Tighten graph endpoint typing and pin 404 in API tests

- direction: Literal["backward","forward","both"] in service and manager
- HistoriesService.graph annotated -> HistoryGraphResponse
- Pin 404 for missing seed_scope and missing history (was loose 4xx)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: guerler

lib/galaxy/managers/history_graph.py

@@ -8,6 +8,7 @@
 import json
 import logging
 from typing import (
+    Literal,
     Optional,
     Union,
 )
@@ -82,7 +83,7 @@ def __init__(
         toolbox: Optional[AbstractToolBox] = None,
         include_deleted: bool = False,
         seed: Optional[str] = None,
-        direction: str = "both",
+        direction: Literal["backward", "forward", "both"] = "both",
         depth: int = 5,
         seed_scope_hid: Optional[int] = None,
     ):

lib/galaxy/webapps/galaxy/services/histories.py

@@ -54,6 +54,7 @@
 )
 from galaxy.schema.fields import DecodedDatabaseIdField
 from galaxy.schema.history import HistoryIndexQueryPayload
+from galaxy.schema.history_graph import HistoryGraphResponse
 from galaxy.schema.schema import (
     AnyArchivedHistoryView,
     AnyHistoryView,
@@ -390,10 +391,10 @@ def graph(
         limit: int = 500,
         include_deleted: bool = False,
         seed: Optional[str] = None,
-        direction: str = "both",
+        direction: Literal["backward", "forward", "both"] = "both",
         depth: int = 20,
         seed_scope: Optional[str] = None,
-    ):
+    ) -> HistoryGraphResponse:
         history = self.manager.get_accessible(history_id, trans.user, current_history=trans.history)
         seed_scope_hid = self._resolve_seed_scope_hid(trans, history.id, seed_scope) if seed_scope else None
         builder = HistoryGraphBuilder(

lib/galaxy_test/api/test_histories.py

@@ -1322,7 +1322,7 @@ def test_seed_scope_not_in_target_history_is_rejected(self):
         dataset = self.dataset_populator.new_dataset(source_history, content="a", wait=True)
         target_history = self.dataset_populator.new_history()
         response = self.dataset_populator.get_history_graph_raw(target_history, seed_scope=f"d{dataset['id']}")
-        assert 400 <= response.status_code < 500
+        self._assert_status_code_is(response, 404)
 
     # ── auth ──
 
@@ -1334,4 +1334,4 @@ def test_other_users_history_is_forbidden(self):
 
     def test_nonexistent_history_is_rejected(self):
         response = self.dataset_populator.get_history_graph_raw("0000000000000000")
-        assert 400 <= response.status_code < 500
+        self._assert_status_code_is(response, 404)