Do not arm a scheduled step of a module held as found on an adopted node (hq ADR 0103)

internal/apply/schedule.go

@@ -86,7 +86,11 @@ func NewScheduler(clock Clock, run Runner, log func(string)) *Scheduler {
 // A job whose declaration is unchanged keeps its place in the cadence — its next due time and
 // whether a run is in flight — so an ordinary reconcile every few minutes does not keep resetting
 // the clock out from under a schedule and prevent it ever firing.
-func (s *Scheduler) Sync(d *declaration.Declaration) {
+// held is the ids this node holds as found — what an adopted node keeps until its module is taken
+// (novox/hq ADR 0100). A step of a module not yet taken is not armed: run on its cadence it would
+// work on the predecessor's data, under the predecessor's service, which is the one thing an
+// adopted node must not do. Nil on a converged node, where nothing is held.
+func (s *Scheduler) Sync(d *declaration.Declaration, held map[string]bool) {
 	s.mu.Lock()
 	defer s.mu.Unlock()
 
@@ -96,6 +100,14 @@ func (s *Scheduler) Sync(d *declaration.Declaration) {
 		if !ok || c.Schedule == "" {
 			continue
 		}
+		if module, untaken := d.Adoption.UntakenModuleOf(c.Identity()); untaken || held[c.Identity()] {
+			if module == "" {
+				module = "its module"
+			}
+			s.log(fmt.Sprintf("scheduled step %s: not armed while %s is held as found on this node",
+				c.Identity(), module))
+			continue
+		}
 		cron, err := declaration.ParseCron(c.Schedule)
 		if err != nil {
 			// The declaration parser already refused a malformed cron before this runs, so a

internal/apply/schedule_test.go

@@ -244,7 +244,7 @@ func TestAScheduledStepRunsWhenDueAndNotBefore(t *testing.T) {
 	d := &declaration.Declaration{Version: 1, Resources: []declaration.Resource{
 		scheduledContainer(t, "* * * * *"), // every minute; next due 12:01:00
 	}}
-	s.Sync(d)
+	s.Sync(d, nil)
 
 	// Not yet due: 12:00:45 is before 12:01:00, so nothing runs.
 	s.Advance(context.Background(), time.Date(2026, 9, 7, 12, 0, 45, 0, time.UTC))
@@ -306,7 +306,7 @@ func TestAFailedRunIsRecordedAndDoesNotFailAnything(t *testing.T) {
 	s := NewScheduler(clock, run, log)
 	s.Sync(&declaration.Declaration{Version: 1, Resources: []declaration.Resource{
 		scheduledContainer(t, "* * * * *"),
-	}})
+	}}, nil)
 
 	// Fire a run that exits non-zero. Advance returns nothing — there is no error to fail an apply,
 	// because the run happens outside any apply and outside the store.
@@ -371,7 +371,7 @@ func TestASlowRunSkipsTheNextDueRunRatherThanStacking(t *testing.T) {
 	s := NewScheduler(clock, run, log)
 	s.Sync(&declaration.Declaration{Version: 1, Resources: []declaration.Resource{
 		scheduledContainer(t, "* * * * *"), // every minute
-	}})
+	}}, nil)
 
 	// First occurrence: 12:01 is due — starts a run that blocks in the runner.
 	s.Advance(context.Background(), time.Date(2026, 9, 7, 12, 1, 5, 0, time.UTC))
@@ -414,7 +414,7 @@ func TestSyncForgetsAScheduleTheDeclarationNoLongerNames(t *testing.T) {
 
 	s.Sync(&declaration.Declaration{Version: 1, Resources: []declaration.Resource{
 		scheduledContainer(t, "* * * * *"),
-	}})
+	}}, nil)
 	s.mu.Lock()
 	have := len(s.jobs)
 	s.mu.Unlock()
@@ -427,10 +427,55 @@ func TestSyncForgetsAScheduleTheDeclarationNoLongerNames(t *testing.T) {
 		parseTrusted(t, `{"declaration":1,"resources":[
 		  {"id":"web","type":"container","name":"web","image":"`+pinned+`"}
 		]}`).Resources[0],
-	}})
+	}}, nil)
 	s.Advance(context.Background(), time.Date(2026, 9, 7, 12, 5, 5, 0, time.UTC))
 	s.Wait()
 	if n := rec.fireCount(); n != 0 {
 		t.Errorf("a schedule the declaration no longer names still fired (%d run(s))", n)
 	}
 }
+
+// Defends novox/hq ADR 0103: a scheduled step of a module not yet taken is not armed — run on its
+// cadence it would work on the predecessor's data.
+func TestAScheduledStepOfAnUntakenModuleIsNotArmed(t *testing.T) {
+	clock := &fixedClock{now: time.Date(2026, 9, 7, 12, 0, 30, 0, time.UTC)}
+	rec := &recordingRun{}
+	var said []string
+	s := NewScheduler(clock, rec.run, func(line string) { said = append(said, line) })
+
+	d := &declaration.Declaration{Version: 1,
+		Adoption: &declaration.Adoption{Untaken: map[string][]string{"backups": {"sync"}}},
+		Resources: []declaration.Resource{
+			scheduledContainer(t, "* * * * *"),
+		}}
+	s.Sync(d, nil)
+	s.Advance(context.Background(), time.Date(2026, 9, 7, 12, 1, 5, 0, time.UTC))
+	s.Wait()
+	if rec.fireCount() != 0 {
+		t.Errorf("a held module's scheduled step ran %d time(s)", rec.fireCount())
+	}
+	if len(said) == 0 || !strings.Contains(said[0], "held as found") {
+		t.Errorf("nothing said why the step was not armed: %v", said)
+	}
+
+	// Held by id — a step whose own container was found on the machine.
+	s2 := NewScheduler(clock, rec.run, nil)
+	s2.Sync(&declaration.Declaration{Version: 1, Resources: []declaration.Resource{
+		scheduledContainer(t, "* * * * *"),
+	}}, map[string]bool{"sync": true})
+	s2.Advance(context.Background(), time.Date(2026, 9, 7, 12, 1, 5, 0, time.UTC))
+	s2.Wait()
+	if rec.fireCount() != 0 {
+		t.Errorf("a held scheduled step ran %d time(s)", rec.fireCount())
+	}
+
+	// Taken: the same step is armed and runs.
+	taken := &declaration.Declaration{Version: 1, Adoption: &declaration.Adoption{Taken: []string{"backups"}},
+		Resources: []declaration.Resource{scheduledContainer(t, "* * * * *")}}
+	s.Sync(taken, nil)
+	s.Advance(context.Background(), time.Date(2026, 9, 7, 12, 2, 5, 0, time.UTC))
+	s.Wait()
+	if rec.fireCount() == 0 {
+		t.Error("a taken module's scheduled step never ran")
+	}
+}