From 543b4ce6e6fa45e02fef99887bdaba35d14fcac4 Mon Sep 17 00:00:00 2001
From: Nathan Flurry <git@nathanflurry.com>
Date: Mon, 6 Jul 2026 20:03:11 -0700
Subject: [PATCH] fix(native-sidecar): propagate guest wasm deletions and
 renames to the VM shadow root

---
 crates/native-sidecar/src/filesystem.rs   | 75 ++++++++++++++++++++---
 packages/core/tests/wasm-commands.test.ts | 14 +++++
 2 files changed, 79 insertions(+), 10 deletions(-)

diff --git a/crates/native-sidecar/src/filesystem.rs b/crates/native-sidecar/src/filesystem.rs
index cdddf0b20a..d85aba7153 100644
--- a/crates/native-sidecar/src/filesystem.rs
+++ b/crates/native-sidecar/src/filesystem.rs
@@ -1964,8 +1964,13 @@ pub(crate) fn service_javascript_fs_sync_rpc(
             }
             kernel
                 .rename(source, destination)
-                .map(|()| Value::Null)
-                .map_err(kernel_error)
+                .map_err(kernel_error)?;
+            // Mirror the rename into the process shadow tree, otherwise the
+            // exit-time shadow->kernel sync resurrects the stale source path
+            // (the shadow walk only copies entries in, it cannot express
+            // deletions).
+            rename_process_shadow_path(process, source, destination)?;
+            Ok(Value::Null)
         }
         "fs.rmdirSync" | "fs.promises.rmdir" => {
             let path =
@@ -1997,10 +2002,11 @@ pub(crate) fn service_javascript_fs_sync_rpc(
                 }
                 None => {}
             }
-            kernel
-                .remove_dir(path)
-                .map(|()| Value::Null)
-                .map_err(kernel_error)
+            kernel.remove_dir(path).map_err(kernel_error)?;
+            // Mirror the removal into the process shadow tree, otherwise the
+            // exit-time shadow->kernel sync resurrects the deleted directory.
+            remove_process_shadow_path(process, path)?;
+            Ok(Value::Null)
         }
         "fs.unlinkSync" | "fs.promises.unlink" => {
             let path =
@@ -2034,10 +2040,13 @@ pub(crate) fn service_javascript_fs_sync_rpc(
                 }
                 None => {}
             }
-            kernel
-                .remove_file(path)
-                .map(|()| Value::Null)
-                .map_err(kernel_error)
+            kernel.remove_file(path).map_err(kernel_error)?;
+            // Mirror the deletion into the process shadow tree: wasm guest
+            // deletions route kernel-direct, and without removing the shadow
+            // copy the exit-time shadow->kernel sync resurrects the file for
+            // later builtins in the same shell and for subsequent execs.
+            remove_process_shadow_path(process, path)?;
+            Ok(Value::Null)
         }
         "fs.chmodSync" | "fs.promises.chmod" => {
             let path =
@@ -4349,6 +4358,52 @@ fn resolve_process_guest_path_to_host(
     ))
 }
 
+/// Removes the host shadow copy of `guest_path` after a kernel-direct guest
+/// deletion so the exit-time shadow->kernel sync cannot resurrect it.
+fn remove_process_shadow_path(
+    process: &ActiveProcess,
+    guest_path: &str,
+) -> Result<(), SidecarError> {
+    let Some(shadow_path) = resolve_process_guest_path_to_host(process, guest_path) else {
+        return Ok(());
+    };
+    remove_shadow_path_if_exists(&shadow_path, guest_path)
+}
+
+/// Mirrors a kernel-direct guest rename into the host shadow tree. If the
+/// source shadow entry is missing the stale destination copy is still removed
+/// so the shadow walk cannot resurrect pre-rename content.
+fn rename_process_shadow_path(
+    process: &ActiveProcess,
+    source: &str,
+    destination: &str,
+) -> Result<(), SidecarError> {
+    let Some(source_shadow) = resolve_process_guest_path_to_host(process, source) else {
+        return Ok(());
+    };
+    let Some(destination_shadow) = resolve_process_guest_path_to_host(process, destination) else {
+        return Ok(());
+    };
+
+    if fs::symlink_metadata(&source_shadow).is_err() {
+        return remove_shadow_path_if_exists(&destination_shadow, destination);
+    }
+
+    if let Some(parent) = destination_shadow.parent() {
+        fs::create_dir_all(parent).map_err(|error| {
+            SidecarError::Io(format!(
+                "failed to create shadow parent for rename {source} -> {destination}: {error}"
+            ))
+        })?;
+    }
+    remove_shadow_path_if_exists(&destination_shadow, destination)?;
+    fs::rename(&source_shadow, &destination_shadow).map_err(|error| {
+        SidecarError::Io(format!(
+            "failed to mirror guest rename {source} -> {destination} into shadow root: {error}"
+        ))
+    })
+}
+
 fn sync_host_directory_to_kernel(
     vm: &mut VmState,
     guest_path: &str,
diff --git a/packages/core/tests/wasm-commands.test.ts b/packages/core/tests/wasm-commands.test.ts
index 9001cb1894..ec915894a7 100644
--- a/packages/core/tests/wasm-commands.test.ts
+++ b/packages/core/tests/wasm-commands.test.ts
@@ -152,6 +152,20 @@ EOF`);
 			expect(r.stdout.trim()).toBe("ok");
 		});
 
+		test("rm deletion is visible across execs and to the host", async () => {
+			await vm.writeFile("/tmp/rm-cross-exec.txt", "x");
+			const rm = await vm.exec("rm /tmp/rm-cross-exec.txt");
+			expect(rm.exitCode).toBe(0);
+			// The deletion must survive the exit-time shadow sync: the host
+			// filesystem API and a later exec both observe the file as gone.
+			expect(await vm.exists("/tmp/rm-cross-exec.txt")).toBe(false);
+			const probe = await vm.exec(
+				"sh -c 'test ! -f /tmp/rm-cross-exec.txt && echo gone'",
+			);
+			expect(probe.exitCode).toBe(0);
+			expect(probe.stdout.trim()).toBe("gone");
+		});
+
 		test("mkdir -p and rmdir", async () => {
 			const r = await vm.exec(
 				"mkdir -p /tmp/a/b/c && test -d /tmp/a/b/c && echo ok",