Smoke-sweep fixes: exact saves, local dates, safer remove, readable markers

- Garden and plant dialogs keep centimeters as the source of truth
  (LengthField in lib/units.ts): a no-change Save no longer rewrites
  900 cm as 899.922 or a 45 cm spacing as 44.958, bumping versions and
  writing bogus history entries on the way.
- The UI stamps every date with the browser's local day (lib/dates.ts).
  Journal notes already did; plop placement, fill and removal now do too,
  so a 9 pm placement isn't "planted tomorrow". The fill endpoint gained an
  optional plantedAt; API and agent callers still default to UTC today.
- Removing an object that holds plants asks first and says how many go
  with it. An empty one still goes straight away (one Undo restores it).
- The expanded plant card's action row wraps instead of clipping "Delete".
- Monogram lettering switches to a dark ink on pale marker colors (garlic,
  cabbage, marigold) instead of near-white on near-white.
- Copy-as-plan proposes the next free year and warns when the typed name
  already exists, so two gardens can't both read as "the 2027 plan".
- Plan cards show the base name with a "2027 plan" tag, so the year — the
  point of the name — survives truncation.
- A rejected model spec now says which model and why: a wrapped
  ErrInvalidInput's reason reaches the client as the 400's message, and the
  Settings field shows it inline instead of toasting "invalid input".

Also defuses a clock bomb in TestRemainingReturnsWhenAPlantingIsRemoved,
which only passed while the real date was before 2026-08-01.

Co-Authored-By: Claude Fable 5 <[email protected]>

internal/service/ops_test.go

@@ -59,7 +59,7 @@ func TestFillRegionCappedForHugeArea(t *testing.T) {
 	bed := seedFillBed(t, s, owner, g.ID, 6000, 6000) // ~46k lattice points at radius 15 → over the cap
 	plant := seedOwnPlant(t, s, owner, 10)
 	region, _ := NamedRegion(bed, "all")
-	if _, err := s.FillRegion(ctx, owner, bed.ID, region, plant.ID, nil, FillClump); !errors.Is(err, domain.ErrInvalidInput) {
+	if _, err := s.FillRegion(ctx, owner, bed.ID, region, plant.ID, nil, FillClump, nil); !errors.Is(err, domain.ErrInvalidInput) {
 		t.Errorf("oversized fill err = %v, want ErrInvalidInput (over maxFillPlops)", err)
 	}
 }
@@ -199,7 +199,7 @@ func TestFillRegionRejectsNonFiniteRegion(t *testing.T) {
 		{MinX: nan, MinY: -50, MaxX: 50, MaxY: 50},
 		{MinX: -50, MinY: -50, MaxX: 50, MaxY: math.Inf(1)},
 	} {
-		created, err := s.FillRegion(ctx, owner, bed.ID, r, plant.ID, nil, FillClump)
+		created, err := s.FillRegion(ctx, owner, bed.ID, r, plant.ID, nil, FillClump, nil)
 		if !errors.Is(err, domain.ErrInvalidInput) {
 			t.Errorf("FillRegion(%+v) err = %v, want ErrInvalidInput", r, err)
 		}
@@ -223,7 +223,7 @@ func TestFillRegionOutsideObjectPlantsNothing(t *testing.T) {
 	plant := seedOwnPlant(t, s, owner, 10)
 
 	// Wholly east of the bed: clampTo gives MinX=500, MaxX=50.
-	created, err := s.FillRegion(ctx, owner, bed.ID, rect(500, -50, 600, 50), plant.ID, nil, FillClump)
+	created, err := s.FillRegion(ctx, owner, bed.ID, rect(500, -50, 600, 50), plant.ID, nil, FillClump, nil)
 	if err != nil {
 		t.Fatalf("FillRegion: %v", err)
 	}
@@ -256,7 +256,7 @@ func TestFillRegionDeterministicPacking(t *testing.T) {
 	plant := seedOwnPlant(t, s, owner, 10)        // radius = max(15,15) = 15
 
 	region, _ := NamedRegion(bed, "all")
-	created, err := s.FillRegion(ctx, owner, bed.ID, region, plant.ID, nil, FillClump)
+	created, err := s.FillRegion(ctx, owner, bed.ID, region, plant.ID, nil, FillClump, nil)
 	if err != nil {
 		t.Fatalf("FillRegion: %v", err)
 	}
@@ -283,7 +283,7 @@ func TestFillRegionDeterministicPacking(t *testing.T) {
 
 	// Re-filling the same region skips everything (each candidate sits exactly on
 	// an existing plop → entirely inside it).
-	again, err := s.FillRegion(ctx, owner, bed.ID, region, plant.ID, nil, FillClump)
+	again, err := s.FillRegion(ctx, owner, bed.ID, region, plant.ID, nil, FillClump, nil)
 	if err != nil {
 		t.Fatalf("second FillRegion: %v", err)
 	}
@@ -305,14 +305,14 @@ func TestFillGridLaysOutIndividualPlants(t *testing.T) {
 	plant := seedOwnPlant(t, s, owner, 10) // spacing 10
 
 	region, _ := NamedRegion(bed, "all")
-	clump, err := s.FillRegion(ctx, owner, bed.ID, region, plant.ID, nil, FillClump)
+	clump, err := s.FillRegion(ctx, owner, bed.ID, region, plant.ID, nil, FillClump, nil)
 	if err != nil {
 		t.Fatalf("clump: %v", err)
 	}
 	if _, err := s.ClearObject(ctx, owner, bed.ID); err != nil {
 		t.Fatalf("clear: %v", err)
 	}
-	grid, err := s.FillRegion(ctx, owner, bed.ID, region, plant.ID, nil, FillGrid)
+	grid, err := s.FillRegion(ctx, owner, bed.ID, region, plant.ID, nil, FillGrid, nil)
 	if err != nil {
 		t.Fatalf("grid: %v", err)
 	}
@@ -351,7 +351,7 @@ func TestFillRejectsUnknownLayout(t *testing.T) {
 	bed := seedFillBed(t, s, owner, g.ID, 60, 60)
 	plant := seedOwnPlant(t, s, owner, 10)
 	region, _ := NamedRegion(bed, "all")
-	if _, err := s.FillRegion(ctx, owner, bed.ID, region, plant.ID, nil, FillLayout("spiral")); !errors.Is(err, domain.ErrInvalidInput) {
+	if _, err := s.FillRegion(ctx, owner, bed.ID, region, plant.ID, nil, FillLayout("spiral"), nil); !errors.Is(err, domain.ErrInvalidInput) {
 		t.Errorf("unknown layout err = %v, want ErrInvalidInput", err)
 	}
 }
@@ -368,7 +368,7 @@ func TestFillRegionRotatedBedUsesLocalFrame(t *testing.T) {
 	plant := seedOwnPlant(t, s, owner, 20)
 
 	region, _ := NamedRegion(bed, "ne")
-	created, err := s.FillRegion(ctx, owner, bed.ID, region, plant.ID, nil, FillClump)
+	created, err := s.FillRegion(ctx, owner, bed.ID, region, plant.ID, nil, FillClump, nil)
 	if err != nil {
 		t.Fatalf("FillRegion: %v", err)
 	}
@@ -391,7 +391,7 @@ func TestClearObject(t *testing.T) {
 	bed := seedBed(t, s, owner, g.ID)
 	plant := seedOwnPlant(t, s, owner, 10)
 	region, _ := NamedRegion(bed, "all")
-	if _, err := s.FillRegion(ctx, owner, bed.ID, region, plant.ID, nil, FillClump); err != nil {
+	if _, err := s.FillRegion(ctx, owner, bed.ID, region, plant.ID, nil, FillClump, nil); err != nil {
 		t.Fatalf("fill: %v", err)
 	}
 
@@ -425,7 +425,7 @@ func TestOpsForbiddenForViewer(t *testing.T) {
 	}
 	region, _ := NamedRegion(bed, "all")
 
-	if _, err := s.FillRegion(ctx, viewer, bed.ID, region, plant.ID, nil, FillClump); !errors.Is(err, domain.ErrForbidden) {
+	if _, err := s.FillRegion(ctx, viewer, bed.ID, region, plant.ID, nil, FillClump, nil); !errors.Is(err, domain.ErrForbidden) {
 		t.Errorf("viewer fill = %v, want ErrForbidden", err)
 	}
 	if _, err := s.ClearObject(ctx, viewer, bed.ID); !errors.Is(err, domain.ErrForbidden) {
@@ -455,7 +455,7 @@ func TestFillScenario(t *testing.T) {
 		if err != nil {
 			t.Fatalf("region %q: %v", name, err)
 		}
-		if _, err := s.FillRegion(ctx, owner, bed.ID, region, plantID, nil, FillClump); err != nil {
+		if _, err := s.FillRegion(ctx, owner, bed.ID, region, plantID, nil, FillClump, nil); err != nil {
 			t.Fatalf("fill %q: %v", name, err)
 		}
 	}
@@ -507,3 +507,34 @@ func seedNamedPlant(t *testing.T, s *Service, owner int64, name string, spacingC
 	}
 	return p
 }
+
+// TestFillRegionPlantedAt: a fill dates its plops as told and refuses a date
+// that isn't one. The UI sends its local day, so an evening fill isn't stamped
+// with UTC's tomorrow; API and agent callers that omit it still get UTC today.
+func TestFillRegionPlantedAt(t *testing.T) {
+	ctx := context.Background()
+	s := newTestService(t, openConfig())
+	owner := seedUser(t, s, "[email protected]")
+	g, _ := s.CreateGarden(ctx, owner, GardenInput{Name: "Dated", WidthCM: 2000, HeightCM: 2000})
+	bed := seedFillBed(t, s, owner, g.ID, 200, 100)
+	plant := seedOwnPlant(t, s, owner, 30)
+
+	day := "2026-04-01"
+	created, err := s.FillNamedRegion(ctx, owner, bed.ID, "all", plant.ID, nil, FillClump, &day)
+	if err != nil {
+		t.Fatalf("fill: %v", err)
+	}
+	if len(created) == 0 {
+		t.Fatal("fill created nothing")
+	}
+	for _, p := range created {
+		if p.PlantedAt == nil || *p.PlantedAt != day {
+			t.Errorf("planting %d plantedAt = %v, want %s", p.ID, p.PlantedAt, day)
+		}
+	}
+
+	bad := "April 1st"
+	if _, err := s.FillNamedRegion(ctx, owner, bed.ID, "all", plant.ID, nil, FillClump, &bad); !errors.Is(err, domain.ErrInvalidInput) {
+		t.Errorf("bad date err = %v, want ErrInvalidInput", err)
+	}
+}