v0.121.1: 'nothing is due' must be AUDIBLE (R-86 + standing rule 3)

Before R-86 every tick ran a heavy restore-test, so the scheduler was audible by
construction. After it, 'nothing is due' is the NORMAL outcome — and it was
logged at DEBUG, which journald drops. An empty journal would then be equally
consistent with a healthy loop and a dead goroutine: the shape the R-88 watcher
was retired for, re-created by making the quiet path the common one.

A not-due evaluation now logs one INFO line naming every tier's verdict (four
lines a day at the 6h default), and an unlistable tier reads UNKNOWN with its
error in that same line, so a lookup failure can never present as 'nothing due'.

Red-proved through the scheduler's own tick, not the helper.

internal/backup/restoretest_due.go

@@ -140,3 +140,29 @@ func (s *Scheduler) evaluateTier(ctx context.Context, target string, cutoff time
 func (s *Scheduler) EvaluateDueTier(ctx context.Context, target string) DueVerdict {
 	return s.evaluateTier(ctx, target, s.settleCutoff())
 }
+
+// verdictSummary renders one compact line of per-tier verdicts for the "nothing due" log.
+//
+// It re-evaluates rather than threading the verdicts out of pickForThisRun, and that is a
+// deliberate trade: this runs only on the path where NOTHING is due, so the cost is one extra
+// storage listing per tier on an otherwise idle evaluation (measured 18 ms local / 392 ms offsite,
+// R-86 Part 1.4), and in exchange the logging path cannot drift from the deciding path by holding a
+// stale copy of it. If that cost ever matters, pass the verdicts in — do not let the two diverge.
+func (s *Scheduler) verdictSummary(ctx context.Context) string {
+	out := ""
+	for _, v := range s.EvaluateDue(ctx) {
+		if out != "" {
+			out += "; "
+		}
+		switch {
+		case v.Err != nil:
+			out += v.Target + ": UNKNOWN (" + v.Err.Error() + ")"
+		default:
+			out += v.Target + ": " + v.Reason
+		}
+	}
+	if out == "" {
+		return "no tiers configured"
+	}
+	return out
+}

internal/backup/restoretest_due_test.go

@@ -4,8 +4,10 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"log/slog"
 	"os"
 	"path/filepath"
+	"strings"
 	"testing"
 	"time"
 
@@ -124,8 +126,8 @@ func dailyArchives(tier string, n int) []archiveStub {
 // COMPANION RED-PROOF (observed 2026-08-03). In Scheduler.evaluateTier, the per-archive comparison
 // was replaced by the naive age rule:
 //
-//	-	if ok && proven == archive { … not due … }
-//	+	if s.now().Sub(landed) < s.settle { … not due … }   // and the proven-archive check deleted
+//   - if ok && proven == archive { … not due … }
+//   - if s.now().Sub(landed) < s.settle { … not due … }   // and the proven-archive check deleted
 //
 // and the picker cutoff was removed (`cutoff := time.Time{}`), i.e. exactly "is the newest archive
 // old enough". Result:
@@ -194,12 +196,13 @@ func TestDue_WeeklyTierIsProvedOncePerArchive(t *testing.T) {
 // COMPANION RED-PROOF (observed 2026-08-03): revert the state to per-tier TIME by making
 // ProvenArchive ignore the stored archive —
 //
-//	-	if !ok || p.Archive == "" { return "", false }
-//	+	return "", false     // per-tier time only, the pre-R-86 state
+//   - if !ok || p.Archive == "" { return "", false }
+//   - return "", false     // per-tier time only, the pre-R-86 state
 //
 // →	--- FAIL: TestDue_RestartRunsNothing
-//	    restoretest_due_test.go:226: an agent restart must not trigger a restore-test; 2 restart(s)
-//	    produced 4 run(s)
+//
+//	restoretest_due_test.go:226: an agent restart must not trigger a restore-test; 2 restart(s)
+//	produced 4 run(s)
 //
 // Four: the same already-proven archive re-tested on EVERY evaluation after EVERY restart, which is
 // today's behaviour with the ticker's phase reset by the deploy. Restored.
@@ -256,12 +259,13 @@ func TestDue_NewSettledArchiveMakesAProvedTierDueAgain(t *testing.T) {
 //
 // COMPANION RED-PROOF (observed 2026-08-03): give credit on failure in Scheduler.tick —
 //
-//	-	if rt.Pass && s.rtState != nil && target != "" {
-//	+	if s.rtState != nil && target != "" {
+//   - if rt.Pass && s.rtState != nil && target != "" {
+//   - if s.rtState != nil && target != "" {
 //
 // →	--- FAIL: TestDue_FailingTierIsRetriedAndNeverProven
-//	    restoretest_due_test.go: a failing tier must keep being retried; got 1 run(s) over 3
-//	    evaluations
+//
+//	restoretest_due_test.go: a failing tier must keep being retried; got 1 run(s) over 3
+//	evaluations
 //
 // A single failure would have retired the archive as proven — a permanently broken DR tier looking
 // freshly verified, which is the loudest signal this system produces going silent. Restored.
@@ -456,3 +460,48 @@ func TestRestoreTestState_ArchiveRoundTrips(t *testing.T) {
 func writeFileForTest(path, content string) error {
 	return os.WriteFile(path, []byte(content), 0o600)
 }
+
+// Standing rule 3: an absent log line is not evidence. "Nothing is due" is now the NORMAL outcome of
+// an evaluation, so it must produce a POSITIVE observable naming each tier's verdict — otherwise a
+// quiet journal is equally consistent with a healthy loop and a dead goroutine.
+//
+// COMPANION RED-PROOF (observed 2026-08-03): drop the summary back to a bare
+// `s.logger.Debug("backup: restore-test not due this evaluation")` and this fails with
+// "a not-due evaluation must name each tier's verdict; got \"\"" — i.e. nothing at INFO at all.
+func TestDue_NothingDueStillNamesEveryTiersVerdict(t *testing.T) {
+	ts := &tierStorage{archives: map[string][]archiveStub{
+		"local":      {{volid: "local:backup/a.tar.zst", landed: day0}},
+		"felhom-pbs": nil, // no archive at all
+	}}
+	h := newDueHarness(t, day0.AddDate(0, 0, 1), 24*time.Hour, true, []string{"local", "felhom-pbs"}, ts)
+	// Prove the local tier so NOTHING is due.
+	if err := h.st.RecordSuccess("local", "local:backup/a.tar.zst", h.clock); err != nil {
+		t.Fatal(err)
+	}
+
+	// Assert what the SCHEDULER emits on a real evaluation, not what a helper returns — a helper
+	// test would pass against a tick that never calls it.
+	var logbuf strings.Builder
+	h.s.logger = slog.New(slog.NewTextHandler(&logbuf, &slog.HandlerOptions{Level: slog.LevelInfo}))
+	h.s.tick(context.Background())
+	got := logbuf.String()
+	for _, want := range []string{"local", "felhom-pbs", "already proven", "no settled archive"} {
+		if !strings.Contains(got, want) {
+			t.Fatalf("a not-due evaluation must name each tier's verdict; got %q (missing %q)", got, want)
+		}
+	}
+}
+
+// A tier whose storage cannot be listed must say UNKNOWN in that same line — a lookup failure that
+// reads as "nothing due" is the silence this rule exists to prevent.
+func TestDue_VerdictSummaryNamesAnUnknownTier(t *testing.T) {
+	ts := &tierStorage{
+		archives: map[string][]archiveStub{"local": nil},
+		err:      map[string]error{"felhom-pbs": errors.New("storage unreachable")},
+	}
+	h := newDueHarness(t, day0, 24*time.Hour, true, []string{"local", "felhom-pbs"}, ts)
+	got := h.s.verdictSummary(context.Background())
+	if !strings.Contains(got, "UNKNOWN") || !strings.Contains(got, "storage unreachable") {
+		t.Fatalf("an unlistable tier must read as UNKNOWN with its error; got %q", got)
+	}
+}

internal/backup/schedule.go

@@ -180,7 +180,15 @@ func (s *Scheduler) tick(ctx context.Context) {
 		return
 	}
 	if archive == "" {
-		s.logger.Debug("backup: restore-test not due this evaluation")
+		// A POSITIVE OBSERVABLE, at INFO, and this is not noise — it is standing rule 3.
+		//
+		// Before R-86 every tick ran a heavy restore-test, so the scheduler was audible by
+		// construction. Now "nothing is due" is the NORMAL outcome, and at DEBUG it is silent: an
+		// empty journal would be equally consistent with a healthy loop and with a dead goroutine,
+		// which is the exact shape the R-88 watcher was retired for. One line per evaluation is four
+		// lines a day at the 6h default, and it names each tier's verdict so the answer to "why did
+		// nothing run last night?" is in the log rather than in a re-derivation.
+		s.logger.Info("backup: restore-test evaluated — nothing due", "verdicts", s.verdictSummary(ctx))
 		return
 	}