Added `SendLogMessageToSpecificClient` to send log notifications to a specific client
- Added `SendLogMessageToClient` to send log notifications to the current session client
- Implemented `SessionWithLogging` interface for `streamableHttpSession`
- Added `sessionLogLevelsStore` to manage per-session log levels
- Updated `StreamableHTTPServer` to support setting and retrieving log levels
- Added tests covering log notification sending logic and format validation
* fix(staticcheck): simplify embedded field access in log notification
- Replaced `notification.Notification.Method` with `notification.Method` to resolve QF1008 from staticcheck
- No functional change; improves code clarity and eliminates linter warning

Implement sampling in Stdio (#461)
* Implement sampling in Stdio
* Update docs
* Update server/sampling_test.go
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* use proper context
* Update www/docs/pages/clients/advanced-sampling.mdx
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* enhance test
* tweak example server
* fix test
* fix test
* fixes
* fix
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more docs fixes

fix(Srv/stream): add ID field to `PingRequest` (#353)
* fix(Srv/stream): add ID field to PingRequest
* fix: make session requestID unique and incremental

fix(server): Implement MCP protocol negotiation. (#341)
According to [the MCP spec](https://modelcontextprotocol.io/specification/2025-03-26/basic/lifecycle#version-negotiation):
> If the server supports the requested protocol version, it MUST respond with
> the same version. Otherwise, the server MUST respond with another protocol
> version it supports.
This adds `mcp.ValidProtocolVersions`, a slice with all currently specified MCP
versions.
In the `server` package we check if the client provided a known MCP version
and, if so, return that version. Otherwise `LATEST_PROTOCOL_VERSION` is
returned as previously.

Formatting

Release v0.29.0

feat(MCPServer): support `logging/setlevel` request (#276)
* feat(MCPServer): support logging/setlevel request
* update template file and adopt coderabbitai suggestion

fix(session): Don't send tool changed notifications if session not in…
…itialized yet (#289)
AddSessionTools and DeleteSessionTools can be called before the session
is registered, in particular in the RegisterSession hook.
They should not attempt to send `notifications/tools/list_changed`
notifications in this case as it will only generate errors.