C4: a statement keeps since when its engine is unanswered, and the keeper names each node unanswered past a bound while heard (issue 1966, ADR 0668 §3; review round 1, finding 4)

Claude-Session: https://claude.ai/code/session_01JG73KEq4zoDfM9WtYpcQgZ

go/clients/nodeengineclient/enginereads/enginereads.go

@@ -137,6 +137,9 @@ type Statement struct {
 	Answered      bool      `json:"answered"`
 	Words         string    `json:"words,omitempty"`
 	AskAgain      *Again    `json:"ask-again,omitempty"`
+	// UnansweredSince is when the engine first did not answer, of the asks since its last answer; zero once answered
+	// (ADR 0668 §3: a kept call unanswered past five minutes is a finding of its caller).
+	UnansweredSince time.Time `json:"unanswered-since,omitzero"`
 }
 
 // Again is a person's ask again of one node, written by the tool and answered by the part that keeps the state.
@@ -328,6 +331,31 @@ func (k *Keeper) settle(s Statement, why string) {
 	k.take(s)
 }
 
+// Unanswered is, of nodes, each whose engine the kept call has not answered for bound or longer by now while heard says
+// its machine is heard, with since when (novox/hq ADR 0668 §3); a node whose machine is away is none. With no Call, none.
+func (k *Keeper) Unanswered(nodes []string, heard func(node string) bool, bound time.Duration, now time.Time) map[string]time.Time {
+	out := map[string]time.Time{}
+	if k.Call == nil {
+		return out
+	}
+	k.mu.Lock()
+	defer k.mu.Unlock()
+	for _, node := range nodes {
+		s, ok := k.by[node]
+		if ok && !s.Answered && !s.UnansweredSince.IsZero() && now.Sub(s.UnansweredSince) >= bound && heard(node) {
+			out[node] = s.UnansweredSince
+		}
+	}
+	return out
+}
+
+// Asking says an ask of node runs now.
+func (k *Keeper) Asking(node string) bool {
+	k.mu.Lock()
+	defer k.mu.Unlock()
+	return k.asking[node]
+}
+
 // take keeps s, unless the node did not answer and an earlier statement stands: an away node keeps its last one (ADR 0624
 // §1), marked as not answering.
 func (k *Keeper) take(s Statement) {
@@ -335,8 +363,14 @@ func (k *Keeper) take(s Statement) {
 	if k.by == nil {
 		k.by = map[string]Statement{}
 	}
+	if !s.Answered {
+		s.UnansweredSince = s.AskedAt
+		if old, ok := k.by[s.Node]; ok && !old.Answered && !old.UnansweredSince.IsZero() {
+			s.UnansweredSince = old.UnansweredSince
+		}
+	}
 	if old, ok := k.by[s.Node]; ok && !s.Answered && old.From != FromNone {
-		old.Answered, old.AskedAt, old.Words, old.AskAgain = false, s.AskedAt, s.Words, nil
+		old.Answered, old.AskedAt, old.Words, old.AskAgain, old.UnansweredSince = false, s.AskedAt, s.Words, nil, s.UnansweredSince
 		s = old
 	}
 	k.by[s.Node] = s

go/clients/nodeengineclient/enginereads/enginereads_test.go

@@ -71,6 +71,30 @@ func TestTheAnswerAndTheEventAreJudged(t *testing.T) {
 	if during.From != FromRecord || during.Answered || f.Statements()["g14"].From != FromVerb {
 		t.Errorf("while the kept call asked g14 read %+v; after it %+v", during, f.Statements()["g14"])
 	}
+	// ADR 0668 §3: a node unanswered keeps when it first was not, across asks; past the bound it is unanswered while its
+	// machine is heard, none while away, and none once it answers.
+	clock := time.Date(2026, 11, 10, 3, 0, 0, 0, time.UTC)
+	answers := false
+	u := &Keeper{Sync: true, Now: func() time.Time { return clock }, Call: func(node, _ string, _ any) (json.RawMessage, error) {
+		if answers {
+			return json.RawMessage(`{"v":1,"node":"` + node + `","manifest-reads":["a.b"],"stated-at":"` + at + `"}`), nil
+		}
+		return nil, context.DeadlineExceeded
+	}}
+	first := clock
+	u.AskNode("ace", "the first view")
+	clock = clock.Add(6 * time.Minute)
+	u.AskNode("ace", "asked on")
+	heard := func(string) bool { return true }
+	if got := u.Unanswered([]string{"ace"}, heard, 5*time.Minute, clock); !got["ace"].Equal(first) ||
+		len(u.Unanswered([]string{"ace"}, func(string) bool { return false }, 5*time.Minute, clock)) != 0 {
+		t.Errorf("unanswered past the bound: %v", got)
+	}
+	answers = true
+	u.AskNode("ace", "answered")
+	if got := u.Unanswered([]string{"ace"}, heard, 5*time.Minute, clock); len(got) != 0 || !u.Statements()["ace"].UnansweredSince.IsZero() {
+		t.Errorf("an answered node is unanswered: %v", got)
+	}
 	if Verb != "manifest-reads" || Event != "manifest-reads-changed" || Consumes != "node-engine.manifest-reads-changed" || Invoke != "seat:node-engine.manifest-reads" {
 		t.Errorf("the names are %s %s %s %s", Verb, Event, Consumes, Invoke)
 	}