RR2-5: the reader reads a seat-named view in consumes and a seat's views

G's builder and checker follow the assigner's views by the seat,
seat:mesh-module-assigner.views.assignments; SeatViewConsume splits that
form, and a seat compiled from its definition names the states it offers
as views, which the validator checks the form against.

Builds: design 47 G §621, §616, §699

Claude-Session: https://claude.ai/code/session_01NcbgfGKaxw984XyAPfLm4h

go/catalogue/reader_release_test.go

@@ -5,6 +5,8 @@ import (
 	"slices"
 	"strings"
 	"testing"
+
+	"git.novox.be/novox/mesh-sdk/go/seatdef"
 )
 
 // A manifest carrying the words design 47 G writes is read whole by the reader release (design 47 G §340, §409):
@@ -69,3 +71,31 @@ func TestTheSecondReaderReleaseReadsGsManifestWords(t *testing.T) {
 		}
 	}
 }
+
+// A consumed view of a seat, `seat:<seat>.views.<state>`, is read apart from a consumed event, and a seat's compiled form
+// names the states its definition offers as views (design 47 G §616, §699, §621).
+func TestTheSecondReaderReleaseReadsASeatNamedView(t *testing.T) {
+	for _, row := range []struct {
+		consume, seat, state string
+		ok, bad              bool
+	}{
+		{"seat:mesh-module-assigner.views.assignments", "mesh-module-assigner", "assignments", true, false},
+		{"mesh-delivery-assigner.views.assignments", "", "", false, false},
+		{"seat:mesh-module-assigner.assignments", "", "", true, true},
+		{"seat:.views.assignments", "", "", true, true},
+	} {
+		seat, state, ok, err := SeatViewConsume(row.consume)
+		if seat != row.seat || state != row.state || ok != row.ok || (err != nil) != row.bad {
+			t.Errorf("SeatViewConsume(%q) = %q, %q, %v, %v", row.consume, seat, state, ok, err)
+		}
+	}
+	m, err := decodeForTest([]byte(`{"module":"m","version":"1.0","consumes":["seat:mesh-module-assigner.views.assignments"]}`))
+	if err != nil || len(m.UnknownField()) != 0 || m.Consumes[0] != "seat:mesh-module-assigner.views.assignments" {
+		t.Errorf("a seat-named view in consumes read as %v, %v", m.Consumes, err)
+	}
+	s := SeatFromDefinition(seatdef.Definition{Seat: "mesh-module-assigner", Scope: "mesh",
+		States: []seatdef.State{{Name: "assignments", View: true}, {Name: "placement"}}})
+	if !slices.Equal(s.Views, []string{"assignments"}) {
+		t.Errorf("the seat's views = %v", s.Views)
+	}
+}

go/catalogue/seat_from_definition.go

@@ -25,6 +25,11 @@ func SeatFromDefinition(d seatdef.Definition) Seat {
 			Input: seatdef.ResolveRefs(v.Input, d.Defs), Output: seatdef.ResolveRefs(v.Answer, d.Defs),
 			Optional: v.Optional, Replaces: v.Replaces})
 	}
+	for _, st := range d.States {
+		if st.View {
+			s.Views = append(s.Views, st.Name)
+		}
+	}
 	for _, r := range d.Receives {
 		rv := Receivable{Kind: r.Kind, Comment: r.Comment, Dirs: r.Dirs, Offered: r.Offered}
 		if r.Shape != nil {

go/catalogue/seats.go

@@ -45,6 +45,9 @@ type Seat struct {
 	// Serves carries each verb in full — name, description, schema — because a role's tools are the
 	// mesh's to define and an agent's to call (novox/hq ADR 0132, design 33 §2).
 	Serves []Verb
+	// Views are the names of the states the seat offers as views, which a module follows by `consumes`
+	// `seat:<seat>.views.<state>` (design 47 G §616, §699). Compiled from the definition's states marked `view`.
+	Views []string
 	// Receives is what other modules may contribute to the seat's holder, by kind (novox/hq ADR
 	// 0212): each kind is text in the tool's own grammar, placed by the holder with
 	// ${contribution:<seat>:<kind>}. Compiled, never stored: like the protocol, it is the mesh's

go/catalogue/state.go

@@ -78,6 +78,25 @@ func (s StateDeclaration) MarshalJSON() ([]byte, error) {
 	return json.Marshal(plain(s))
 }
 
+// SeatViewPrefix opens a consumed view of a seat, `seat:<seat>.views.<state>` (design 47 G §616).
+const SeatViewPrefix = "seat:"
+
+// SeatViewConsume splits a consumed view of a seat, `seat:<seat>.views.<state>`, into the seat and the state; ok is false for a
+// consumed entry that is not of this kind (an event, `<emitter>.<event>`), and err says why a `seat:` entry is malformed. The
+// holder is not in it: it is resolved where the view is followed, so a new holder is followed with no change of the
+// manifest (design 47 G §616, §621).
+func SeatViewConsume(consume string) (seat, state string, ok bool, err error) {
+	rest, isSeat := strings.CutPrefix(consume, SeatViewPrefix)
+	if !isSeat {
+		return "", "", false, nil
+	}
+	seat, view, named := strings.Cut(rest, ".views.")
+	if !named || !stateName.MatchString(seat) || !stateName.MatchString(view) {
+		return "", "", true, fmt.Errorf("%q does not name a seat and its view: a consumed view of a seat is seat:<seat>.views.<state>", consume)
+	}
+	return seat, view, true, nil
+}
+
 // ReadState splits a read into the owning module and the local name, or says why it is not one.
 func ReadState(read string) (module, local string, err error) {
 	at := strings.LastIndex(read, ".")