- update_seed_lot / delete_seed_lot: correct or drop a recorded purchase
  ("it was three packets, not two"); the plant a lot is for stays fixed.
- delete_plant: remove a duplicate from the user's catalog. The service
  already refuses while plantings (past seasons included) or a lot reference
  it; the tool turns that sentinel into words the model can pass on, and
  tells it not to clear those references to get its way.
- create_garden: a new place, with the service's defaults; the prompt says a
  plan is still a copy_garden.
- describe_garden groups carry readyAround — planting date plus days to
  maturity for the plops still in the ground — so "what can I pick this
  week?" is a lookup rather than arithmetic the model got wrong live.

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

@@ -837,0 +887,4 @@
+	GerminationPct *float64 `json:"germinationPct" description:"optional germination rate, 0–100"`
+	Notes          *string  `json:"notes" description:"optional replacement notes"`
+}) (any, error) {
+	if args.Quantity == nil && args.Unit == nil && args.Vendor == nil && args.SourceURL == nil &&

@@ -837,0 +924,4 @@
+	if errors.Is(err, domain.ErrPlantInUse) {
+		// The sentinel's text is for a log line; the model needs to know what
+		// to tell the person, and what not to do about it.
+		return nil, fmt.Errorf("%w: the plant is still used — by plantings (past seasons count) or a seed lot — so it stays; tell the user rather than removing those", domain.ErrPlantInUse)

@@ -934,0 +935,4 @@
+// TestCatalogAndGardenTools — the catalog side of the record: correct or delete
+// a seed lot, delete a duplicate plant (refused while anything references it,
+// in words the model can pass on), and start a new garden with sane defaults.
+func TestCatalogAndGardenTools(t *testing.T) {

@@ -934,0 +940,4 @@
+	svc, owner := newAgentTestService(t)
+	box := NewToolbox(svc, owner, "2026-08-23")
+
+	call := func(name string, args any) llm.ToolResult {

@@ -934,0 +944,4 @@
+		t.Helper()
+		return box.Execute(ctx, llm.ToolCall{ID: "1", Name: name, Arguments: mustJSON(t, args)})
+	}
+	mustCall := func(name string, args any, into any) {