feat: align mcp transport with streamable http

TASKS.md

@@ -2,18 +2,20 @@
 
 ## Current
 
-### `feat/streaming-implementation-spec`
+### `feat/mcp-streamable-http-alignment`
 
 Status: completed
 
 DoD:
-- Streaming slices are defined file-by-file
-- Acceptance criteria and tests are explicit for each slice
-- State transitions and sequence outlines are documented
+- `mcp-server` transport semantics match MCP Streamable HTTP
+- `GET` SSE stream is supported for initialized sessions
+- `POST` can return JSON or SSE depending on negotiated response mode
+- session and protocol headers are validated consistently
+- transport tests cover JSON mode, SSE mode, GET stream and session deletion
 
 ## Next
 
-- `feat/mcp-streamable-http-alignment`
+- `feat/streaming-core-model`
 
 ## Backlog