diff --git a/backend/tests/test_api_backups.py b/backend/tests/test_api_backups.py
index 73cf7c6..100db71 100644
--- a/backend/tests/test_api_backups.py
+++ b/backend/tests/test_api_backups.py
@@ -58,3 +58,54 @@ def test_backup_history_populated(client, db_session):
     assert response.status_code == 200
     assert len(response.json()) == 1
     assert response.json()[0]["status"] == "COMPLETED"
+
+
+def test_trigger_backup_already_running(client, db_session):
+    """Tests triggering backup when one is already active returns 400."""
+    media = models.StorageMedia(
+        media_type="hdd", identifier="DISK_1", capacity=1000, status="active"
+    )
+    db_session.add(media)
+    db_session.flush()
+
+    # Create an active backup job
+    active_job = models.Job(job_type="BACKUP", status="RUNNING", is_cancelled=False)
+    db_session.add(active_job)
+    db_session.commit()
+
+    response = client.post(f"/backups/trigger/{media.id}")
+    assert response.status_code == 400
+    assert "already running" in response.json()["detail"]
+
+
+def test_trigger_auto_backup_no_media(client):
+    """Tests auto backup with no active media returns 400."""
+    response = client.post("/backups/trigger/auto")
+    assert response.status_code == 400
+    assert "No active media" in response.json()["detail"]
+
+
+def test_trigger_auto_backup_already_running(client, db_session):
+    """Tests auto backup when one is already active returns 400."""
+    active_job = models.Job(job_type="BACKUP", status="PENDING", is_cancelled=False)
+    db_session.add(active_job)
+    db_session.commit()
+
+    response = client.post("/backups/trigger/auto")
+    assert response.status_code == 400
+    assert "already running" in response.json()["detail"]
+
+
+def test_trigger_auto_backup_success(client, db_session):
+    """Tests triggering auto backup creates a job."""
+    media = models.StorageMedia(
+        media_type="hdd", identifier="AUTO_DISK", capacity=1000000000, status="active"
+    )
+    db_session.add(media)
+    db_session.commit()
+
+    response = client.post("/backups/trigger/auto")
+    assert response.status_code == 200
+    data = response.json()
+    assert "job_id" in data
+    assert "Auto-archival job submitted" in data["message"]
diff --git a/backend/tests/test_api_discrepancies.py b/backend/tests/test_api_discrepancies.py
new file mode 100644
index 0000000..24a4219
--- /dev/null
+++ b/backend/tests/test_api_discrepancies.py
@@ -0,0 +1,445 @@
+from datetime import datetime, timezone
+
+from app.db import models
+
+
+# ── list_discrepancies ──
+
+
+def test_list_discrepancies_empty(client):
+    """Tests listing discrepancies when none exist."""
+    response = client.get("/system/discrepancies")
+    assert response.status_code == 200
+    assert response.json() == []
+
+
+def test_list_discrepancies_deleted_file(client, db_session):
+    """Tests listing a confirmed-deleted file in discrepancies."""
+    file_record = models.FilesystemState(
+        file_path="/data/old.txt",
+        size=100,
+        mtime=1000,
+        is_deleted=True,
+        is_ignored=False,
+        sha256_hash=None,
+    )
+    db_session.add(file_record)
+    db_session.commit()
+
+    response = client.get("/system/discrepancies")
+    assert response.status_code == 200
+    data = response.json()
+    assert len(data) == 1
+    assert data[0]["path"] == "/data/old.txt"
+    assert data[0]["is_deleted"] is True
+
+
+def test_list_discrepancies_unhashed_missing(client, db_session, tmp_path):
+    """Tests listing an unhashed file that is missing from disk."""
+    # File path that does not exist on disk
+    missing_path = str(tmp_path / "nonexistent" / "file.txt")
+    file_record = models.FilesystemState(
+        file_path=missing_path,
+        size=100,
+        mtime=1000,
+        sha256_hash=None,
+        is_deleted=False,
+        is_ignored=False,
+    )
+    db_session.add(file_record)
+    db_session.commit()
+
+    response = client.get("/system/discrepancies")
+    assert response.status_code == 200
+    data = response.json()
+    assert len(data) == 1
+    assert data[0]["path"] == missing_path
+    assert data[0]["is_deleted"] is False
+
+
+def test_list_discrepancies_ignored_excluded(client, db_session):
+    """Tests that ignored files are excluded from discrepancies."""
+    file_record = models.FilesystemState(
+        file_path="/data/ignored.txt",
+        size=100,
+        mtime=1000,
+        is_deleted=True,
+        is_ignored=True,
+    )
+    db_session.add(file_record)
+    db_session.commit()
+
+    response = client.get("/system/discrepancies")
+    assert response.status_code == 200
+    assert response.json() == []
+
+
+def test_list_discrepancies_acknowledged_excluded(client, db_session):
+    """Tests that acknowledged discrepancies are excluded."""
+    file_record = models.FilesystemState(
+        file_path="/data/dismissed.txt",
+        size=100,
+        mtime=1000,
+        is_deleted=True,
+        is_ignored=False,
+        missing_acknowledged_at=datetime.now(timezone.utc),
+    )
+    db_session.add(file_record)
+    db_session.commit()
+
+    response = client.get("/system/discrepancies")
+    assert response.status_code == 200
+    assert response.json() == []
+
+
+def test_list_discrepancies_has_versions_flag(client, db_session):
+    """Tests that has_versions is set based on active/full media."""
+    active_media = models.StorageMedia(
+        media_type="hdd", identifier="M1", capacity=1000, status="active"
+    )
+    db_session.add(active_media)
+    db_session.flush()
+
+    file1 = models.FilesystemState(
+        file_path="/data/deleted_with_backup.txt",
+        size=100,
+        mtime=1000,
+        is_deleted=True,
+        is_ignored=False,
+    )
+    db_session.add(file1)
+    db_session.flush()
+
+    db_session.add(
+        models.FileVersion(
+            filesystem_state_id=file1.id,
+            media_id=active_media.id,
+            file_number="1",
+            offset_start=0,
+            offset_end=100,
+        )
+    )
+    db_session.commit()
+
+    response = client.get("/system/discrepancies")
+    assert response.status_code == 200
+    data = response.json()
+    assert len(data) == 1
+    assert data[0]["has_versions"] is True
+
+
+# ── confirm_discrepancy ──
+
+
+def test_confirm_discrepancy(client, db_session):
+    """Tests confirming a file as deleted."""
+    file_record = models.FilesystemState(
+        file_path="/data/verify.txt", size=50, mtime=2000, is_deleted=False
+    )
+    db_session.add(file_record)
+    db_session.commit()
+
+    response = client.post(f"/system/discrepancies/{file_record.id}/confirm")
+    assert response.status_code == 200
+    assert "marked as deleted" in response.json()["message"]
+
+    db_session.expire_all()
+    db_session.refresh(file_record)
+    assert file_record.is_deleted is True
+
+
+def test_confirm_discrepancy_not_found(client):
+    """Tests confirming a non-existent file returns 404."""
+    response = client.post("/system/discrepancies/9999/confirm")
+    assert response.status_code == 404
+
+
+# ── dismiss_discrepancy ──
+
+
+def test_dismiss_discrepancy(client, db_session):
+    """Tests dismissing a deleted file."""
+    file_record = models.FilesystemState(
+        file_path="/data/dismiss.txt", size=50, mtime=2000, is_deleted=True
+    )
+    db_session.add(file_record)
+    db_session.commit()
+
+    response = client.post(f"/system/discrepancies/{file_record.id}/dismiss")
+    assert response.status_code == 200
+    assert "dismissed" in response.json()["message"]
+
+    db_session.expire_all()
+    db_session.refresh(file_record)
+    assert file_record.missing_acknowledged_at is not None
+
+
+def test_undo_dismiss_discrepancy(client, db_session):
+    """Tests undoing a dismissed discrepancy."""
+    file_record = models.FilesystemState(
+        file_path="/data/undo.txt",
+        size=50,
+        mtime=2000,
+        is_deleted=True,
+        missing_acknowledged_at=datetime.now(timezone.utc),
+    )
+    db_session.add(file_record)
+    db_session.commit()
+
+    response = client.post(f"/system/discrepancies/{file_record.id}/undo-dismiss")
+    assert response.status_code == 200
+    assert "undo" in response.json()["message"].lower()
+
+    db_session.expire_all()
+    db_session.refresh(file_record)
+    assert file_record.missing_acknowledged_at is None
+
+
+# ── delete_discrepancy ──
+
+
+def test_delete_discrepancy_hard_delete(client, db_session):
+    """Tests hard-deleting a file record and its versions/cart entries."""
+    media = models.StorageMedia(
+        media_type="hdd", identifier="M1", capacity=1000, status="active"
+    )
+    db_session.add(media)
+    db_session.flush()
+
+    file_record = models.FilesystemState(
+        file_path="/data/hard_delete.txt", size=100, mtime=1000, is_deleted=True
+    )
+    db_session.add(file_record)
+    db_session.flush()
+
+    db_session.add(
+        models.FileVersion(
+            filesystem_state_id=file_record.id,
+            media_id=media.id,
+            file_number="1",
+            offset_start=0,
+            offset_end=100,
+        )
+    )
+    db_session.add(models.RestoreCart(filesystem_state_id=file_record.id))
+    db_session.commit()
+
+    file_id = file_record.id
+
+    response = client.delete(f"/system/discrepancies/{file_id}")
+    assert response.status_code == 200
+
+    db_session.expire_all()
+    assert db_session.get(models.FilesystemState, file_id) is None
+    assert (
+        db_session.query(models.FileVersion)
+        .filter_by(filesystem_state_id=file_id)
+        .first()
+        is None
+    )
+    assert (
+        db_session.query(models.RestoreCart)
+        .filter_by(filesystem_state_id=file_id)
+        .first()
+        is None
+    )
+
+
+def test_delete_discrepancy_not_found(client):
+    """Tests deleting a non-existent discrepancy returns 404."""
+    response = client.delete("/system/discrepancies/9999")
+    assert response.status_code == 404
+
+
+# ── batch operations ──
+
+
+def test_batch_confirm_discrepancies(client, db_session):
+    """Tests batch confirming files as deleted."""
+    file1 = models.FilesystemState(
+        file_path="/data/batch1.txt", size=100, mtime=1000, is_deleted=False
+    )
+    file2 = models.FilesystemState(
+        file_path="/data/batch2.txt", size=200, mtime=1000, is_deleted=False
+    )
+    db_session.add_all([file1, file2])
+    db_session.commit()
+
+    response = client.post(
+        "/system/discrepancies/batch/confirm",
+        json={"ids": [file1.id, file2.id]},
+    )
+    assert response.status_code == 200
+    assert response.json()["count"] == 2
+
+    db_session.expire_all()
+    assert db_session.get(models.FilesystemState, file1.id).is_deleted is True
+    assert db_session.get(models.FilesystemState, file2.id).is_deleted is True
+
+
+def test_batch_dismiss_discrepancies(client, db_session):
+    """Tests batch dismissing discrepancies."""
+    file1 = models.FilesystemState(
+        file_path="/data/dismiss1.txt", size=100, mtime=1000, is_deleted=True
+    )
+    db_session.add(file1)
+    db_session.commit()
+
+    response = client.post(
+        "/system/discrepancies/batch/dismiss",
+        json={"ids": [file1.id]},
+    )
+    assert response.status_code == 200
+    assert response.json()["count"] == 1
+
+    db_session.expire_all()
+    assert (
+        db_session.get(models.FilesystemState, file1.id).missing_acknowledged_at
+        is not None
+    )
+
+
+def test_batch_delete_discrepancies(client, db_session):
+    """Tests batch hard-deleting discrepancy records."""
+    file1 = models.FilesystemState(
+        file_path="/data/del1.txt", size=100, mtime=1000, is_deleted=True
+    )
+    db_session.add(file1)
+    db_session.commit()
+
+    response = client.post(
+        "/system/discrepancies/batch/delete",
+        json={"ids": [file1.id]},
+    )
+    assert response.status_code == 200
+    assert response.json()["count"] == 1
+
+    db_session.expire_all()
+    assert db_session.get(models.FilesystemState, file1.id) is None
+
+
+def test_batch_resolve_discrepancies(client, db_session):
+    """Tests smart batch resolve: recoverable -> queue, lost -> confirm delete."""
+    media = models.StorageMedia(
+        media_type="hdd", identifier="M1", capacity=1000, status="active"
+    )
+    db_session.add(media)
+    db_session.flush()
+
+    # File with backup (recoverable)
+    file_recover = models.FilesystemState(
+        file_path="/data/recover.txt", size=100, mtime=1000, is_deleted=True
+    )
+    # File without backup (lost)
+    file_lost = models.FilesystemState(
+        file_path="/data/lost.txt", size=200, mtime=1000, is_deleted=True
+    )
+    db_session.add_all([file_recover, file_lost])
+    db_session.flush()
+
+    db_session.add(
+        models.FileVersion(
+            filesystem_state_id=file_recover.id,
+            media_id=media.id,
+            file_number="1",
+            offset_start=0,
+            offset_end=100,
+        )
+    )
+    db_session.commit()
+
+    response = client.post(
+        "/system/discrepancies/batch/resolve",
+        json={"ids": [file_recover.id, file_lost.id]},
+    )
+    assert response.status_code == 200
+    data = response.json()
+    assert data["recovered_count"] == 1
+    assert data["lost_count"] == 1
+    assert "/data/recover.txt" in data["recovered_paths"]
+    assert "/data/lost.txt" in data["lost_paths"]
+
+    db_session.expire_all()
+    # Recoverable should be in restore cart
+    assert (
+        db_session.query(models.RestoreCart)
+        .filter_by(filesystem_state_id=file_recover.id)
+        .first()
+        is not None
+    )
+    # Lost should be marked deleted and dismissed
+    lost_record = db_session.get(models.FilesystemState, file_lost.id)
+    assert lost_record.is_deleted is True
+    assert lost_record.missing_acknowledged_at is not None
+
+
+def test_batch_resolve_by_path_prefix(client, db_session):
+    """Tests batch resolve using path_prefix instead of ids."""
+    file1 = models.FilesystemState(
+        file_path="/data/lost1.txt", size=100, mtime=1000, is_deleted=True
+    )
+    db_session.add(file1)
+    db_session.commit()
+
+    response = client.post(
+        "/system/discrepancies/batch/resolve",
+        json={"path_prefix": "/data"},
+    )
+    assert response.status_code == 200
+    assert response.json()["lost_count"] == 1
+
+
+def test_batch_action_no_ids_or_prefix(client):
+    """Tests batch actions without ids or path_prefix return 400."""
+    for endpoint in ["confirm", "dismiss", "delete", "resolve"]:
+        response = client.post(f"/system/discrepancies/batch/{endpoint}", json={})
+        assert response.status_code == 400
+
+
+# ── discrepancy tree ──
+
+
+def test_discrepancy_tree_empty(client):
+    """Tests discrepancy tree when no discrepancies exist."""
+    response = client.get("/system/discrepancies/tree")
+    assert response.status_code == 200
+    assert response.json() == []
+
+
+def test_discrepancy_tree_root(client, db_session):
+    """Tests discrepancy tree at ROOT level."""
+    file1 = models.FilesystemState(
+        file_path="data/file1.txt", size=100, mtime=1000, is_deleted=True
+    )
+    db_session.add(file1)
+    db_session.commit()
+
+    response = client.get("/system/discrepancies/tree")
+    assert response.status_code == 200
+    data = response.json()
+    assert len(data) >= 1
+
+
+# ── discrepancy browse ──
+
+
+def test_discrepancy_browse_empty(client):
+    """Tests discrepancy browse when no discrepancies exist."""
+    response = client.get("/system/discrepancies/browse")
+    assert response.status_code == 200
+    data = response.json()
+    assert data["files"] == []
+
+
+def test_discrepancy_browse_with_files(client, db_session):
+    """Tests discrepancy browse returns files and directories."""
+    file1 = models.FilesystemState(
+        file_path="data/sub/file1.txt", size=100, mtime=1000, is_deleted=True
+    )
+    db_session.add(file1)
+    db_session.commit()
+
+    response = client.get("/system/discrepancies/browse?path=ROOT")
+    assert response.status_code == 200
+    data = response.json()
+    assert "files" in data
diff --git a/backend/tests/test_api_inventory.py b/backend/tests/test_api_inventory.py
index 0f334a3..005bfa0 100644
--- a/backend/tests/test_api_inventory.py
+++ b/backend/tests/test_api_inventory.py
@@ -560,3 +560,137 @@ def test_update_status_to_retired_purges_versions(client, db_session):
         {"media_id": media.id},
     ).scalar()
     assert result == 0
+
+
+# ── Archive Tree ──
+
+
+def test_archive_tree_with_versions(client, db_session):
+    """Tests archive tree returns source roots with versions."""
+    db_session.add(models.SystemSetting(key="source_roots", value=json.dumps(["data"])))
+    db_session.flush()
+
+    media = models.StorageMedia(
+        media_type="hdd", identifier="M1", capacity=1000, status="active"
+    )
+    db_session.add(media)
+    db_session.flush()
+
+    file1 = models.FilesystemState(file_path="data/file1.txt", size=100, mtime=1000)
+    db_session.add(file1)
+    db_session.flush()
+
+    db_session.add(
+        models.FileVersion(
+            filesystem_state_id=file1.id,
+            media_id=media.id,
+            file_number="1",
+            offset_start=0,
+            offset_end=100,
+        )
+    )
+    db_session.commit()
+
+    response = client.get("/archive/tree")
+    assert response.status_code == 200
+    data = response.json()
+    assert len(data) == 1
+    assert data[0]["name"] == "data"
+    assert data[0]["has_children"] is True
+
+
+def test_archive_tree_nested_directories(client, db_session):
+    """Tests archive tree with nested directories."""
+    db_session.add(models.SystemSetting(key="source_roots", value=json.dumps(["data"])))
+    db_session.flush()
+
+    media = models.StorageMedia(
+        media_type="hdd", identifier="M1", capacity=1000, status="active"
+    )
+    db_session.add(media)
+    db_session.flush()
+
+    file1 = models.FilesystemState(
+        file_path="data/subdir/file1.txt", size=100, mtime=1000
+    )
+    db_session.add(file1)
+    db_session.flush()
+
+    db_session.add(
+        models.FileVersion(
+            filesystem_state_id=file1.id,
+            media_id=media.id,
+            file_number="1",
+            offset_start=0,
+            offset_end=100,
+        )
+    )
+    db_session.commit()
+
+    response = client.get("/archive/tree")
+    assert response.status_code == 200
+    data = response.json()
+    assert len(data) == 1
+    assert data[0]["name"] == "data"
+
+
+def test_archive_tree_empty_no_versions(client, db_session):
+    """Tests archive tree excludes roots with no versions."""
+    db_session.add(models.SystemSetting(key="source_roots", value=json.dumps(["data"])))
+    db_session.flush()
+
+    # Add file but no versions
+    file1 = models.FilesystemState(file_path="data/file1.txt", size=100, mtime=1000)
+    db_session.add(file1)
+    db_session.commit()
+
+    response = client.get("/archive/tree")
+    assert response.status_code == 200
+    assert response.json() == []
+
+
+# ── Metadata Directory ──
+
+
+def test_metadata_directory(client, db_session):
+    """Tests metadata endpoint for a directory returns aggregated stats."""
+    db_session.add(models.SystemSetting(key="source_roots", value=json.dumps(["data"])))
+    db_session.flush()
+
+    media = models.StorageMedia(
+        media_type="hdd", identifier="M1", capacity=1000, status="active"
+    )
+    db_session.add(media)
+    db_session.flush()
+
+    file1 = models.FilesystemState(file_path="data/sub/file1.txt", size=100, mtime=1000)
+    file2 = models.FilesystemState(file_path="data/sub/file2.txt", size=200, mtime=1000)
+    db_session.add_all([file1, file2])
+    db_session.flush()
+
+    db_session.add(
+        models.FileVersion(
+            filesystem_state_id=file1.id,
+            media_id=media.id,
+            file_number="1",
+            offset_start=0,
+            offset_end=100,
+        )
+    )
+    db_session.add(
+        models.FileVersion(
+            filesystem_state_id=file2.id,
+            media_id=media.id,
+            file_number="2",
+            offset_start=0,
+            offset_end=200,
+        )
+    )
+    db_session.commit()
+
+    response = client.get("/archive/metadata?path=data/sub")
+    assert response.status_code == 200
+    data = response.json()
+    assert data["type"] == "directory"
+    assert data["child_count"] == 2
+    assert data["size"] == 300
diff --git a/backend/tests/test_api_system.py b/backend/tests/test_api_system.py
index 967a2d9..d9ada3f 100644
--- a/backend/tests/test_api_system.py
+++ b/backend/tests/test_api_system.py
@@ -504,3 +504,177 @@ def test_update_existing_secret(client):
     response = client.get("/system/secrets/ rotating-key ")
     assert response.status_code == 200
     assert response.json()["value"] == "new-value"
+
+
+# ── Filesystem Browse ──
+
+
+def test_filesystem_browse_root(client, db_session):
+    """Tests browsing the filesystem at ROOT level."""
+    db_session.add(models.SystemSetting(key="source_roots", value='["/source_data"]'))
+    db_session.commit()
+
+    response = client.get("/system/browse?path=ROOT")
+    assert response.status_code == 200
+    data = response.json()
+    assert len(data["files"]) == 1
+    assert data["files"][0]["path"] == "/source_data"
+    assert data["files"][0]["type"] == "directory"
+
+
+def test_filesystem_browse_subdirectory(client, db_session):
+    """Tests browsing a subdirectory of the filesystem index."""
+    db_session.add(models.SystemSetting(key="source_roots", value='["/source_data"]'))
+    db_session.flush()
+
+    file1 = models.FilesystemState(
+        file_path="/source_data/subdir/file1.txt", size=100, mtime=1000
+    )
+    db_session.add(file1)
+    db_session.commit()
+
+    response = client.get("/system/browse?path=/source_data/subdir")
+    assert response.status_code == 200
+    data = response.json()
+    assert len(data["files"]) == 1
+    assert data["files"][0]["name"] == "file1.txt"
+    assert data["files"][0]["type"] == "file"
+
+
+def test_filesystem_browse_outside_roots(client, db_session):
+    """Tests browsing outside configured roots returns 403."""
+    db_session.add(models.SystemSetting(key="source_roots", value='["/source_data"]'))
+    db_session.commit()
+
+    response = client.get("/system/browse?path=/etc")
+    assert response.status_code == 403
+
+
+# ── Filesystem Search ──
+
+
+def test_filesystem_search_too_short(client):
+    """Tests search with query < 3 chars returns empty list."""
+    response = client.get("/system/search?q=ab")
+    assert response.status_code == 200
+    assert response.json() == []
+
+
+# ── Hardware Discover ──
+
+
+def test_discover_hardware_empty(client):
+    """Tests hardware discovery endpoint returns a list (may contain real mounts)."""
+    response = client.get("/system/hardware/discover")
+    assert response.status_code == 200
+    data = response.json()
+    assert isinstance(data, list)
+    # Each discovered node should have required fields if present
+    for node in data:
+        assert "type" in node
+        assert "identifier" in node
+        assert "is_registered" in node
+
+
+# ── Hardware Ignore ──
+
+
+def test_ignore_hardware_duplicate(client):
+    """Tests ignoring the same hardware twice is idempotent."""
+    client.post("/system/hardware/ignore", json={"identifier": "DISK_DUP"})
+    response = client.post("/system/hardware/ignore", json={"identifier": "DISK_DUP"})
+    assert response.status_code == 200
+
+    response = client.get("/system/settings")
+    assert response.json()["ignored_hardware"].count("DISK_DUP") == 1
+
+
+# ── Database Export ──
+
+
+def test_database_export(client):
+    """Tests database export endpoint returns a file response."""
+    response = client.get("/system/database/export")
+    # May return 200 with file or 404 if db path not found
+    assert response.status_code in (200, 404)
+
+
+# ── Tracking Batch ──
+
+
+def test_batch_track_include(client, db_session):
+    """Tests batch tracking include action sets is_ignored=0."""
+    file1 = models.FilesystemState(
+        file_path="/data/important.txt", size=100, mtime=1000, is_ignored=True
+    )
+    db_session.add(file1)
+    db_session.commit()
+
+    response = client.post(
+        "/system/track/batch",
+        json={"tracks": ["/data/important.txt"], "untracks": []},
+    )
+    assert response.status_code == 200
+    assert "synchronized" in response.json()["message"]
+
+    db_session.expire_all()
+    assert db_session.get(models.FilesystemState, file1.id).is_ignored is False
+
+    # Verify tracked source record was created
+    ts = (
+        db_session.query(models.TrackedSource)
+        .filter_by(path="/data/important.txt")
+        .first()
+    )
+    assert ts is not None
+    assert ts.action == "include"
+
+
+def test_batch_track_exclude(client, db_session):
+    """Tests batch tracking exclude action sets is_ignored=1."""
+    file1 = models.FilesystemState(
+        file_path="/data/temp.txt", size=100, mtime=1000, is_ignored=False
+    )
+    db_session.add(file1)
+    db_session.commit()
+
+    response = client.post(
+        "/system/track/batch",
+        json={"tracks": [], "untracks": ["/data/temp.txt"]},
+    )
+    assert response.status_code == 200
+
+    db_session.expire_all()
+    assert db_session.get(models.FilesystemState, file1.id).is_ignored is True
+
+    ts = db_session.query(models.TrackedSource).filter_by(path="/data/temp.txt").first()
+    assert ts is not None
+    assert ts.action == "exclude"
+
+
+def test_batch_track_empty(client):
+    """Tests batch track with empty lists succeeds."""
+    response = client.post("/system/track/batch", json={"tracks": [], "untracks": []})
+    assert response.status_code == 200
+
+
+# ── Archive Tree ──
+
+
+def test_archive_tree_empty(client):
+    """Tests archive tree when index is empty."""
+    response = client.get("/archive/tree")
+    assert response.status_code == 200
+    assert response.json() == []
+
+
+# ── Notifications ──
+
+
+def test_test_notification_invalid_url(client):
+    """Tests test notification with invalid URL returns 500."""
+    response = client.post(
+        "/system/notifications/test", json={"url": "not-a-valid-url"}
+    )
+    # Notification manager may succeed or fail depending on apprise parsing
+    assert response.status_code in (200, 500)