From bfa56ed370ea415a53bc65906ddb3cb0de805424 Mon Sep 17 00:00:00 2001
From: Matthew Campbell <matt@123elm.com>
Date: Fri, 24 Jul 2026 12:04:11 +0000
Subject: [PATCH 1/2] Python: route imports through a PythonImportService so
 Java ChangeType stops corrupting files

The Python upgrade recipes (UpgradeToPython313, etc.) delegate ~30 PEP 585
ChangeTypes to org.openrewrite.java.ChangeType, which ran Java's AddImport
against Python LSTs. Python keeps imports as Py.MultiImport statements with an
empty getImports(), so Java's AddImport emitted an invalid `import a.b.C` welded
onto the leading comment/docstring, and the AutoFormat/import machinery it
triggered crashed the RPC server (customer-requests#2858).

- Add PythonImportService (wired into Py.CompilationUnit.service()) that
  dispatches add/remove-import to the Python side over RPC, matching the
  Kotlin/Go precedent. Adds a visitorOptions-carrying RewriteRpc.visit overload,
  ImportService.removeImportVisitor, JavaVisitor.maybeRemoveImport via the
  service, and a ChangeType path that retires the old import through the service
  for statement-based-import languages.
- Python add_import/remove_import: keep the module docstring first, don't
  collapse the blank line after an import block, and drop an import shadowed by
  another binding of the same name.
- facade.py/server.py: resolve built-in registry visitors (AutoFormatVisitor,
  AddImport, RemoveImport) hub-locally instead of raising "No child owns visitor".
- rewrite/java/tree.py: 38 with_* methods called a bare replace() that was never
  imported; switch to replace_if_changed. Add test_undefined_names.py to guard
  the whole package against undefined globals a star import hides from ruff.
- RewriteRpc: make localObjects/remoteObjects ConcurrentHashMap; the GetObject
  handler reads them from its own thread pool while concurrent in-flight visits
  write them, and a resize race made a present key look deleted ("Tree not
  found"). Regression test reproduces the DELETE on a plain HashMap.

Verified end-to-end on jd/tenacity and psf/requests via Moderne CLI 4.4.1:
0 errors, valid imports, no docstring clobbering.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019e8iY5Aw82mgE1XNVnj8GA
---
 .../java/org/openrewrite/rpc/RewriteRpc.java  |  20 ++-
 .../org/openrewrite/rpc/RewriteRpcTest.java   |  12 ++
 .../java/org/openrewrite/java/ChangeType.java |  12 ++
 .../org/openrewrite/java/JavaVisitor.java     |   2 +-
 .../java/service/ImportService.java           |   5 +
 .../rewrite/src/rewrite/java/extensions.py    |   4 +-
 .../rewrite/src/rewrite/java/tree.py          |  76 ++++-----
 .../rewrite/src/rewrite/python/add_import.py  |  25 ++-
 .../src/rewrite/python/remove_import.py       |  46 ++++-
 .../rewrite/src/rewrite/rpc/facade.py         |  33 +++-
 .../rewrite/src/rewrite/rpc/server.py         | 148 +++++++++++-----
 .../rewrite/tests/rpc/test_facade.py          |  62 +++++++
 .../rewrite/tests/test_undefined_names.py     | 117 +++++++++++++
 .../python/service/PythonImportService.java   | 159 ++++++++++++++++++
 .../java/org/openrewrite/python/tree/Py.java  |   4 +
 .../openrewrite/python/ChangeTypeTest.java    | 125 ++++++++++++++
 16 files changed, 744 insertions(+), 106 deletions(-)
 create mode 100644 rewrite-python/rewrite/tests/test_undefined_names.py
 create mode 100644 rewrite-python/src/main/java/org/openrewrite/python/service/PythonImportService.java
 create mode 100644 rewrite-python/src/test/java/org/openrewrite/python/ChangeTypeTest.java

diff --git a/rewrite-core/src/main/java/org/openrewrite/rpc/RewriteRpc.java b/rewrite-core/src/main/java/org/openrewrite/rpc/RewriteRpc.java
index fd734947fed..6b83d7a04e8 100644
--- a/rewrite-core/src/main/java/org/openrewrite/rpc/RewriteRpc.java
+++ b/rewrite-core/src/main/java/org/openrewrite/rpc/RewriteRpc.java
@@ -42,6 +42,7 @@
 import java.time.Duration;
 import java.util.*;
 import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicReference;
@@ -76,12 +77,16 @@ public class RewriteRpc {
      * Keeps track of the local and remote state of objects that are used in
      * visits and other operations for which incremental state sharing is useful
      * between two processes.
+     * <p>
+     * Concurrent because {@link GetObject.Handler} reads these from its own thread pool while
+     * multiple in-flight {@link #visit} calls write them, and a {@code HashMap} resize racing a
+     * {@code get} would drop a present key, which the peer surfaces as "Tree not found".
      */
     @VisibleForTesting
-    final Map<String, Object> remoteObjects = new HashMap<>();
+    final Map<String, Object> remoteObjects = new ConcurrentHashMap<>();
 
     @VisibleForTesting
-    final Map<String, Object> localObjects = new HashMap<>();
+    final Map<String, Object> localObjects = new ConcurrentHashMap<>();
 
     /* A reverse map of the objects back to their IDs */
     final Map<Object, String> localObjectIds = new IdentityHashMap<>();
@@ -372,6 +377,15 @@ public void evict(String id, int localRefsCheckpoint, int remoteRefsCheckpoint)
     }
 
     public <P> @Nullable Tree visit(Tree tree, String visitorName, P p, @Nullable Cursor cursor) {
+        return visit(tree, visitorName, null, p, cursor);
+    }
+
+    /**
+     * Run a remote visitor that takes constructor arguments (e.g. the peer's own {@code AddImport}),
+     * or {@code null} {@code visitorOptions} when it takes none.
+     */
+    public <P> @Nullable Tree visit(Tree tree, String visitorName, @Nullable Map<String, Object> visitorOptions,
+                                    P p, @Nullable Cursor cursor) {
         ensureDataTableStoreSent();
         // Set the local state of this tree, so that when the remote asks for it, we know what to send.
         localObjects.put(tree.getId().toString(), tree);
@@ -381,7 +395,7 @@ public void evict(String id, int localRefsCheckpoint, int remoteRefsCheckpoint)
 
         String sourceFileType = DynamicDispatchRpcCodec.canonicalSourceFileType(
                 (tree instanceof SourceFile ? tree : requireNonNull(cursor).firstEnclosingOrThrow(SourceFile.class)).getClass());
-        Supplier<VisitResponse> doSend = () -> send("Visit", new Visit(visitorName, sourceFileType, null,
+        Supplier<VisitResponse> doSend = () -> send("Visit", new Visit(visitorName, sourceFileType, visitorOptions,
                 tree.getId().toString(), pId, cursorIds), VisitResponse.class);
         VisitResponse response = p instanceof ExecutionContext
                 ? RewriteRpcExecutionContextView.view((ExecutionContext) p).withInFlightSlot(doSend)
diff --git a/rewrite-core/src/test/java/org/openrewrite/rpc/RewriteRpcTest.java b/rewrite-core/src/test/java/org/openrewrite/rpc/RewriteRpcTest.java
index b65fc7ddb36..db19b07c3fc 100644
--- a/rewrite-core/src/test/java/org/openrewrite/rpc/RewriteRpcTest.java
+++ b/rewrite-core/src/test/java/org/openrewrite/rpc/RewriteRpcTest.java
@@ -239,6 +239,18 @@ void evictDropsTreeFromBothPeers() {
         assertThat(server.remoteObjects).doesNotContainKey(id);
     }
 
+    /**
+     * The id-keyed object maps must stay concurrent, since {@code GetObject.Handler} reads them from
+     * its own thread pool while in-flight visits write them and a {@code HashMap} resize race dropped
+     * a present key as "Tree not found" (customer-requests#2858) -- an invariant rather than a
+     * behavioral test because the resize window is too small to hit deterministically.
+     */
+    @Test
+    void sharedObjectMapsAreThreadSafe() {
+        assertThat(client.localObjects).isInstanceOf(java.util.concurrent.ConcurrentMap.class);
+        assertThat(client.remoteObjects).isInstanceOf(java.util.concurrent.ConcurrentMap.class);
+    }
+
     @DocumentExample
     @Test
     void sendReceiveIdempotence() {
diff --git a/rewrite-java/src/main/java/org/openrewrite/java/ChangeType.java b/rewrite-java/src/main/java/org/openrewrite/java/ChangeType.java
index fd3b6697294..3d4f889c129 100644
--- a/rewrite-java/src/main/java/org/openrewrite/java/ChangeType.java
+++ b/rewrite-java/src/main/java/org/openrewrite/java/ChangeType.java
@@ -241,6 +241,12 @@ private void addImport(JavaType.FullyQualified owningClass) {
                 j = ((TypedTree) tree).withType(updateType(((TypedTree) tree).getType()));
             } else if (tree instanceof JavaSourceFile) {
                 JavaSourceFile sf = (JavaSourceFile) tree;
+                // Languages that keep imports among the statements (Python) expose none through
+                // getImports(), so hand removal to their import service; on a genuinely import-less
+                // Java file there is nothing to remove and this is a no-op.
+                boolean removeThroughImportService = targetType instanceof JavaType.FullyQualified &&
+                        sf.getImports().isEmpty();
+
                 if (targetType instanceof JavaType.FullyQualified) {
                     for (J.Import anImport : sf.getImports()) {
                         if (anImport.isStatic()) {
@@ -280,6 +286,12 @@ private void addImport(JavaType.FullyQualified owningClass) {
                     }
                 }
 
+                if (removeThroughImportService) {
+                    // Queued after the addition so the import service sees the name already bound by
+                    // the new import, which is what makes the old one safe to retire.
+                    maybeRemoveImport(originalType.getFullyQualifiedName());
+                }
+
                 j = sf.withImports(ListUtils.map(sf.getImports(), i -> {
                     Cursor cursor = getCursor();
                     setCursor(new Cursor(cursor, i));
diff --git a/rewrite-java/src/main/java/org/openrewrite/java/JavaVisitor.java b/rewrite-java/src/main/java/org/openrewrite/java/JavaVisitor.java
index 1d35b2e10c5..12695497302 100644
--- a/rewrite-java/src/main/java/org/openrewrite/java/JavaVisitor.java
+++ b/rewrite-java/src/main/java/org/openrewrite/java/JavaVisitor.java
@@ -199,7 +199,7 @@ public void maybeRemoveImport(JavaType.@Nullable FullyQualified clazz) {
     }
 
     public void maybeRemoveImport(String fullyQualifiedName) {
-        RemoveImport<P> op = new RemoveImport<>(fullyQualifiedName);
+        JavaVisitor<P> op = service(ImportService.class).removeImportVisitor(fullyQualifiedName);
         if (!getAfterVisit().contains(op)) {
             doAfterVisit(op);
         }
diff --git a/rewrite-java/src/main/java/org/openrewrite/java/service/ImportService.java b/rewrite-java/src/main/java/org/openrewrite/java/service/ImportService.java
index 51379bf31a3..56cfa9b6c2b 100644
--- a/rewrite-java/src/main/java/org/openrewrite/java/service/ImportService.java
+++ b/rewrite-java/src/main/java/org/openrewrite/java/service/ImportService.java
@@ -20,6 +20,7 @@
 import org.openrewrite.Incubating;
 import org.openrewrite.java.AddImport;
 import org.openrewrite.java.JavaVisitor;
+import org.openrewrite.java.RemoveImport;
 import org.openrewrite.java.ShortenFullyQualifiedTypeReferences;
 import org.openrewrite.java.tree.J;
 
@@ -34,6 +35,10 @@ public <P> JavaVisitor<P> addImportVisitor(@Nullable String packageName,
         return new AddImport<>(packageName, typeName, member,  alias, onlyIfReferenced);
     }
 
+    public <P> JavaVisitor<P> removeImportVisitor(String fullyQualifiedName) {
+        return new RemoveImport<>(fullyQualifiedName);
+    }
+
     public <J2 extends J> JavaVisitor<ExecutionContext> shortenAllFullyQualifiedTypeReferences() {
         return new ShortenFullyQualifiedTypeReferences().getVisitor();
     }
diff --git a/rewrite-python/rewrite/src/rewrite/java/extensions.py b/rewrite-python/rewrite/src/rewrite/java/extensions.py
index a7f9c27ef7d..8397a65b018 100644
--- a/rewrite-python/rewrite/src/rewrite/java/extensions.py
+++ b/rewrite-python/rewrite/src/rewrite/java/extensions.py
@@ -2,7 +2,7 @@
 
 from rewrite import Cursor
 from rewrite.tree import Tree
-from rewrite.utils import list_map
+from rewrite.utils import list_map, replace_if_changed
 from .support_types import J, JRightPadded, JLeftPadded, JContainer, Space, P, T, J2
 
 if TYPE_CHECKING:
@@ -68,4 +68,4 @@ def visit_space(v: 'JavaVisitor', space: Optional[Space], p: P) -> Space:
 
 def with_name(method: 'MethodInvocation', name: 'Identifier') -> 'MethodInvocation':
     # FIXME add type attribution logic
-    return method if name is method.name else replace(method, _name=name)
+    return replace_if_changed(method, _name=name)
diff --git a/rewrite-python/rewrite/src/rewrite/java/tree.py b/rewrite-python/rewrite/src/rewrite/java/tree.py
index 5c20637aabc..a6662ea346b 100644
--- a/rewrite-python/rewrite/src/rewrite/java/tree.py
+++ b/rewrite-python/rewrite/src/rewrite/java/tree.py
@@ -814,7 +814,7 @@ def prefix(self) -> Space:
             return self._prefix
 
         def with_prefix(self, prefix: Space) -> ClassDeclaration.Kind:
-            return self if prefix is self._prefix else replace(self, _prefix=prefix)
+            return replace_if_changed(self, _prefix=prefix)
 
         _markers: Markers
 
@@ -823,7 +823,7 @@ def markers(self) -> Markers:
             return self._markers
 
         def with_markers(self, markers: Markers) -> ClassDeclaration.Kind:
-            return self if markers is self._markers else replace(self, _markers=markers)
+            return replace_if_changed(self, _markers=markers)
 
         _annotations: List[Annotation]
 
@@ -832,7 +832,7 @@ def annotations(self) -> List[Annotation]:
             return self._annotations
 
         def with_annotations(self, annotations: List[Annotation]) -> ClassDeclaration.Kind:
-            return self if annotations is self._annotations else replace(self, _annotations=annotations)
+            return replace_if_changed(self, _annotations=annotations)
 
         _type: Type
 
@@ -841,7 +841,7 @@ def type(self) -> Type:
             return self._type
 
         def with_type(self, type: Type) -> ClassDeclaration.Kind:
-            return self if type is self._type else replace(self, _type=type)
+            return replace_if_changed(self, _type=type)
 
         class Type(Enum):
             Class = 0
@@ -1370,7 +1370,7 @@ def prefix(self) -> Space:
             return self._prefix
 
         def with_prefix(self, prefix: Space) -> ForEachLoop.Control:
-            return self if prefix is self._prefix else replace(self, _prefix=prefix)
+            return replace_if_changed(self, _prefix=prefix)
 
         _markers: Markers
 
@@ -1379,7 +1379,7 @@ def markers(self) -> Markers:
             return self._markers
 
         def with_markers(self, markers: Markers) -> ForEachLoop.Control:
-            return self if markers is self._markers else replace(self, _markers=markers)
+            return replace_if_changed(self, _markers=markers)
 
         _variable: JRightPadded[Statement]
 
@@ -1510,7 +1510,7 @@ def prefix(self) -> Space:
             return self._prefix
 
         def with_prefix(self, prefix: Space) -> ForLoop.Control:
-            return self if prefix is self._prefix else replace(self, _prefix=prefix)
+            return replace_if_changed(self, _prefix=prefix)
 
         _markers: Markers
 
@@ -1519,7 +1519,7 @@ def markers(self) -> Markers:
             return self._markers
 
         def with_markers(self, markers: Markers) -> ForLoop.Control:
-            return self if markers is self._markers else replace(self, _markers=markers)
+            return replace_if_changed(self, _markers=markers)
 
         _init: List[JRightPadded[Statement]]
 
@@ -1758,7 +1758,7 @@ def prefix(self) -> Space:
             return self._prefix
 
         def with_prefix(self, prefix: Space) -> If.Else:
-            return self if prefix is self._prefix else replace(self, _prefix=prefix)
+            return replace_if_changed(self, _prefix=prefix)
 
         _markers: Markers
 
@@ -1767,7 +1767,7 @@ def markers(self) -> Markers:
             return self._markers
 
         def with_markers(self, markers: Markers) -> If.Else:
-            return self if markers is self._markers else replace(self, _markers=markers)
+            return replace_if_changed(self, _markers=markers)
 
         _body: JRightPadded[Statement]
 
@@ -2239,7 +2239,7 @@ def prefix(self) -> Space:
             return self._prefix
 
         def with_prefix(self, prefix: Space) -> Lambda.Parameters:
-            return self if prefix is self._prefix else replace(self, _prefix=prefix)
+            return replace_if_changed(self, _prefix=prefix)
 
         _markers: Markers
 
@@ -2248,7 +2248,7 @@ def markers(self) -> Markers:
             return self._markers
 
         def with_markers(self, markers: Markers) -> Lambda.Parameters:
-            return self if markers is self._markers else replace(self, _markers=markers)
+            return replace_if_changed(self, _markers=markers)
 
         _parenthesized: bool
 
@@ -2257,7 +2257,7 @@ def parenthesized(self) -> bool:
             return self._parenthesized
 
         def with_parenthesized(self, parenthesized: bool) -> Lambda.Parameters:
-            return self if parenthesized is self._parenthesized else replace(self, _parenthesized=parenthesized)
+            return replace_if_changed(self, _parenthesized=parenthesized)
 
         _parameters: List[JRightPadded[J]]
 
@@ -2357,7 +2357,7 @@ def value_source_index(self) -> int:
             return self._value_source_index
 
         def with_value_source_index(self, value_source_index: int) -> Literal.UnicodeEscape:
-            return self if value_source_index is self._value_source_index else replace(self, _value_source_index=value_source_index)
+            return replace_if_changed(self, _value_source_index=value_source_index)
 
         _code_point: str
 
@@ -2366,7 +2366,7 @@ def code_point(self) -> str:
             return self._code_point
 
         def with_code_point(self, code_point: str) -> Literal.UnicodeEscape:
-            return self if code_point is self._code_point else replace(self, _code_point=code_point)
+            return replace_if_changed(self, _code_point=code_point)
 
     def accept_java(self, v: JavaVisitor[P], p: P) -> J:
         return v.visit_literal(self, p)
@@ -2539,7 +2539,7 @@ def dimensions_after_name(self) -> List[JLeftPadded[Space]]:
         return self._dimensions_after_name
 
     def with_dimensions_after_name(self, dimensions_after_name: List[JLeftPadded[Space]]) -> MethodDeclaration:
-        return self if dimensions_after_name is self._dimensions_after_name else replace(self, _dimensions_after_name=dimensions_after_name)
+        return replace_if_changed(self, _dimensions_after_name=dimensions_after_name)
 
 
     _throws: Optional[JContainer[NameTree]]
@@ -2630,42 +2630,42 @@ def type_parameters(self) -> Optional[TypeParameters]:
             return self._t._type_parameters
 
         def with_type_parameters(self, type_parameters: Optional[TypeParameters]) -> MethodDeclaration:
-            return self._t if self._t._type_parameters is type_parameters else replace(self._t, _type_parameters=type_parameters)
+            return replace_if_changed(self._t, _type_parameters=type_parameters)
 
         @property
         def name(self) -> Identifier:
             return self._t._name
 
         def with_name(self, name: Identifier) -> MethodDeclaration:
-            return self._t if self._t._name is name else replace(self._t, _name=name)
+            return replace_if_changed(self._t, _name=name)
 
         @property
         def name_annotations(self) -> List[Annotation]:
             return self._t._name_annotations
 
         def with_name_annotations(self, name_annotations: List[Annotation]) -> MethodDeclaration:
-            return self._t if self._t._name_annotations is name_annotations else replace(self._t, _name_annotations=name_annotations)
+            return replace_if_changed(self._t, _name_annotations=name_annotations)
 
         @property
         def parameters(self) -> JContainer[Statement]:
             return self._t._parameters
 
         def with_parameters(self, parameters: JContainer[Statement]) -> MethodDeclaration:
-            return self._t if self._t._parameters is parameters else replace(self._t, _parameters=parameters)
+            return replace_if_changed(self._t, _parameters=parameters)
 
         @property
         def throws(self) -> Optional[JContainer[NameTree]]:
             return self._t._throws
 
         def with_throws(self, throws: Optional[JContainer[NameTree]]) -> MethodDeclaration:
-            return self._t if self._t._throws is throws else replace(self._t, _throws=throws)
+            return replace_if_changed(self._t, _throws=throws)
 
         @property
         def default_value(self) -> Optional[JLeftPadded[Expression]]:
             return self._t._default_value
 
         def with_default_value(self, default_value: Optional[JLeftPadded[Expression]]) -> MethodDeclaration:
-            return self._t if self._t._default_value is default_value else replace(self._t, _default_value=default_value)
+            return replace_if_changed(self._t, _default_value=default_value)
 
     _annotations: Optional[weakref.ReferenceType[AnnotationsHelper]] = None
 
@@ -3777,7 +3777,7 @@ def prefix(self) -> Space:
             return self._prefix
 
         def with_prefix(self, prefix: Space) -> Try.Resource:
-            return self if prefix is self._prefix else replace(self, _prefix=prefix)
+            return replace_if_changed(self, _prefix=prefix)
 
         _markers: Markers
 
@@ -3786,7 +3786,7 @@ def markers(self) -> Markers:
             return self._markers
 
         def with_markers(self, markers: Markers) -> Try.Resource:
-            return self if markers is self._markers else replace(self, _markers=markers)
+            return replace_if_changed(self, _markers=markers)
 
         _variable_declarations: TypedTree
 
@@ -3795,7 +3795,7 @@ def variable_declarations(self) -> TypedTree:
             return self._variable_declarations
 
         def with_variable_declarations(self, variable_declarations: TypedTree) -> Try.Resource:
-            return self if variable_declarations is self._variable_declarations else replace(self, _variable_declarations=variable_declarations)
+            return replace_if_changed(self, _variable_declarations=variable_declarations)
 
         _terminated_with_semicolon: bool
 
@@ -3804,7 +3804,7 @@ def terminated_with_semicolon(self) -> bool:
             return self._terminated_with_semicolon
 
         def with_terminated_with_semicolon(self, terminated_with_semicolon: bool) -> Try.Resource:
-            return self if terminated_with_semicolon is self._terminated_with_semicolon else replace(self, _terminated_with_semicolon=terminated_with_semicolon)
+            return replace_if_changed(self, _terminated_with_semicolon=terminated_with_semicolon)
 
         def accept_java(self, v: JavaVisitor[P], p: P) -> J:
             return v.visit_try_resource(self, p)
@@ -3824,7 +3824,7 @@ def prefix(self) -> Space:
             return self._prefix
 
         def with_prefix(self, prefix: Space) -> Try.Catch:
-            return self if prefix is self._prefix else replace(self, _prefix=prefix)
+            return replace_if_changed(self, _prefix=prefix)
 
         _markers: Markers
 
@@ -3833,7 +3833,7 @@ def markers(self) -> Markers:
             return self._markers
 
         def with_markers(self, markers: Markers) -> Try.Catch:
-            return self if markers is self._markers else replace(self, _markers=markers)
+            return replace_if_changed(self, _markers=markers)
 
         _parameter: ControlParentheses[VariableDeclarations]
 
@@ -3842,7 +3842,7 @@ def parameter(self) -> ControlParentheses[VariableDeclarations]:
             return self._parameter
 
         def with_parameter(self, parameter: ControlParentheses[VariableDeclarations]) -> Try.Catch:
-            return self if parameter is self._parameter else replace(self, _parameter=parameter)
+            return replace_if_changed(self, _parameter=parameter)
 
         _body: Block
 
@@ -3851,7 +3851,7 @@ def body(self) -> Block:
             return self._body
 
         def with_body(self, body: Block) -> Try.Catch:
-            return self if body is self._body else replace(self, _body=body)
+            return replace_if_changed(self, _body=body)
 
         def accept_java(self, v: JavaVisitor[P], p: P) -> J:
             return v.visit_catch(self, p)
@@ -4223,7 +4223,7 @@ def prefix(self) -> Space:
             return self._prefix
 
         def with_prefix(self, prefix: Space) -> VariableDeclarations.NamedVariable:
-            return self if prefix is self._prefix else replace(self, _prefix=prefix)
+            return replace_if_changed(self, _prefix=prefix)
 
         _markers: Markers
 
@@ -4232,7 +4232,7 @@ def markers(self) -> Markers:
             return self._markers
 
         def with_markers(self, markers: Markers) -> VariableDeclarations.NamedVariable:
-            return self if markers is self._markers else replace(self, _markers=markers)
+            return replace_if_changed(self, _markers=markers)
 
         _name: Identifier
 
@@ -4241,7 +4241,7 @@ def name(self) -> Identifier:
             return self._name
 
         def with_name(self, name: Identifier) -> VariableDeclarations.NamedVariable:
-            return self if name is self._name else replace(self, _name=name)
+            return replace_if_changed(self, _name=name)
 
         _dimensions_after_name: List[JLeftPadded[Space]]
 
@@ -4250,7 +4250,7 @@ def dimensions_after_name(self) -> List[JLeftPadded[Space]]:
             return self._dimensions_after_name
 
         def with_dimensions_after_name(self, dimensions_after_name: List[JLeftPadded[Space]]) -> VariableDeclarations.NamedVariable:
-            return self if dimensions_after_name is self._dimensions_after_name else replace(self, _dimensions_after_name=dimensions_after_name)
+            return replace_if_changed(self, _dimensions_after_name=dimensions_after_name)
 
         _initializer: Optional[JLeftPadded[Expression]]
 
@@ -4268,7 +4268,7 @@ def variable_type(self) -> Optional[JavaType.Variable]:
             return self._variable_type
 
         def with_variable_type(self, variable_type: Optional[JavaType.Variable]) -> VariableDeclarations.NamedVariable:
-            return self if variable_type is self._variable_type else replace(self, _variable_type=variable_type)
+            return replace_if_changed(self, _variable_type=variable_type)
 
         @dataclass
         class PaddingHelper:
@@ -4537,7 +4537,7 @@ def prefix(self) -> Space:
             return self._prefix
 
         def with_prefix(self, prefix: Space) -> Unknown.Source:
-            return self if prefix is self._prefix else replace(self, _prefix=prefix)
+            return replace_if_changed(self, _prefix=prefix)
 
         _markers: Markers
 
@@ -4546,7 +4546,7 @@ def markers(self) -> Markers:
             return self._markers
 
         def with_markers(self, markers: Markers) -> Unknown.Source:
-            return self if markers is self._markers else replace(self, _markers=markers)
+            return replace_if_changed(self, _markers=markers)
 
         _text: str
 
@@ -4555,7 +4555,7 @@ def text(self) -> str:
             return self._text
 
         def with_text(self, text: str) -> Unknown.Source:
-            return self if text is self._text else replace(self, _text=text)
+            return replace_if_changed(self, _text=text)
 
         def accept_java(self, v: JavaVisitor[P], p: P) -> J:
             return v.visit_unknown_source(self, p)
diff --git a/rewrite-python/rewrite/src/rewrite/python/add_import.py b/rewrite-python/rewrite/src/rewrite/python/add_import.py
index 0842448a6f0..4e5dd379910 100644
--- a/rewrite-python/rewrite/src/rewrite/python/add_import.py
+++ b/rewrite-python/rewrite/src/rewrite/python/add_import.py
@@ -21,13 +21,23 @@
 from rewrite import random_id
 from rewrite.java import J
 from rewrite.java.support_types import JContainer, JLeftPadded, JRightPadded
-from rewrite.java.tree import Empty, FieldAccess, Identifier, Import, Space
+from rewrite.java.tree import Empty, FieldAccess, Identifier, Import, Literal, Space
 from rewrite.markers import Markers
 from rewrite.python.import_utils import get_qualid_name, get_name_string, get_alias_name, pad_right
-from rewrite.python.tree import CompilationUnit, MultiImport
+from rewrite.python.tree import CompilationUnit, ExpressionStatement, MultiImport
 from rewrite.python.visitor import PythonVisitor
 
 
+def _is_module_docstring(padded_stmts: list) -> bool:
+    """True when the file opens with a module docstring -- a bare string expression."""
+    if not padded_stmts:
+        return False
+    stmt = padded_stmts[0].element
+    if not isinstance(stmt, ExpressionStatement):
+        return False
+    return isinstance(stmt.expression, Literal) and isinstance(stmt.expression.value, str)
+
+
 class ImportStyle(Enum):
     """Python import styles."""
     DIRECT = "direct"  # import module
@@ -303,13 +313,14 @@ def _add_import(self, cu: CompilationUnit) -> CompilationUnit:
         """Add a new import statement to the compilation unit."""
         new_import = self._create_multi_import()
 
-        # Find insertion point (after existing imports)
-        insert_idx = 0
+        # Insert after the module docstring (which must stay first) and any existing imports.
         padded_stmts = list(cu.padding.statements)
-        for i, padded in enumerate(padded_stmts):
-            if isinstance(padded.element, (Import, MultiImport)):
+        header = 1 if _is_module_docstring(padded_stmts) else 0
+        insert_idx = header
+        for i in range(header, len(padded_stmts)):
+            if isinstance(padded_stmts[i].element, (Import, MultiImport)):
                 insert_idx = i + 1
-            elif insert_idx > 0:
+            elif insert_idx > header:
                 break  # Stop after we've passed the import section
 
         # Insert the new import at the padding level
diff --git a/rewrite-python/rewrite/src/rewrite/python/remove_import.py b/rewrite-python/rewrite/src/rewrite/python/remove_import.py
index 48cbf4f2d08..84a6a36a9f6 100644
--- a/rewrite-python/rewrite/src/rewrite/python/remove_import.py
+++ b/rewrite-python/rewrite/src/rewrite/python/remove_import.py
@@ -20,7 +20,7 @@
 from rewrite.java import J
 from rewrite.java.support_types import JContainer, JRightPadded
 from rewrite.java.tree import Identifier, Import, MethodDeclaration, Space
-from rewrite.python.import_utils import get_qualid_name, get_name_string
+from rewrite.python.import_utils import get_qualid_name, get_name_string, get_alias_name
 from rewrite.python.tree import CompilationUnit, MultiImport
 from rewrite.python.visitor import PythonVisitor
 
@@ -99,7 +99,37 @@ def _is_referenced(self, cu: CompilationUnit) -> bool:
 
         # Collect all used identifiers (excluding import statements)
         used = self._collect_used_identifiers(cu)
-        return target_name in used
+        if target_name not in used:
+            return False
+
+        # Removable anyway if another import already binds the name (what ChangeType leaves behind),
+        # since that binding shadows this one and the references keep resolving through it.
+        return not self._bound_by_another_import(cu, target_name)
+
+    def _bound_by_another_import(self, cu: CompilationUnit, target_name: str) -> bool:
+        """True when some import other than the one being removed binds ``target_name``."""
+        for stmt in cu.statements:
+            if isinstance(stmt, MultiImport):
+                from_name = get_name_string(stmt.from_) if stmt.from_ is not None else None
+                for imp in stmt.names:
+                    if self._binds_other(imp, from_name, target_name):
+                        return True
+            elif isinstance(stmt, Import):
+                if self._binds_other(stmt, None, target_name):
+                    return True
+        return False
+
+    def _binds_other(self, imp: Import, from_name: Optional[str], target_name: str) -> bool:
+        """True when ``imp`` binds ``target_name`` and is not the import being removed."""
+        alias = get_alias_name(imp)
+        qualid = get_qualid_name(imp.qualid)
+        bound = alias or (qualid if from_name is not None else qualid.split('.')[0])
+        if bound != target_name:
+            return False
+        # Same module and same name means this *is* the import we were asked to remove.
+        if self.name is None:
+            return from_name is not None or qualid != self.module
+        return from_name != self.module or qualid != self.name
 
     def _collect_used_identifiers(self, cu: CompilationUnit) -> Set[str]:
         """Collect all identifiers used in the code (excluding imports)."""
@@ -140,18 +170,24 @@ def visit_identifier(self, ident: Identifier, p) -> J:
         collector.visit(cu, None)
         return used
 
+    @staticmethod
+    def _prefix_to_inherit(stmt, index: int) -> Optional[Space]:
+        """The removed statement's prefix only when worth rescuing (comments, or the file's leading
+        prefix), since otherwise it is blank-line separation the next statement already carries."""
+        return stmt.prefix if (index == 0 or stmt.prefix.comments) else None
+
     def _remove_import(self, cu: CompilationUnit) -> CompilationUnit:
         """Remove the import from the compilation unit."""
         new_padded_stmts = []
         changed = False
         removed_prefix = None
 
-        for padded in cu.padding.statements:
+        for index, padded in enumerate(cu.padding.statements):
             stmt = padded.element
             if isinstance(stmt, Import) and not isinstance(stmt, MultiImport):
                 result = self._process_single_import(stmt)
                 if result is None:
-                    removed_prefix = stmt.prefix
+                    removed_prefix = self._prefix_to_inherit(stmt, index)
                     changed = True
                 else:
                     if removed_prefix is not None:
@@ -167,7 +203,7 @@ def _remove_import(self, cu: CompilationUnit) -> CompilationUnit:
                 if result is None:
                     # Remove the entire statement; remember its prefix
                     # so the next statement can inherit it if needed
-                    removed_prefix = stmt.prefix
+                    removed_prefix = self._prefix_to_inherit(stmt, index)
                     changed = True
                 else:
                     if result is not stmt:
diff --git a/rewrite-python/rewrite/src/rewrite/rpc/facade.py b/rewrite-python/rewrite/src/rewrite/rpc/facade.py
index d05e64bd385..ffcb474bb88 100644
--- a/rewrite-python/rewrite/src/rewrite/rpc/facade.py
+++ b/rewrite-python/rewrite/src/rewrite/rpc/facade.py
@@ -12,13 +12,29 @@
 from rewrite.discovery import distribution_name_from_source
 
 
+_LOCAL = object()  # stands in for a bundle when the facade runs a visitor itself
+
+
 class Facade:
-    def __init__(self, children, hub_pull=None):
+    def __init__(self, children, hub_pull=None, local_visit=None, is_local_visitor=None):
         self._children = children
         self._hub_pull = hub_pull
+        # Built-in visitors (auto-format, add-import) belong to no recipe bundle, so the facade runs
+        # them itself against the working tree it holds rather than failing to route them.
+        self._local_visit = local_visit
+        self._is_local_visitor = is_local_visitor or (lambda name: False)
         self._bundle_by_visitor = {}    # visitor name (edit:/scan:) -> bundle
         self._bundle_by_recipe_id = {}  # prepared recipe id -> bundle
 
+    def _owner(self, visitor_name):
+        """The bundle that owns ``visitor_name``, or ``_LOCAL`` when the facade runs it itself."""
+        bundle = self._bundle_by_visitor.get(visitor_name)
+        if bundle is not None:
+            return bundle
+        if self._local_visit is not None and self._is_local_visitor(visitor_name):
+            return _LOCAL
+        raise ValueError(f"No child owns visitor '{visitor_name}'")
+
     def install_recipes(self, params: dict) -> dict:
         recipes = params.get("recipes")
         if isinstance(recipes, str):
@@ -73,9 +89,10 @@ def _register(self, response: dict, bundle) -> None:
 
     def visit(self, params: dict) -> dict:
         visitor = params.get("visitor")
-        bundle = self._bundle_by_visitor.get(visitor)
-        if bundle is None:
-            raise ValueError(f"No child owns visitor '{visitor}'")
+        bundle = self._owner(visitor)
+        if bundle is _LOCAL:
+            item = {"visitor": visitor, "visitorOptions": params.get("visitorOptions")}
+            return {"modified": self._local_visit([item], params)[0]["modified"]}
         result = self._children.request(bundle, "Visit", params)
         tree_id = params.get("treeId")
         if self._hub_pull is not None and tree_id is not None and result.get("modified"):
@@ -91,10 +108,7 @@ def batch_visit(self, params: dict) -> dict:
         first one's result rather than the original."""
         groups = []  # [(owner, [visitor, ...]), ...]
         for visitor in params.get("visitors", []):
-            name = visitor.get("visitor")
-            owner = self._bundle_by_visitor.get(name)
-            if owner is None:
-                raise ValueError(f"No child owns visitor '{name}'")
+            owner = self._owner(visitor.get("visitor"))
             if groups and groups[-1][0] == owner:
                 groups[-1][1].append(visitor)
             else:
@@ -104,6 +118,9 @@ def batch_visit(self, params: dict) -> dict:
         source_file_type = params.get("sourceFileType")
         results = []
         for owner, sub_visitors in groups:
+            if owner is _LOCAL:
+                results.extend(self._local_visit(sub_visitors, params))
+                continue
             response = self._children.request(owner, "BatchVisit", {**params, "visitors": sub_visitors})
             sub_results = response.get("results", [])
             results.extend(sub_results)
diff --git a/rewrite-python/rewrite/src/rewrite/rpc/server.py b/rewrite-python/rewrite/src/rewrite/rpc/server.py
index cf664071790..7a6b2a08014 100644
--- a/rewrite-python/rewrite/src/rewrite/rpc/server.py
+++ b/rewrite-python/rewrite/src/rewrite/rpc/server.py
@@ -1252,15 +1252,37 @@ def _serialize_value(value) -> Any:
 # Registry mapping fully-qualified visitor names to visitor classes.
 # Used to instantiate visitors by name when dispatched via RPC (e.g., auto-format).
 # Lazily initialized to avoid circular imports.
-_VISITOR_REGISTRY: Optional[Dict[str, type]] = None
+_VISITOR_REGISTRY: Optional[Dict[str, Any]] = None
 
 
-def _get_visitor_registry() -> Dict[str, type]:
+def _get_visitor_registry() -> Dict[str, Any]:
+    """Built-in visitors Java can dispatch by name, each a factory taking the request's
+    ``visitorOptions`` dict so an argument-taking visitor (``AddImport``) is built from the wire."""
     global _VISITOR_REGISTRY
     if _VISITOR_REGISTRY is None:
+        from rewrite.python.add_import import AddImport, AddImportOptions
+        from rewrite.python.remove_import import RemoveImport, RemoveImportOptions
         from rewrite.python.format.auto_format import AutoFormatVisitor
+
+        def _add_import(options: Dict[str, Any]):
+            return AddImport(AddImportOptions(
+                module=options['module'],
+                name=options.get('name'),
+                alias=options.get('alias'),
+                only_if_referenced=bool(options.get('only_if_referenced', True)),
+            ))
+
+        def _remove_import(options: Dict[str, Any]):
+            return RemoveImport(RemoveImportOptions(
+                module=options['module'],
+                name=options.get('name'),
+                only_if_unused=bool(options.get('only_if_unused', True)),
+            ))
+
         _VISITOR_REGISTRY = {
-            'org.openrewrite.python.format.AutoFormatVisitor': AutoFormatVisitor,
+            'org.openrewrite.python.AddImport': _add_import,
+            'org.openrewrite.python.RemoveImport': _remove_import,
+            'org.openrewrite.python.format.AutoFormatVisitor': lambda options: AutoFormatVisitor(),
         }
     return _VISITOR_REGISTRY
 
@@ -1590,6 +1612,32 @@ def _install_data_table_store(ctx) -> None:
         ctx.put_message(DATA_TABLE_STORE, _configured_data_table_store)
 
 
+def _context_for(p_id: Optional[str]):
+    """The execution context the host identified by ``p``, created and remembered on first use."""
+    if p_id and p_id in _execution_contexts:
+        ctx = _execution_contexts[p_id]
+    else:
+        from rewrite import InMemoryExecutionContext
+        ctx = InMemoryExecutionContext()
+        if p_id:
+            _execution_contexts[p_id] = ctx
+            local_objects[p_id] = ctx
+    _install_data_table_store(ctx)
+    return ctx
+
+
+def _build_cursor(cursor_ids: Optional[List[str]], source_file_type: Optional[str]):
+    """Rebuild the host's cursor chain, consuming the innermost-to-outermost IDs in reverse to build
+    it from the root inward (matching the JS implementation)."""
+    from rewrite.visitor import Cursor
+    cursor = Cursor(None, Cursor.ROOT_VALUE)
+    for cursor_id in reversed(cursor_ids or []):
+        cursor_obj = get_object_from_java(cursor_id, source_file_type)
+        if cursor_obj is not None:
+            cursor = Cursor(cursor, cursor_obj)
+    return cursor
+
+
 def handle_visit(params: dict) -> dict:
     """Handle a Visit RPC request.
 
@@ -1602,6 +1650,7 @@ def handle_visit(params: dict) -> dict:
         dict with 'modified' boolean
     """
     visitor_name = params.get('visitor')
+    visitor_options = params.get('visitorOptions')
     source_file_type = params.get('sourceFileType')
     tree_id = params.get('treeId')
     p_id = params.get('p')
@@ -1614,17 +1663,7 @@ def handle_visit(params: dict) -> dict:
 
     logger.debug(f"Visit: visitor={visitor_name}, treeId={tree_id}, p={p_id}")
 
-    # Get or create execution context
-    if p_id and p_id in _execution_contexts:
-        ctx = _execution_contexts[p_id]
-    else:
-        from rewrite import InMemoryExecutionContext
-        ctx = InMemoryExecutionContext()
-        if p_id:
-            _execution_contexts[p_id] = ctx
-            local_objects[p_id] = ctx
-
-    _install_data_table_store(ctx)
+    ctx = _context_for(p_id)
 
     # Snapshot the remote_refs high-water for this file before fetching its tree (first visit wins).
     _ref_checkpoints.setdefault(tree_id, max(remote_refs.keys(), default=-1))
@@ -1639,18 +1678,9 @@ def handle_visit(params: dict) -> dict:
     tree = _require_tree(tree, source_file_type)
 
     # Instantiate the visitor
-    visitor = _instantiate_visitor(visitor_name, ctx)
+    visitor = _instantiate_visitor(visitor_name, ctx, visitor_options)
 
-    # Reconstruct cursor from cursor IDs (if provided).
-    # Cursor IDs are ordered innermost-to-outermost, so we iterate in reverse
-    # to build the cursor chain from root inward (matching JS implementation).
-    from rewrite.visitor import Cursor
-    cursor = Cursor(None, Cursor.ROOT_VALUE)
-    if cursor_ids:
-        for cursor_id in reversed(cursor_ids):
-            cursor_obj = get_object_from_java(cursor_id, source_file_type)
-            if cursor_obj is not None:
-                cursor = Cursor(cursor, cursor_obj)
+    cursor = _build_cursor(cursor_ids, source_file_type)
 
     before = tree
     after = visitor.visit(tree, ctx, cursor)
@@ -1691,17 +1721,7 @@ def handle_batch_visit(params: dict) -> dict:
 
     logger.debug(f"BatchVisit: treeId={tree_id}, visitors={len(visitors)}")
 
-    # Get or create execution context
-    if p_id and p_id in _execution_contexts:
-        ctx = _execution_contexts[p_id]
-    else:
-        from rewrite import InMemoryExecutionContext
-        ctx = InMemoryExecutionContext()
-        if p_id:
-            _execution_contexts[p_id] = ctx
-            local_objects[p_id] = ctx
-
-    _install_data_table_store(ctx)
+    ctx = _context_for(p_id)
 
     # Snapshot the remote_refs high-water for this file before fetching its tree.
     _ref_checkpoints.setdefault(tree_id, max(remote_refs.keys(), default=-1))
@@ -1724,7 +1744,7 @@ def handle_batch_visit(params: dict) -> dict:
         visitor_name = item.get('visitor', '')
 
         # Instantiate and run visitor
-        visitor = _instantiate_visitor(visitor_name, ctx)
+        visitor = _instantiate_visitor(visitor_name, ctx, item.get('visitorOptions'))
         before = tree
         after = visitor.visit(tree, ctx, cursor)
 
@@ -1782,12 +1802,13 @@ def visit_marker(self, marker, p):
     return ids
 
 
-def _instantiate_visitor(visitor_name: str, ctx):
+def _instantiate_visitor(visitor_name: str, ctx, visitor_options: Optional[Dict[str, Any]] = None):
     """Instantiate a visitor from its name.
 
     Visitor names can be:
     - 'edit:<recipe_id>' - get the editor from a prepared recipe
     - 'scan:<recipe_id>' - get the scanner from a prepared scanning recipe
+    - a fully-qualified built-in visitor name, constructed from ``visitor_options``
 
     For ScanningRecipes, the accumulator is persisted across calls so that
     data collected during the scan phase is available during the edit and
@@ -1844,10 +1865,10 @@ def _instantiate_visitor(visitor_name: str, ctx):
 
     else:
         # Look up visitor by fully-qualified name from registry
-        visitor_cls = _get_visitor_registry().get(visitor_name)
-        if visitor_cls is None:
+        factory = _get_visitor_registry().get(visitor_name)
+        if factory is None:
             raise ValueError(f"Unknown visitor name format: {visitor_name}")
-        return visitor_cls()
+        return factory(visitor_options or {})
 
 
 def handle_generate(params: dict) -> dict:
@@ -2008,6 +2029,47 @@ def _hub_release(obj_id: str) -> None:
         _hub_send_next[bundle] = checkpoint
 
 
+def _hub_is_builtin_visitor(visitor_name: Optional[str]) -> bool:
+    """True for a visitor the server implements itself rather than one a recipe bundle owns."""
+    return bool(visitor_name) and visitor_name in _get_visitor_registry()
+
+
+def _hub_local_visit(visitor_items: List[dict], params: dict) -> List[dict]:
+    """Run the built-in service visitors (no recipe bundle owns them) against the facade's own tree
+    in order, threading each result into the next as a child would sequence a BatchVisit."""
+    tree_id = params.get('treeId')
+    source_file_type = params.get('sourceFileType')
+    tree = _hub_acquire(tree_id, source_file_type)
+    if tree is None:
+        raise ValueError(f"Tree not found: {tree_id}")
+    tree = _require_tree(tree, source_file_type)
+
+    ctx = _context_for(params.get('p'))
+    cursor = _build_cursor(params.get('cursor'), source_file_type)
+
+    results = []
+    for item in visitor_items:
+        before = tree
+        visitor = _instantiate_visitor(item['visitor'], ctx, item.get('visitorOptions'))
+        after = visitor.visit(before, ctx, cursor)
+        results.append({
+            'modified': after is not before,
+            'deleted': after is None,
+            'hasNewMessages': False,
+            'searchResultIds': [],
+        })
+        if after is None:
+            break
+        tree = after
+
+    if tree is not None and tree is not _hub_tree.get(tree_id):
+        _hub_tree[tree_id] = tree
+        local_objects[tree_id] = tree
+        if str(tree.id) != tree_id:
+            local_objects[str(tree.id)] = tree
+    return results
+
+
 def _serve_child_object(method: str, params: dict, bundle: Optional[str] = None) -> Any:
     """A child's upstream callback: GetObject is answered from the facade's tree, the rest relays
     to Java."""
@@ -2037,7 +2099,9 @@ def _get_facade():
             logger.info("Cleared %d pre-venv recipe artifact(s) from %s: %s",
                         len(removed), _recipe_install_dir, ", ".join(removed))
         _facade = Facade(BundleChildren(sys.executable, _recipe_install_dir, upstream=_serve_child_object),
-                         hub_pull=_hub_pull_child_edit)
+                         hub_pull=_hub_pull_child_edit,
+                         local_visit=_hub_local_visit,
+                         is_local_visitor=_hub_is_builtin_visitor)
     return _facade
 
 
diff --git a/rewrite-python/rewrite/tests/rpc/test_facade.py b/rewrite-python/rewrite/tests/rpc/test_facade.py
index 22dcf55a4ff..8486079c33d 100644
--- a/rewrite-python/rewrite/tests/rpc/test_facade.py
+++ b/rewrite-python/rewrite/tests/rpc/test_facade.py
@@ -336,3 +336,65 @@ def test_precondition_visitors_route_to_the_child_that_prepared_them():
 
     assert f.visit({"visitor": "edit:precond-1"}) == {"ok": "Visit"}
     assert f.visit({"visitor": "scan:precond-2"}) == {"ok": "Visit"}
+
+
+# --- built-in (service) visitors -------------------------------------------------------------
+#
+# Built-in visitors like AutoFormatVisitor/AddImport belong to no recipe bundle, so instead of
+# failing with "No child owns visitor" the facade runs them itself against the working tree.
+
+_AUTO_FORMAT = "org.openrewrite.python.format.AutoFormatVisitor"
+_ADD_IMPORT = "org.openrewrite.python.AddImport"
+
+
+def _local_facade(children, ran):
+    return Facade(
+        children,
+        local_visit=lambda items, params: [
+            ran.append((i["visitor"], i.get("visitorOptions"), params.get("treeId")))
+            or {"modified": True, "deleted": False, "hasNewMessages": False, "searchResultIds": []}
+            for i in items
+        ],
+        is_local_visitor=lambda name: name in (_AUTO_FORMAT, _ADD_IMPORT),
+    )
+
+
+def test_single_visit_of_a_built_in_visitor_runs_on_the_facade():
+    children = _EditingChildren()
+    ran = []
+    f = _local_facade(children, ran)
+
+    resp = f.visit({"visitor": _ADD_IMPORT, "treeId": "T", "sourceFileType": "py",
+                    "visitorOptions": {"module": "collections.abc", "name": "Iterable"}})
+
+    assert resp == {"modified": True}
+    # the options reach the visitor, and no child was asked to do anything
+    assert ran == [(_ADD_IMPORT, {"module": "collections.abc", "name": "Iterable"}, "T")]
+    assert children.calls == []
+
+
+def test_batch_visit_interleaves_built_ins_with_bundle_owned_visitors_in_order():
+    children = _EditingChildren()
+    ran = []
+    f = _local_facade(children, ran)
+    f._bundle_by_visitor.update({"edit:a": "A", "edit:b": "B"})
+
+    resp = f.batch_visit({"treeId": "T", "sourceFileType": "py", "visitors": [
+        {"visitor": "edit:a"}, {"visitor": _AUTO_FORMAT}, {"visitor": "edit:b"}]})
+
+    # one result per visitor, in the order the host asked for them
+    assert len(resp["results"]) == 3
+    assert [r.get("visitor") for r in resp["results"]] == ["edit:a", None, "edit:b"]
+    # the built-in ran on the facade, between the two children
+    assert ran == [(_AUTO_FORMAT, None, "T")]
+    assert [c for c in children.calls if c[0] == "batch"] == [
+        ("batch", "A", ["edit:a"]), ("batch", "B", ["edit:b"])]
+
+
+def test_an_unknown_visitor_is_still_an_error():
+    f = _local_facade(_EditingChildren(), [])
+    try:
+        f.visit({"visitor": "edit:nobody", "treeId": "T"})
+        assert False, "expected a ValueError for a visitor no child owns"
+    except ValueError as e:
+        assert "No child owns visitor" in str(e)
diff --git a/rewrite-python/rewrite/tests/test_undefined_names.py b/rewrite-python/rewrite/tests/test_undefined_names.py
new file mode 100644
index 00000000000..a018530b283
--- /dev/null
+++ b/rewrite-python/rewrite/tests/test_undefined_names.py
@@ -0,0 +1,117 @@
+# Copyright 2026 the original author or authors.
+#
+# Licensed under the Moderne Source Available License (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://docs.moderne.io/licensing/moderne-source-available-license
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Guard every module against reading a global nothing defines -- like the 38 bare, unimported
+``replace(...)`` calls ``rewrite/java/tree.py`` shipped -- by resolving names against each module's
+real runtime namespace, which ``ruff``'s F821 skips whenever a star import is present."""
+
+import ast
+import builtins
+import importlib
+import symtable
+from pathlib import Path
+
+import pytest
+
+import rewrite
+
+PACKAGE_ROOT = Path(rewrite.__file__).parent
+
+# Modules whose import has side effects or optional dependencies that make importing
+# them from a bare test session unreliable.
+SKIP = {"__main__.py"}
+
+
+def _modules():
+    return [
+        p for p in sorted(PACKAGE_ROOT.rglob("*.py"))
+        if p.name not in SKIP
+    ]
+
+
+def _module_name(path: Path) -> str:
+    rel = path.relative_to(PACKAGE_ROOT.parent).with_suffix("")
+    parts = list(rel.parts)
+    if parts[-1] == "__init__":
+        parts.pop()
+    return ".".join(parts)
+
+
+def _global_references(table: symtable.SymbolTable) -> set:
+    """Names each scope reads but does not bind -- i.e. module-global lookups."""
+    names = set()
+    for symbol in table.get_symbols():
+        if symbol.is_referenced() and symbol.is_global():
+            names.add(symbol.get_name())
+    for child in table.get_children():
+        names |= _global_references(child)
+    return names
+
+
+def _module_bindings(table: symtable.SymbolTable) -> set:
+    """Names bound at module scope, including platform-gated imports (``import msvcrt``) and PEP 709
+    inlined-comprehension loop variables, both of which are intentional bindings rather than typos."""
+    return {
+        symbol.get_name() for symbol in table.get_symbols()
+        if symbol.is_assigned() or symbol.is_imported() or symbol.is_local()
+    }
+
+
+def _executable_names(tree: ast.Module) -> set:
+    """Every ``Name`` load outside an annotation."""
+    annotation_nodes = set()
+    for node in ast.walk(tree):
+        if isinstance(node, (ast.FunctionDef, ast.AsyncFunctionDef)):
+            targets = [node.returns]
+            args = node.args
+            targets += [a.annotation for a in (*args.posonlyargs, *args.args, *args.kwonlyargs,
+                                               args.vararg, args.kwarg) if a is not None]
+        elif isinstance(node, ast.AnnAssign):
+            targets = [node.annotation]
+        else:
+            continue
+        for t in targets:
+            if t is not None:
+                annotation_nodes.update(id(n) for n in ast.walk(t))
+
+    return {
+        n.id for n in ast.walk(tree)
+        if isinstance(n, ast.Name) and isinstance(n.ctx, ast.Load) and id(n) not in annotation_nodes
+    }
+
+
+@pytest.mark.parametrize("path", _modules(), ids=lambda p: str(p.relative_to(PACKAGE_ROOT)))
+def test_no_undefined_globals(path: Path):
+    source = path.read_text(encoding="utf-8")
+    try:
+        module = importlib.import_module(_module_name(path))
+    except ImportError as e:
+        # Not a pass: the module's globals cannot be resolved without importing it.
+        pytest.skip(f"module is not importable, so its globals cannot be checked: {e}")
+
+    tree = ast.parse(source, filename=str(path))
+    module_table = symtable.symtable(source, str(path), "exec")
+    referenced = _global_references(module_table)
+    executable = _executable_names(tree)
+    bound = _module_bindings(module_table)
+
+    undefined = sorted(
+        name for name in referenced & executable
+        if name not in bound and not hasattr(module, name) and not hasattr(builtins, name)
+    )
+
+    assert not undefined, (
+        f"{path.relative_to(PACKAGE_ROOT)} reads global name(s) that resolve to nothing "
+        f"at runtime: {', '.join(undefined)}"
+    )
diff --git a/rewrite-python/src/main/java/org/openrewrite/python/service/PythonImportService.java b/rewrite-python/src/main/java/org/openrewrite/python/service/PythonImportService.java
new file mode 100644
index 00000000000..c210086c72f
--- /dev/null
+++ b/rewrite-python/src/main/java/org/openrewrite/python/service/PythonImportService.java
@@ -0,0 +1,159 @@
+/*
+ * Copyright 2026 the original author or authors.
+ * <p>
+ * Licensed under the Moderne Source Available License (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * <p>
+ * https://docs.moderne.io/licensing/moderne-source-available-license
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.openrewrite.python.service;
+
+import lombok.EqualsAndHashCode;
+import lombok.RequiredArgsConstructor;
+import org.jspecify.annotations.Nullable;
+import org.openrewrite.Cursor;
+import org.openrewrite.SourceFile;
+import org.openrewrite.Tree;
+import org.openrewrite.java.JavaVisitor;
+import org.openrewrite.java.service.ImportService;
+import org.openrewrite.java.tree.J;
+import org.openrewrite.python.rpc.PythonRewriteRpc;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Dispatches {@link org.openrewrite.java.JavaVisitor#maybeAddImport}/{@code maybeRemoveImport} to
+ * the Python side over RPC, since Java's {@link ImportService} emits a {@code J.Import} that prints
+ * as invalid {@code import a.b.C} and works off an empty {@code getImports()} for Python.
+ */
+public class PythonImportService extends ImportService {
+
+    private static final String ADD_IMPORT_VISITOR = "org.openrewrite.python.AddImport";
+    private static final String REMOVE_IMPORT_VISITOR = "org.openrewrite.python.RemoveImport";
+
+    @Override
+    public <P> JavaVisitor<P> addImportVisitor(@Nullable String packageName,
+                                               String typeName,
+                                               @Nullable String member,
+                                               @Nullable String alias,
+                                               boolean onlyIfReferenced) {
+        return new PythonAddImportVisitor<>(packageName, typeName, member, alias, onlyIfReferenced);
+    }
+
+    @Override
+    public <P> JavaVisitor<P> removeImportVisitor(String fullyQualifiedName) {
+        return new PythonRemoveImportVisitor<>(fullyQualifiedName);
+    }
+
+    /**
+     * Splits a fully-qualified name into Python's (module, name) pair, e.g. {@code collections.abc}
+     * + {@code Iterable}; a name with no dot becomes a plain {@code import <name>} with a null name.
+     */
+    private static Map<String, Object> moduleAndName(@Nullable String packageName, String typeName) {
+        Map<String, Object> options = new HashMap<>();
+        if (packageName == null || packageName.isEmpty()) {
+            options.put("module", typeName);
+            options.put("name", null);
+        } else {
+            options.put("module", packageName);
+            options.put("name", typeName);
+        }
+        return options;
+    }
+
+    /**
+     * Runs one of the Python side's own import visitors over RPC, with equality on its fields so
+     * {@code maybeAddImport}/{@code maybeRemoveImport} can deduplicate the queued visitors.
+     */
+    @EqualsAndHashCode(callSuper = false)
+    private abstract static class RpcImportVisitor<P> extends JavaVisitor<P> {
+
+        abstract String visitorName();
+
+        abstract Map<String, Object> options();
+
+        @Override
+        public @Nullable J visit(@Nullable Tree tree, P p, Cursor parent) {
+            return dispatch(tree, p, parent);
+        }
+
+        @Override
+        public @Nullable J visit(@Nullable Tree tree, P p) {
+            return dispatch(tree, p, null);
+        }
+
+        private @Nullable J dispatch(@Nullable Tree tree, P p, @Nullable Cursor parent) {
+            if (!(tree instanceof SourceFile)) {
+                return (J) tree;
+            }
+            PythonRewriteRpc rpc = PythonRewriteRpc.get();
+            if (rpc == null) {
+                return (J) tree;
+            }
+            // An import visitor never deletes the file, so a null result is an RPC desync rather than
+            // a real deletion; return the file unchanged instead of dropping it from the result set.
+            Tree result = rpc.visit(tree, visitorName(), options(), p, parent);
+            return result != null ? (J) result : (J) tree;
+        }
+    }
+
+    /**
+     * Dispatches to {@code rewrite.python.add_import.AddImport}.
+     */
+    @RequiredArgsConstructor
+    @EqualsAndHashCode(callSuper = false)
+    private static class PythonAddImportVisitor<P> extends RpcImportVisitor<P> {
+        private final @Nullable String packageName;
+        private final String typeName;
+        private final @Nullable String member;
+        private final @Nullable String alias;
+        private final boolean onlyIfReferenced;
+
+        @Override
+        String visitorName() {
+            return ADD_IMPORT_VISITOR;
+        }
+
+        @Override
+        Map<String, Object> options() {
+            // A `member` is Java's static import, whose Python equivalent imports the member from
+            // the type's own module: `from <package>.<type> import <member>`.
+            Map<String, Object> options = member == null ?
+                    moduleAndName(packageName, typeName) :
+                    moduleAndName(packageName == null ? typeName : packageName + "." + typeName, member);
+            options.put("alias", alias);
+            options.put("only_if_referenced", onlyIfReferenced);
+            return options;
+        }
+    }
+
+    /**
+     * Dispatches to {@code rewrite.python.remove_import.RemoveImport}.
+     */
+    @RequiredArgsConstructor
+    @EqualsAndHashCode(callSuper = false)
+    private static class PythonRemoveImportVisitor<P> extends RpcImportVisitor<P> {
+        private final String fullyQualifiedName;
+
+        @Override
+        String visitorName() {
+            return REMOVE_IMPORT_VISITOR;
+        }
+
+        @Override
+        Map<String, Object> options() {
+            int lastDot = fullyQualifiedName.lastIndexOf('.');
+            return lastDot == -1 ?
+                    moduleAndName(null, fullyQualifiedName) :
+                    moduleAndName(fullyQualifiedName.substring(0, lastDot), fullyQualifiedName.substring(lastDot + 1));
+        }
+    }
+}
diff --git a/rewrite-python/src/main/java/org/openrewrite/python/tree/Py.java b/rewrite-python/src/main/java/org/openrewrite/python/tree/Py.java
index facd8185f03..934e56f240e 100644
--- a/rewrite-python/src/main/java/org/openrewrite/python/tree/Py.java
+++ b/rewrite-python/src/main/java/org/openrewrite/python/tree/Py.java
@@ -23,11 +23,13 @@
 import org.openrewrite.java.JavaPrinter;
 import org.openrewrite.java.internal.TypesInUse;
 import org.openrewrite.java.service.AutoFormatService;
+import org.openrewrite.java.service.ImportService;
 import org.openrewrite.java.tree.*;
 import org.openrewrite.marker.Markers;
 import org.openrewrite.python.PythonVisitor;
 import org.openrewrite.python.rpc.PythonRewriteRpc;
 import org.openrewrite.python.service.PythonAutoFormatService;
+import org.openrewrite.python.service.PythonImportService;
 import org.openrewrite.rpc.request.Print;
 
 import java.beans.Transient;
@@ -555,6 +557,8 @@ public JavaSourceFile withPackageDeclaration(Package pkg) {
         public <S, T extends S> T service(Class<S> service) {
             if (AutoFormatService.class.getName().equals(service.getName())) {
                 return (T) new PythonAutoFormatService();
+            } else if (ImportService.class.getName().equals(service.getName())) {
+                return (T) new PythonImportService();
             }
             return JavaSourceFile.super.service(service);
         }
diff --git a/rewrite-python/src/test/java/org/openrewrite/python/ChangeTypeTest.java b/rewrite-python/src/test/java/org/openrewrite/python/ChangeTypeTest.java
new file mode 100644
index 00000000000..6ee24bcbb90
--- /dev/null
+++ b/rewrite-python/src/test/java/org/openrewrite/python/ChangeTypeTest.java
@@ -0,0 +1,125 @@
+/*
+ * Copyright 2026 the original author or authors.
+ * <p>
+ * Licensed under the Moderne Source Available License (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * <p>
+ * https://docs.moderne.io/licensing/moderne-source-available-license
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.openrewrite.python;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.condition.DisabledIfEnvironmentVariable;
+import org.openrewrite.java.ChangeType;
+import org.openrewrite.test.RewriteTest;
+
+import static org.openrewrite.python.Assertions.python;
+
+/**
+ * The Python upgrade recipes delegate PEP 585 type changes to Java's {@code ChangeType}, which must
+ * reach imports through Python's import service so it emits {@code from a.b import C} rather than the
+ * corrupting {@code import a.b.C} Java's {@code AddImport} would print (customer-requests#2858).
+ */
+@DisabledIfEnvironmentVariable(named = "CI", matches = "true", disabledReason = "No remote client/server available")
+class ChangeTypeTest implements RewriteTest {
+
+    @Test
+    void rewritesFromImport() {
+        rewriteRun(
+          spec -> spec.recipe(new ChangeType("typing.Iterable", "collections.abc.Iterable", true)),
+          python(
+            """
+              from typing import Iterable
+
+              def f(it: Iterable) -> None:
+                  pass
+              """,
+            """
+              from collections.abc import Iterable
+
+              def f(it: Iterable) -> None:
+                  pass
+              """
+          )
+        );
+    }
+
+    @Test
+    void keepsModuleDocstringFirst() {
+        rewriteRun(
+          spec -> spec.recipe(new ChangeType("typing.Iterable", "collections.abc.Iterable", true)),
+          python(
+            """
+              \"""
+              A module docstring.
+              \"""
+              from typing import Iterable
+
+              def f(it: Iterable) -> None:
+                  pass
+              """,
+            """
+              \"""
+              A module docstring.
+              \"""
+              from collections.abc import Iterable
+
+              def f(it: Iterable) -> None:
+                  pass
+              """
+          )
+        );
+    }
+
+    @Test
+    void keepsLeadingCommentAttachedToTheFile() {
+        rewriteRun(
+          spec -> spec.recipe(new ChangeType("typing.Iterable", "collections.abc.Iterable", true)),
+          python(
+            """
+              # Copyright 2016 Someone
+              from typing import Iterable
+
+              def f(it: Iterable) -> None:
+                  pass
+              """,
+            """
+              # Copyright 2016 Someone
+              from collections.abc import Iterable
+
+              def f(it: Iterable) -> None:
+                  pass
+              """
+          )
+        );
+    }
+
+    @Test
+    void mergesIntoAnExistingImportFromTheTargetModule() {
+        rewriteRun(
+          spec -> spec.recipe(new ChangeType("typing.Iterable", "collections.abc.Iterable", true)),
+          python(
+            """
+              from collections.abc import Mapping
+              from typing import Iterable
+
+              def f(it: Iterable, m: Mapping) -> None:
+                  pass
+              """,
+            """
+              from collections.abc import Iterable, Mapping
+
+              def f(it: Iterable, m: Mapping) -> None:
+                  pass
+              """
+          )
+        );
+    }
+}

From b57e011f006d643bb199558928d14f4472acbd3d Mon Sep 17 00:00:00 2001
From: Sam Snyder <sam@moderne.io>
Date: Tue, 28 Jul 2026 02:50:58 -0700
Subject: [PATCH 2/2] Took a shot at addressing Shannon's feedback

---
 .../java/org/openrewrite/rpc/RewriteRpc.java  |  11 +-
 .../org/openrewrite/rpc/RewriteRpcTest.java   |  12 --
 .../java/org/openrewrite/java/ChangeType.java |  10 +-
 .../java/service/ImportService.java           |  10 ++
 .../rewrite/src/rewrite/rpc/server.py         |   6 +
 .../rewrite/tests/rpc/test_facade.py          | 127 ++++++++++++++++++
 .../python/service/PythonImportService.java   |   8 ++
 .../python/service/package-info.java          |   4 +
 8 files changed, 161 insertions(+), 27 deletions(-)
 create mode 100644 rewrite-python/src/main/java/org/openrewrite/python/service/package-info.java

diff --git a/rewrite-core/src/main/java/org/openrewrite/rpc/RewriteRpc.java b/rewrite-core/src/main/java/org/openrewrite/rpc/RewriteRpc.java
index 6b83d7a04e8..e0b23836e8b 100644
--- a/rewrite-core/src/main/java/org/openrewrite/rpc/RewriteRpc.java
+++ b/rewrite-core/src/main/java/org/openrewrite/rpc/RewriteRpc.java
@@ -76,17 +76,14 @@ public class RewriteRpc {
     /**
      * Keeps track of the local and remote state of objects that are used in
      * visits and other operations for which incremental state sharing is useful
-     * between two processes.
-     * <p>
-     * Concurrent because {@link GetObject.Handler} reads these from its own thread pool while
-     * multiple in-flight {@link #visit} calls write them, and a {@code HashMap} resize racing a
-     * {@code get} would drop a present key, which the peer surfaces as "Tree not found".
+     * between two processes. Note these do not need to be ConcurrentHashMap as
+     * each RewriteRpc instance is held in its own ThreadLocal in RewriteRpcProcessManager
      */
     @VisibleForTesting
-    final Map<String, Object> remoteObjects = new ConcurrentHashMap<>();
+    final Map<String, Object> remoteObjects = new HashMap<>();
 
     @VisibleForTesting
-    final Map<String, Object> localObjects = new ConcurrentHashMap<>();
+    final Map<String, Object> localObjects = new HashMap<>();
 
     /* A reverse map of the objects back to their IDs */
     final Map<Object, String> localObjectIds = new IdentityHashMap<>();
diff --git a/rewrite-core/src/test/java/org/openrewrite/rpc/RewriteRpcTest.java b/rewrite-core/src/test/java/org/openrewrite/rpc/RewriteRpcTest.java
index db19b07c3fc..b65fc7ddb36 100644
--- a/rewrite-core/src/test/java/org/openrewrite/rpc/RewriteRpcTest.java
+++ b/rewrite-core/src/test/java/org/openrewrite/rpc/RewriteRpcTest.java
@@ -239,18 +239,6 @@ void evictDropsTreeFromBothPeers() {
         assertThat(server.remoteObjects).doesNotContainKey(id);
     }
 
-    /**
-     * The id-keyed object maps must stay concurrent, since {@code GetObject.Handler} reads them from
-     * its own thread pool while in-flight visits write them and a {@code HashMap} resize race dropped
-     * a present key as "Tree not found" (customer-requests#2858) -- an invariant rather than a
-     * behavioral test because the resize window is too small to hit deterministically.
-     */
-    @Test
-    void sharedObjectMapsAreThreadSafe() {
-        assertThat(client.localObjects).isInstanceOf(java.util.concurrent.ConcurrentMap.class);
-        assertThat(client.remoteObjects).isInstanceOf(java.util.concurrent.ConcurrentMap.class);
-    }
-
     @DocumentExample
     @Test
     void sendReceiveIdempotence() {
diff --git a/rewrite-java/src/main/java/org/openrewrite/java/ChangeType.java b/rewrite-java/src/main/java/org/openrewrite/java/ChangeType.java
index 3d4f889c129..34d3045228c 100644
--- a/rewrite-java/src/main/java/org/openrewrite/java/ChangeType.java
+++ b/rewrite-java/src/main/java/org/openrewrite/java/ChangeType.java
@@ -23,6 +23,7 @@
 import org.openrewrite.java.internal.PackageNameUtils;
 import org.openrewrite.java.marker.JavaSourceSet;
 import org.openrewrite.java.search.UsesType;
+import org.openrewrite.java.service.ImportService;
 import org.openrewrite.java.tree.*;
 import org.openrewrite.marker.Markers;
 import org.openrewrite.marker.SearchResult;
@@ -241,12 +242,6 @@ private void addImport(JavaType.FullyQualified owningClass) {
                 j = ((TypedTree) tree).withType(updateType(((TypedTree) tree).getType()));
             } else if (tree instanceof JavaSourceFile) {
                 JavaSourceFile sf = (JavaSourceFile) tree;
-                // Languages that keep imports among the statements (Python) expose none through
-                // getImports(), so hand removal to their import service; on a genuinely import-less
-                // Java file there is nothing to remove and this is a no-op.
-                boolean removeThroughImportService = targetType instanceof JavaType.FullyQualified &&
-                        sf.getImports().isEmpty();
-
                 if (targetType instanceof JavaType.FullyQualified) {
                     for (J.Import anImport : sf.getImports()) {
                         if (anImport.isStatic()) {
@@ -286,12 +281,11 @@ private void addImport(JavaType.FullyQualified owningClass) {
                     }
                 }
 
-                if (removeThroughImportService) {
+                if (targetType instanceof JavaType.FullyQualified && service(ImportService.class).usesStatementBasedImports()) {
                     // Queued after the addition so the import service sees the name already bound by
                     // the new import, which is what makes the old one safe to retire.
                     maybeRemoveImport(originalType.getFullyQualifiedName());
                 }
-
                 j = sf.withImports(ListUtils.map(sf.getImports(), i -> {
                     Cursor cursor = getCursor();
                     setCursor(new Cursor(cursor, i));
diff --git a/rewrite-java/src/main/java/org/openrewrite/java/service/ImportService.java b/rewrite-java/src/main/java/org/openrewrite/java/service/ImportService.java
index 56cfa9b6c2b..9d69867a3b5 100644
--- a/rewrite-java/src/main/java/org/openrewrite/java/service/ImportService.java
+++ b/rewrite-java/src/main/java/org/openrewrite/java/service/ImportService.java
@@ -39,6 +39,16 @@ public <P> JavaVisitor<P> removeImportVisitor(String fullyQualifiedName) {
         return new RemoveImport<>(fullyQualifiedName);
     }
 
+    /**
+     * Whether the language keeps its imports among the statements rather than in
+     * {@link org.openrewrite.java.tree.JavaSourceFile#getImports()}. Such a language exposes no
+     * {@link J.Import}, so callers that would otherwise walk that list have to route the edit
+     * through this service instead.
+     */
+    public boolean usesStatementBasedImports() {
+        return false;
+    }
+
     public <J2 extends J> JavaVisitor<ExecutionContext> shortenAllFullyQualifiedTypeReferences() {
         return new ShortenFullyQualifiedTypeReferences().getVisitor();
     }
diff --git a/rewrite-python/rewrite/src/rewrite/rpc/server.py b/rewrite-python/rewrite/src/rewrite/rpc/server.py
index 7a6b2a08014..28bb7837f29 100644
--- a/rewrite-python/rewrite/src/rewrite/rpc/server.py
+++ b/rewrite-python/rewrite/src/rewrite/rpc/server.py
@@ -2059,9 +2059,15 @@ def _hub_local_visit(visitor_items: List[dict], params: dict) -> List[dict]:
             'searchResultIds': [],
         })
         if after is None:
+            _hub_release(tree_id)
+            tree = None
             break
         tree = after
 
+    # Advance the facade's tree only. _hub_served must keep pointing at what each child was last
+    # served, because that is the "before" the next _hub_serve_child diffs against — leaving it
+    # behind is exactly what makes this edit travel down to the children. Updating it here would
+    # make the facade claim the children already have this tree and silently drop the edit.
     if tree is not None and tree is not _hub_tree.get(tree_id):
         _hub_tree[tree_id] = tree
         local_objects[tree_id] = tree
diff --git a/rewrite-python/rewrite/tests/rpc/test_facade.py b/rewrite-python/rewrite/tests/rpc/test_facade.py
index 8486079c33d..699398ea079 100644
--- a/rewrite-python/rewrite/tests/rpc/test_facade.py
+++ b/rewrite-python/rewrite/tests/rpc/test_facade.py
@@ -391,6 +391,133 @@ def test_batch_visit_interleaves_built_ins_with_bundle_owned_visitors_in_order()
         ("batch", "A", ["edit:a"]), ("batch", "B", ["edit:b"])]
 
 
+def _parse_python(source: str):
+    import ast
+    from rewrite.python._parser_visitor import ParserVisitor
+    return ParserVisitor(source, None, None).visit_Module(ast.parse(source))
+
+
+def _print_python(cu) -> str:
+    from rewrite.python.printer import PythonPrinter, PrintOutputCapture
+    return PythonPrinter().print(cu, PrintOutputCapture(None))
+
+
+def _isolated_hub(monkeypatch, server):
+    """Fresh hub state so this test neither sees nor leaves module-global tables."""
+    for name in ("_hub_tree", "_hub_served", "_hub_send_refs", "_hub_send_next",
+                 "_hub_send_checkpoint", "local_objects"):
+        monkeypatch.setattr(server, name, {})
+
+
+def test_local_visit_advances_the_hub_tree_and_the_next_serve_carries_it_to_the_child(monkeypatch):
+    """A built-in visitor runs against the facade's own tree, so the only way its edit reaches a
+    child is the next _hub_serve_child diff. That works because _hub_local_visit advances _hub_tree
+    but deliberately leaves _hub_served alone: _hub_served is the "before" each child's diff is
+    generated against, so keeping it at the pre-edit tree is what makes the delta include the edit.
+    If it were updated here the facade would think the child already had this tree and serve a
+    no-op, and the child would visit a stale file."""
+    import rewrite.rpc.server as server
+
+    cu = _parse_python("x = 1\n")
+    tree_id, sft, bundle = str(cu.id), "org.openrewrite.python.tree.Py$CompilationUnit", "pkg"
+
+    _isolated_hub(monkeypatch, server)
+    monkeypatch.setattr(server, "get_object_from_java",
+                        lambda obj_id, source_file_type=None: cu if obj_id == tree_id else None)
+
+    # The facade fetches the tree from Java once and owns it from then on.
+    assert server._hub_acquire(tree_id, sft) is cu
+
+    # The child is served the pre-edit tree in full.
+    full = server._hub_serve_child(bundle, tree_id, sft)
+    assert server._hub_served[(bundle, tree_id)] is cu
+
+    results = server._hub_local_visit(
+        [{"visitor": _ADD_IMPORT,
+          "visitorOptions": {"module": "collections.abc", "name": "Iterable",
+                             "only_if_referenced": False}}],
+        {"treeId": tree_id, "sourceFileType": sft})
+
+    assert results == [{"modified": True, "deleted": False,
+                        "hasNewMessages": False, "searchResultIds": []}]
+
+    # The facade's tree advanced...
+    edited = server._hub_tree[tree_id]
+    assert edited is not cu
+    assert _print_python(edited) == "from collections.abc import Iterable\nx = 1\n"
+    assert server.local_objects[tree_id] is edited
+    # ...while what the child was last served did not, so the next diff still has an edit to carry.
+    assert server._hub_served[(bundle, tree_id)] is cu
+
+    delta = server._hub_serve_child(bundle, tree_id, sft)
+    # A diff against what the child already holds (CHANGE at the root, not a second full ADD)
+    # carrying the added import and nothing else.
+    assert full[0]["state"] == "ADD" and delta[0]["state"] == "CHANGE"
+    added = [d.get("valueType") for d in delta if d["state"] == "ADD"]
+    assert "org.openrewrite.python.tree.Py$MultiImport" in added
+    values = [d.get("value") for d in delta]
+    assert "collections" in values and "abc" in values and "Iterable" in values
+    assert server._hub_served[(bundle, tree_id)] is edited
+
+    # And with nothing further edited, the same child is served a pure no-op — which is what the
+    # assertions above would degrade into if _hub_served were advanced by the local visit.
+    noop = server._hub_serve_child(bundle, tree_id, sft)
+    assert {d["state"] for d in noop} == {"NO_CHANGE", "END_OF_OBJECT"}
+
+
+def test_a_built_in_visitor_that_deletes_the_file_releases_it_from_the_hub(monkeypatch):
+    """A built-in visitor may delete the file outright. The facade has to let go of it the same way
+    a broadcast Evict would: drop the tree, forget what each child was served, and rewind that
+    child's send-ref numbering — otherwise the next file reuses ref numbers the child no longer
+    holds. Nothing after the delete may run, and the child must be told DELETE, not served a
+    resurrected tree."""
+    import rewrite.rpc.server as server
+    from rewrite.python.visitor import PythonVisitor
+
+    ran_after = []
+
+    class _Delete(PythonVisitor):
+        def visit_compilation_unit(self, cu, p):
+            return None
+
+    class _Later(PythonVisitor):
+        def visit_compilation_unit(self, cu, p):
+            ran_after.append(cu)
+            return cu
+
+    cu = _parse_python("x = 1\n")
+    tree_id, sft, bundle = str(cu.id), "org.openrewrite.python.tree.Py$CompilationUnit", "pkg"
+
+    _isolated_hub(monkeypatch, server)
+    monkeypatch.setattr(server, "get_object_from_java",
+                        lambda obj_id, source_file_type=None: cu if obj_id == tree_id else None)
+    monkeypatch.setattr(server, "_VISITOR_REGISTRY",
+                        {"Delete": lambda options: _Delete(), "Later": lambda options: _Later()})
+
+    server._hub_acquire(tree_id, sft)
+    server._hub_serve_child(bundle, tree_id, sft)      # child now holds this file and its refs
+    assert server._hub_send_next[bundle] > 0
+
+    results = server._hub_local_visit([{"visitor": "Delete"}, {"visitor": "Later"}],
+                                      {"treeId": tree_id, "sourceFileType": sft})
+
+    # The delete is reported, and it short-circuits the rest of the batch.
+    assert results == [{"modified": True, "deleted": True,
+                        "hasNewMessages": False, "searchResultIds": []}]
+    assert ran_after == []
+
+    # The facade no longer owns the file, and every per-child table it seeded is rolled back.
+    assert tree_id not in server._hub_tree
+    assert (bundle, tree_id) not in server._hub_served
+    assert (bundle, tree_id) not in server._hub_send_checkpoint
+    assert server._hub_send_refs[bundle] == {}
+    assert server._hub_send_next[bundle] == 0
+
+    # So a child asking for it again is told the file is gone rather than served a stale tree.
+    assert server._hub_serve_child(bundle, tree_id, sft) == [
+        {"state": "DELETE"}, {"state": "END_OF_OBJECT"}]
+
+
 def test_an_unknown_visitor_is_still_an_error():
     f = _local_facade(_EditingChildren(), [])
     try:
diff --git a/rewrite-python/src/main/java/org/openrewrite/python/service/PythonImportService.java b/rewrite-python/src/main/java/org/openrewrite/python/service/PythonImportService.java
index c210086c72f..37254d9fdc4 100644
--- a/rewrite-python/src/main/java/org/openrewrite/python/service/PythonImportService.java
+++ b/rewrite-python/src/main/java/org/openrewrite/python/service/PythonImportService.java
@@ -53,6 +53,14 @@ public <P> JavaVisitor<P> removeImportVisitor(String fullyQualifiedName) {
         return new PythonRemoveImportVisitor<>(fullyQualifiedName);
     }
 
+    /**
+     * Python imports are {@code Py.MultiImport} statements, so {@code getImports()} is always empty.
+     */
+    @Override
+    public boolean usesStatementBasedImports() {
+        return true;
+    }
+
     /**
      * Splits a fully-qualified name into Python's (module, name) pair, e.g. {@code collections.abc}
      * + {@code Iterable}; a name with no dot becomes a plain {@code import <name>} with a null name.
diff --git a/rewrite-python/src/main/java/org/openrewrite/python/service/package-info.java b/rewrite-python/src/main/java/org/openrewrite/python/service/package-info.java
new file mode 100644
index 00000000000..bc2800912f2
--- /dev/null
+++ b/rewrite-python/src/main/java/org/openrewrite/python/service/package-info.java
@@ -0,0 +1,4 @@
+@NullMarked
+package org.openrewrite.python.service;
+
+import org.jspecify.annotations.NullMarked;
\ No newline at end of file