Name the sizes a node can ask for

Raw cpus and gpus are a property of the machines an installation has, so a node
written against a cluster quietly stops meaning anything when the cluster is
replaced. A node says "gpu-small" instead, and what that is stored here —
editable, and read again every time the node is built, so changing the flavor
changes what the next run gets.

Memory joins the schema properly (`ram`, in MB, accepting "2G"), along with
`duration_s` for how long a node is expected to take. That one is recorded and
shown and nothing else yet: a statement for whoever is planning around the node,
not a limit — the limit is still `timeout`.

A flavor and a number for the same thing is refused, compared by value so an
editor writing the whole object back with its defaults still round-trips. A name
nothing stores is refused at the save, which covers the canvas and `fluksio
sync` at once, and deleting one a node still asks for says which node.

Four sizes are seeded on an installation that has none, and never re-seeded:
re-adding one somebody deliberately removed is an argument nobody wins.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01A6HeySA27EkGANZN95QySW

backend/tests/api/routes/test_flavors.py

@@ -0,0 +1,180 @@
+"""Named sizes: storing them, and what happens to a node that asks for one."""
+
+import pytest
+from fastapi.testclient import TestClient
+from sqlmodel import Session, select
+
+from fluksio.core.config import settings
+from fluksio.core.db import seed_flavors
+from fluksio.models import Flavor
+
+
+def test_an_installation_starts_with_sizes_to_pick_from(
+    client: TestClient, superuser_token_headers: dict[str, str]
+) -> None:
+    response = client.get(
+        f"{settings.API_V1_STR}/flavors/", headers=superuser_token_headers
+    )
+    assert response.status_code == 200
+    names = {row["name"] for row in response.json()["data"]}
+    assert {"small", "medium", "large", "gpu-small"} <= names
+
+
+def test_seeding_leaves_an_installation_that_has_its_own_alone(db: Session) -> None:
+    """Re-adding a size somebody deliberately removed is an argument to avoid."""
+    before = {row.name for row in db.exec(select(Flavor)).all()}
+    seed_flavors(db)
+    assert {row.name for row in db.exec(select(Flavor)).all()} == before
+
+
+def test_a_size_can_be_added_changed_and_removed(
+    client: TestClient, superuser_token_headers: dict[str, str]
+) -> None:
+    created = client.post(
+        f"{settings.API_V1_STR}/flavors/",
+        headers=superuser_token_headers,
+        json={"name": "gpu-big", "cpus": 16, "gpus": 4, "ram": 65536},
+    )
+    assert created.status_code == 200
+    assert created.json()["gpus"] == 4
+
+    again = client.post(
+        f"{settings.API_V1_STR}/flavors/",
+        headers=superuser_token_headers,
+        json={"name": "gpu-big", "cpus": 1},
+    )
+    assert again.status_code == 409
+
+    changed = client.patch(
+        f"{settings.API_V1_STR}/flavors/gpu-big",
+        headers=superuser_token_headers,
+        json={"cpus": 32},
+    )
+    assert changed.status_code == 200
+    # Only what was sent: the rest of the size is untouched.
+    assert (changed.json()["cpus"], changed.json()["gpus"]) == (32, 4)
+
+    removed = client.delete(
+        f"{settings.API_V1_STR}/flavors/gpu-big", headers=superuser_token_headers
+    )
+    assert removed.status_code == 200
+    listed = client.get(
+        f"{settings.API_V1_STR}/flavors/", headers=superuser_token_headers
+    ).json()
+    assert "gpu-big" not in {row["name"] for row in listed["data"]}
+
+
+def test_changing_a_size_is_a_superusers(
+    client: TestClient, normal_user_token_headers: dict[str, str]
+) -> None:
+    """Reading is open — the node panel offers them — and writing is not."""
+    assert (
+        client.get(
+            f"{settings.API_V1_STR}/flavors/", headers=normal_user_token_headers
+        ).status_code
+        == 200
+    )
+    refused = client.post(
+        f"{settings.API_V1_STR}/flavors/",
+        headers=normal_user_token_headers,
+        json={"name": "sneaky", "cpus": 99},
+    )
+    assert refused.status_code == 403
+
+
+def test_a_name_nobody_could_type_is_refused(
+    client: TestClient, superuser_token_headers: dict[str, str]
+) -> None:
+    refused = client.post(
+        f"{settings.API_V1_STR}/flavors/",
+        headers=superuser_token_headers,
+        json={"name": "GPU Big!", "cpus": 1},
+    )
+    assert refused.status_code == 422
+
+
+def test_a_flow_cannot_name_a_size_that_does_not_exist(
+    client: TestClient, superuser_token_headers: dict[str, str]
+) -> None:
+    """Caught at the save, which covers the canvas and `fluksio sync` at once."""
+    response = client.put(
+        f"{settings.API_V1_STR}/flows/flavor_check",
+        headers=superuser_token_headers,
+        json={
+            "name": "flavor_check",
+            "version": 1,
+            "nodes": [
+                {"id": "fit", "type": "python", "resources": {"flavor": "imaginary"}}
+            ],
+        },
+    )
+    assert response.status_code == 422
+    assert "imaginary" in str(response.json()["detail"])
+
+
+def test_a_size_a_node_still_asks_for_is_not_deleted(
+    client: TestClient, superuser_token_headers: dict[str, str]
+) -> None:
+    client.post(
+        f"{settings.API_V1_STR}/flavors/",
+        headers=superuser_token_headers,
+        json={"name": "in-use", "cpus": 2},
+    )
+    client.put(
+        f"{settings.API_V1_STR}/flows/flavor_user",
+        headers=superuser_token_headers,
+        json={
+            "name": "flavor_user",
+            "version": 1,
+            "nodes": [
+                {"id": "fit", "type": "python", "resources": {"flavor": "in-use"}}
+            ],
+        },
+    )
+    try:
+        refused = client.delete(
+            f"{settings.API_V1_STR}/flavors/in-use", headers=superuser_token_headers
+        )
+        assert refused.status_code == 409
+        assert "flavor_user.fit" in refused.json()["detail"]
+    finally:
+        client.delete(
+            f"{settings.API_V1_STR}/flows/flavor_user", headers=superuser_token_headers
+        )
+        client.delete(
+            f"{settings.API_V1_STR}/flavors/in-use", headers=superuser_token_headers
+        )
+
+
+def test_a_named_size_resolves_to_the_numbers_stored_for_it(db: Session) -> None:
+    from fluksio.flow.resources import UnknownFlavor, resolve_flavor
+    from fluksio.flow.schemas import Resources
+
+    resolved = resolve_flavor(Resources(flavor="gpu-small", duration_s=60))
+    seeded = db.get(Flavor, "gpu-small")
+    assert (resolved.cpus, resolved.gpus, resolved.ram) == (
+        seeded.cpus,
+        seeded.gpus,
+        seeded.ram,
+    )
+    # What the node said about itself survives; the flavor only sizes it.
+    assert resolved.duration_s == 60
+    assert resolved.flavor is None
+
+    # Read at build time, so editing a flavor edits what the next run gets.
+    seeded.cpus = 12
+    db.add(seeded)
+    db.commit()
+    assert resolve_flavor(Resources(flavor="gpu-small")).cpus == 12
+
+    with pytest.raises(UnknownFlavor, match="does not exist"):
+        resolve_flavor(Resources(flavor="never-stored"))
+
+
+def test_declaring_nothing_never_looks_anything_up() -> None:
+    """The common node pays nothing for a feature it does not use."""
+    from fluksio.flow.resources import resolve_flavor
+    from fluksio.flow.schemas import Resources
+
+    wanted = Resources(cpus=2)
+    assert resolve_flavor(wanted) is wanted