refactor: LangGraph gateway layer for UI-agnostic graph and thread access (#295)

* feat(gateway): graph gateway protocol

* refactor(cli): wire gateway in cli/tui

* refactor(gateway): centralize runtime gateway init

* chore(gateway): restrict RunRequest message type

* feat(gateway): add langgraph server gateway

* chore(cli): tighten serve runtime state typing

* refactor(cli): route async task state reads through graph gateway

* refactor(gateway): support graph targets in server gateway

* refactor(cli): route session commands through graph gateway

* refactor(cli): fold thread store under graph gateway

* refactor(gateway): route graph state access through gateway

* refactor(channels): wire graph gateway

* refactor(memory): preserve graph threads for cloning

* feat(gateway): add thread cloning

* fix(tui): pass effective workspace for thread creation

* chore(memory): add workspare dir to memory worker metadata

* fix(sessions): filter preloaded UUID registy entries by the current scope

* test(fakes): use https

* refactor(consumer): consolidate imports

* fix(stream): optional summarization event

* fix(gateway): resolve abbreviated thread IDs by search

* fix(gateway): page server thread listings

* fix(gateway): emit pending interrupt events

* style: fmt

* feat(gateway): persist workspace_dir & model in thread metadata

* fix(gateway): page server thread prefix resolution

* fix(gateway): expose server thread list metadata

* refactor: add back type def

* refactor: tighten types

* revert: add back worker thread deletion

The worker thread forking changes are out of scope for now, so to
maintain parity with the existing behavior we'll leave this intact.

* fix(gateway): apply compaction to server thread history

* refactor(stream): restore direct summary replay suppression

* fix(gateway): preserve compaction state and server stream output

* fix(gateway): close local stream generator on cancellation

---------

Co-authored-by: Xi Zhang <106144707+X-iZhang@users.noreply.github.com>

tests/test_rich_command_ui.py

@@ -283,14 +283,16 @@ class TestPhaseBMigrated:
     """Session lifecycle callbacks (start/resume) filled in Phase B."""
 
     def test_start_new_session_fires_callback(self):
-        called = []
-        ui, _ = _make_ui(on_start_new_session=lambda: called.append("new"))
-        ui.start_new_session()
-        assert called == ["new"]
+        from unittest.mock import AsyncMock
+
+        cb = AsyncMock()
+        ui, _ = _make_ui(on_start_new_session=cb)
+        _run(ui.start_new_session())
+        cb.assert_awaited_once()
 
     def test_start_new_session_without_callback_is_noop(self):
         ui, console = _make_ui()
-        ui.start_new_session()
+        _run(ui.start_new_session())
         console.print.assert_not_called()
 
     def test_handle_session_resume_awaits_callback(self):