feat: add streaming core domain model

TASKS.md

@@ -2,20 +2,20 @@
 
 ## Current
 
-### `feat/mcp-streamable-http-alignment`
+### `feat/streaming-core-model`
 
 Status: completed
 
 DoD:
-- `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
+- core domain types exist for window/session/job execution
+- `ExecutionConfig` can carry `streaming`
+- protocol-aware validation follows documented capability matrix
+- streaming types are exported from `crank-core`
+- core tests cover serde and validation rules
 
 ## Next
 
-- `feat/streaming-core-model`
+- `feat/stream-session-store`
 
 ## Backlog