review: a cancelled turn keeps its trace, and a quiet box still expires (V-629)

Two defects found reviewing the PR.

The insert ran on the turn's own context, so a caller that hung up or timed out
cancelled it. That is exactly the turn worth having. It now runs detached, with
a one-second bound of its own, because a write must not hold the reply.

Retention was enforced on write alone, so a box that goes quiet for a month kept
every row until the next sixty-fourth turn. pruneTracesOnStart closes that, and
RoutingTraceRetention is exported so the daemon reads the same number the store
enforces.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0117tgnmbgZpHVV3XSNw8Qua

cmd/mavend/routingtrace.go

@@ -16,6 +16,7 @@ import (
 	"encoding/json"
 	"log"
 	"strings"
+	"time"
 
 	"github.com/kami/maven/internal/decision"
 	"github.com/kami/maven/internal/store"
@@ -37,6 +38,21 @@ func traceSink(s *store.Store) traceWriter {
 	return s
 }
 
+// pruneTracesOnStart enforces retention once at wiring time. Pruning on write
+// alone is not enough: a box that goes quiet for a month keeps every row until
+// the next sixty-fourth turn, and "kept for fourteen days" would then be true
+// only of a box in daily use. Called for its effect and never blocks a start.
+func pruneTracesOnStart(s *store.Store, now time.Time) {
+	if s == nil {
+		return
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+	if err := s.PruneRoutingTraces(ctx, now.Add(-store.RoutingTraceRetention)); err != nil {
+		log.Printf("routing trace: prune on start: %v", err)
+	}
+}
+
 // persistDecision writes one finished record. It takes the same *decision.Record
 // the ring takes, so the two sinks cannot disagree about what the turn did.
 //
@@ -46,6 +62,13 @@ func (h *reactiveHandler) persistDecision(ctx context.Context, rec *decision.Rec
 	if h.traces == nil || rec == nil || strings.TrimSpace(rec.Utterance) == "" {
 		return
 	}
+	// Detached from the turn's context, and bounded on its own. Two reasons, and
+	// the first is the one that matters: the turn is over by the time this runs,
+	// so a caller that hung up or timed out would cancel the insert, and the turn
+	// he abandoned halfway is exactly the one worth having. The second is that a
+	// write must not hold the reply, so it gets a second and no more.
+	ctx, cancel := context.WithTimeout(context.WithoutCancel(ctx), time.Second)
+	defer cancel()
 	claims, err := json.Marshal(rec.Claims)
 	if err != nil {
 		log.Printf("routing trace: marshal claims: %v", err)

cmd/mavend/voicewire.go

@@ -149,6 +149,9 @@ func wireVoice(cfg *config.Config, coreAPI ipc.CoreAPI, phr phraser.Phraser, mem
 	w.embedder = emb
 	repairFactVectors(dataStore, emb)
 	checkStoredEmbedder(dataStore, emb)
+	// Retention is enforced on write, which is not enough on its own: a box that
+	// goes quiet keeps every trace until the next sixty-fourth turn (V-629).
+	pruneTracesOnStart(dataStore, time.Now())
 
 	// ----- tool executor (the enabled act allowlist, store-backed) -----
 	// Config tools are the declarative bootstrap: seed them into the store as