* fix(http): reject unsupported subscription streams
Use the Mcp-Method header to reject subscriptions/listen with the spec-defined 404 Method Not Found response instead of opening an idle SSE stream. Preserve SDK validation for missing or mismatched headers.
Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 06d5dda1-4086-4996-8d18-152e45e611b0
* refactor(http): clarify subscription rejection
Document why header validation precedes the unsupported-method rejection and use named SDK error constants in tests.
Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 06d5dda1-4086-4996-8d18-152e45e611b0
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Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 06d5dda1-4086-4996-8d18-152e45e611b0