DLV-FB1 (indexer's side): a FORGE message of a kind the indexer does not take is acknowledged and passed over

The forge bridge now says a branch's end as branch-deleted (design 51); the
indexer terminated it as unreadable. It acknowledges it, writes it to heard
as ignored, and the two handle tests are one table (mesh-delivery is over
its unit budget).

Issue 1966.

Claude-Session: https://claude.ai/code/session_01JG73KJNrH5EgFXMKKYSrig

modules/mesh-delivery-indexer/cmd/mesh-delivery-indexer/main.go

@@ -10,6 +10,7 @@ package main
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
@@ -171,6 +172,13 @@ func handle(ctx context.Context, m delivered, ix *index.Indexer, heard index.Sto
 			logger.Printf("%s: sequence %d is not written to the heard state: %v", h.Subject, h.Sequence, err)
 		}
 	}()
+	if kind, known := forgeKind(m.Data()); !known {
+		// A kind the indexer does not take (the bridge's branch-deleted, design 51) is acknowledged and passed over, never
+		// terminated as unreadable: a new kind on FORGE is no fault of the message.
+		h.Kind, h.Outcome, h.Words = kind, index.HeardIgnored, "a "+kind+" message, which the indexer does not take"
+		_ = m.Ack()
+		return
+	}
 	f, err := delivery.DecodeForge(m.Data())
 	if err != nil {
 		logger.Printf("%s: not a forge message, dropped: %v", m.Subject(), err)
@@ -203,6 +211,22 @@ func handle(ctx context.Context, m delivered, ix *index.Indexer, heard index.Sto
 	}
 }
 
+// forgeKind is the kind a FORGE message names, and whether it is one the indexer takes; a body naming no kind is taken,
+// so DecodeForge says why it is unreadable.
+func forgeKind(data []byte) (string, bool) {
+	var probe struct {
+		Kind string `json:"kind"`
+	}
+	if json.Unmarshal(data, &probe) != nil || probe.Kind == "" {
+		return "", true
+	}
+	switch probe.Kind {
+	case delivery.ForgePull, delivery.ForgeMerged, delivery.ForgeRefused, delivery.ForgeOpen:
+		return probe.Kind, true
+	}
+	return probe.Kind, false
+}
+
 func opOf(e jetstream.KeyValueEntry) bool {
 	return e.Operation() == jetstream.KeyValuePut
 }

modules/mesh-delivery-indexer/cmd/mesh-delivery-indexer/main_test.go

@@ -71,6 +71,32 @@ func (m *memStore) Delete(_ context.Context, k string, _ uint64) error { delete(
 const head = "0123456789abcdef0123456789abcdef01234567"
 
 func TestAMessageIsIndexedAndAcked(t *testing.T) { // 1238/AC2 (unit part)
+	t.Run("not a forge message: terminated and logged", func(t *testing.T) { // 1238 (never redelivered)
+		var logs bytes.Buffer
+		st := &memStore{vals: map[string][]byte{}}
+		m := &fakeMsg{subject: "mesh.stream.mesh-delivery-forge-bridge.event.forge.x.y.pull", data: []byte(`{"v":1,"kind":"pull"}`)}
+		heard := &memStore{vals: map[string][]byte{}}
+		handle(context.Background(), m, &index.Indexer{Store: st, Builds: index.NewBuilds()}, heard, log.New(&logs, "", 0))
+		if m.termd != 1 || m.acked != 0 || len(st.vals) != 0 || !strings.Contains(logs.String(), m.subject) {
+			t.Errorf("terminated %d acked %d keys %d log %q", m.termd, m.acked, len(st.vals), logs.String())
+		}
+		if h := heardOf(t, heard); h.Outcome != index.HeardDropped || h.Sequence != 41 || h.Words == "" {
+			t.Errorf("heard = %+v", h)
+		}
+	})
+	t.Run("a kind it does not take (branch-deleted): acknowledged and passed over", func(t *testing.T) { // design 51, DLV-FB1
+		st := &memStore{vals: map[string][]byte{}}
+		m := &fakeMsg{subject: "mesh.stream.mesh-delivery-forge-bridge.event.forge.novox.mesh-sdk.branch-deleted",
+			data: []byte(`{"v":1,"kind":"branch-deleted","repository":"novox/mesh-sdk","branch":"feat/x","head":"` + head + `"}`)}
+		heard := &memStore{vals: map[string][]byte{}}
+		handle(context.Background(), m, &index.Indexer{Store: st, Builds: index.NewBuilds()}, heard, log.New(&bytes.Buffer{}, "", 0))
+		if m.termd != 0 || m.acked != 1 || len(st.vals) != 0 {
+			t.Errorf("terminated %d acked %d keys %d", m.termd, m.acked, len(st.vals))
+		}
+		if h := heardOf(t, heard); h.Outcome != index.HeardIgnored || h.Kind != "branch-deleted" {
+			t.Errorf("heard = %+v", h)
+		}
+	})
 	st := &memStore{vals: map[string][]byte{}}
 	ix := &index.Indexer{Store: st, Builds: index.NewBuilds()}
 	data, _ := delivery.EncodeForge(delivery.Forge{Kind: delivery.ForgePull, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12, Head: head,
@@ -90,20 +116,6 @@ func TestAMessageIsIndexedAndAcked(t *testing.T) { // 1238/AC2 (unit part)
 	}
 }
 
-func TestAMessageThatIsNoForgeMessageIsTerminatedAndLogged(t *testing.T) { // 1238 (never redelivered)
-	var logs bytes.Buffer
-	st := &memStore{vals: map[string][]byte{}}
-	m := &fakeMsg{subject: "mesh.stream.mesh-delivery-forge-bridge.event.forge.x.y.pull", data: []byte(`{"v":1,"kind":"pull"}`)}
-	heard := &memStore{vals: map[string][]byte{}}
-	handle(context.Background(), m, &index.Indexer{Store: st, Builds: index.NewBuilds()}, heard, log.New(&logs, "", 0))
-	if m.termd != 1 || m.acked != 0 || len(st.vals) != 0 || !strings.Contains(logs.String(), m.subject) {
-		t.Errorf("terminated %d acked %d keys %d log %q", m.termd, m.acked, len(st.vals), logs.String())
-	}
-	if h := heardOf(t, heard); h.Outcome != index.HeardDropped || h.Sequence != 41 || h.Words == "" {
-		t.Errorf("heard = %+v", h)
-	}
-}
-
 func TestTheSourceMainKeyIsTakenAtItsRevision(t *testing.T) { // 1344/AC1 (the watch's side: key, revision, value)
 	var logs bytes.Buffer
 	logger := log.New(&logs, "", 0)

modules/mesh-delivery-indexer/internal/index/heard.go

@@ -21,6 +21,9 @@ const (
 	HeardApplied = "applied"
 	HeardLeft    = "left for redelivery"
 	HeardDropped = "dropped"
+	// HeardIgnored is a message of a kind the indexer does not take (a branch-deleted one, design 51): acknowledged and
+	// passed over, as every existing consumer of FORGE passes over a kind it does not know.
+	HeardIgnored = "ignored"
 )
 
 // Heard is one FORGE message as the indexer handled it.

sdk/views/views_test.go

@@ -114,7 +114,9 @@ func TestViews(t *testing.T) {
 			Raise: func(s Status) { said = append(said, "raised "+s.Tool) }, Clear: func(s Status) { said = append(said, "cleared") }}
 		return f, &said
 	}
-	answer := func(context.Context, string) (Answer, error) { return FirstView("o", "modules", values, marks, "", now()) }
+	answer := func(context.Context, string) (Answer, error) {
+		return FirstView("o", "modules", values, marks, "", now())
+	}
 	ev := func(rev uint64, key, value string) Event {
 		e := Event{V: Version, Owner: "o", State: "modules", Key: key, Revision: rev, Created: made}
 		if value == "" {