fix: prevent devices limit flicker

tests/test_webapp_devices_labels.py

@@ -0,0 +1,65 @@
+import json
+import shutil
+import subprocess
+import textwrap
+from pathlib import Path
+
+import pytest
+
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+
+
+def test_devices_labels_use_subscription_limit_before_devices_payload():
+    node = shutil.which("node")
+    if not node:
+        pytest.skip("node is required to exercise the webapp label helpers")
+
+    script = textwrap.dedent(
+        """
+        const mod = await import("./frontend/src/lib/webapp/devicesLabels.js");
+        const t = (key, params = {}, fallback = "") => {
+          if (key === "wa_devices_count") return `${params.current}/${params.max}`;
+          if (key === "wa_devices_unlimited") return "Unlimited";
+          return fallback || key;
+        };
+        const result = {
+          missingLimit: mod.devicesLimitLabel(null, t),
+          fallbackLimit: mod.devicesLimitLabel(null, t, 5),
+          fallbackCount: mod.devicesCountLabel({ current_devices: 2 }, t, 5),
+          fallbackPercent: mod.devicesPercent({ current_devices: 2 }, 5),
+          unlimitedLimit: mod.devicesLimitLabel({ max_devices: 0 }, t),
+          unlimitedPercent: mod.devicesPercent({ current_devices: 2, max_devices: 0 }),
+        };
+        console.log(JSON.stringify(result));
+        """
+    )
+
+    completed = subprocess.run(
+        [node, "--input-type=module", "--eval", script],
+        cwd=REPO_ROOT,
+        check=True,
+        capture_output=True,
+        text=True,
+    )
+
+    payload = json.loads(completed.stdout)
+    assert payload == {
+        "missingLimit": "...",
+        "fallbackLimit": "5",
+        "fallbackCount": "2/5",
+        "fallbackPercent": 40,
+        "unlimitedLimit": "Unlimited",
+        "unlimitedPercent": 100,
+    }
+
+
+def test_devices_screen_passes_subscription_limit_as_initial_fallback():
+    source = (REPO_ROOT / "frontend/src/webapp/screens/DevicesScreen.svelte").read_text(
+        encoding="utf-8"
+    )
+
+    assert "effectiveMaxDevices = devicesData?.max_devices ?? subscription?.max_devices" in source
+    assert "devicesCountLabel(devicesData, t, effectiveMaxDevices)" in source
+    assert "devicesPercent(devicesData, effectiveMaxDevices)" in source
+    assert "devicesLimitLabel(devicesData, t, effectiveMaxDevices)" in source