refactor(config): eliminate global mutable state, wire DeerFlowContext into runtime

- Freeze all config models (AppConfig + 15 sub-configs) with frozen=True
- Purify from_file() — remove 9 load_*_from_dict() side-effect calls
- Replace mtime/reload/push/pop machinery with single ContextVar + init_app_config()
- Delete 10 sub-module globals and their getters/setters/loaders
- Migrate 50+ consumers from get_*_config() to get_app_config().xxx

- Expand DeerFlowContext: app_config + thread_id + agent_name (frozen dataclass)
- Wire into Gateway runtime (worker.py) and DeerFlowClient via context= parameter
- Remove sandbox_id from runtime.context — flows through ThreadState.sandbox only
- Middleware/tools access runtime.context directly via Runtime[DeerFlowContext] generic
- resolve_context() retained at server entry points for LangGraph Server fallback

backend/tests/test_memory_updater.py

@@ -10,7 +10,9 @@ from deerflow.agents.memory.updater import (
     import_memory_data,
     update_memory_fact,
 )
+from deerflow.config.app_config import AppConfig
 from deerflow.config.memory_config import MemoryConfig
+from deerflow.config.sandbox_config import SandboxConfig
 
 
 def _make_memory(facts: list[dict[str, object]] | None = None) -> dict[str, object]:
@@ -31,11 +33,8 @@ def _make_memory(facts: list[dict[str, object]] | None = None) -> dict[str, obje
     }
 
 
-def _memory_config(**overrides: object) -> MemoryConfig:
-    config = MemoryConfig()
-    for key, value in overrides.items():
-        setattr(config, key, value)
-    return config
+def _memory_config(**overrides: object) -> AppConfig:
+    return AppConfig(sandbox=SandboxConfig(use="test"), memory=MemoryConfig().model_copy(update=overrides))
 
 
 def test_apply_updates_skips_existing_duplicate_and_preserves_removals() -> None:
@@ -67,8 +66,7 @@ def test_apply_updates_skips_existing_duplicate_and_preserves_removals() -> None
         ],
     }
 
-    with patch(
-        "deerflow.agents.memory.updater.get_memory_config",
+    with patch.object(AppConfig, "current",
         return_value=_memory_config(max_facts=100, fact_confidence_threshold=0.7),
     ):
         result = updater._apply_updates(current_memory, update_data, thread_id="thread-b")
@@ -88,8 +86,7 @@ def test_apply_updates_skips_same_batch_duplicates_and_keeps_source_metadata() -
         ],
     }
 
-    with patch(
-        "deerflow.agents.memory.updater.get_memory_config",
+    with patch.object(AppConfig, "current",
         return_value=_memory_config(max_facts=100, fact_confidence_threshold=0.7),
     ):
         result = updater._apply_updates(current_memory, update_data, thread_id="thread-42")
@@ -132,8 +129,7 @@ def test_apply_updates_preserves_threshold_and_max_facts_trimming() -> None:
         ],
     }
 
-    with patch(
-        "deerflow.agents.memory.updater.get_memory_config",
+    with patch.object(AppConfig, "current",
         return_value=_memory_config(max_facts=2, fact_confidence_threshold=0.7),
     ):
         result = updater._apply_updates(current_memory, update_data, thread_id="thread-9")
@@ -160,8 +156,7 @@ def test_apply_updates_preserves_source_error() -> None:
         ]
     }
 
-    with patch(
-        "deerflow.agents.memory.updater.get_memory_config",
+    with patch.object(AppConfig, "current",
         return_value=_memory_config(max_facts=100, fact_confidence_threshold=0.7),
     ):
         result = updater._apply_updates(current_memory, update_data, thread_id="thread-correction")
@@ -184,8 +179,7 @@ def test_apply_updates_ignores_empty_source_error() -> None:
         ]
     }
 
-    with patch(
-        "deerflow.agents.memory.updater.get_memory_config",
+    with patch.object(AppConfig, "current",
         return_value=_memory_config(max_facts=100, fact_confidence_threshold=0.7),
     ):
         result = updater._apply_updates(current_memory, update_data, thread_id="thread-correction")
@@ -532,7 +526,7 @@ class TestUpdateMemoryStructuredResponse:
 
         with (
             patch.object(updater, "_get_model", return_value=self._make_mock_model(valid_json)),
-            patch("deerflow.agents.memory.updater.get_memory_config", return_value=_memory_config(enabled=True)),
+            patch.object(AppConfig, "current", return_value=_memory_config(enabled=True)),
             patch("deerflow.agents.memory.updater.get_memory_data", return_value=_make_memory()),
             patch("deerflow.agents.memory.updater.get_memory_storage", return_value=MagicMock(save=MagicMock(return_value=True))),
         ):
@@ -555,7 +549,7 @@ class TestUpdateMemoryStructuredResponse:
 
         with (
             patch.object(updater, "_get_model", return_value=self._make_mock_model(list_content)),
-            patch("deerflow.agents.memory.updater.get_memory_config", return_value=_memory_config(enabled=True)),
+            patch.object(AppConfig, "current", return_value=_memory_config(enabled=True)),
             patch("deerflow.agents.memory.updater.get_memory_data", return_value=_make_memory()),
             patch("deerflow.agents.memory.updater.get_memory_storage", return_value=MagicMock(save=MagicMock(return_value=True))),
         ):
@@ -577,7 +571,7 @@ class TestUpdateMemoryStructuredResponse:
 
         with (
             patch.object(updater, "_get_model", return_value=model),
-            patch("deerflow.agents.memory.updater.get_memory_config", return_value=_memory_config(enabled=True)),
+            patch.object(AppConfig, "current", return_value=_memory_config(enabled=True)),
             patch("deerflow.agents.memory.updater.get_memory_data", return_value=_make_memory()),
             patch("deerflow.agents.memory.updater.get_memory_storage", return_value=MagicMock(save=MagicMock(return_value=True))),
         ):
@@ -602,7 +596,7 @@ class TestUpdateMemoryStructuredResponse:
 
         with (
             patch.object(updater, "_get_model", return_value=model),
-            patch("deerflow.agents.memory.updater.get_memory_config", return_value=_memory_config(enabled=True)),
+            patch.object(AppConfig, "current", return_value=_memory_config(enabled=True)),
             patch("deerflow.agents.memory.updater.get_memory_data", return_value=_make_memory()),
             patch("deerflow.agents.memory.updater.get_memory_storage", return_value=MagicMock(save=MagicMock(return_value=True))),
         ):
@@ -646,8 +640,7 @@ class TestFactDeduplicationCaseInsensitive:
             ],
         }
 
-        with patch(
-            "deerflow.agents.memory.updater.get_memory_config",
+        with patch.object(AppConfig, "current",
             return_value=_memory_config(max_facts=100, fact_confidence_threshold=0.7),
         ):
             result = updater._apply_updates(current_memory, update_data, thread_id="thread-b")
@@ -677,8 +670,7 @@ class TestFactDeduplicationCaseInsensitive:
             ],
         }
 
-        with patch(
-            "deerflow.agents.memory.updater.get_memory_config",
+        with patch.object(AppConfig, "current",
             return_value=_memory_config(max_facts=100, fact_confidence_threshold=0.7),
         ):
             result = updater._apply_updates(current_memory, update_data, thread_id="thread-b")
@@ -704,7 +696,7 @@ class TestReinforcementHint:
 
         with (
             patch.object(updater, "_get_model", return_value=model),
-            patch("deerflow.agents.memory.updater.get_memory_config", return_value=_memory_config(enabled=True)),
+            patch.object(AppConfig, "current", return_value=_memory_config(enabled=True)),
             patch("deerflow.agents.memory.updater.get_memory_data", return_value=_make_memory()),
             patch("deerflow.agents.memory.updater.get_memory_storage", return_value=MagicMock(save=MagicMock(return_value=True))),
         ):
@@ -729,7 +721,7 @@ class TestReinforcementHint:
 
         with (
             patch.object(updater, "_get_model", return_value=model),
-            patch("deerflow.agents.memory.updater.get_memory_config", return_value=_memory_config(enabled=True)),
+            patch.object(AppConfig, "current", return_value=_memory_config(enabled=True)),
             patch("deerflow.agents.memory.updater.get_memory_data", return_value=_make_memory()),
             patch("deerflow.agents.memory.updater.get_memory_storage", return_value=MagicMock(save=MagicMock(return_value=True))),
         ):
@@ -754,7 +746,7 @@ class TestReinforcementHint:
 
         with (
             patch.object(updater, "_get_model", return_value=model),
-            patch("deerflow.agents.memory.updater.get_memory_config", return_value=_memory_config(enabled=True)),
+            patch.object(AppConfig, "current", return_value=_memory_config(enabled=True)),
             patch("deerflow.agents.memory.updater.get_memory_data", return_value=_make_memory()),
             patch("deerflow.agents.memory.updater.get_memory_storage", return_value=MagicMock(save=MagicMock(return_value=True))),
         ):