v0.4.0

[0.4.0] - 2026-06-10

Added

• MCP initialize handshake verification during connect: a connection now only
  counts as established once the server completes the MCP handshake. Plain
  HTTPS endpoints that are not MCP servers are rejected with
  "Not a valid MCP server (handshake failed)" instead of a false success.
• MCPClient.initialize() returns the handshake result cached at connect time
  instead of re-initializing the session.
• TLS version probing: the auditor now reports the actually negotiated TLS
  version (e.g. TLSv1.3) instead of a hardcoded value.
• CapabilityToolsPresentRule, ToolsNamesUniqueRule, and
  ToolsNamesValidFormatRule are now exported from mcpscore.rules.

Changed

• Python 3.11+ is now supported (previously 3.13+ only). CI tests against
  3.11, 3.12, and 3.13 on Linux, macOS, and Windows.
• SSETransportSupportRule replaced by StreamableHTTPTransportRule: the MCP
  specification deprecated standalone SSE in favor of Streamable HTTP, so the
  rule now rewards Streamable HTTP and flags SSE-only servers with migration
  advice (previously it did the opposite).
• Tool schema validation aligned with the MCP specification / JSON Schema:
  title, properties, and required are optional (zero-argument tools are
  valid), top-level anyOf/oneOf/allOf/$ref schemas are accepted, and
  properties without a type (enum/$ref) are valid.
• outputSchema is optional per the MCP specification: tools without one are
  no longer penalized; only declared output schemas are validated.
• AuditData.transport_type is typed as MCPTransportType | None
  (previously str | None).

Fixed

• Failed connection attempts are torn down immediately on their own exit
  stack; previously they leaked into the client lifecycle and could re-raise
  buffered transport errors during cleanup().
• A CancelledError leaked by the MCP SDK transport's task group (e.g. when
  the endpoint is not an MCP server) is treated as a failed connection
  instead of escaping to the caller.
• The CLI now always calls client.cleanup(), including when the audit
  raises (previously connections leaked on error paths).