Require --force to delete a non-empty or attached space

A destructive-operations incident: `smriti space delete <space> -y`
cascade-deleted a fully populated space. `-y` skipped the only gate (the
confirmation prompt), and `cmd_space_delete` never checked how much the
space held — so one flag irreversibly deleted the space and every
checkpoint, session, and turn under it.

Gate destructive deletes in `cmd_space_delete`: a space that holds
checkpoints, or that the current repo is attached to (.smriti.json), now
requires an explicit `--force` — `-y` alone is refused, with a message
naming the reason and the flag. `--force` and `-y` stay orthogonal, the
same shape as `checkpoint delete --cascade`. Empty, unattached spaces keep
the existing `-y` convenience. CLI-side only; no backend change.

cli/smriti_cli/main.py

@@ -612,11 +612,45 @@ def cmd_space_delete(client: SmritiClient, args: argparse.Namespace) -> None:
     space = _resolve_space(client, args)
     commits = client.list_commits(space["id"])
     commit_count = len(commits)
+
+    # Is this the space the current repo is attached to?
+    record = attachment.read_attachment()
+    is_attached = bool(record) and (
+        record.get("space_id") == space["id"]
+        or record.get("space") == space["name"]
+    )
+
+    # Destructive-delete guard. `-y` skips the confirmation prompt, but it must
+    # NOT, on its own, delete a space that holds real work or is attached to a
+    # repo. Those need an explicit, separate --force signal — the same
+    # "name the stronger flag" shape as `checkpoint delete --cascade`.
+    blockers: list[str] = []
+    if commit_count > 0:
+        blockers.append(
+            f"it holds {commit_count} checkpoint(s); deletion cascades to all of "
+            f"them plus every session and turn, and cannot be undone"
+        )
+    if is_attached:
+        blockers.append(
+            "this repo is attached to it (.smriti.json); deleting it unbinds the repo"
+        )
+    if blockers and not args.force:
+        lines = [f"Refusing to delete space '{space['name']}' (`{space['id']}`):"]
+        lines += [f"  - {b}" for b in blockers]
+        lines.append("")
+        lines.append(
+            "  -y is not enough for a destructive delete like this. If you are "
+            "certain,\n  re-run with --force (required in addition to -y or the prompt)."
+        )
+        _fail("\n".join(lines))
+
     preview = (
         f"Delete space '{space['name']}' (`{space['id']}`)?\n"
         f"  This will permanently delete {commit_count} checkpoint(s) "
         f"and all sessions/turns under this space."
     )
+    if is_attached:
+        preview += "\n  This repo is attached to this space — deleting it unbinds the repo."
     if not _confirm(preview, args.yes):
         _fail("Cancelled.", code=0)
     client.delete_space(space["id"])
@@ -1916,6 +1950,11 @@ def _build_parser() -> argparse.ArgumentParser:
     sp_delete.add_argument(
         "-y", "--yes", action="store_true", help="Skip confirmation prompt"
     )
+    sp_delete.add_argument(
+        "--force",
+        action="store_true",
+        help="Required to delete a non-empty or attached space (irreversible)",
+    )
     sp_delete.add_argument("--json", action="store_true", help="Output structured JSON")
     sp_delete.set_defaults(func=cmd_space_delete)
 

cli/tests/test_space_cli.py

@@ -5,6 +5,7 @@ from unittest.mock import MagicMock
 
 import pytest
 
+from smriti_cli import attachment
 from smriti_cli import main as cli_main
 from smriti_cli.client import SmritiClient
 
@@ -195,3 +196,78 @@ def test_cmd_space_set_project_root_here_flag_resolves_cwd(tmp_path, monkeypatch
     cli_main.cmd_space_set_project_root(client, args)
 
     client.set_project_root.assert_called_once_with("space-uuid", str(tmp_path))
+
+
+# ── space delete: destructive-delete guard ───────────────────────────────────
+#
+# Incident: `smriti space delete <space> -y` cascade-deleted a populated space.
+# A non-empty or attached space must now require an explicit --force.
+
+
+def _delete_args(space="my-project", yes=False, force=False, json=False):
+    return argparse.Namespace(space=space, yes=yes, force=force, json=json)
+
+
+def test_space_delete_parser_has_force_flag():
+    parser = cli_main._build_parser()
+    args = parser.parse_args(["space", "delete", "my-project", "--force", "-y"])
+    assert args.force is True
+    assert args.yes is True
+    # --force defaults off
+    assert parser.parse_args(["space", "delete", "my-project"]).force is False
+
+
+def test_cmd_space_delete_empty_unattached_space_allows_yes(tmp_path, monkeypatch):
+    """Empty, unattached space: -y still deletes it (convenience retained)."""
+    monkeypatch.chdir(tmp_path)
+    client = MagicMock(spec=SmritiClient)
+    client.resolve_space.return_value = _space_dict()
+    client.list_commits.return_value = []  # empty
+    cli_main.cmd_space_delete(client, _delete_args(yes=True))
+    client.delete_space.assert_called_once_with("space-uuid")
+
+
+def test_cmd_space_delete_nonempty_refused_without_force(tmp_path, monkeypatch, capsys):
+    """The incident path: -y alone must NOT delete a populated space."""
+    monkeypatch.chdir(tmp_path)
+    client = MagicMock(spec=SmritiClient)
+    client.resolve_space.return_value = _space_dict()
+    client.list_commits.return_value = [{"id": "c1"}, {"id": "c2"}]  # non-empty
+    with pytest.raises(SystemExit):
+        cli_main.cmd_space_delete(client, _delete_args(yes=True, force=False))
+    client.delete_space.assert_not_called()
+    err = capsys.readouterr().err
+    assert "Refusing to delete" in err
+    assert "--force" in err
+
+
+def test_cmd_space_delete_nonempty_allowed_with_force(tmp_path, monkeypatch):
+    """A populated space deletes only with --force (in addition to -y)."""
+    monkeypatch.chdir(tmp_path)
+    client = MagicMock(spec=SmritiClient)
+    client.resolve_space.return_value = _space_dict()
+    client.list_commits.return_value = [{"id": "c1"}, {"id": "c2"}]
+    cli_main.cmd_space_delete(client, _delete_args(yes=True, force=True))
+    client.delete_space.assert_called_once_with("space-uuid")
+
+
+def test_cmd_space_delete_attached_space_refused_without_force(tmp_path, monkeypatch):
+    """An attached space is force-gated even when it is empty."""
+    monkeypatch.chdir(tmp_path)
+    attachment.write_attachment(tmp_path, "my-project", "space-uuid")
+    client = MagicMock(spec=SmritiClient)
+    client.resolve_space.return_value = _space_dict()
+    client.list_commits.return_value = []  # empty, but attached
+    with pytest.raises(SystemExit):
+        cli_main.cmd_space_delete(client, _delete_args(yes=True, force=False))
+    client.delete_space.assert_not_called()
+
+
+def test_cmd_space_delete_attached_space_allowed_with_force(tmp_path, monkeypatch):
+    monkeypatch.chdir(tmp_path)
+    attachment.write_attachment(tmp_path, "my-project", "space-uuid")
+    client = MagicMock(spec=SmritiClient)
+    client.resolve_space.return_value = _space_dict()
+    client.list_commits.return_value = []
+    cli_main.cmd_space_delete(client, _delete_args(yes=True, force=True))
+    client.delete_space.assert_called_once_with("space-uuid")