fix(web): require clone dir strictly under build_vms on remove (W6)

remove_vm() deletes vmx.parent, so containment must check the clone dir, not just the vmx: a crafted vmx_id of build_vms/x.vmx passed the old check and would rmtree the entire clone base. Now the parent must be strictly inside build_vms.

plans/web-ui-management-plan.md

@@ -24,7 +24,7 @@ Stato passi (spunta man mano):
 - [x] **W3** — `operations/audit.py`: append-only JSONL + lettura. Config `[web]` in `config.py`.
 - [x] **W4** — App web core: `web/app.py` factory + `commands/web.py` (`ci web serve`). Dashboard **read-only** (VM, cache, disco, runner). Ancora **senza auth**, bind localhost.
 - [x] **W5** — Auth: Gitea OIDC (Authlib) + sessione firmata + allowlist utenti (fail-closed) + secret solo da keyring. Tutte le route dati protette (`/healthz`,`/static`,`/login`,`/auth/callback` aperte). Hardening: `ci web serve` rifiuta bind non-loopback quando `[web.oidc]` assente (open mode solo su localhost).
-- [ ] **W6** — Azioni mutanti + safety: remove VM, cleanup orfane, purge cache, backup. Confirm gate + CSRF + audit + dry-run. HTMX partials.
+- [x] **W6** — Azioni mutanti + safety: remove VM, cleanup orfane, purge cache, backup. Confirm gate 2-step (preview dry-run → execute) + CSRF sincronizzatore + audit (preview+execute) + path-containment (clone dir **strettamente** sotto build_vms) + 409 job-race guard. `SessionMiddleware` sempre attivo (secret effimero in open mode) per CSRF. HTMX partials.
 - [ ] **W7** — UI dark Gitea-style (asset vendorizzati) + installer ripetibile (`setup-web-linux.sh`, unit systemd, `docs/WEB-UI.md`) + validazione finale (test, coverage, mypy, ruff, smoke manuale).
 
 **Definition of done globale**: `ci web serve` gira come `ci-web.service`, login via Gitea, dashboard dark mostra stato live, le 4 azioni (kill VM / cleanup orfane / purge cache / backup) funzionano con conferma + audit, suite test verde con coverage ≥ 90 % e `mypy --strict` pulito.

src/ci_orchestrator/web/routes.py

@@ -197,7 +197,12 @@ async def vms_remove(
     config: Config = request.app.state.config
 
     vmx = _decode_vmx_id(vmx_id)
-    if vmx is None or not _is_contained(vmx, config.paths.build_vms):
+    # remove_vm() deletes vmx.parent (the clone dir), so the *clone dir* — not
+    # merely the vmx — must be STRICTLY inside build_vms. Checking vmx.parent
+    # rejects a crafted ``build_vms/x.vmx`` whose parent IS build_vms itself,
+    # which would otherwise rmtree the entire clone base. build_vms being an
+    # ancestor of vmx.parent also implies vmx is contained.
+    if vmx is None or not _is_contained(vmx.parent, config.paths.build_vms):
         raise HTTPException(
             status_code=status.HTTP_400_BAD_REQUEST,
             detail="vmx path is not contained in config.paths.build_vms",

tests/python/test_web_actions.py

@@ -356,6 +356,38 @@ def test_vm_remove_outside_build_vms_is_400_and_does_not_delete(tmp_path: Path)
     assert not any(e.result == "ok" for e in entries)
 
 
+def test_vm_remove_vmx_directly_in_build_vms_is_400_not_wiping_base(tmp_path: Path) -> None:
+    """A vmx whose parent IS build_vms would rmtree the whole clone base -- reject.
+
+    remove_vm() deletes vmx.parent; for ``build_vms/x.vmx`` that parent is
+    build_vms itself. The containment check must reject it so a crafted
+    vmx_id can't wipe every clone at once.
+    """
+    config = _make_config(tmp_path)
+    build_vms = config.paths.build_vms
+    build_vms.mkdir(parents=True, exist_ok=True)
+    survivor = build_vms / "Clone_keep"
+    survivor.mkdir()
+    (survivor / "Clone_keep.vmx").write_text("keep", encoding="utf-8")
+
+    danger_vmx = build_vms / "x.vmx"  # parent == build_vms itself
+    danger_vmx.write_text("x", encoding="utf-8")
+
+    fake_backend = _FakeBackend([])
+    app = create_app(config)
+    app.dependency_overrides[get_backend] = lambda: fake_backend
+    client = TestClient(app)
+    csrf = _get_csrf(client)
+    vmx_id = routes_module.encode_vmx_id(danger_vmx)
+
+    resp = client.post(f"/vms/{vmx_id}/remove", data={"csrf": csrf, "stage": "execute"})
+
+    assert resp.status_code == 400
+    assert build_vms.exists()  # clone base NOT wiped
+    assert survivor.exists()  # sibling clone survived
+    assert fake_backend.delete_calls == []
+
+
 def test_vm_remove_malformed_vmx_id_is_400(tmp_path: Path) -> None:
     config = _make_config(tmp_path)
     app = create_app(config)