Make the Supply run from the plan revision Push to Calendar pushed

A plan edit landing between a successful Push and the Generate that
followed it made the Supply run from the newer plan while the push answer
reported supply_run generated, so the list could hold a dinner Calendar
never showed (MQ-133-01).

Push now returns the revision it pushed, and the push hook calls
shopping.GeneratePushed, which checks inside its transaction that the
week's plan is still at that revision (week_plans.revision, as the draft
path does) and otherwise fails with ErrPlanChanged, leaving the Supply run
as it was. The push answer then reports supply_run failed with error
plan_changed (retryable: push again), logged as a warning.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/ARCHITECTURE.md

@@ -739,14 +739,18 @@ Runs are recorded in `schedule_runs` and executed through `jobs`.
     has no plan, 400 `invalid_week`. The push holds the account lock
     across its Google requests and its record, like listing and choosing.
   - The week's Supply run (Feature 17) is made from a pushed plan: after
-    a successful `Push`, the handler runs `shopping.Generate` for the week
-    and the 200 answer carries `supply_run: {status, error}`. `status` is
-    `generated`; `archived` when the week's Supply run is in the Supply
-    archive and was left as it was; or `failed` (error
-    `supply_run_failed`, retryable, logged as an error) when it could not
-    be made. Generation never fails or undoes the push — Calendar already
-    shows the plan — and `POST /api/v1/shopping/{weekStart}/generate`
-    makes it again.
+    a successful `Push`, the handler runs `shopping.GeneratePushed` for
+    the week at the plan revision `Push` pushed, and the 200 answer
+    carries `supply_run: {status, error}`. `status` is `generated`;
+    `archived` when the week's Supply run is in the Supply archive and was
+    left as it was; or `failed` — error `plan_changed` (retryable, logged
+    as a warning) when the plan was edited between the push and
+    generation, so no Supply run is made from a plan Calendar does not
+    show and pushing again makes it; or error `supply_run_failed`
+    (retryable, logged as an error) when it could not be made, and
+    `POST /api/v1/shopping/{weekStart}/generate` makes it again.
+    Generation checks the revision inside its own transaction, and never
+    fails or undoes the push — Calendar already shows the plan.
 
 ## Supply run API (Feature 17)
 

internal/plan/push.go

@@ -84,20 +84,20 @@ type pushDay struct {
 //
 // A successful Push is the household confirming the week's plan, which is
 // what the week's Supply run (Feature 17) is made from; the returned plan
-// is the one pushed.
-func (s *Service) Push(ctx context.Context, weekStart store.LocalDate) (Plan, error) {
+// is the one pushed, and revision is its revision as pushed, so the Supply
+// run can be made from that plan and no later edit of it.
+func (s *Service) Push(ctx context.Context, weekStart store.LocalDate) (p Plan, revision int64, err error) {
 	if _, err := household.WeekDays(weekStart); err != nil {
-		return Plan{}, &InvalidWeekError{Value: weekStart.String()}
+		return Plan{}, 0, &InvalidWeekError{Value: weekStart.String()}
 	}
 	planID, revision, days, err := s.pushDays(ctx, weekStart)
 	if err != nil {
-		return Plan{}, err
+		return Plan{}, 0, err
 	}
 	events := make([]gcal.Event, len(days))
 	for i, d := range days {
 		events[i] = d.event
 	}
-	var p Plan
 	record := func() error {
 		return s.st.WithTx(ctx, func(tx *sql.Tx) error {
 			q := db.New(tx)
@@ -133,9 +133,9 @@ func (s *Service) Push(ctx context.Context, weekStart store.LocalDate) (Plan, er
 		})
 	}
 	if err := s.cal.PushEvents(ctx, events, record); err != nil {
-		return Plan{}, fmt.Errorf("plan: push %s to Calendar: %w", weekStart, err)
+		return Plan{}, 0, fmt.Errorf("plan: push %s to Calendar: %w", weekStart, err)
 	}
-	return p, nil
+	return p, revision, nil
 }
 
 // pushDays reads, in one read transaction, the plan of the week starting

internal/plan/push_test.go

@@ -135,7 +135,7 @@ func TestPushCreatesOneEventPerDay(t *testing.T) {
 	e.connectCalendar(t)
 	dates := e.storePlan(t, week, fullWeek...)
 
-	p, err := e.svc.Push(t.Context(), week)
+	p, _, err := e.svc.Push(t.Context(), week)
 	if err != nil {
 		t.Fatalf("Push: %v", err)
 	}
@@ -197,7 +197,7 @@ func TestPushAgainUpdatesOnly(t *testing.T) {
 	e := newEnv(t)
 	e.connectCalendar(t)
 	e.storePlan(t, week, fullWeek...)
-	if _, err := e.svc.Push(t.Context(), week); err != nil {
+	if _, _, err := e.svc.Push(t.Context(), week); err != nil {
 		t.Fatal(err)
 	}
 	// The household deletes Monday's event in Google Calendar; Google keeps
@@ -206,7 +206,7 @@ func TestPushAgainUpdatesOnly(t *testing.T) {
 	e.google.CancelEvent(dinnersCal.ID, monday)
 	e.google.ResetEventWrites()
 
-	p, err := e.svc.Push(t.Context(), week)
+	p, _, err := e.svc.Push(t.Context(), week)
 	if err != nil {
 		t.Fatalf("second Push: %v", err)
 	}
@@ -229,7 +229,7 @@ func TestSwapThenPushUpdatesThatDay(t *testing.T) {
 	e := newEnv(t)
 	e.connectCalendar(t)
 	e.storePlan(t, week, fullWeek...)
-	if _, err := e.svc.Push(t.Context(), week); err != nil {
+	if _, _, err := e.svc.Push(t.Context(), week); err != nil {
 		t.Fatal(err)
 	}
 	before := e.google.Events(dinnersCal.ID)
@@ -247,7 +247,7 @@ func TestSwapThenPushUpdatesThatDay(t *testing.T) {
 		t.Errorf("swapped day kept event id %q", id)
 	}
 
-	p, err := e.svc.Push(t.Context(), week)
+	p, _, err := e.svc.Push(t.Context(), week)
 	if err != nil {
 		t.Fatalf("Push: %v", err)
 	}
@@ -296,7 +296,7 @@ func TestPushAcrossDaylightSavingTime(t *testing.T) {
 			e := newEnv(t)
 			e.connectCalendar(t)
 			dates := e.storePlan(t, tc.week, fullWeek...)
-			if _, err := e.svc.Push(t.Context(), tc.week); err != nil {
+			if _, _, err := e.svc.Push(t.Context(), tc.week); err != nil {
 				t.Fatalf("Push: %v", err)
 			}
 			events := e.google.Events(dinnersCal.ID)
@@ -330,12 +330,12 @@ func TestPushAcrossDaylightSavingTime(t *testing.T) {
 func TestPushNeedsAChosenCalendar(t *testing.T) {
 	e := newEnv(t)
 	e.storePlan(t, week, fullWeek...)
-	if _, err := e.svc.Push(t.Context(), week); !errors.Is(err, gcal.ErrNotConnected) {
+	if _, _, err := e.svc.Push(t.Context(), week); !errors.Is(err, gcal.ErrNotConnected) {
 		t.Errorf("Push with nothing connected = %v, want ErrNotConnected", err)
 	}
 	e.google.SetCalendars(0, dinnersCal)
 	e.google.Connect(t, e.gcal)
-	if _, err := e.svc.Push(t.Context(), week); !errors.Is(err, gcal.ErrNoCalendar) {
+	if _, _, err := e.svc.Push(t.Context(), week); !errors.Is(err, gcal.ErrNoCalendar) {
 		t.Errorf("Push with no calendar chosen = %v, want ErrNoCalendar", err)
 	}
 	if inserts, updates := e.google.EventWrites(); inserts+updates != 0 {
@@ -348,7 +348,7 @@ func TestPushWithoutAPlan(t *testing.T) {
 	e := newEnv(t)
 	e.connectCalendar(t)
 	before := e.google.TokenCalls()
-	if _, err := e.svc.Push(t.Context(), week); !errors.Is(err, plan.ErrNotFound) {
+	if _, _, err := e.svc.Push(t.Context(), week); !errors.Is(err, plan.ErrNotFound) {
 		t.Errorf("Push = %v, want ErrNotFound", err)
 	}
 	if n := e.google.TokenCalls() - before; n != 0 {
@@ -363,7 +363,7 @@ func TestPushPartialFailureLeavesPlanUnsynced(t *testing.T) {
 	// Google fails the fourth event on every try.
 	e.google.FailEventWrites(4, 3, http.StatusServiceUnavailable)
 
-	_, err := e.svc.Push(t.Context(), week)
+	_, _, err := e.svc.Push(t.Context(), week)
 	var calendar *gcal.CalendarError
 	if !errors.As(err, &calendar) || !calendar.Retryable() {
 		t.Fatalf("Push = %v, want a retryable *gcal.CalendarError", err)
@@ -377,7 +377,7 @@ func TestPushPartialFailureLeavesPlanUnsynced(t *testing.T) {
 	// Pushing again writes every day: the three already there are updated,
 	// not added twice.
 	e.google.ResetEventWrites()
-	p, err := e.svc.Push(t.Context(), week)
+	p, _, err := e.svc.Push(t.Context(), week)
 	if err != nil {
 		t.Fatalf("retried Push: %v", err)
 	}
@@ -393,7 +393,7 @@ func TestPushPartialFailureKeepsAChangedPlanChanged(t *testing.T) {
 	e := newEnv(t)
 	e.connectCalendar(t)
 	e.storePlan(t, week, fullWeek...)
-	first, err := e.svc.Push(t.Context(), week)
+	first, _, err := e.svc.Push(t.Context(), week)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -403,7 +403,7 @@ func TestPushPartialFailureKeepsAChangedPlanChanged(t *testing.T) {
 		}
 	}
 	e.google.FailEventWrite(2, http.StatusBadRequest)
-	if _, err := e.svc.Push(t.Context(), week); err == nil {
+	if _, _, err := e.svc.Push(t.Context(), week); err == nil {
 		t.Fatal("Push succeeded, want the second event to fail")
 	}
 	p, err := e.svc.Get(t.Context(), week)
@@ -431,7 +431,7 @@ func TestPushToStaleCalendar(t *testing.T) {
 			e.connectCalendar(t)
 			e.storePlan(t, week, fullWeek...)
 			edit(e.google)
-			if _, err := e.svc.Push(t.Context(), week); !errors.Is(err, gcal.ErrCalendarUnavailable) {
+			if _, _, err := e.svc.Push(t.Context(), week); !errors.Is(err, gcal.ErrCalendarUnavailable) {
 				t.Errorf("Push = %v, want ErrCalendarUnavailable", err)
 			}
 			e.assertUnsynced(t, week, plan.StatusDraft)
@@ -444,7 +444,7 @@ func TestPushGrantNoLongerAccepted(t *testing.T) {
 	e.connectCalendar(t)
 	e.storePlan(t, week, fullWeek...)
 	e.google.RevokeGrant()
-	_, err := e.svc.Push(t.Context(), week)
+	_, _, err := e.svc.Push(t.Context(), week)
 	if !errors.Is(err, gcal.ErrReconnect) {
 		t.Fatalf("Push = %v, want ErrReconnect", err)
 	}
@@ -479,12 +479,12 @@ func TestRefusedGrantKeepsPushedWeeks(t *testing.T) {
 	dates := map[store.LocalDate][]string{}
 	for _, w := range pushedWeeks {
 		dates[w] = e.storePlan(t, w, fullWeek...)
-		if _, err := e.svc.Push(t.Context(), w); err != nil {
+		if _, _, err := e.svc.Push(t.Context(), w); err != nil {
 			t.Fatalf("Push %s: %v", w, err)
 		}
 	}
 	e.google.RevokeGrant()
-	if _, err := e.svc.Push(t.Context(), week); !errors.Is(err, gcal.ErrReconnect) {
+	if _, _, err := e.svc.Push(t.Context(), week); !errors.Is(err, gcal.ErrReconnect) {
 		t.Fatalf("Push = %v, want ErrReconnect", err)
 	}
 	e.assertRefused(t)
@@ -497,7 +497,7 @@ func TestRefusedGrantKeepsPushedWeeks(t *testing.T) {
 
 	// The refused token is not offered to Google again.
 	before := e.google.TokenCalls()
-	if _, err := e.svc.Push(t.Context(), week); !errors.Is(err, gcal.ErrReconnect) {
+	if _, _, err := e.svc.Push(t.Context(), week); !errors.Is(err, gcal.ErrReconnect) {
 		t.Fatalf("Push again = %v, want ErrReconnect", err)
 	}
 	if n := e.google.TokenCalls() - before; n != 0 {
@@ -506,7 +506,7 @@ func TestRefusedGrantKeepsPushedWeeks(t *testing.T) {
 
 	e.google.Connect(t, e.gcal)
 	e.google.ResetEventWrites()
-	p, err := e.svc.Push(t.Context(), week)
+	p, _, err := e.svc.Push(t.Context(), week)
 	if err != nil || p.Status != plan.StatusSynced {
 		t.Fatalf("Push after connecting again = %s, %v; want synced", p.Status, err)
 	}
@@ -523,7 +523,7 @@ func TestDisconnectAfterRefusedGrant(t *testing.T) {
 	e := newEnv(t)
 	e.connectCalendar(t)
 	e.storePlan(t, week, fullWeek...)
-	if _, err := e.svc.Push(t.Context(), week); err != nil {
+	if _, _, err := e.svc.Push(t.Context(), week); err != nil {
 		t.Fatal(err)
 	}
 	e.google.RevokeGrant()
@@ -551,7 +551,7 @@ func TestPushFailsWhenPlanSwappedWhilePushing(t *testing.T) {
 	defer release()
 	pushed := make(chan error, 1)
 	go func() {
-		_, err := e.svc.Push(t.Context(), week)
+		_, _, err := e.svc.Push(t.Context(), week)
 		pushed <- err
 	}()
 	<-arrived
@@ -596,7 +596,7 @@ func TestPushAfterChoosingAnotherCalendarWritesTheWholeWeek(t *testing.T) {
 			e := newEnv(t)
 			e.connectCalendar(t)
 			dates := e.storePlan(t, week, fullWeek...)
-			first, err := e.svc.Push(t.Context(), week)
+			first, _, err := e.svc.Push(t.Context(), week)
 			if err != nil {
 				t.Fatal(err)
 			}
@@ -640,14 +640,14 @@ func TestPushAfterChoosingAnotherCalendarWritesTheWholeWeek(t *testing.T) {
 			// A push that fails part way leaves the plan changed.
 			e.google.ResetEventWrites()
 			e.google.FailEventWrite(4, http.StatusBadRequest)
-			if _, err := e.svc.Push(t.Context(), week); err == nil {
+			if _, _, err := e.svc.Push(t.Context(), week); err == nil {
 				t.Fatal("Push succeeded, want the fourth event to fail")
 			}
 			if p, err := e.svc.Get(t.Context(), week); err != nil || p.Status != plan.StatusChanged {
 				t.Errorf("plan after a failed push = %s, %v; want changed", p.Status, err)
 			}
 
-			p, err = e.svc.Push(t.Context(), week)
+			p, _, err = e.svc.Push(t.Context(), week)
 			if err != nil {
 				t.Fatalf("Push: %v", err)
 			}
@@ -678,7 +678,7 @@ func TestChoosingAnotherCalendarWaitsForAPush(t *testing.T) {
 	defer release()
 	pushed := make(chan error, 1)
 	go func() {
-		_, err := e.svc.Push(t.Context(), week)
+		_, _, err := e.svc.Push(t.Context(), week)
 		pushed <- err
 	}()
 	<-arrived
@@ -712,7 +712,7 @@ func TestChoosingAnotherCalendarWaitsForAPush(t *testing.T) {
 		}
 	}
 
-	if p, err = e.svc.Push(t.Context(), week); err != nil || p.Status != plan.StatusSynced {
+	if p, _, err = e.svc.Push(t.Context(), week); err != nil || p.Status != plan.StatusSynced {
 		t.Fatalf("Push = %s, %v; want synced", p.Status, err)
 	}
 	e.assertWeekOn(t, kitchenCal.ID, week, dates, fullWeek...)
@@ -746,7 +746,7 @@ func TestDisconnectForgetsEveryPushedWeek(t *testing.T) {
 	dates := map[store.LocalDate][]string{}
 	for _, w := range pushedWeeks {
 		dates[w] = e.storePlan(t, w, fullWeek...)
-		if _, err := e.svc.Push(t.Context(), w); err != nil {
+		if _, _, err := e.svc.Push(t.Context(), w); err != nil {
 			t.Fatalf("Push %s: %v", w, err)
 		}
 	}
@@ -764,7 +764,7 @@ func TestDisconnectForgetsEveryPushedWeek(t *testing.T) {
 	// Connecting again chooses no calendar, so nothing is pushed until one
 	// is chosen; then a push writes the whole week to it.
 	e.google.Connect(t, e.gcal)
-	if _, err := e.svc.Push(t.Context(), week); !errors.Is(err, gcal.ErrNoCalendar) {
+	if _, _, err := e.svc.Push(t.Context(), week); !errors.Is(err, gcal.ErrNoCalendar) {
 		t.Fatalf("Push after connecting again = %v, want ErrNoCalendar", err)
 	}
 	e.google.SetCalendars(0, dinnersCal, kitchenCal)
@@ -773,7 +773,7 @@ func TestDisconnectForgetsEveryPushedWeek(t *testing.T) {
 	}
 	for _, w := range pushedWeeks {
 		e.assertForgotten(t, w, "after connecting again")
-		p, err := e.svc.Push(t.Context(), w)
+		p, _, err := e.svc.Push(t.Context(), w)
 		if err != nil || p.Status != plan.StatusSynced {
 			t.Fatalf("Push %s = %s, %v; want synced", w, p.Status, err)
 		}
@@ -789,7 +789,7 @@ func TestDisconnectRefusedKeepsPushedWeeks(t *testing.T) {
 	dates := map[store.LocalDate][]string{}
 	for _, w := range pushedWeeks {
 		dates[w] = e.storePlan(t, w, fullWeek...)
-		if _, err := e.svc.Push(t.Context(), w); err != nil {
+		if _, _, err := e.svc.Push(t.Context(), w); err != nil {
 			t.Fatalf("Push %s: %v", w, err)
 		}
 	}
@@ -816,7 +816,7 @@ func TestDisconnectWaitsForAPush(t *testing.T) {
 	defer release()
 	pushed := make(chan error, 1)
 	go func() {
-		_, err := e.svc.Push(t.Context(), week)
+		_, _, err := e.svc.Push(t.Context(), week)
 		pushed <- err
 	}()
 	<-arrived

internal/server/plans.go

@@ -106,9 +106,12 @@ type pushedPlan struct {
 // pushedSupplyRun says whether a Push to Calendar made the week's Supply
 // run. status is generated when it did; archived when the week's Supply
 // run is in the Supply archive and was left as it was; or failed when it
-// could not be made, when error says so and POST
-// /shopping/{weekStart}/generate makes it again. error is null when
-// status is generated.
+// was not made. A failed Supply run's error is plan_changed when the plan
+// was edited after it was pushed, so the Supply run was not made from a
+// plan Calendar does not show and pushing again makes it; or
+// supply_run_failed when it could not be made, and POST
+// /shopping/{weekStart}/generate makes it again. error is null when status
+// is generated.
 type pushedSupplyRun struct {
 	Status string    `json:"status"`
 	Error  *apiError `json:"error"`
@@ -122,15 +125,16 @@ type pushedSupplyRun struct {
 // The Supply run is made after the push, never as part of it: Calendar
 // already shows the plan, so a Supply run that cannot be made does not
 // undo or fail the push. The answer is still 200 with supply_run failed,
-// and the failure is logged as an error, so nothing claims a Supply run
-// that was not made.
+// and the failure is logged, so nothing claims a Supply run that was not
+// made. It is made only from the plan as pushed: one edited between the
+// push and the Supply run is not made into a Supply run.
 func postPlanPush(logger *slog.Logger, svc *plan.Service, shop *shopping.Service) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		week, ok := weekStartOrFail(w, r, logger)
 		if !ok {
 			return
 		}
-		p, err := svc.Push(r.Context(), week)
+		p, revision, err := svc.Push(r.Context(), week)
 		if err != nil {
 			writePlanPushError(w, r, logger, err)
 			return
@@ -139,9 +143,16 @@ func postPlanPush(logger *slog.Logger, svc *plan.Service, shop *shopping.Service
 		// gone.
 		ctx := context.WithoutCancel(r.Context())
 		run := pushedSupplyRun{Status: "generated"}
-		if _, err := shop.Generate(ctx, week); errors.Is(err, shopping.ErrFrozen) {
+		if _, err := shop.GeneratePushed(ctx, week, revision); errors.Is(err, shopping.ErrFrozen) {
 			logger.InfoContext(ctx, "Supply run in the Supply archive left as it was after Push to Calendar", "week", week.String())
 			run = pushedSupplyRun{Status: "archived", Error: &apiError{Code: "archived", Message: err.Error()}}
+		} else if errors.Is(err, shopping.ErrPlanChanged) {
+			logger.WarnContext(ctx, "plan edited after Push to Calendar; Supply run not made", "week", week.String())
+			run = pushedSupplyRun{Status: "failed", Error: &apiError{
+				Code:      "plan_changed",
+				Message:   "the plan is on Calendar as pushed, but it was edited before its Supply run was made, so no Supply run was made from it; push again",
+				Retryable: true,
+			}}
 		} else if err != nil {
 			logger.ErrorContext(ctx, "generate Supply run after Push to Calendar", "week", week.String(), "error", err)
 			run = pushedSupplyRun{Status: "failed", Error: &apiError{

internal/server/shopping_test.go

@@ -437,6 +437,51 @@ func TestPushPlanSupplyRunFails(t *testing.T) {
 	}
 }
 
+// TestPushPlanEditedBeforeSupplyRun: a plan edit landing after the push
+// is recorded but before the Supply run is made does not make the Supply
+// run from the edited plan, which Calendar does not show. The push stands
+// (200, on Calendar) and the answer says the Supply run was not made
+// because the plan changed.
+func TestPushPlanEditedBeforeSupplyRun(t *testing.T) {
+	t.Parallel()
+	e := newPlansRouter(t)
+	e.groundWeek(t)
+	e.connectCalendar(t, true)
+	// Once the push records Sunday's event, the household swaps Tuesday to
+	// Pad Thai, as a swap does: committed before the Supply run is made.
+	if _, err := e.st.Writer.ExecContext(t.Context(), `CREATE TRIGGER edit_after_push
+		AFTER UPDATE OF calendar_event_id ON plan_days
+		WHEN NEW.date = '2026-10-18' AND NEW.calendar_event_id IS NOT NULL
+		BEGIN
+			UPDATE plan_days SET dinner_id = '`+e.questLog+`', is_new = 1, calendar_event_id = NULL WHERE date = '2026-10-13';
+			UPDATE week_plans SET status = CASE WHEN status = 'synced' THEN 'changed' ELSE status END, revision = revision + 1;
+		END`); err != nil {
+		t.Fatal(err)
+	}
+
+	rec, body := e.push(t, "2026-10-12")
+	if rec.Code != http.StatusOK {
+		t.Fatalf("push = %d %s, want 200", rec.Code, rec.Body)
+	}
+	want := map[string]any{"status": "failed", "error": map[string]any{
+		"code":      "plan_changed",
+		"message":   "the plan is on Calendar as pushed, but it was edited before its Supply run was made, so no Supply run was made from it; push again",
+		"retryable": true,
+	}}
+	if !reflect.DeepEqual(body["supply_run"], want) {
+		t.Errorf("supply_run = %v, want %v", body["supply_run"], want)
+	}
+	if n := len(e.google.Events(pushCalendar.ID)); n != 7 {
+		t.Errorf("calendar has %d events, want 7", n)
+	}
+	if status, got := callShopping(t, e, http.MethodGet, shoppingPath+"2026-10-12", "", nil); status != http.StatusNotFound {
+		t.Errorf("GET after the edit = %d %v, want 404: no Supply run from the edited plan", status, got)
+	}
+	if !strings.Contains(e.logs.String(), `"level":"WARN","msg":"plan edited after Push to Calendar; Supply run not made"`) {
+		t.Errorf("logs = %s, want the edit logged as a warning", e.logs)
+	}
+}
+
 // TestPushPlanLeavesArchivedSupplyRun: pushing a week whose Supply run is
 // in the Supply archive leaves it as it was and says so.
 func TestPushPlanLeavesArchivedSupplyRun(t *testing.T) {

internal/shopping/shopping.go

@@ -39,6 +39,11 @@ const (
 // ErrPlanNotFound is a generation for a week with no plan.
 var ErrPlanNotFound = errors.New("the week has no plan")
 
+// ErrPlanChanged is a generation from a pushed plan the household has
+// edited since it was pushed: the Supply run would not match Calendar, so
+// none is made, and pushing the plan again makes it.
+var ErrPlanChanged = errors.New("the plan changed after it was pushed to Calendar; push again")
+
 // ErrFrozen is a generation of, or a change to an item of, a Supply run
 // frozen into the Supply archive, which is read-only.
 var ErrFrozen = errors.New("the week's Supply run is in the Supply archive and can no longer change")
@@ -165,6 +170,26 @@ type Generated struct {
 // archive is ErrFrozen. A fetched recipe's ingredient without a name is an
 // error: grounding always names one.
 func (s *Service) Generate(ctx context.Context, weekStart store.LocalDate) (Generated, error) {
+	return s.generate(ctx, weekStart, func(db.WeekPlan) error { return nil })
+}
+
+// GeneratePushed makes the Supply run of the week starting weekStart as
+// Generate does, from the plan a Push to Calendar pushed at revision. A
+// plan edited since (another revision) is ErrPlanChanged, and the Supply
+// run is left as it was.
+func (s *Service) GeneratePushed(ctx context.Context, weekStart store.LocalDate, revision int64) (Generated, error) {
+	return s.generate(ctx, weekStart, func(plan db.WeekPlan) error {
+		if plan.Revision != revision {
+			return ErrPlanChanged
+		}
+		return nil
+	})
+}
+
+// generate makes the Supply run of the week starting weekStart from the
+// week's plan, as Generate says, once check accepts that plan, in the same
+// transaction.
+func (s *Service) generate(ctx context.Context, weekStart store.LocalDate, check func(db.WeekPlan) error) (Generated, error) {
 	if _, err := household.WeekDays(weekStart); err != nil {
 		return Generated{}, fmt.Errorf("shopping: generate: %w", err)
 	}
@@ -178,6 +203,9 @@ func (s *Service) Generate(ctx context.Context, weekStart store.LocalDate) (Gene
 		if err != nil {
 			return fmt.Errorf("shopping: read plan: %w", err)
 		}
+		if err := check(plan); err != nil {
+			return err
+		}
 		want, skipped, err := wanted(ctx, q, plan.ID)
 		if err != nil {
 			return err

internal/shopping/shopping_test.go

@@ -561,6 +561,33 @@ func TestGenerateRefusesFrozenList(t *testing.T) {
 	wantLines(t, "stored list", e.stored(t), []string{"0 2026-10-12 Beef Chili: 0 ground beef [1 lb] needed"})
 }
 
+// TestGeneratePushedRefusesEditedPlan makes the Supply run of a pushed
+// plan at the revision pushed, then edits the plan: the pushed revision no
+// longer makes one, and the Supply run is left as it was.
+func TestGeneratePushedRefusesEditedPlan(t *testing.T) {
+	e := newEnv(t)
+	e.dinner(t, "Beef Chili", ing{"ground beef", "1", "lb"})
+	e.dinner(t, "Pad Thai", ing{"rice noodles", "8", "oz"})
+	e.plan(t, "Beef Chili")
+	q := db.New(e.st.Writer)
+	pushed, err := q.GetWeekPlan(t.Context(), week.String())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := e.svc.GeneratePushed(t.Context(), week, pushed.Revision); err != nil {
+		t.Fatalf("GeneratePushed at the pushed revision: %v", err)
+	}
+	e.swap(t, "2026-10-12", "Pad Thai")
+	if err := q.MarkWeekPlanEdited(t.Context(), db.MarkWeekPlanEditedParams{UpdatedAt: store.Now().String(), ID: e.planID}); err != nil {
+		t.Fatal(err)
+	}
+
+	if _, err := e.svc.GeneratePushed(t.Context(), week, pushed.Revision); !errors.Is(err, shopping.ErrPlanChanged) {
+		t.Fatalf("GeneratePushed after an edit = %v, want ErrPlanChanged", err)
+	}
+	wantLines(t, "stored list", e.stored(t), []string{"0 2026-10-12 Beef Chili: 0 ground beef [1 lb] needed"})
+}
+
 // TestGenerateRefusesUnnamedIngredient: grounding always names a fetched
 // recipe's ingredient, so one without a name is an error, and nothing is
 // stored.