review: verdigris patina, honest Lane figures, tests that can fail (#102)

Two-axis review found the shipped colour and three weak tests.

- --patina was a warm gold at the same hue family as --brass; the spec
  asked for a cool blue-green so an unhealthy Lane is unmistakably not
  ember. Now verdigris in both branches, with docs/design-system.md
  stating why the far side of the wheel is the point.
- A Lane pass that returns before computing its figures carries the
  previous pass's due count and gap forward instead of recording zeroes,
  and Checked rides beside Due so a stopped Lane is distinguishable from
  a quiet one.
- TestAdminPageWithoutAPollerSaysSo now separates the two causes it
  conflated, TestOwnerClearsReaderMarks seeds real counters so the
  clearing assertion can fail, and TestLaneStatus asserts Checked and
  the carry-forward.
- backend/AGENTS.md records the one deliberate owner comparison outside
  requireOwner and the carry-forward rule.

backend/internal/latest/poller.go

@@ -246,19 +246,23 @@ func (p *Poller) runLanePass(ctx context.Context, name string, paced bool) time.
 		// No fetcher at all right now (browser absent, no fallback): every
 		// Series stays unstamped and due, so a browser that appears after a
 		// restart finds its full queue waiting (issue #100).
+		st.Gap = defaultGap
 		return defaultGap
 	}
 
 	due, err := p.Store.DueForLatestCheck(name, now.Add(-s.Rest).UnixMilli())
 	if err != nil {
 		log.Printf("latest poll %s: due query: %v", name, err)
+		st.Gap = defaultGap
 		return defaultGap
 	}
 	st.Due = len(due)
 	if s.Browser != nil && f == p.BrowserFetch && !browserWakeDue(due, now, s.Rest) {
 		// Below both thresholds Chrome stays asleep (ADR-0005 on-demand
 		// browser): waking it for a single Poll would cost a challenge solve
-		// per request.
+		// per request. The Lane still paces at the default gap, which is what
+		// the owner's page must show rather than a zero.
+		st.Gap = defaultGap
 		return defaultGap
 	}
 	if s.Browser != nil {
@@ -274,6 +278,7 @@ func (p *Poller) runLanePass(ctx context.Context, name string, paced bool) time.
 	eligible, err := p.Store.EligibleSeriesCount(name)
 	if err != nil {
 		log.Printf("latest poll %s: eligible count: %v", name, err)
+		st.Gap = defaultGap
 		return defaultGap
 	}
 	gap, clamped := effectiveGap(s, eligible)
@@ -288,7 +293,6 @@ func (p *Poller) runLanePass(ctx context.Context, name string, paced bool) time.
 	}
 
 	refusals := 0
-	checked := 0
 	for i, sr := range due {
 		if ctx.Err() != nil {
 			break
@@ -323,10 +327,10 @@ func (p *Poller) runLanePass(ctx context.Context, name string, paced bool) time.
 		} else {
 			refusals = 0
 		}
-		checked++
+		st.Checked++
 	}
-	if checked > 0 {
-		log.Printf("latest poll %s: due=%d checked=%d", name, len(due), checked)
+	if st.Checked > 0 {
+		log.Printf("latest poll %s: due=%d checked=%d", name, len(due), st.Checked)
 	}
 	if refusals >= 2 {
 		p.setRefusalBackoff(name, now.Add(refuseBackoff))

backend/internal/latest/poller_test.go

@@ -1640,6 +1640,27 @@ func TestLaneStatus(t *testing.T) {
 	if !st.BrowserConfigured || !st.BrowserReachable {
 		t.Fatalf("browser after round = configured=%v reachable=%v, want true/true (sidecar never lost)", st.BrowserConfigured, st.BrowserReachable)
 	}
+	if asura.Checked != 1 {
+		t.Fatalf("asura Checked = %d, want the one Series it read", asura.Checked)
+	}
+
+	// A pass that declines to look (kagane is now in backoff) must not restate
+	// the figures it never gathered as zeroes: the last real pass's due count
+	// and pace stand until a pass replaces them.
+	before := kagane
+	if before.Due == 0 || before.Gap == 0 {
+		t.Fatalf("kagane after its refusing pass = %+v, want the figures that pass gathered", before)
+	}
+	p.runOnce(context.Background())
+	for _, lane := range p.LaneStatus().Lanes {
+		if lane.Site != "kagane" {
+			continue
+		}
+		if lane.Due != before.Due || lane.Gap != before.Gap {
+			t.Fatalf("kagane after a skipped pass = due %d gap %s, want the previous pass's %d / %s",
+				lane.Due, lane.Gap, before.Due, before.Gap)
+		}
+	}
 
 	// A lost sidecar reads as unreachable for the same window the Lanes skip.
 	p.setBrowserDown(now)

backend/internal/latest/status.go

@@ -3,14 +3,19 @@ package latest
 import "time"
 
 // LaneState is the administrative page's view of one Poll Lane (issue #102):
-// what the Lane's last completed pass saw. Due and Gap are filled in as the
-// pass computes them, so a pass that returned before reaching a figure (Lane
-// in refusal backoff, no fetcher) records a zero in its place.
+// what the Lane's last pass saw. Due, Gap and Checked are filled in as the
+// pass computes them; a pass that returned before reaching a figure (refusal
+// backoff, sidecar down) carries the previous pass's figures forward rather
+// than overwriting them with zeroes the page would state as fact.
 type LaneState struct {
-	Site     string
-	Due      int
-	LastRun  time.Time
-	Gap      time.Duration
+	Site    string
+	Due     int
+	LastRun time.Time
+	Gap     time.Duration
+	// Checked is how many Series this pass actually read. A Lane with Series
+	// due and nothing checked has stopped working; one with nothing due is
+	// merely quiet, and the page must not draw the two the same (story 13).
+	Checked  int
 	Clamped  bool
 	Refusing bool
 	Browser  bool
@@ -53,11 +58,17 @@ func (p *Poller) LaneStatus() Status {
 
 // recordLaneState stores one Lane's last pass for LaneStatus. Called deferred
 // from runLanePass so every return path records, even a pass that refused.
+// A pass that never reached the pace (Gap zero) keeps the last pass's figures:
+// the Lane's due count and gap did not become zero because this pass declined
+// to look, and the row's own marks say why it declined.
 func (p *Poller) recordLaneState(st LaneState) {
 	p.mu.Lock()
 	defer p.mu.Unlock()
 	if p.laneStates == nil {
 		p.laneStates = make(map[string]LaneState)
 	}
+	if prev, ok := p.laneStates[st.Site]; ok && st.Gap == 0 {
+		st.Due, st.Gap, st.Clamped, st.Checked = prev.Due, prev.Gap, prev.Clamped, prev.Checked
+	}
 	p.laneStates[st.Site] = st
 }