Pick cheapest GPU SKU and pin the VM to an existing disk AZ.

Scan ru-6 by Nova availability zones (a/b/c). First boot uses FLAVOR_SIZE_PRESET=cheap; reruns stay on the disk segment.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/test_placement.py

@@ -0,0 +1,58 @@
+from gpu_rent.config import load_config
+from gpu_rent.flavor_presets import format_char_impact, normalize_size_preset
+from gpu_rent.placement import apply_az_policy, existing_disk_az
+from gpu_rent.pools import PoolGpuOffer
+from gpu_rent.state import SessionState
+
+
+def test_normalize_size_preset():
+    assert normalize_size_preset("RAM") == "ram"
+    assert normalize_size_preset("nope") == "cheap"
+    assert "GPU" in "\n".join(format_char_impact())
+
+
+def test_apply_az_policy_disk_wins(monkeypatch):
+    monkeypatch.setenv("OS_AUTH_URL", "https://example.invalid/identity/v3")
+    monkeypatch.setenv("OS_USER_DOMAIN_NAME", "1")
+    monkeypatch.setenv("OS_USERNAME", "u")
+    monkeypatch.setenv("OS_PASSWORD", "p")
+    monkeypatch.setenv("OS_PROJECT_ID", "proj")
+    monkeypatch.setenv("OS_REGION_NAME", "ru-6")
+    monkeypatch.setenv("GPU_RENT_AZ", "ru-6b")
+    cfg = load_config(require_auth=True)
+    best = PoolGpuOffer(region="ru-6", multizone=True, recommended_az="ru-6a")
+    placed = apply_az_policy(cfg, disk_az="ru-6a", best=best)
+    assert placed.reason == "disk"
+    assert placed.cfg.gpu_rent_az == "ru-6a"
+
+
+def test_apply_az_policy_first_boot_cheap(monkeypatch):
+    monkeypatch.setenv("OS_AUTH_URL", "https://example.invalid/identity/v3")
+    monkeypatch.setenv("OS_USER_DOMAIN_NAME", "1")
+    monkeypatch.setenv("OS_USERNAME", "u")
+    monkeypatch.setenv("OS_PASSWORD", "p")
+    monkeypatch.setenv("OS_PROJECT_ID", "proj")
+    monkeypatch.setenv("OS_REGION_NAME", "ru-6")
+    monkeypatch.setenv("GPU_RENT_AZ", "ru-6b")
+    cfg = load_config(require_auth=True)
+    best = PoolGpuOffer(region="ru-6", multizone=True, recommended_az="ru-6a")
+    placed = apply_az_policy(cfg, disk_az=None, best=best)
+    assert placed.reason == "cheap"
+    assert placed.cfg.gpu_rent_az == "ru-6a"
+
+
+def test_existing_disk_az_from_volume():
+    class Vol:
+        availability_zone = "ru-6a"
+
+    class Storage:
+        def get_volume(self, vid):
+            assert vid == "boot-1"
+            return Vol()
+
+    class Conn:
+        block_storage = Storage()
+
+    cfg = load_config(require_auth=False)
+    state = SessionState(boot_volume_id="boot-1")
+    assert existing_disk_az(Conn(), cfg, state) == "ru-6a"