fix(mount): retain late-bound remote paths

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@agent-relay/sandbox",
-  "version": "0.1.6",
+  "version": "0.1.7",
   "description": "Provider-agnostic sandbox runtimes and orchestration for agent workloads.",
   "license": "Apache-2.0",
   "type": "module",

src/mount-script.test.ts

@@ -286,6 +286,16 @@ describe("exact local-layout contract", () => {
       stateDir: join(localRoot, ".state"),
       websocket: false,
     });
+    for (const renderedTemplate of [
+      template.startShellTemplate,
+      template.flushShellTemplate,
+    ]) {
+      assert.match(
+        renderedTemplate,
+        /--remote-path "\$relayfile_mount_remote_path"/,
+        "late-bound exact mounts must retain their remote-path filter",
+      );
+    }
     const values = {
       baseUrl: BASE.baseUrl,
       workspaceId: BASE.workspaceId,

src/mount-script.ts

@@ -732,7 +732,9 @@ function buildMountPathArg(path: string): string {
 }
 
 const DYNAMIC_LOCAL_DIR = "__relayfile_dynamic_local_dir__";
-const DYNAMIC_REMOTE_PATH = "__relayfile_dynamic_remote_path__";
+// Must be absolute so scopedRemoteRoots/buildMountArgs retain the sentinel
+// until dynamicMountArgs replaces it with the late-bound shell variable.
+const DYNAMIC_REMOTE_PATH = "/__relayfile_dynamic_remote_path__";
 
 function dynamicMountArgs(
   opts: RelayfileMountShellOptions,