Keep the assignments and each module's declared config on the bus

mesh-config resolves a module's config values per node from which module runs
where and what each registered module declares, and both lived only in the
controller's store (hq issue 652, design 57 F3). The controller now keeps two
record mirrors, mesh-controller_assignments (<node>.<module>) and
mesh-controller_declared-config (<module>), built from the store by the lease
holder every ten seconds and written only where a value differs, by
compare-and-set, with one assignment-changed or declared-config-changed per
write and a purge said as removed (ADR 0289, design 54 §2-3). A module reads
them through `reads` as mesh-controller.<mirror>; the writers table keeps every
other writer out. Neither holds a secret: an assignment names its node and
module, a declaration is what the public manifest declares.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/broker/controller_buckets.go

@@ -40,6 +40,39 @@ var (
 	AskedBucket = BucketName(ControllerSeat, "asked")
 )
 
+// The controller's record mirrors (novox/hq ADR 0289, design 54, design 57 package F3): a bucket per kind of
+// record, one key per record, written from the store by the lease holder only when the record changed, with
+// one event on the controller's seat per write. Read by whatever names them in `reads` as
+// `mesh-controller.<mirror>` (ADR 0201 §1), written by nobody else. **No secret in either** (ADR 0201): an
+// assignment's value names its module and node; a module's declared config is what its manifest, which is
+// public, declares.
+//
+// AssignmentsBucket holds which module is assigned to which node, keyed `<node>.<module>`; and
+// DeclaredConfigBucket each registered module's config declarations as its manifest holds them, keyed by
+// the module: what mesh-config resolves a config value from (ADR 0348 clauses 2 and 4).
+var (
+	AssignmentsBucket    = BucketName(ControllerSeat, MirrorAssignments)
+	DeclaredConfigBucket = BucketName(ControllerSeat, MirrorDeclaredConfig)
+)
+
+// The mirrors' local names, as a reader names them in `reads` after `mesh-controller.`.
+const (
+	MirrorAssignments    = "assignments"
+	MirrorDeclaredConfig = "declared-config"
+)
+
+// ControllerMirrors are the local names of the controller's record mirrors, which a module may read.
+func ControllerMirrors() []string { return []string{MirrorAssignments, MirrorDeclaredConfig} }
+
+// The mirrors' caps (design 54 §5): one value per key, no age, 64 KiB a value, 64 MiB a bucket.
+const (
+	MirrorValueBytes = 64 << 10
+	MirrorBytes      = 64 << 20
+	// MirrorMarkerTTL is the longest a purge's marker is kept (design 54 §2): the bucket allows a
+	// per-message age for it, and the writer gives each marker a day.
+	MirrorMarkerTTL = 24 * time.Hour
+)
+
 // AskedKeptFor is how long an ask is kept after it was made: a month, as the router keeps its own.
 const AskedKeptFor = 30 * 24 * time.Hour
 
@@ -66,12 +99,14 @@ const (
 // IsControllerBucket says a bucket is the controller's own, not a module's state nothing declares.
 func IsControllerBucket(bucket string) bool {
 	return bucket == CallsBucket || bucket == HandActsBucket || bucket == ConditionsBucket ||
-		bucket == ConditionHistoryBucket || bucket == LeaseBucket || bucket == AskedBucket
+		bucket == ConditionHistoryBucket || bucket == LeaseBucket || bucket == AskedBucket ||
+		bucket == AssignmentsBucket || bucket == DeclaredConfigBucket
 }
 
 // ControllerBuckets are the controller's own buckets, in the order they are asserted.
 func ControllerBuckets() []string {
-	return []string{LeaseBucket, CallsBucket, HandActsBucket, ConditionsBucket, ConditionHistoryBucket, AskedBucket}
+	return []string{LeaseBucket, CallsBucket, HandActsBucket, ConditionsBucket, ConditionHistoryBucket, AskedBucket,
+		AssignmentsBucket, DeclaredConfigBucket}
 }
 
 // ControllerBucketsAsserter is what raising the controller's buckets needs of a connection.
@@ -168,6 +203,27 @@ func (j *JetStream) EnsureControllerBuckets() error {
 	}); err != nil {
 		return fmt.Errorf("asserting bucket %s: %w", AskedBucket, err)
 	}
+	// **The record mirrors: no age** (design 54 §5). A key is removed when its record is, by a purge whose
+	// marker lives a day; a key that expired would be a record the bus forgot while the store still holds it.
+	for _, m := range []struct{ bucket, why string }{
+		{AssignmentsBucket, "which module is assigned to which node, keyed <node>.<module> (novox/hq ADR 0289, " +
+			"design 54): written by the controller alone from its store when an assignment changes, read through `reads`"},
+		{DeclaredConfigBucket, "each registered module's config declarations as its manifest holds them, keyed by " +
+			"the module (novox/hq ADR 0348, design 57 F3): written by the controller alone from its store when a " +
+			"registration changes them, read through `reads`"},
+	} {
+		if _, err := js.CreateOrUpdateKeyValue(ctx, jetstream.KeyValueConfig{
+			Bucket:         m.bucket,
+			Description:    m.why,
+			History:        1,
+			MaxValueSize:   MirrorValueBytes,
+			MaxBytes:       MirrorBytes,
+			Storage:        jetstream.FileStorage,
+			LimitMarkerTTL: MirrorMarkerTTL,
+		}); err != nil {
+			return fmt.Errorf("asserting bucket %s: %w", m.bucket, err)
+		}
+	}
 	return nil
 }