mesh-issues: keep every issue in the log changes and the bucket as its fold, so the record outlives the bucket's cap and a week of events (hq ADR 0300, issues 501, 502)

Every write appends one operation at the issue's last sequence before the
bucket is written; a refused append writes nothing. The start carries what
the bucket holds, refolds what is behind and indexes every issue in memory,
so list answers from memory with a ranked search and a before cursor.

modules/mesh-issues/cmd/mesh-issues/tracker_test.go

@@ -106,19 +106,19 @@ func TestAnIssuesKeyIsNeverOverwrittenAndTheFaultIsSaid(t *testing.T) {
 func TestANumberTakenAndNotWrittenIsSaidAndNeverHandedOutAgain(t *testing.T) {
 	h := newHarness(t)
 	h.open(t, "first")
-	h.mem.fail[IssuesState] = errors.New("the bus did not answer")
+	h.log.failNext = 1
 	// One failure is tried again and succeeds: no gap.
 	if got := h.open(t, "second"); got != 366 {
 		t.Fatalf("got %d", got)
 	}
-	// Failing every time leaves a gap, said.
-	failing := &failingStore{memory: h.mem, failCreates: createAttempts}
-	h.Store = failing
+	// Failing every time spends the number, said (novox/hq ADR 0300 §2).
+	h.log.failNext = createAttempts
 	_, err := h.Open(OpenAsk{Title: "third", Report: "r"})
-	if err == nil || !strings.Contains(err.Error(), "may have been written") || !strings.Contains(err.Error(), "get 367") {
-		t.Fatalf("a write that never landed: %v", err)
+	if err == nil || !strings.Contains(err.Error(), "367 is spent") || !strings.Contains(err.Error(), "did not answer") {
+		t.Fatalf("an append that never landed: %v", err)
 	}
-	h.Store = h.mem
+	// A bucket that takes no write after the log took the issue: the issue is opened, the bucket folds it later.
+	h.mem.fail[IssuesState] = errors.New("the bus did not answer")
 	if got := h.open(t, "fourth"); got != 368 {
 		t.Fatalf("got %d, want 368: a number is never handed out twice", got)
 	}
@@ -189,17 +189,30 @@ func (u unreadable) Get(state, key string) (*Entry, error) {
 	return u.memory.Get(state, key)
 }
 
-// An open whose write may have landed never says nothing was opened (the review of 2026-10-10).
+// unreadableLog loses every append's answer and cannot be read back.
+type unreadableLog struct{ *fakeLog }
+
+func (u unreadableLog) AppendAt(key string, value any, expect uint64) (uint64, error) {
+	_, _ = u.fakeLog.AppendAt(key, value, expect)
+	return 0, errors.New("no answer in 30 s")
+}
+func (u unreadableLog) Last(string) (*stdio.LogEntry, error) {
+	return nil, errors.New("no answer in 30 s")
+}
+
+// An open whose write may have landed never says nothing was opened (the review of 2026-10-10), in the bucket
+// or in the log.
 func TestAnOpenWhoseWriteMayHaveLandedNeverSaysNothingWasOpened(t *testing.T) {
 	h := newHarness(t)
 	h.Store = lostEvery{h.mem}
 	if o, err := h.Open(OpenAsk{Title: "t", Report: "r"}); err != nil || o.Number != 365 {
 		t.Fatalf("a write that landed, every answer lost: %v %v", o, err)
 	}
-	h.Store = unreadable{h.mem}
+	h.Store = h.mem
+	h.Log = unreadableLog{h.log}
 	_, err := h.Open(OpenAsk{Title: "t", Report: "r"})
 	if err == nil || strings.Contains(err.Error(), "nothing was opened") || !strings.Contains(err.Error(), "get 366") {
-		t.Fatalf("a taken key that cannot be read back: %v", err)
+		t.Fatalf("an append whose answer was lost and cannot be read back: %v", err)
 	}
 }