refactor(agents): move filesystem_state, path_resolver, sandbox to app/agents/shared (slice 3b)

Relocate three leaf filesystem-cluster modules to the shared kernel and flip
all 38 importers. No re-export shims needed (no frozen single-agent importer).
This also resolves the pre-existing shared->new_chat back-edge from
shared/receipt_command.py onto filesystem_state.

filesystem_backends is intentionally deferred to slice 5: it depends on
new_chat middleware (kb_postgres_backend, multi_root_local_folder_backend)
that have not yet moved, so relocating it now would create a shared->new_chat edge.

surfsense_backend/app/agents/multi_agent_chat/middleware/shared/filesystem/middleware/middleware.py

@@ -8,8 +8,8 @@ from deepagents import FilesystemMiddleware
 from langchain_core.tools import BaseTool
 
 from app.agents.shared.filesystem_selection import FilesystemMode
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
-from app.agents.new_chat.sandbox import is_sandbox_enabled
+from app.agents.shared.sandbox import is_sandbox_enabled
 
 from ..system_prompt import build_system_prompt
 from ..tools import (

surfsense_backend/app/agents/multi_agent_chat/middleware/shared/filesystem/middleware/mode.py

@@ -3,7 +3,7 @@
 from __future__ import annotations
 
 from app.agents.shared.filesystem_selection import FilesystemMode
-from app.agents.new_chat.path_resolver import DOCUMENTS_ROOT
+from app.agents.shared.path_resolver import DOCUMENTS_ROOT
 
 
 def is_cloud(mode: FilesystemMode) -> bool:

surfsense_backend/app/agents/multi_agent_chat/middleware/shared/filesystem/middleware/namespace_policy.py

@@ -11,8 +11,8 @@ from typing import TYPE_CHECKING
 
 from langchain.tools import ToolRuntime
 
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
-from app.agents.new_chat.path_resolver import DOCUMENTS_ROOT
+from app.agents.shared.path_resolver import DOCUMENTS_ROOT
 
 from ..shared.paths import TEMP_PREFIX, basename
 from .mode import is_cloud

surfsense_backend/app/agents/multi_agent_chat/middleware/shared/filesystem/middleware/path_resolution.py

@@ -8,7 +8,7 @@ from typing import TYPE_CHECKING
 from langchain.tools import ToolRuntime
 
 from app.agents.shared.filesystem_selection import FilesystemMode
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
 from app.agents.new_chat.middleware.multi_root_local_folder_backend import (
     MultiRootLocalFolderBackend,
 )

surfsense_backend/app/agents/multi_agent_chat/middleware/shared/filesystem/tools/cd/index.py

@@ -10,8 +10,8 @@ from langchain_core.messages import ToolMessage
 from langchain_core.tools import BaseTool, StructuredTool
 from langgraph.types import Command
 
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
-from app.agents.new_chat.path_resolver import DOCUMENTS_ROOT
+from app.agents.shared.path_resolver import DOCUMENTS_ROOT
 
 from ...middleware.async_dispatch import run_async_blocking
 from ...middleware.path_resolution import resolve_relative

surfsense_backend/app/agents/multi_agent_chat/middleware/shared/filesystem/tools/edit_file/index.py

@@ -11,7 +11,7 @@ from langchain_core.messages import ToolMessage
 from langchain_core.tools import BaseTool, StructuredTool
 from langgraph.types import Command
 
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
 from app.agents.new_chat.middleware.kb_postgres_backend import KBPostgresBackend
 
 from ...middleware.async_dispatch import run_async_blocking

surfsense_backend/app/agents/multi_agent_chat/middleware/shared/filesystem/tools/execute_code/helpers.py

@@ -14,8 +14,8 @@ from typing import TYPE_CHECKING
 from daytona.common.errors import DaytonaError
 from langchain.tools import ToolRuntime
 
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
-from app.agents.new_chat.sandbox import (
+from app.agents.shared.sandbox import (
     _evict_sandbox_cache,
     delete_sandbox,
     get_or_create_sandbox,

surfsense_backend/app/agents/multi_agent_chat/middleware/shared/filesystem/tools/execute_code/index.py

@@ -7,7 +7,7 @@ from typing import TYPE_CHECKING, Annotated
 from langchain.tools import ToolRuntime
 from langchain_core.tools import BaseTool, StructuredTool
 
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
 
 from ...middleware.async_dispatch import run_async_blocking
 from .description import select_description

surfsense_backend/app/agents/multi_agent_chat/middleware/shared/filesystem/tools/list_tree/index.py

@@ -9,7 +9,7 @@ from deepagents.backends.utils import validate_path
 from langchain.tools import ToolRuntime
 from langchain_core.tools import BaseTool, StructuredTool
 
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
 from app.agents.new_chat.middleware.kb_postgres_backend import KBPostgresBackend
 
 from ...middleware.async_dispatch import run_async_blocking

surfsense_backend/app/agents/multi_agent_chat/middleware/shared/filesystem/tools/ls/index.py

@@ -8,7 +8,7 @@ from deepagents.backends.utils import validate_path
 from langchain.tools import ToolRuntime
 from langchain_core.tools import BaseTool, StructuredTool
 
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
 from app.agents.new_chat.middleware.kb_postgres_backend import paginate_listing
 
 from ...middleware.async_dispatch import run_async_blocking

surfsense_backend/app/agents/multi_agent_chat/middleware/shared/filesystem/tools/mkdir/index.py

@@ -11,8 +11,8 @@ from langchain_core.messages import ToolMessage
 from langchain_core.tools import BaseTool, StructuredTool
 from langgraph.types import Command
 
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
-from app.agents.new_chat.path_resolver import DOCUMENTS_ROOT
+from app.agents.shared.path_resolver import DOCUMENTS_ROOT
 
 from ...middleware.async_dispatch import run_async_blocking
 from ...middleware.mode import is_cloud

surfsense_backend/app/agents/multi_agent_chat/middleware/shared/filesystem/tools/move_file/helpers.py

@@ -8,9 +8,9 @@ from langchain.tools import ToolRuntime
 from langchain_core.messages import ToolMessage
 from langgraph.types import Command
 
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
 from app.agents.new_chat.middleware.kb_postgres_backend import KBPostgresBackend
-from app.agents.new_chat.path_resolver import DOCUMENTS_ROOT
+from app.agents.shared.path_resolver import DOCUMENTS_ROOT
 from app.agents.shared.state_reducers import _CLEAR
 
 if TYPE_CHECKING:

surfsense_backend/app/agents/multi_agent_chat/middleware/shared/filesystem/tools/move_file/index.py

@@ -11,7 +11,7 @@ from langchain_core.messages import ToolMessage
 from langchain_core.tools import BaseTool, StructuredTool
 from langgraph.types import Command
 
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
 
 from ...middleware.async_dispatch import run_async_blocking
 from ...middleware.mode import is_cloud

surfsense_backend/app/agents/multi_agent_chat/middleware/shared/filesystem/tools/pwd/index.py

@@ -7,7 +7,7 @@ from typing import TYPE_CHECKING
 from langchain.tools import ToolRuntime
 from langchain_core.tools import BaseTool, StructuredTool
 
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
 
 from ...middleware.path_resolution import current_cwd
 from .description import select_description

surfsense_backend/app/agents/multi_agent_chat/middleware/shared/filesystem/tools/read_file/index.py

@@ -10,7 +10,7 @@ from langchain_core.messages import ToolMessage
 from langchain_core.tools import BaseTool, StructuredTool
 from langgraph.types import Command
 
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
 from app.agents.new_chat.middleware.kb_postgres_backend import KBPostgresBackend
 
 from ...middleware.async_dispatch import run_async_blocking

surfsense_backend/app/agents/multi_agent_chat/middleware/shared/filesystem/tools/rm/helpers.py

@@ -12,9 +12,9 @@ from langchain.tools import ToolRuntime
 from langchain_core.messages import ToolMessage
 from langgraph.types import Command
 
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
 from app.agents.new_chat.middleware.kb_postgres_backend import KBPostgresBackend
-from app.agents.new_chat.path_resolver import DOCUMENTS_ROOT
+from app.agents.shared.path_resolver import DOCUMENTS_ROOT
 from app.agents.shared.state_reducers import _CLEAR
 
 if TYPE_CHECKING:

surfsense_backend/app/agents/multi_agent_chat/middleware/shared/filesystem/tools/rm/index.py

@@ -9,7 +9,7 @@ from langchain.tools import ToolRuntime
 from langchain_core.tools import BaseTool, StructuredTool
 from langgraph.types import Command
 
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
 
 from ...middleware.async_dispatch import run_async_blocking
 from ...middleware.mode import is_cloud

surfsense_backend/app/agents/multi_agent_chat/middleware/shared/filesystem/tools/rmdir/helpers.py

@@ -13,9 +13,9 @@ from langchain.tools import ToolRuntime
 from langchain_core.messages import ToolMessage
 from langgraph.types import Command
 
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
 from app.agents.new_chat.middleware.kb_postgres_backend import KBPostgresBackend
-from app.agents.new_chat.path_resolver import DOCUMENTS_ROOT
+from app.agents.shared.path_resolver import DOCUMENTS_ROOT
 from app.agents.shared.state_reducers import _CLEAR
 
 from ...middleware.path_resolution import current_cwd

surfsense_backend/app/agents/multi_agent_chat/middleware/shared/filesystem/tools/rmdir/index.py

@@ -9,7 +9,7 @@ from langchain.tools import ToolRuntime
 from langchain_core.tools import BaseTool, StructuredTool
 from langgraph.types import Command
 
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
 
 from ...middleware.async_dispatch import run_async_blocking
 from ...middleware.mode import is_cloud

surfsense_backend/app/agents/multi_agent_chat/middleware/shared/filesystem/tools/write_file/index.py

@@ -11,7 +11,7 @@ from langchain_core.messages import ToolMessage
 from langchain_core.tools import BaseTool, StructuredTool
 from langgraph.types import Command
 
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
 
 from ...middleware.async_dispatch import run_async_blocking
 from ...middleware.mode import is_cloud

surfsense_backend/app/agents/multi_agent_chat/middleware/shared/kb_context_projection.py

@@ -9,7 +9,7 @@ from langchain.agents.middleware import AgentMiddleware, AgentState
 from langchain_core.messages import SystemMessage
 from langgraph.runtime import Runtime
 
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
 from app.agents.new_chat.middleware.knowledge_search import _render_priority_message
 from app.utils.perf import get_perf_logger
 

surfsense_backend/app/agents/new_chat/mention_resolver.py

@@ -36,7 +36,7 @@ from dataclasses import dataclass, field
 from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from app.agents.new_chat.path_resolver import (
+from app.agents.shared.path_resolver import (
     DOCUMENTS_ROOT,
     build_path_index,
     doc_to_virtual_path,

surfsense_backend/app/agents/new_chat/middleware/anonymous_document.py

@@ -24,8 +24,8 @@ from typing import Any
 from langchain.agents.middleware import AgentMiddleware, AgentState
 from langgraph.runtime import Runtime
 
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
-from app.agents.new_chat.path_resolver import DOCUMENTS_ROOT, safe_filename
+from app.agents.shared.path_resolver import DOCUMENTS_ROOT, safe_filename
 
 logger = logging.getLogger(__name__)
 

surfsense_backend/app/agents/new_chat/middleware/filesystem.py

@@ -47,7 +47,7 @@ from langchain_core.tools import BaseTool, StructuredTool
 from langgraph.types import Command
 
 from app.agents.shared.filesystem_selection import FilesystemMode
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
 from app.agents.new_chat.middleware.kb_postgres_backend import (
     KBPostgresBackend,
     paginate_listing,
@@ -55,8 +55,8 @@ from app.agents.new_chat.middleware.kb_postgres_backend import (
 from app.agents.new_chat.middleware.multi_root_local_folder_backend import (
     MultiRootLocalFolderBackend,
 )
-from app.agents.new_chat.path_resolver import DOCUMENTS_ROOT
+from app.agents.shared.path_resolver import DOCUMENTS_ROOT
-from app.agents.new_chat.sandbox import (
+from app.agents.shared.sandbox import (
     _evict_sandbox_cache,
     delete_sandbox,
     get_or_create_sandbox,

surfsense_backend/app/agents/new_chat/middleware/kb_persistence.py

@@ -47,8 +47,8 @@ from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.agents.shared.feature_flags import get_flags
 from app.agents.shared.filesystem_selection import FilesystemMode
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
-from app.agents.new_chat.path_resolver import (
+from app.agents.shared.path_resolver import (
     DOCUMENTS_ROOT,
     parse_documents_path,
     safe_folder_segment,

surfsense_backend/app/agents/new_chat/middleware/kb_postgres_backend.py

@@ -43,7 +43,7 @@ from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.agents.new_chat.document_xml import build_document_xml
-from app.agents.new_chat.path_resolver import (
+from app.agents.shared.path_resolver import (
     DOCUMENTS_ROOT,
     build_path_index,
     doc_to_virtual_path,

surfsense_backend/app/agents/new_chat/middleware/knowledge_search.py

@@ -43,8 +43,8 @@ from sqlalchemy import select
 
 from app.agents.shared.feature_flags import get_flags
 from app.agents.shared.filesystem_selection import FilesystemMode
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
-from app.agents.new_chat.path_resolver import (
+from app.agents.shared.path_resolver import (
     PathIndex,
     build_path_index,
     doc_to_virtual_path,

surfsense_backend/app/agents/new_chat/middleware/knowledge_tree.py

@@ -34,8 +34,8 @@ from langgraph.runtime import Runtime
 from sqlalchemy import select
 
 from app.agents.shared.filesystem_selection import FilesystemMode
-from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
+from app.agents.shared.filesystem_state import SurfSenseFilesystemState
-from app.agents.new_chat.path_resolver import (
+from app.agents.shared.path_resolver import (
     DOCUMENTS_ROOT,
     PathIndex,
     build_path_index,

surfsense_backend/app/agents/shared/receipt_command.py

@@ -6,7 +6,7 @@ participate in the verification teaching from
 ``multi_agent_chat/subagents/shared/snippets/verifiable_handle.md`` those
 tools now also need to write a :class:`Receipt` into the parent's
 ``state['receipts']`` list (declared on
-:class:`~app.agents.new_chat.filesystem_state.SurfSenseFilesystemState`
+:class:`~app.agents.shared.filesystem_state.SurfSenseFilesystemState`
 and backed by the append reducer).
 
 :func:`with_receipt` wraps both behaviours: it returns the tool payload as
@@ -51,7 +51,7 @@ def with_receipt(
     """Return a Command that ships ``payload`` as a ToolMessage AND appends ``receipt``.
 
     The append happens via the ``_list_append_reducer`` on the ``receipts``
-    field of :class:`~app.agents.new_chat.filesystem_state.SurfSenseFilesystemState`,
+    field of :class:`~app.agents.shared.filesystem_state.SurfSenseFilesystemState`,
     so concurrent subagent batches (item 4 in the plan) won't clobber each
     other's receipts.
     """

surfsense_backend/app/routes/documents_routes.py

@@ -7,7 +7,7 @@ from sqlalchemy.ext.asyncio import AsyncSession
 from sqlalchemy.future import select
 from sqlalchemy.orm import selectinload
 
-from app.agents.new_chat.path_resolver import virtual_path_to_doc
+from app.agents.shared.path_resolver import virtual_path_to_doc
 from app.db import (
     Chunk,
     Document,

surfsense_backend/app/routes/new_chat_routes.py

@@ -476,7 +476,7 @@ async def _revert_turns_for_regenerate(
 
 def _try_delete_sandbox(thread_id: int) -> None:
     """Fire-and-forget sandbox + local file deletion so the HTTP response isn't blocked."""
-    from app.agents.new_chat.sandbox import (
+    from app.agents.shared.sandbox import (
         delete_local_sandbox_files,
         delete_sandbox,
         is_sandbox_enabled,

surfsense_backend/app/routes/sandbox_routes.py

@@ -51,7 +51,7 @@ async def download_sandbox_file(
 ):
     """Download a file from the Daytona sandbox associated with a chat thread."""
 
-    from app.agents.new_chat.sandbox import get_or_create_sandbox, is_sandbox_enabled
+    from app.agents.shared.sandbox import get_or_create_sandbox, is_sandbox_enabled
 
     if not is_sandbox_enabled():
         raise HTTPException(status_code=404, detail="Sandbox is not enabled")
@@ -71,7 +71,7 @@ async def download_sandbox_file(
         "You don't have permission to access files in this thread",
     )
 
-    from app.agents.new_chat.sandbox import get_local_sandbox_file
+    from app.agents.shared.sandbox import get_local_sandbox_file
 
     # Prefer locally-persisted copy (sandbox may already be deleted)
     local_content = get_local_sandbox_file(thread_id, path)

surfsense_backend/app/services/revert_service.py

@@ -38,7 +38,7 @@ from typing import Any, Literal
 from sqlalchemy import delete, select
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from app.agents.new_chat.path_resolver import (
+from app.agents.shared.path_resolver import (
     DOCUMENTS_ROOT,
     safe_filename,
     safe_folder_segment,

surfsense_backend/app/tasks/chat/stream_new_chat.py

@@ -2175,7 +2175,7 @@ async def stream_new_chat(
         # remain downloadable after the Daytona sandbox auto-deletes.
         if stream_result and stream_result.sandbox_files:
             with contextlib.suppress(Exception):
-                from app.agents.new_chat.sandbox import (
+                from app.agents.shared.sandbox import (
                     is_sandbox_enabled,
                     persist_and_delete_sandbox,
                 )

surfsense_backend/app/tasks/chat/streaming/flows/new_chat/orchestrator.py

@@ -833,7 +833,7 @@ async def stream_new_chat(
         # downloadable after the Daytona sandbox auto-deletes.
         if stream_result and stream_result.sandbox_files:
             with contextlib.suppress(Exception):
-                from app.agents.new_chat.sandbox import (
+                from app.agents.shared.sandbox import (
                     is_sandbox_enabled,
                     persist_and_delete_sandbox,
                 )

surfsense_backend/tests/unit/agents/new_chat/test_mention_resolver.py

@@ -22,7 +22,7 @@ from app.agents.new_chat.mention_resolver import (
     resolve_mentions,
     substitute_in_text,
 )
-from app.agents.new_chat.path_resolver import DOCUMENTS_ROOT, PathIndex
+from app.agents.shared.path_resolver import DOCUMENTS_ROOT, PathIndex
 from app.schemas.new_chat import MentionedDocumentInfo
 
 pytestmark = pytest.mark.unit

surfsense_backend/tests/unit/agents/new_chat/test_path_resolver.py

@@ -7,7 +7,7 @@ from unittest.mock import AsyncMock, MagicMock
 
 import pytest
 
-from app.agents.new_chat.path_resolver import (
+from app.agents.shared.path_resolver import (
     DOCUMENTS_ROOT,
     PathIndex,
     doc_to_virtual_path,

surfsense_backend/tests/unit/middleware/test_knowledge_tree.py

@@ -10,7 +10,7 @@ contract cannot silently regress.
 from __future__ import annotations
 
 from app.agents.new_chat.middleware.knowledge_tree import KnowledgeTreeMiddleware
-from app.agents.new_chat.path_resolver import DOCUMENTS_ROOT
+from app.agents.shared.path_resolver import DOCUMENTS_ROOT
 
 
 def _compute(folder_paths: list[str], doc_paths: list[str]) -> set[str]:
@@ -86,7 +86,7 @@ class TestFormatTreeRendering:
         folder_paths: list[str],
         doc_specs: list[dict],
     ) -> str:
-        from app.agents.new_chat.path_resolver import PathIndex
+        from app.agents.shared.path_resolver import PathIndex
 
         index = PathIndex(
             folder_paths={i + 1: p for i, p in enumerate(folder_paths)},