diff --git a/changes/440.fixed.md b/changes/440.fixed.md
new file mode 100644
index 000000000..693f0032b
--- /dev/null
+++ b/changes/440.fixed.md
@@ -0,0 +1,4 @@
+**Backups from a test, demo or second data folder no longer default to your real Documents backups.** Only the
+default data folder (`~/.sentient`) backs up to Documents now; any other `SENTIENT_HOME` keeps its backups in its own
+`backups` folder unless you pick a folder. If such a data folder already had backups in Documents, they stay there; pick
+that folder to see them again.
diff --git a/desktop/src/features/settings/sections/Backups.tsx b/desktop/src/features/settings/sections/Backups.tsx
index eb4450173..4ef16ed71 100644
--- a/desktop/src/features/settings/sections/Backups.tsx
+++ b/desktop/src/features/settings/sections/Backups.tsx
@@ -189,7 +189,9 @@ export function BackupsSection({ query }: SectionProps) {
                 {customFolder
                   ? 'The folder you picked.'
                   : data.folder_in_home
-                    ? "Inside Sentient's data folder, because your Documents folder can't be used. Pick a folder elsewhere so a backup survives losing it."
+                    ? data.home_is_default
+                      ? "Inside Sentient's data folder, because your Documents folder can't be used. Pick a folder elsewhere so a backup survives losing it."
+                      : 'Backups for this data folder stay inside it. Pick a folder elsewhere so a backup survives losing it.'
                     : 'In your Documents folder, apart from your data, so a backup survives losing it.'}
               </span>
             </>
diff --git a/desktop/src/lib/types.ts b/desktop/src/lib/types.ts
index c164fc29d..1268a0ddd 100644
--- a/desktop/src/lib/types.ts
+++ b/desktop/src/lib/types.ts
@@ -3227,6 +3227,8 @@ export interface BackupOverview {
   home: string
   /** The backup folder is inside the data folder (so a backup would not survive losing it). */
   folder_in_home: boolean
+  /** The data folder is the default `~/.sentient`; any other one keeps its backups inside itself. */
+  home_is_default: boolean
   /** The sync service the backup folder is inside (its backups are copied to the cloud too). */
   folder_cloud: 'OneDrive' | 'Dropbox' | 'Google Drive' | 'iCloud' | null
   backups: BackupEntry[]
diff --git a/docs/API.md b/docs/API.md
index 81bb8c518..25bdca10e 100644
--- a/docs/API.md
+++ b/docs/API.md
@@ -3605,7 +3605,8 @@ survives losing it: on Windows the Known Folder API's Documents (`SHGetKnownFold
 folder redirected to OneDrive is used), else `~/Documents`; `~/Documents` on macOS; on Linux `XDG_DOCUMENTS_DIR` when
 set, else `~/Documents`
 (`SENTIENT_DOCUMENTS_DIR` overrides it, and tests always set it). When Documents is missing or can't be written to,
-`<home>/backups`. A backup holds the devices certificate (`tls/`), so it should be kept somewhere private.
+`<home>/backups`, and always `<home>/backups` for a data folder other than the default `~/.sentient`
+(`home_is_default` in the overview), so a test or demo home never mixes its backups with the real ones. A backup holds the devices certificate (`tls/`), so it should be kept somewhere private.
 `folder_cloud` names the sync service the folder is inside, from the `OneDrive`, `OneDriveConsumer` and
 `OneDriveCommercial` environment variables and the path (`OneDrive...`, `Dropbox...`, `Google Drive`, `My Drive`,
 `GoogleDrive-...`, `iCloud Drive`, `Mobile Documents`, `com~apple~CloudDocs`); Settings then says the backups are
@@ -3656,7 +3657,7 @@ back; if even that fails, it stays in `<home>/backups/restore-old-<time>/` and t
 
 **BackupOverview**
 ```json
-{"folder": "...", "default_folder": "~/Documents/Sentient Backups", "home": "<home>", "folder_in_home": false, "folder_cloud": "OneDrive|Dropbox|Google Drive|iCloud|null",
+{"folder": "...", "default_folder": "~/Documents/Sentient Backups", "home": "<home>", "folder_in_home": false, "home_is_default": true, "folder_cloud": "OneDrive|Dropbox|Google Drive|iCloud|null",
  "backups": [BackupEntry], "snapshots": [BackupEntry],
  "schedule": "off|daily|weekly", "keep": 5, "snapshots_keep": 5, "last_scheduled_at": "...|null",
  "pending_restore": {"source", "created_at", "staged_at", "kind"} | null,
diff --git a/sentient/backup/archive.py b/sentient/backup/archive.py
index 34f939ef5..29ecd8f58 100644
--- a/sentient/backup/archive.py
+++ b/sentient/backup/archive.py
@@ -10,7 +10,8 @@
 Never inside: keychain secrets (API keys, tokens, sign-ins), ``gateway.token``, logs, the browser profile,
 WhatsApp's link, downloaded voice models, scratch folders, the backups folder itself, and open incognito chats.
 
-Backups go to ``Documents/Sentient Backups`` by default (:func:`default_folder`), outside the data folder.
+Backups go to ``Documents/Sentient Backups`` by default (:func:`default_folder`), outside the data folder; any
+data folder other than ``~/.sentient`` keeps them in its own ``backups`` folder instead.
 
 A snapshot is the same format without ``files/`` (nothing that takes one changes files). Sentient takes one before
 it updates its database and before an import; the last N are kept.
@@ -37,7 +38,7 @@
 from pathlib import Path, PurePosixPath
 from typing import Any
 
-from sentient import __version__, paths
+from sentient import __version__, paths, secrets
 
 log = logging.getLogger(__name__)
 
@@ -92,7 +93,11 @@ def cloud_service(path: Path) -> str | None:
 
 def default_folder(home: Path | None = None) -> Path:
     """Where backups go unless the user picked a folder: ``Documents/Sentient Backups``, outside the data folder so a
-    backup survives losing it. ``<home>/backups`` when Documents is missing or can't be written to."""
+    backup survives losing it. ``<home>/backups`` when Documents is missing or can't be written to, and always for a
+    data folder other than the default ``~/.sentient`` (a test or demo home, another profile), so its backups never
+    land next to the real ones."""
+    if not secrets.is_default_home(home):
+        return backups_root(home)
     docs = paths.documents_dir()
     target = docs / BACKUP_FOLDER_NAME
     try:
diff --git a/sentient/backup/service.py b/sentient/backup/service.py
index 4a72d52d1..7b5ddc4be 100644
--- a/sentient/backup/service.py
+++ b/sentient/backup/service.py
@@ -106,6 +106,7 @@ async def overview(self) -> dict:
             "default_folder": str(archive.default_folder()),
             "home": str(paths.home()),
             "folder_in_home": archive.is_inside(folder, paths.home()),
+            "home_is_default": secrets.is_default_home(),
             "folder_cloud": archive.cloud_service(folder),
             "backups": [b for b in backups if b["kind"] != "snapshot"],
             "snapshots": [s for s in snapshots if s["kind"] == "snapshot"],
diff --git a/sentient/cli.py b/sentient/cli.py
index 7074cebf9..4e28a0f9b 100644
--- a/sentient/cli.py
+++ b/sentient/cli.py
@@ -143,7 +143,7 @@ def claude_code_tools(tools_file: str):
 
 @app.command()
 def backup(
-    to: Path | None = typer.Option(None, "--to", help="Folder for the backup (default: Documents/Sentient Backups)."),
+    to: Path | None = typer.Option(None, "--to", help="Folder for the backup (default: Documents/Sentient Backups; a data folder other than ~/.sentient uses its own backups folder)."),
 ):
     """Back up the data folder (database, config, workspace, skills, files) to one zip file."""
     from sentient.backup import archive
diff --git a/sentient/config/schema.py b/sentient/config/schema.py
index de7613ec1..485c76fb8 100644
--- a/sentient/config/schema.py
+++ b/sentient/config/schema.py
@@ -1262,8 +1262,8 @@ class BackupsConfig(BaseModel):
     folder: str | None = Field(
         None,
         description="Folder for backups. Empty uses Sentient Backups in your Documents folder (or the backups folder "
-        "inside Sentient's data folder when Documents can't be used). A folder on another drive or a synced cloud "
-        "folder keeps them safe if this computer fails.",
+        "inside Sentient's data folder when Documents can't be used, and always for a data folder other than the "
+        "default ~/.sentient). A folder on another drive or a synced cloud folder keeps them safe if this computer fails.",
     )
     schedule: Literal["off", "daily", "weekly"] = Field(
         "off", description="Back up automatically every day or every week, while Sentient is running."
diff --git a/tests/test_backup.py b/tests/test_backup.py
index ee0b36d63..f5cea4e31 100644
--- a/tests/test_backup.py
+++ b/tests/test_backup.py
@@ -345,6 +345,12 @@ def stuck(src, dst, tries=6):
     assert len(kept) == 1 and (kept[0] / "files" / "mine.txt").read_text(encoding="utf-8") == "only copy"
 
 
+@pytest.fixture
+def default_home(monkeypatch):
+    """Treat the test's data folder as the default ``~/.sentient``, the only one whose backups go to Documents."""
+    monkeypatch.setattr(archive.secrets, "is_default_home", lambda home=None: True)
+
+
 def test_tests_never_use_the_real_folders(isolated_home, tmp_path):
     """The guard in conftest compares REAL_GUARDED before and after every test; here the overrides themselves."""
     assert paths.home() == isolated_home and paths.documents_dir() == tmp_path / "documents"
@@ -353,7 +359,7 @@ def test_tests_never_use_the_real_folders(isolated_home, tmp_path):
         assert not str(archive.default_folder()).startswith(str(real.parent))
 
 
-async def test_backups_go_to_documents_by_default(config, isolated_home, tmp_path):
+async def test_backups_go_to_documents_by_default(config, isolated_home, tmp_path, default_home):
     docs = tmp_path / "documents"
     docs.mkdir()
     app = await _app(config)
@@ -363,6 +369,7 @@ async def test_backups_go_to_documents_by_default(config, isolated_home, tmp_pat
         overview = await app.backups.overview()
         assert overview["folder"] == overview["default_folder"] == str(docs / "Sentient Backups")
         assert overview["home"] == str(isolated_home) and overview["folder_in_home"] is False
+        assert overview["home_is_default"] is True
         assert [b["name"] for b in overview["backups"]] == [made["name"]]
         # snapshots, a staged restore and the restore result stay in the data folder
         assert (await app.backups.snapshot("before a test"))["path"].startswith(str(isolated_home / "backups"))
@@ -370,7 +377,7 @@ async def test_backups_go_to_documents_by_default(config, isolated_home, tmp_pat
         await app.stop()
 
 
-def test_a_documents_folder_that_cant_be_written_falls_back(isolated_home, tmp_path, monkeypatch):
+def test_a_documents_folder_that_cant_be_written_falls_back(isolated_home, tmp_path, monkeypatch, default_home):
     docs = tmp_path / "documents"
     docs.mkdir()
     assert archive.default_folder() == docs / "Sentient Backups"
@@ -378,6 +385,34 @@ def test_a_documents_folder_that_cant_be_written_falls_back(isolated_home, tmp_p
     assert archive.default_folder() == isolated_home / "backups"
 
 
+async def test_another_data_folder_keeps_its_backups_inside_itself(config, isolated_home, tmp_path):
+    """A test or demo home (any SENTIENT_HOME but ~/.sentient) must not default to the real Documents backups (#440)."""
+    docs = tmp_path / "documents"
+    docs.mkdir()
+    assert not secrets.is_default_home()
+    assert archive.default_folder() == isolated_home / "backups"
+    app = await _app(config)
+    try:
+        made = await app.backups.backup_now()
+        assert Path(made["path"]).parent == isolated_home / "backups"
+        overview = await app.backups.overview()
+        assert overview["folder"] == overview["default_folder"] == str(isolated_home / "backups")
+        assert overview["folder_in_home"] is True and overview["home_is_default"] is False
+        assert not (docs / "Sentient Backups").exists()
+    finally:
+        await app.stop()
+
+
+def test_only_the_default_data_folder_backs_up_to_documents(isolated_home, tmp_path, monkeypatch):
+    docs = tmp_path / "documents"
+    docs.mkdir()
+    monkeypatch.setattr(Path, "home", classmethod(lambda cls: tmp_path / "me"))
+    monkeypatch.setenv("SENTIENT_HOME", str(tmp_path / "me" / ".sentient"))
+    assert archive.default_folder() == docs / "Sentient Backups"
+    monkeypatch.setenv("SENTIENT_HOME", str(tmp_path / "me" / "demo"))
+    assert archive.default_folder() == tmp_path / "me" / "demo" / "backups"
+
+
 def test_where_documents_is_on_each_system(tmp_path, monkeypatch):
     # only resolves paths: nothing here creates or writes a folder
     monkeypatch.delenv("SENTIENT_DOCUMENTS_DIR")
@@ -463,7 +498,9 @@ def test_cloud_synced_folders_are_named(tmp_path, monkeypatch):
     assert archive.cloud_service(synced / "Documents" / "Sentient Backups") == "OneDrive"
 
 
-async def test_the_overview_says_when_backups_sync_to_the_cloud(config, isolated_home, tmp_path, monkeypatch):
+async def test_the_overview_says_when_backups_sync_to_the_cloud(
+    config, isolated_home, tmp_path, monkeypatch, default_home
+):
     docs = tmp_path / "OneDrive" / "Documents"
     docs.mkdir(parents=True)
     monkeypatch.setenv("SENTIENT_DOCUMENTS_DIR", str(docs))