Leave out a module whose stored manifest has an unknown field, and raise it (hq ADR 0262 review)

A key dropped silently ran a module without what its manifest says, and a key inside a block still
failed the whole catalogue. Judge a key by what it is about, and narrow the listing to one machine.

cmd/mesh-controller/unknown_fields_test.go

@@ -0,0 +1,50 @@
+package main
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/novox/mesh-controller/internal/catalogue"
+	"github.com/novox/mesh-controller/internal/conditions"
+)
+
+// A module whose stored manifest has a key this controller does not know is a condition, in plain
+// words, until it is read again; every other module raises nothing (novox/hq ADR 0262).
+func TestAModuleWithAnUnknownFieldIsACondition(t *testing.T) {
+	var later, now catalogue.Manifest
+	if err := json.Unmarshal([]byte(`{"module": "dunst", "version": "2", "settings": {}, "a-field-from-later": 1}`), &later); err != nil {
+		t.Fatal(err)
+	}
+	if err := json.Unmarshal([]byte(`{"module": "xorg", "version": "1"}`), &now); err != nil {
+		t.Fatal(err)
+	}
+	observed := unknownFieldObservations(map[string]catalogue.Manifest{"dunst": later, "xorg": now})
+	if len(observed) != 1 || observed[0].ID != "dunst" || observed[0].Kind != kindUnknownField {
+		t.Fatalf("observed: %+v", observed)
+	}
+	o := observed[0]
+	if why, ok := conditions.PlainWords(conditions.Words{Headline: o.Headline, Explanation: o.Explanation,
+		Resolved: o.Resolved, Needs: o.Needs}); !ok {
+		t.Fatalf("not plain: %s", why)
+	}
+
+	k, _ := withConditionsInMemory(t)
+	if err := k.Reconcile(t.Context(), sourceUnknownFields, observed); err != nil {
+		t.Fatal(err)
+	}
+	if _, open, _ := k.Get(t.Context(), o.Key()); !open {
+		t.Fatal("not raised")
+	}
+	if err := k.Reconcile(t.Context(), sourceUnknownFields, unknownFieldObservations(map[string]catalogue.Manifest{"xorg": now})); err != nil {
+		t.Fatal(err)
+	}
+	still, err := k.Open(t.Context())
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, c := range still {
+		if c.Key == o.Key() {
+			t.Fatalf("not cleared once read again: %+v", c)
+		}
+	}
+}