Save data

Save data lives in per-user, per-title directories the system manages. SaveDataManager in SharpProspero.Platform lists those directories, mounts one so its files become readable and writable paths, and deletes them — the surface a save-data manager or a backup tool is built on. SaveDataPicker puts the choice in the user’s hands with the system dialog.

The lifecycle

Every task starts by opening the service, ends by disposing it, and does its file I/O through a mount that commits and unmounts when disposed.

flowchart LR
  Open["SaveDataManager.Open()"] --> Enum["Enumerate(titleId)"]
  Enum --> Mount["Mount(dirName)"]
  Mount --> IO["read / write files<br/>under MountPoint"]
  IO --> Unmount["Dispose → commit + unmount"]
  Enum --> Delete["Delete(dirName)"]
  Open --> Term["Dispose → stop service"]

Opening the manager

SaveDataManager.Open starts the save-data service. With no argument it targets the signed-in user; pass a user id to target another. It implements IDisposable, so keep it in a using and the service stops when the block ends.

using var saves = SaveDataManager.Open();

Listing saves

Enumerate returns an IReadOnlyList<SaveDataInfo>, sorted by directory name. It lists the running application’s own saves. Leaving the title id out does not widen the search — the service fills in the calling title — and passing another title’s id does not reach that title’s saves.

using var saves = SaveDataManager.Open();
foreach (SaveDataInfo save in saves.Enumerate())
    Show(save.Title, save.SubTitle, save.ModifiedTime);

SaveDataInfo is a readonly record struct carrying the fields the save’s parameter block holds:

Field	Type	Meaning
DirName	string	The save’s directory name — its identity within the title, and the key you pass to Mount and Delete.
Title	string	The save’s title line.
SubTitle	string	The subtitle line.
Detail	string	The longer detail text.
UserParam	uint	An integer the title stored alongside the save.
ModifiedTime	DateTimeOffset	When the save was last written.

Reading a save’s files

Mount mounts one save and returns a MountedSave. Its MountPoint is the path the save’s files live under (for example /savedata0); join your file names onto it and read them with the storage APIs. Mounts are read-only by default. Dispose the MountedSave to unmount.

using var saves = SaveDataManager.Open();
string dirName = saves.Enumerate()[0].DirName;

using MountedSave mounted = saves.Mount(dirName);
byte[] data = FileSystem.ReadAllBytes(mounted.MountPoint + "/progress.dat");

Writing to a save

Pass readOnly: false to mount for writing. Files written under the mount point are held until the mount is unmounted, at which point disposing the MountedSave commits them.

using var saves = SaveDataManager.Open();
using MountedSave mounted = saves.Mount(dirName, readOnly: false);

FileSystem.WriteAllBytes(mounted.MountPoint + "/progress.dat", payload);
// leaving the using block commits the write and unmounts.

Writes are committed on unmount, not on each WriteAllBytes call. Let the using block dispose the MountedSave — or dispose it yourself — before you rely on the data being persisted. An abandoned mount leaves the changes uncommitted.

Deleting a save

Delete removes a save by directory name. It cannot be undone, so confirm the choice with the user first.

using var saves = SaveDataManager.Open();
saves.Delete(dirName);

Letting the user pick

SaveDataPicker, also in SharpProspero.Platform, opens the system dialog that lists a user’s saves and reports which one they chose — the same list-and-select flow the system shows, with none of the enumeration wiring on your side. Open it with a user id (the signed-in user’s id comes from Users.InitialUserId), then poll it each frame while presenting the display until it finishes.

using var picker = SaveDataPicker.OpenList(Users.InitialUserId);
while (!picker.TryGetResult(out string? directory))
    display.Present();

if (directory is not null)
    using (var saves = SaveDataManager.Open())
    using (MountedSave mounted = saves.Mount(directory))
        Load(mounted.MountPoint);

TryGetResult returns false while the dialog is still open and true once it has finished. When it finishes, directory holds the chosen save’s directory name, or null if the user backed out without choosing. OpenList takes an optional SaveDataDialogType (Load by default; also Save and Delete) that sets the dialog’s wording. The Status property exposes the raw CommonDialogStatus (Running, Finished, and so on) if you would rather branch on it than on TryGetResult. Both enums live in SharpProspero.Interop.Dialog, so add that using directive to name them.

The picker only advances while the frame loop keeps presenting. If you stop calling Present, the dialog freezes. See Dialogs and overlays for the shared poll-until-finished pattern the message, text-input, and browser dialogs use as well.

Where the versioned payload fits

SaveDataManager gives you the mount point and raw file access; it does not define what goes in the files. For a self-describing, versioned blob — a header, a schema version, and forward/backward handling as your save format changes — write a SaveState (in SharpProspero.Storage) into the mounted directory. See Files and storage for that payload format.