Add task sync push milestone

Tasks could start from host content in 2.2.0, but there was still no post-create path to update a live workspace from the host. This change adds the next host-to-task step so repeated fix or review loops do not require recreating the task for every local change.

Add task sync push across the CLI, Python SDK, and MCP server, reusing the existing safe archive import path from seeded task creation instead of introducing a second transfer stack. The implementation keeps sync separate from workspace_seed metadata, validates destinations under /workspace, and documents the current non-atomic recovery path as delete-and-recreate.

Validation:
- uv lock
- UV_CACHE_DIR=.uv-cache uv run pytest --no-cov tests/test_cli.py tests/test_vm_manager.py tests/test_api.py tests/test_server.py tests/test_public_contract.py
- UV_CACHE_DIR=.uv-cache make check
- UV_CACHE_DIR=.uv-cache make dist-check
- real guest-backed smoke: task create --source-path, task sync push, task exec to verify both files, task delete

src/pyro_mcp/vm_manager.py

@@ -194,11 +194,11 @@ class PreparedWorkspaceSeed:
     bytes_written: int = 0
     cleanup_dir: Path | None = None
 
-    def to_payload(self) -> dict[str, Any]:
+    def to_payload(self, *, destination: str = TASK_WORKSPACE_GUEST_PATH) -> dict[str, Any]:
         return {
             "mode": self.mode,
             "source_path": self.source_path,
-            "destination": TASK_WORKSPACE_GUEST_PATH,
+            "destination": destination,
             "entry_count": self.entry_count,
             "bytes_written": self.bytes_written,
         }
@@ -372,6 +372,8 @@ def _normalize_workspace_destination(destination: str) -> tuple[str, PurePosixPa
     if candidate == "":
         raise ValueError("workspace destination must not be empty")
     destination_path = PurePosixPath(candidate)
+    if any(part == ".." for part in destination_path.parts):
+        raise ValueError("workspace destination must stay inside /workspace")
     workspace_root = PurePosixPath(TASK_WORKSPACE_GUEST_PATH)
     if not destination_path.is_absolute():
         destination_path = workspace_root / destination_path
@@ -1218,6 +1220,52 @@ class VmManager:
         finally:
             prepared_seed.cleanup()
 
+    def push_task_sync(
+        self,
+        task_id: str,
+        *,
+        source_path: str | Path,
+        dest: str = TASK_WORKSPACE_GUEST_PATH,
+    ) -> dict[str, Any]:
+        prepared_seed = self._prepare_workspace_seed(source_path)
+        if prepared_seed.archive_path is None:
+            prepared_seed.cleanup()
+            raise ValueError("source_path is required")
+        normalized_destination, _ = _normalize_workspace_destination(dest)
+        with self._lock:
+            task = self._load_task_locked(task_id)
+            self._ensure_task_not_expired_locked(task, time.time())
+            self._refresh_task_liveness_locked(task)
+            if task.state != "started":
+                raise RuntimeError(
+                    f"task {task_id} must be in 'started' state before task_sync_push"
+                )
+            instance = task.to_instance(workdir=self._task_runtime_dir(task.task_id))
+        try:
+            import_summary = self._backend.import_archive(
+                instance,
+                archive_path=prepared_seed.archive_path,
+                destination=normalized_destination,
+            )
+        finally:
+            prepared_seed.cleanup()
+        workspace_sync = prepared_seed.to_payload(destination=normalized_destination)
+        workspace_sync["entry_count"] = int(import_summary["entry_count"])
+        workspace_sync["bytes_written"] = int(import_summary["bytes_written"])
+        workspace_sync["destination"] = str(import_summary["destination"])
+        with self._lock:
+            task = self._load_task_locked(task_id)
+            task.state = instance.state
+            task.firecracker_pid = instance.firecracker_pid
+            task.last_error = instance.last_error
+            task.metadata = dict(instance.metadata)
+            self._save_task_locked(task)
+        return {
+            "task_id": task_id,
+            "execution_mode": instance.metadata.get("execution_mode", "pending"),
+            "workspace_sync": workspace_sync,
+        }
+
     def exec_task(self, task_id: str, *, command: str, timeout_seconds: int = 30) -> dict[str, Any]:
         if timeout_seconds <= 0:
             raise ValueError("timeout_seconds must be positive")