Let a module's log keep its entries for an age, so the hand-act log holds each act 400 days as ADR 0565 decides instead of refusing when full (issue 1953 S-age)

go/buscompose/log.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"sort"
 	"strings"
+	"time"
 
 	"github.com/nats-io/nats.go/jetstream"
 )
@@ -37,6 +38,8 @@ type Log struct {
 	Name   string
 	// MaxMiB is its cap in MiB; zero is LogDefaultMiB.
 	MaxMiB int
+	// MaxAgeDays is how long an entry is kept; zero is as long as the log (catalogue.LogDeclaration).
+	MaxAgeDays int
 }
 
 // LogStreamPrefix starts every log's stream name, which no other stream of the mesh's starts with.
@@ -74,7 +77,7 @@ func (l Log) Why() string {
 }
 
 // Config is the stream a log is, field by field as novox/hq ADR 0297 fixes it: a file stream kept by
-// limits, with no maximum age and no cap per key, whose message is an entry's value and 4 KiB of
+// limits, with no maximum age unless the log says one (ADR 0565 §10) and no cap per key, whose message is an entry's value and 4 KiB of
 // headers at most, that refuses a new entry when full rather than
 // drop an old one, and that refuses deleting an entry or purging it. Direct gets are allowed, which
 // is how the runtime reads it.
@@ -85,7 +88,7 @@ func (l Log) Config() jetstream.StreamConfig {
 		Subjects:          []string{l.Subject() + ".>"},
 		Storage:           jetstream.FileStorage,
 		Retention:         jetstream.LimitsPolicy,
-		MaxAge:            0,
+		MaxAge:            time.Duration(l.MaxAgeDays) * 24 * time.Hour,
 		MaxMsgs:           -1,
 		MaxMsgsPerSubject: -1,
 		MaxBytes:          l.MaxBytes(),