refactor(#20): delete the orphaned hand-rolled turn-stream paths (slice-2, part 2b-iii)

DEC-4 live smoke PASSED first (personal :8081, b127/b128): create → streamed turn
that rendered (worker_phase/text/text_boundary/done with usage) → SIGINT cancel that
round-tripped to a cancelled terminal. With both CLI + web on the adapter, the
hand-rolled turn-stream family is fully orphaned — deleting it now.

- sse_client.py (714 → 224): removed stream_turn / reconnect_turn /
  stream_turn_resilient / cancel_turn + the Event dataclasses (Text/Done/…/Event
  union) + CancelResult + the SSE parse helpers (_iter_events / _envelope_for_type /
  _parse_sse_id / _eager_failure_fields / _INT_RE). KEPT: the caller-semantic
  exceptions (the adapter raises them, DEC-2), SseId, AdminEvent, stream_admin_events
  (slice-6 admin surface).
- sessions.py (677 → 608): removed list_sessions + get_session_tools (no surface
  users) + SessionPage. KEPT: create_session / get_session_messages (the
  --seed-first-message probe still uses them, slice-3) + all exceptions + SessionInfo.
- tests: test_sse_client pruned to TestStreamAdminEvents; test_sessions dropped the
  list_sessions + get_session_tools classes. The deleted turn-stream behavior is now
  covered by test_wt.py + the CLI/web integration tests + the live smoke.

Suite 490 green (570 − 80 deleted turn-stream tests); ruff clean on all touched
files; no new mypy errors. Patch (internal cleanup; behavior preserved).

tests/test_sessions.py

@@ -13,10 +13,8 @@ from ratatoskr.sessions import (
     BifrostBinding,
     BifrostConsumerKeyMissing,
     BifrostHandshakeFailed,
-    InvalidCursor,
     PersonaNotConfigured,
     SessionApiFailed,
-    SessionPage,
     create_character,
     create_session,
     delete_character,
@@ -27,10 +25,8 @@ from ratatoskr.sessions import (
     get_persona_state,
     get_session_bifrost,
     get_session_messages,
-    get_session_tools,
     list_agents,
     list_character_models,
-    list_sessions,
     set_persona_state,
     write_authored_history,
 )
@@ -551,223 +547,6 @@ class TestEndpointForPlane:
             endpoint_for_plane("persona", "10.100.10.50")
 
 
-def _list_item(
-    *,
-    session_id: str = "s1",
-    agent_id: str = "mimir",
-    created_at: str = "2026-04-15T12:00:00+00:00",
-    last_active: str = "2026-04-15T12:05:00+00:00",
-    metadata: dict[str, object] | None = None,
-    name: str | None = "Research session",
-    archived: bool = False,
-    tags: list[str] | None = None,
-) -> dict[str, object]:
-    """Build a GET /sessions list-item body for tests."""
-    item: dict[str, object] = {
-        "session_id": session_id,
-        "agent_id": agent_id,
-        "created_at": created_at,
-        "last_active": last_active,
-        "metadata": metadata if metadata is not None else {},
-        "name": name,
-        "archived": archived,
-        "tags": tags if tags is not None else ["work"],
-    }
-    return item
-
-
-class TestListSessions:
-    @respx.mock
-    async def test_explicit_null_list_defaults(self) -> None:
-        """INV-002: explicit-null archived -> False; explicit-null tags -> []."""
-        raw_item = {
-            "session_id": "s1",
-            "agent_id": "mimir",
-            "created_at": "2026-04-15T12:00:00+00:00",
-            "last_active": "2026-04-15T12:05:00+00:00",
-            "metadata": {},
-            "name": None,
-            "archived": None,
-            "tags": None,
-        }
-        respx.get("https://w.example/sessions").mock(
-            return_value=httpx.Response(
-                200, json={"items": [raw_item], "next_cursor": None}
-            )
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            page = await list_sessions(client)
-        info = page.items[0]
-        assert info.archived is False, "explicit-null archived must default to False"
-        assert info.tags == [], "explicit-null tags must default to []"
-        assert info.name is None
-
-    @respx.mock
-    async def test_happy_first_page(self) -> None:
-        """happy_first_page [happy,tracer]: one item + next_cursor -> SessionPage shape."""
-        respx.get("https://w.example/sessions").mock(
-            return_value=httpx.Response(
-                200,
-                json={
-                    "items": [_list_item()],
-                    "next_cursor": "v1.eyJhYmMifQ",
-                },
-            )
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            page = await list_sessions(client)
-        assert isinstance(page, SessionPage)
-        assert len(page.items) == 1
-        assert page.next_cursor == "v1.eyJhYmMifQ"
-        info = page.items[0]
-        assert info.session_id == "s1"
-        assert info.message_count is None  # INV-002: not in list response
-        assert info.name == "Research session"
-        assert info.archived is False
-        assert info.tags == ["work"]
-
-    @respx.mock
-    async def test_happy_last_page(self) -> None:
-        """happy_last_page: next_cursor=null -> SessionPage(next_cursor=None)."""
-        respx.get("https://w.example/sessions").mock(
-            return_value=httpx.Response(
-                200,
-                json={"items": [_list_item()], "next_cursor": None},
-            )
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            page = await list_sessions(client)
-        assert page.next_cursor is None
-
-    @respx.mock
-    async def test_empty_results(self) -> None:
-        """empty_results: {items: [], next_cursor: null} -> SessionPage([], None)."""
-        respx.get("https://w.example/sessions").mock(
-            return_value=httpx.Response(200, json={"items": [], "next_cursor": None})
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            page = await list_sessions(client)
-        assert page == SessionPage(items=[], next_cursor=None)
-
-    @respx.mock
-    async def test_include_archived_query(self) -> None:
-        """include_archived_query: True -> has param; default -> NO param at all."""
-        route = respx.get("https://w.example/sessions").mock(
-            return_value=httpx.Response(
-                200, json={"items": [], "next_cursor": None}
-            )
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            await list_sessions(client, include_archived=True)
-            await list_sessions(client)  # default
-        url_with = str(route.calls[0].request.url)
-        url_default = str(route.calls[1].request.url)
-        assert "include_archived=true" in url_with
-        assert "include_archived" not in url_default
-
-    @respx.mock
-    async def test_cursor_threaded(self) -> None:
-        """cursor_threaded: cursor=opaque -> URL has cursor=opaque."""
-        route = respx.get("https://w.example/sessions").mock(
-            return_value=httpx.Response(
-                200, json={"items": [], "next_cursor": None}
-            )
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            await list_sessions(client, cursor="opaque-from-prev-page")
-        assert "cursor=opaque-from-prev-page" in str(route.calls[0].request.url)
-
-    @respx.mock
-    async def test_limit_query(self) -> None:
-        """limit_query: limit=10 -> URL has limit=10."""
-        route = respx.get("https://w.example/sessions").mock(
-            return_value=httpx.Response(
-                200, json={"items": [], "next_cursor": None}
-            )
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            await list_sessions(client, limit=10)
-        assert "limit=10" in str(route.calls[0].request.url)
-
-    @respx.mock
-    async def test_invalid_cursor_server(self) -> None:
-        """invalid_cursor_server: 422 cursor_invalid -> InvalidCursor(raw=<passed cursor>)."""
-        respx.get("https://w.example/sessions").mock(
-            return_value=httpx.Response(
-                422,
-                json={"error_code": "cursor_invalid", "message": "bad cursor"},
-            )
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            with pytest.raises(InvalidCursor) as exc_info:
-                await list_sessions(client, cursor="bogus")
-        assert exc_info.value.raw == "bogus"
-
-    @respx.mock
-    async def test_other_validation_failed(self) -> None:
-        """other_validation_failed: 422 other error_code -> SessionApiFailed(422); truncated."""
-        respx.get("https://w.example/sessions").mock(
-            return_value=httpx.Response(
-                422,
-                json={"error_code": "validation_failed", "message": "limit out of range"},
-            )
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            with pytest.raises(SessionApiFailed) as exc_info:
-                await list_sessions(client)
-        assert exc_info.value.status == 422
-        assert len(exc_info.value.body) <= 1024
-
-    @respx.mock
-    async def test_unexpected_status_truncates(self) -> None:
-        """unexpected_status_truncates: 500 + 5000-byte body -> SessionApiFailed; body == 1024."""
-        big = b"x" * 5000
-        respx.get("https://w.example/sessions").mock(
-            return_value=httpx.Response(500, content=big)
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            with pytest.raises(SessionApiFailed) as exc_info:
-                await list_sessions(client)
-        assert exc_info.value.status == 500
-        assert exc_info.value.body == big[:1024]
-
-    @respx.mock
-    async def test_limit_below_one(self) -> None:
-        """limit_below_one [adversarial]: limit=0 -> AssertionError; no HTTP."""
-        route = respx.get("https://w.example/sessions").mock(
-            return_value=httpx.Response(200, json={"items": [], "next_cursor": None})
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            with pytest.raises(AssertionError):
-                await list_sessions(client, limit=0)
-        assert route.call_count == 0
-
-    @respx.mock
-    async def test_limit_above_max(self) -> None:
-        """limit_above_max [adversarial]: limit=300 -> AssertionError; no HTTP."""
-        route = respx.get("https://w.example/sessions").mock(
-            return_value=httpx.Response(200, json={"items": [], "next_cursor": None})
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            with pytest.raises(AssertionError):
-                await list_sessions(client, limit=300)
-        assert route.call_count == 0
-
-    @respx.mock
-    async def test_empty_cursor(self) -> None:
-        """empty_cursor [adversarial]: cursor='' -> AssertionError; no HTTP."""
-        route = respx.get("https://w.example/sessions").mock(
-            return_value=httpx.Response(200, json={"items": [], "next_cursor": None})
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            with pytest.raises(AssertionError):
-                await list_sessions(client, cursor="")
-        assert route.call_count == 0
-
-
-# ---- Issue #8: list_agents + AgentInfo --------------------------------------
-
-
 class TestListAgents:
     @respx.mock
     async def test_happy_full_shape(self) -> None:
@@ -1145,53 +924,6 @@ class TestGetCapabilities:
         assert exc.value.status == 500
 
 
-class TestGetSessionTools:
-    """docs/contracts/issues/2.contract.md — get_session_tools (GET /sessions/{id}/tools, #183)."""
-
-    @respx.mock
-    async def test_happy(self) -> None:
-        """happy [happy,tracer]: 200 → merged tool inventory dict verbatim."""
-        respx.get("https://w.example/sessions/s1/tools").mock(
-            return_value=httpx.Response(
-                200,
-                json={
-                    "agent_id": "alice:wizard",
-                    "builtin_tools": [],
-                    "bifrost_tools": [
-                        {"name": "bifrost.alice.set_field", "description": "d", "parameters": {}}
-                    ],
-                },
-            )
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            tools = await get_session_tools(client, "s1")
-        assert tools["agent_id"] == "alice:wizard"
-        assert tools["builtin_tools"] == []
-        assert tools["bifrost_tools"][0]["name"] == "bifrost.alice.set_field"
-
-    @respx.mock
-    async def test_cross_owner_404_raises(self) -> None:
-        """cross_owner_404 [error]: 404 session_not_found → SessionApiFailed(404)."""
-        respx.get("https://w.example/sessions/s1/tools").mock(
-            return_value=httpx.Response(404, json={"error_code": "session_not_found"})
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            with pytest.raises(SessionApiFailed) as exc:
-                await get_session_tools(client, "s1")
-        assert exc.value.status == 404
-
-    @respx.mock
-    async def test_empty_session_id_asserts(self) -> None:
-        """empty_session_id [adversarial]: '' → AssertionError; no HTTP issued."""
-        route = respx.get("https://w.example/sessions//tools").mock(
-            return_value=httpx.Response(200, json={})
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            with pytest.raises(AssertionError):
-                await get_session_tools(client, "")
-        assert route.call_count == 0
-
-
 class TestGetSessionBifrost:
     """#2 contract — get_session_bifrost (GET /admin/sessions/{id}/bifrost, #176)."""