The indexer binds its taken state when it appears, as issue 1790 asks of every state a delivery adds: an indexer started before the bus holds it still takes merges in and says the key it did not write (issue 1280, ADR 0556 clause 1)

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

@@ -305,10 +305,9 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 	if err != nil {
 		return err
 	}
-	taken, err := process.EssentialBucket(ctx, js, "indexer", delivery.TakenBucket, "say the merge a repository's modules were taken in at")
+	// Its taken state (ADR 0556 clause 1) is bound when it appears, as every state a delivery adds (issue 1790): until then
-	if err != nil {
+	// a merge's taken key is said and not written, and the rest of the indexer runs.
-		return err
+	taken := process.AwaitBucket(ctx, js, conn, delivery.TakenBucket, "no repository's taken key is written", logger.Printf)
-	}
 	// Its placement state (ADR 0549 §2) is bound when it appears, as every state a delivery adds (issue 1790): until then a
 	// catalogue merge's placement is said and not written, and the rest of the indexer runs.
 	placement := process.AwaitBucket(ctx, js, conn, delivery.PlacementBucket, "no catalogue merge's placement is written", logger.Printf)
@@ -345,7 +344,7 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 		return err
 	}
 	defer calls.Close()
-	ix := &index.Indexer{Store: kvStore{candidates}, Modules: kvStore{modules}, Manifests: kvStore{manifests}, Taken: kvStore{taken}, Builds: known, Logf: logger.Printf,
+	ix := &index.Indexer{Store: kvStore{candidates}, Modules: kvStore{modules}, Manifests: kvStore{manifests}, Taken: awaitedStore{taken}, Builds: known, Logf: logger.Printf,
 		Named: namedVia(calls.Call), Trunk: trunkVia(calls.Call), Contains: containsVia(calls.Call), Read: readVia(calls.Call),
 		Placement: awaitedStore{placement}, Say: func(event string, body any) error { return calls.Emit(event, body) }}
 	// The gate's source bucket (mesh-delivery-gate_source) comes with the gate (release 3e, novox/hq ADR 0450 §1): its key

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

@@ -17,8 +17,9 @@ const (
 
 // memStore is the candidates bucket's compare-and-set behaviour in memory: a revision per write, a conflict when the
 // revision read is no longer the key's. Writes counts the writes that went through; beforeWrite lets a test change the
-// key under the indexer.
+// key under the indexer; unbound, when set, is every read's error (a state not yet on the bus).
 type memStore struct {
+	unbound     error
 	vals        map[string][]byte
 	revs        map[string]uint64
 	next        uint64
@@ -29,6 +30,9 @@ type memStore struct {
 func newMem() *memStore { return &memStore{vals: map[string][]byte{}, revs: map[string]uint64{}} }
 
 func (m *memStore) Get(_ context.Context, key string) ([]byte, uint64, bool, error) {
+	if m.unbound != nil {
+		return nil, 0, false, m.unbound
+	}
 	v, ok := m.vals[key]
 	return v, m.revs[key], ok, nil
 }

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

@@ -8,6 +8,7 @@ import (
 	"testing"
 
 	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-sdk/go/process"
 )
 
 const merge = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
@@ -111,6 +112,13 @@ func TestAnUnchangedModuleWritesNothing(t *testing.T) { // 1239 (unchanged value
 				m.Merge = next
 				return ix.Apply(context.Background(), m)
 			}},
+		{name: "a merge while the taken state is not on the bus yet is still taken in", writes: 1, commit: map[string]string{"a": next, "b": merge, "c": merge}, taken: merge,
+			then: func(ix *Indexer) error { // issue 1790: the state is bound when it appears, so the indexer runs before it does
+				ix.Taken = &memStore{unbound: process.ErrNotYet}
+				m := mergedMsg(repo, map[string]string{"modules/a": "treeA2", "modules/b": "treeB", "modules/c": "treeC"})
+				m.Merge = next
+				return ix.Apply(context.Background(), m)
+			}},
 		{name: "an earlier merge heard again after a later one leaves taken", writes: 0, commit: map[string]string{"a": merge, "b": merge, "c": merge}, taken: merge,
 			then: func(ix *Indexer) error {
 				ix.Contains = func(_ context.Context, _, commit, in string) (bool, error) { return commit == next && in == merge, nil }

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

@@ -2,9 +2,11 @@ package index
 
 import (
 	"context"
+	"errors"
 	"time"
 
 	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-sdk/go/process"
 )
 
 // What the indexer took in (novox/hq ADR 0556 clause 1, issue 1280): after a merged message is applied whole, the key of
@@ -23,7 +25,7 @@ func (ix *Indexer) writeTaken(ctx context.Context, f delivery.Forge) error {
 		ix.logf("%s at %s: no taken key is written: %v", f.Repository, f.Merge, err)
 		return nil
 	}
-	return write(ctx, ix.Taken, key, func(value []byte, found bool) ([]byte, bool, error) {
+	err = write(ctx, ix.Taken, key, func(value []byte, found bool) ([]byte, bool, error) {
 		if found {
 			if cur, err := delivery.DecodeTaken(value); err == nil {
 				if cur.Merge == f.Merge {
@@ -48,4 +50,11 @@ func (ix *Indexer) writeTaken(ctx context.Context, f delivery.Forge) error {
 		data, err := delivery.EncodeTaken(delivery.Taken{Repository: delivery.RepositoryName(f.Repository), Merge: f.Merge, At: now().UTC()})
 		return data, false, err
 	})
+	if errors.Is(err, process.ErrNotYet) {
+		// The state is not on the bus yet (a delivery that adds it, bound when it appears as issue 1790 says): said, and
+		// the merge's modules are still taken in; the next merge of the repository writes its key once the state appears.
+		ix.logf("%s at %s: its taken key is not written: %v", f.Repository, f.Merge, err)
+		return nil
+	}
+	return err
 }