diff --git a/src/serena/project_server.py b/src/serena/project_server.py
index 4deaa7c3..4e8a69c8 100644
--- a/src/serena/project_server.py
+++ b/src/serena/project_server.py
@@ -36,7 +36,7 @@ class QueryProjectRequest(BaseModel):
 
 class CallFacadeMethodRequest(BaseModel):
     """
-    Request model for the /call_facade_method endpoint: the execution of a (read-only) REPL facade method
+    Request model for the /call_facade_method endpoint: the execution of a REPL facade method
     in the context of a project.
     """
 
@@ -166,14 +166,11 @@ class ProjectServer:
         """
         Handles a /call_facade_method request by executing the facade method on the agent's REPL facades in the
         context of the specified project (see `_query_project` regarding the lock).
-        Only methods which use the project server and do not edit are admissible.
         """
         project = self._get_project(req.project_name)
         with self._active_project_lock, self._agent.active_project_context(project):
             facade = self._agent.get_repl().entrypoint.get_facade_(req.facade_name)
             method = facade.get_method(req.method_name)
-            if not method.enabled or method.info.can_edit or not method.info.uses_project_server:
-                raise ValueError(f"Method '{req.facade_name}.{req.method_name}' cannot be executed via the project server")
             return self._agent.execute_task(lambda: method(*req.args, **req.kwargs))
 
     def run(self) -> None:
diff --git a/src/serena/repl/api/ext_api.py b/src/serena/repl/api/ext_api.py
index 6554b098..eed18827 100644
--- a/src/serena/repl/api/ext_api.py
+++ b/src/serena/repl/api/ext_api.py
@@ -9,7 +9,7 @@ from typing import TYPE_CHECKING
 from serena.jetbrains.jetbrains_plugin_client import JetBrainsPluginClientManager
 from serena.tools import ListQueryableProjectsTool, QueryProjectTool
 
-from ..external_project import ExternalProjectContext
+from ..external_project import ExternalProjectExecution
 from ..facade import FacadeApi, facade_method
 from ..representable import JsonObject, JsonObjectRenderer
 
@@ -24,14 +24,16 @@ class ExternalProjectContextManager:
     executed in the project's server. Contexts cannot be nested.
     """
 
-    def __init__(self, agent: "SerenaAgent", project_name: str) -> None:
+    def __init__(self, agent: "SerenaAgent", project_name: str, read_only: bool) -> None:
         """
         :param agent: the agent
         :param project_name: the name (or root path) of the registered external project
+        :param read_only: whether the context is read-only
         """
         self._agent = agent
         self._project_name = project_name
         self._active_project_context = None
+        self._read_only = read_only
 
     def __enter__(self) -> None:
         entrypoint = self._agent.get_repl().entrypoint
@@ -46,9 +48,8 @@ class ExternalProjectContextManager:
         self._active_project_context = self._agent.active_project_context(project)
         self._active_project_context.__enter__()
 
-        # switch the facades to the external project (remote execution of language server operations for the LSP backend)
-        remote_execution = self._agent.get_language_backend().is_lsp()
-        entrypoint.set_external_project_(ExternalProjectContext(registered_project.project_name, remote_execution))
+        # switch the facades to the external project
+        entrypoint.set_external_project_(ExternalProjectExecution(registered_project.project_name, self._read_only, self._agent))
 
     def __exit__(self, exc_type: type[BaseException] | None, exc_value: BaseException | None, traceback: TracebackType | None) -> None:
         self._agent.get_repl().entrypoint.set_external_project_(None)
@@ -80,7 +81,7 @@ class ExternalProjectsApi(FacadeApi):
         return JsonObject(result, JsonObjectRenderer(self._agent, -1))
 
     @facade_method(corresponding_tool=QueryProjectTool)
-    def project_context(self, project_name: str) -> ExternalProjectContextManager:
+    def read_project_context(self, project_name: str) -> ExternalProjectContextManager:
         """
         Provides a context (for use in a `with` statement) within which all facades operate on the given external project
         instead of the active one, with read-only access.
@@ -94,4 +95,21 @@ class ExternalProjectsApi(FacadeApi):
         :return: the context manager
 
         """
-        return ExternalProjectContextManager(self._agent, project_name)
+        return ExternalProjectContextManager(self._agent, project_name, read_only=True)
+
+    @facade_method(optional=True)
+    def project_context(self, project_name: str) -> ExternalProjectContextManager:
+        """
+        Provides a context (for use in a `with` statement) within which all facades operate on the given external project
+        instead of the active one (read and write operations are possible).
+
+        Example:
+        `with s.ext.project_context("other"): result = s.lsp.find_symbol("Foo")`
+
+        Results obtained within the context can be used after it (they are self-contained).
+
+        :param project_name: the name (or root path) of the project, as listed by `list_projects`
+        :return: the context manager
+
+        """
+        return ExternalProjectContextManager(self._agent, project_name, read_only=False)
diff --git a/src/serena/repl/external_project.py b/src/serena/repl/external_project.py
index e702d4ff..1e909b39 100644
--- a/src/serena/repl/external_project.py
+++ b/src/serena/repl/external_project.py
@@ -8,8 +8,11 @@ from typing import TYPE_CHECKING, Any
 if TYPE_CHECKING:
     from serena.project_server import ProjectServerClient
 
+    from ..agent import SerenaAgent
+    from .facade import FacadeMethod
 
-class ExternalProjectContext:
+
+class ExternalProjectExecution:
     """
     The context in which facade methods are executed while an external project is being queried:
     methods which use the project server (see `FacadeMethodInfo.uses_project_server`) are executed remotely
@@ -17,26 +20,39 @@ class ExternalProjectContext:
     locally against the temporarily switched project. Editing methods are not permitted.
     """
 
-    def __init__(self, project_name: str, remote_execution: bool) -> None:
+    def __init__(self, project_name: str, read_only: bool, agent: "SerenaAgent") -> None:
         """
         :param project_name: the name of the external project
-        :param remote_execution: whether methods using the project server are to be executed remotely
-            (False for the JetBrains backend, where the IDE serves all projects)
+        :param read_only: whether the external project is to be treated as read-only (editing methods are not permitted)
         """
         self.project_name = project_name
-        self._remote_execution = remote_execution
         self._client: ProjectServerClient | None = None
+        self._read_only = read_only
+        self._agent = agent
 
-    def executes_remotely(self, uses_project_server: bool) -> bool:
+    def is_called_remotely(self, method: "FacadeMethod") -> bool:
         """
-        :param uses_project_server: whether the method in question uses the project server
-        :return: whether the method is to be executed remotely
+        :param method: the method to check
+        :return: whether the given method must be executed remotely
         """
-        return self._remote_execution and uses_project_server
+        # Any method that uses the project server must be executed remotely,
+        # as does any edit operation when using the LSP backend (as edit operations indirectly
+        # use the language server via the CodeEditor abstraction)
+        return method.info.uses_project_server or (self._agent.get_language_backend().is_lsp() and method.info.can_edit)
 
-    def call(self, facade_name: str, method_name: str, args: tuple[Any, ...], kwargs: dict[str, Any]) -> Any:
+    def check_call_permission(self, method: "FacadeMethod") -> None:
         """
-        Executes the given facade method in the external project's server.
+        Checks whether the given method is permitted to be called in the context of this external project execution.
+        Raises an exception if the method is not permitted.
+
+        :param method: the facade method to check
+        """
+        if self._read_only and method.info.can_edit:
+            raise PermissionError(f"Editing methods are not permitted in read-only external project execution: {method.qualified_name}")
+
+    def call_remotely(self, facade_name: str, method_name: str, args: tuple[Any, ...], kwargs: dict[str, Any]) -> Any:
+        """
+        Executes the given facade method remotely via the project server.
 
         :param facade_name: the facade's name
         :param method_name: the method's name
diff --git a/src/serena/repl/facade.py b/src/serena/repl/facade.py
index 2f198fa7..cfe53a7c 100644
--- a/src/serena/repl/facade.py
+++ b/src/serena/repl/facade.py
@@ -26,7 +26,7 @@ if TYPE_CHECKING:
     from serena.code_editor import CodeEditor
     from serena.tools import Tool
 
-    from .external_project import ExternalProjectContext
+    from .external_project import ExternalProjectExecution
 
 log = logging.getLogger(__name__)
 TCallable = TypeVar("TCallable", bound=Callable[..., Any])
@@ -253,7 +253,10 @@ class FacadeMethodInfo:
     uses_project_server: bool = False
     """
     whether the method requires the project's language servers and must therefore be executed in the project server
-    when an external project is queried (see `ExternalProjectContext`)
+    when an external project is queried (see `ExternalProjectContext`).
+    Edit operations are always executed in the project server, regardless of this flag, since they implicitly
+    use the CodeEditor, which requires language servers when using the LSP backend.
+    Polymorphic edit operations therefore must not set this flag to True.
     """
     corresponding_tool: "type[Tool] | None" = None
     """the classic tool offering the same functionality, if any"""
@@ -285,7 +288,7 @@ def facade_method(
     :param beta: whether the method is in beta
     :param can_edit: whether the method can modify the codebase
     :param niche: whether the method is rarely needed (its documentation is then only summarised in the facade's description)
-    :param uses_project_server: whether the method must be executed in the project server when an external project is queried
+    :param uses_project_server: whether the method must be executed remotely in the project server when an external project is queried
     :param corresponding_tool: the classic tool offering the same functionality, if any
     :return: the decorator
     """
@@ -406,12 +409,11 @@ class FacadeMethod:
         return f"{self.facade_name}.{self.name}"
 
     def __call__(self, *args: Any, **kwargs: Any) -> Any:
-        external_project = self.parent.get_external_project_()
-        if external_project is not None:
-            if self.info.can_edit:
-                raise ValueError(f"{self.qualified_name} cannot be called while an external project is being queried (read-only access)")
-            if external_project.executes_remotely(self.info.uses_project_server):
-                return external_project.call(self.facade_name, self.name, args, kwargs)
+        external_project_execution = self.parent.get_external_project_()
+        if external_project_execution is not None:
+            external_project_execution.check_call_permission(self)
+            if external_project_execution.is_called_remotely(self):
+                return external_project_execution.call_remotely(self.facade_name, self.name, args, kwargs)
         return self._implementation(*args, **kwargs)
 
     def get_implementation_(self) -> Callable[..., Any]:
@@ -579,13 +581,13 @@ class Facade:
         object.__setattr__(self, "_types", {t.name: t for t in types})
         object.__setattr__(self, "_external_project", None)
 
-    def set_external_project_(self, external_project: "ExternalProjectContext | None") -> None:
+    def set_external_project_(self, external_project: "ExternalProjectExecution | None") -> None:
         """
         :param external_project: the context of the external project being queried (None if the active project is used)
         """
         object.__setattr__(self, "_external_project", external_project)
 
-    def get_external_project_(self) -> "ExternalProjectContext | None":
+    def get_external_project_(self) -> "ExternalProjectExecution | None":
         return self._external_project
 
     def _add_method(self, method: FacadeMethod) -> None:
diff --git a/src/serena/repl/repl.py b/src/serena/repl/repl.py
index c9c29fe1..9dc1b7b1 100644
--- a/src/serena/repl/repl.py
+++ b/src/serena/repl/repl.py
@@ -12,7 +12,7 @@ from dataclasses import dataclass
 from typing import TYPE_CHECKING, Any
 
 from ..session import SerenaSession
-from .external_project import ExternalProjectContext
+from .external_project import ExternalProjectExecution
 from .facade import ApiScope, Facade, FacadeMethod, ReferencedType
 from .representable import Representable
 
@@ -96,7 +96,7 @@ class SerenaReplEntrypoint:
                 return True
         return False
 
-    def set_external_project_(self, external_project: "ExternalProjectContext | None") -> None:
+    def set_external_project_(self, external_project: "ExternalProjectExecution | None") -> None:
         """
         :param external_project: the context of the external project being queried by the currently executing code
             (None if the active project is used); propagated to all facades
@@ -104,7 +104,7 @@ class SerenaReplEntrypoint:
         for facade in self._facades.values():
             facade.set_external_project_(external_project)
 
-    def get_external_project_(self) -> "ExternalProjectContext | None":
+    def get_external_project_(self) -> "ExternalProjectExecution | None":
         external_projects = {facade.get_external_project_() for facade in self._facades.values()}
         return next(iter(external_projects)) if external_projects else None
 
diff --git a/test/serena/test_external_projects.py b/test/serena/test_external_projects.py
index bee10c4d..a2bb73d7 100644
--- a/test/serena/test_external_projects.py
+++ b/test/serena/test_external_projects.py
@@ -71,10 +71,6 @@ def test_facade_method_results_are_transferred_from_the_project_server(project_s
     assert result.symbols[0].body.startswith("def create_user")
     assert "create_user" in result.represent()
 
-    # editing methods are refused
-    with pytest.raises(ValueError, match="cannot be executed"):
-        client.call_facade_method("test_repo_python", "lsp", "rename_symbol", ["create_user", "test_repo/services.py", "x"], {})
-
 
 @pytest.mark.python
 @pytest.mark.skipif(not language_server_tests_enabled(LanguageServerId.PYTHON), reason="python tests are disabled in this environment")
@@ -96,7 +92,7 @@ def test_external_project_context_in_repl(
         tool = agent.get_tool(SerenaReplTool)
         session_id = agent.create_session().session_id
         code = (
-            'with s.ext.project_context("test_repo_python"):\n'
+            'with s.ext.read_project_context("test_repo_python"):\n'
             '    result = s.lsp.find_symbol("create_user")\n'
             "[s.name for s in result.symbols]"
         )
diff --git a/test/serena/test_repl_tool.py b/test/serena/test_repl_tool.py
index 3be9dc42..f3f0a5f5 100644
--- a/test/serena/test_repl_tool.py
+++ b/test/serena/test_repl_tool.py
@@ -7,10 +7,10 @@ from unittest.mock import MagicMock
 
 import pytest
 
-from serena.config.serena_config import ApiInclusionDefinition
+from serena.config.serena_config import ApiInclusionDefinition, LanguageBackend
 from serena.repl.api.edit_api import EditApi
 from serena.repl.api.lsp_api import LspApi
-from serena.repl.external_project import ExternalProjectContext
+from serena.repl.external_project import ExternalProjectExecution
 from serena.repl.facade import ApiScope, Facade, FacadeApi, FacadeMethodInfo, facade_method
 from serena.repl.repl import SerenaRepl
 from serena.session import SerenaSession
@@ -83,29 +83,51 @@ class TestReplExecution:
         overview = rebuilt_repl.execute("facades()", session)
         assert "s.edit" in overview and "s.lsp" not in overview
 
-    def test_external_project_dispatch(self) -> None:
-        class FakeExternalProject(ExternalProjectContext):
+    @pytest.mark.parametrize("backend", [LanguageBackend.LSP, LanguageBackend.JETBRAINS])
+    @pytest.mark.parametrize("read_only", [True, False])
+    def test_external_project_dispatch(self, backend: LanguageBackend, read_only: bool) -> None:
+        agent = MagicMock()
+        agent.get_language_backend.return_value = backend
+
+        class FakeExternalProject(ExternalProjectExecution):
             def __init__(self) -> None:
-                super().__init__("other", remote_execution=True)
+                super().__init__("other", read_only=read_only, agent=agent)
                 self.calls: list[tuple[str, str, tuple, dict]] = []
 
-            def call(self, facade_name: str, method_name: str, args: tuple, kwargs: dict) -> str:
+            def call_remotely(self, facade_name: str, method_name: str, args: tuple, kwargs: dict) -> str:
                 self.calls.append((facade_name, method_name, args, kwargs))
                 return "remote result"
 
-        facades = [Facade.from_api(LspApi(MagicMock()), ApiScope()), Facade.from_api(EditApi(MagicMock()), ApiScope())]
+        class LocalApi(FacadeApi):
+            @facade_method(can_edit=True)
+            def write(self, content: str) -> str:
+                return f"local result: {content}"
+
+        # expose a server-backed read and a backend-dependent write
+        facades = [Facade.from_api(LspApi(agent), ApiScope()), Facade.from_api(LocalApi(agent, "local", "local operations"), ApiScope())]
         repl = SerenaRepl(facades, ApiScope())
         external_project = FakeExternalProject()
         repl.entrypoint.set_external_project_(external_project)
 
-        # methods using the project server are executed remotely, editing methods are refused
+        # methods explicitly requiring the project server are executed remotely
         assert repl.execute('s.lsp.find_symbol("Foo", depth=1)') == "remote result"
         assert external_project.calls == [("lsp", "find_symbol", ("Foo",), {"depth": 1})]
-        assert "read-only" in repl.execute('s.edit.replace_content("a.py", "x", "y", "literal")')
 
-        # without remote execution (JetBrains backend), methods run locally
-        repl.entrypoint.set_external_project_(ExternalProjectContext("other", remote_execution=False))
-        assert "remote result" not in repl.execute('s.info("lsp.find_symbol")')
+        # writes obey the context's access mode and use the selected backend
+        result = repl.execute('s.local.write("content")')
+        if read_only:
+            assert "PermissionError" in result and "read-only" in result
+            assert len(external_project.calls) == 1
+        elif backend.is_lsp():
+            assert result == "remote result"
+            assert external_project.calls[-1] == ("local", "write", ("content",), {})
+        else:
+            assert result == "local result: content"
+            assert len(external_project.calls) == 1
+
+        # leaving the external execution context restores local execution
+        repl.entrypoint.set_external_project_(None)
+        assert repl.execute('s.local.write("restored")') == "local result: restored"
 
     def test_facade_discovery(self, repl: SerenaRepl) -> None:
         overview = repl.execute("s.info()")