Seed provenance + inventory: source links and seed lots (#50) (#64)

Co-authored-by: Steve Dudenhoeffer <[email protected]>

DESIGN.md

@@ -21,7 +21,8 @@ SQLite, centimeters everywhere (display-side imperial conversion only), `version
 - **gardens** — owner_id, name, width_cm, height_cm, unit_pref (`metric`|`imperial`), notes.
 - **garden_shares** — (garden_id, user_id) unique, role `viewer`|`editor`, created_by. Owner is implicit via `gardens.owner_id`, never a share row.
 - **garden_objects** — one polymorphic table: `kind` (`bed`|`grow_bag`|`container`|`in_ground`|`tree`|`path`|`structure`), name, `shape` (`rect`|`circle`; `polygon` + `points` JSON reserved in schema, not in the v1 editor), center `x_cm`,`y_cm` in garden space, `width_cm`,`height_cm` (circle: width=diameter), `rotation_deg`, `z_index`, `plantable` bool, nullable `color` override, `props` JSON for kind-specific extras (bed height, tree species…), notes.
-- **plants** — catalog. `owner_id NULL` = built-in (~30 seeded via migration, read-only, clone to customize). name, category (`vegetable`|`herb`|`flower`|`fruit`|`tree_shrub`|`cover`), `spacing_cm` (mature spacing), `color` hex, `icon` (emoji string — zero assets in v1), nullable `days_to_maturity`, notes. Users see built-ins + their own.
+- **seed_lots** — one purchase: vendor, source URL, sku, lot code, purchase date, packed-for year, quantity + unit, cost, germination %. `owner_id` is on the LOT, not inherited from the plant, so you can record buying generic built-in Garlic from Johnny's and keep it private. `plantings.seed_lot_id` (ON DELETE SET NULL) attributes a plop to a purchase; **`remaining` is derived** (quantity − summed effective count of active plantings), never stored — a decremented column drifts the moment a planting is edited behind its back and can't be audited afterwards. Lots are never shared along with a garden.
+- **plants** — catalog, plus `source_url`/`vendor` provenance for the variety itself. `owner_id NULL` = built-in (~30 seeded via migration, read-only, clone to customize). name, category (`vegetable`|`herb`|`flower`|`fruit`|`tree_shrub`|`cover`), `spacing_cm` (mature spacing), `color` hex, `icon` (emoji string — zero assets in v1), nullable `days_to_maturity`, notes. Users see built-ins + their own.
 - **change_sets** / **revisions** — the undo substrate. A change set groups the row-level revisions one logical operation produced (`source` ui/agent/api, `summary`, nullable `agent_run_id`, nullable `reverts_id`); a revision is `(entity_type, entity_id, op, before, after)` with full JSON row snapshots. The unit of undo is the **operation, not the row**. Revert is itself a change set, so an undo can be undone; it is version-guarded per entity and reports conflicts rather than clobbering a later edit. Garden *deletion* is deliberately not revertible (the cascade is invisible to the service, and would take the history with it).
 - **plantings** ("plops") — object_id, plant_id, center `x_cm`,`y_cm` **in the parent object's local frame** (moving/rotating a bed moves its plants for free), `radius_cm` (a plop is a circular patch), nullable `count` (NULL = derived: `max(1, round(π·r² / spacing_cm²))`), nullable label, `planted_at`/`removed_at` dates. "Clear bed" sets `removed_at`; v1 shows rows where `removed_at IS NULL`. Year-over-year history and a future plan/scenario layer build on these dates without schema surgery.
 
@@ -59,6 +60,7 @@ POST /gardens/:id/copy        ← deep-copy a garden you own (objects + active p
 POST /gardens/:id/objects     PATCH,DELETE /objects/:id
 POST /objects/:id/plantings   PATCH,DELETE /plantings/:id
 GET,POST /plants              PATCH,DELETE /plants/:id            (own plants only)
+GET,POST /seed-lots           GET,PATCH,DELETE /seed-lots/:id     (own lots only; private)
 GET,POST /gardens/:id/shares  PATCH,DELETE /gardens/:id/shares/:userId    (invite by email)
 ```
 

internal/api/api.go

@@ -124,6 +124,15 @@ func New(cfg *config.Config, svc *service.Service) *gin.Engine {
 	plants.PATCH("/:id", h.updatePlant)
 	plants.DELETE("/:id", h.deletePlant)
 
+	// Seed lots: what the actor bought, and what's left. Private to the buyer,
+	// so these hang off the session actor rather than off a garden.
+	seedLots := v1.Group("/seed-lots", h.requireAuth())
+	seedLots.GET("", h.listSeedLots)
+	seedLots.POST("", h.createSeedLot)
+	seedLots.GET("/:id", h.getSeedLot)
+	seedLots.PATCH("/:id", h.updateSeedLot)
+	seedLots.DELETE("/:id", h.deleteSeedLot)
+
 	// Public, unauthenticated read of a garden by its share token. Deliberately
 	// NOT behind requireAuth: the token is the capability, so a logged-out visitor
 	// opens a shared link without being redirected to /login or OIDC. Only GET,

internal/api/errors.go

@@ -1,6 +1,7 @@
 package api
 
 import (
+	"encoding/json"
 	"errors"
 	"log/slog"
 	"net/http"
@@ -69,6 +70,26 @@ func writeVersionConflict(c *gin.Context, current any) {
 	})
 }
 
+// parseNullable decodes any JSON value into (value, present) for a nullable
+// column: absent → (nil, false); explicit null → (nil, true); anything else →
+// the decoded value. That three-way distinction is what lets a PATCH tell "clear
+// this to NULL" apart from "leave it alone", and every nullable field in the API
+// needs it, so it lives here rather than in whichever file happened to want it
+// first.
+func parseNullable[T any](raw json.RawMessage) (*T, bool, error) {
+	if len(raw) == 0 {
+		return nil, false, nil
+	}
+	if string(raw) == "null" {
+		return nil, true, nil
+	}
+	var v T
+	if err := json.Unmarshal(raw, &v); err != nil {
+		return nil, false, err
+	}
+	return &v, true, nil
+}
+
 // intQuery reads a non-negative integer query parameter, falling back to def on
 // an absent or malformed value.
 func intQuery(c *gin.Context, name string, def int) int {

internal/api/plantings.go

@@ -22,12 +22,13 @@ type plantingCreateRequest struct {
 	Count     *int    `json:"count"`
 	Label     *string `json:"label"`
 	PlantedAt *string `json:"plantedAt"`
+	SeedLotID *int64  `json:"seedLotId"`
 }
 
 func (r plantingCreateRequest) toInput() service.PlantingInput {
 	return service.PlantingInput{
 		PlantID: r.PlantID, XCM: r.XCM, YCM: r.YCM, RadiusCM: r.RadiusCM,
-		Count: r.Count, Label: r.Label, PlantedAt: r.PlantedAt,
+		Count: r.Count, Label: r.Label, PlantedAt: r.PlantedAt, SeedLotID: r.SeedLotID,
 	}
 }
 
@@ -45,6 +46,7 @@ type plantingUpdateRequest struct {
 	Label     json.RawMessage `json:"label"`
 	PlantedAt json.RawMessage `json:"plantedAt"`
 	RemovedAt json.RawMessage `json:"removedAt"`
+	SeedLotID json.RawMessage `json:"seedLotId"`
 	Version   int64           `json:"version" binding:"required,min=1"`
 }
 
@@ -61,6 +63,10 @@ func (r plantingUpdateRequest) toPatch() (service.PlantingPatch, error) {
 	if err != nil {
 		return service.PlantingPatch{}, err
 	}
+	seedLot, setSeedLot, err := parseNullable[int64](r.SeedLotID)
+	if err != nil {
+		return service.PlantingPatch{}, err
+	}
 	removedAt, setRemovedAt, err := parseNullableString(r.RemovedAt)
 	if err != nil {
 		return service.PlantingPatch{}, err
@@ -71,6 +77,7 @@ func (r plantingUpdateRequest) toPatch() (service.PlantingPatch, error) {
 		SetLabel: setLabel, Label: label,
 		SetPlantedAt: setPlantedAt, PlantedAt: plantedAt,
 		SetRemovedAt: setRemovedAt, RemovedAt: removedAt,
+		SetSeedLotID: setSeedLot, SeedLotID: seedLot,
 	}, nil
 }
 

internal/api/plants.go

@@ -20,13 +20,16 @@ type plantCreateRequest struct {
 	Color          string  `json:"color" binding:"required"`
 	Icon           string  `json:"icon" binding:"required"`
 	DaysToMaturity *int    `json:"daysToMaturity"`
+	SourceURL      string  `json:"sourceUrl"`
+	Vendor         string  `json:"vendor"`
 	Notes          string  `json:"notes"`
 }
 
 func (r plantCreateRequest) toInput() service.PlantInput {
 	return service.PlantInput{
 		Name: r.Name, Category: r.Category, SpacingCM: r.SpacingCM,
-		Color: r.Color, Icon: r.Icon, DaysToMaturity: r.DaysToMaturity, Notes: r.Notes,
+		Color: r.Color, Icon: r.Icon, DaysToMaturity: r.DaysToMaturity,
+		SourceURL: r.SourceURL, Vendor: r.Vendor, Notes: r.Notes,
 	}
 }
 
@@ -41,6 +44,8 @@ type plantUpdateRequest struct {
 	Color          *string         `json:"color"`
 	Icon           *string         `json:"icon"`
 	DaysToMaturity json.RawMessage `json:"daysToMaturity"`
+	SourceURL      *string         `json:"sourceUrl"`
+	Vendor         *string         `json:"vendor"`
 	Notes          *string         `json:"notes"`
 	Version        int64           `json:"version" binding:"required,min=1"`
 }
@@ -53,7 +58,8 @@ func (r plantUpdateRequest) toPatch() (service.PlantPatch, error) {
 	return service.PlantPatch{
 		Name: r.Name, Category: r.Category, SpacingCM: r.SpacingCM,
 		Color: r.Color, Icon: r.Icon,
-		SetDays: setDays, DaysToMaturity: days, Notes: r.Notes,
+		SetDays: setDays, DaysToMaturity: days,
+		SourceURL: r.SourceURL, Vendor: r.Vendor, Notes: r.Notes,
 	}, nil
 }
 

internal/api/seed_lots.go

@@ -0,0 +1,166 @@
+package api
+
+import (
+	"encoding/json"
+	"errors"
+	"net/http"
+	"strconv"
+
+	"github.com/gin-gonic/gin"
+
+	"gitea.stevedudenhoeffer.com/steve/pansy/internal/domain"
+	"gitea.stevedudenhoeffer.com/steve/pansy/internal/service"
+)
+
+// Seed lots (#50): what you actually bought, and what's left of it. Private to
+// the buyer — a lot is never shared along with a garden — so every handler here
+// scopes to the session actor with no garden in the picture.
+
+// seedLotCreateRequest is the body for POST /seed-lots.
+type seedLotCreateRequest struct {
+	PlantID        int64    `json:"plantId" binding:"required"`
+	Vendor         string   `json:"vendor"`
+	SourceURL      string   `json:"sourceUrl"`
+	SKU            string   `json:"sku"`
+	LotCode        string   `json:"lotCode"`
+	PurchasedAt    *string  `json:"purchasedAt"`
+	PackedForYear  *int     `json:"packedForYear"`
+	Quantity       float64  `json:"quantity"`
+	Unit           string   `json:"unit" binding:"required"`
+	CostCents      *int     `json:"costCents"`
+	GerminationPct *float64 `json:"germinationPct"`
+	Notes          string   `json:"notes"`
+}
+
+func (r seedLotCreateRequest) toInput() service.SeedLotInput {
+	return service.SeedLotInput{
+		PlantID: r.PlantID, Vendor: r.Vendor, SourceURL: r.SourceURL, SKU: r.SKU,
+		LotCode: r.LotCode, PurchasedAt: r.PurchasedAt, PackedForYear: r.PackedForYear,
+		Quantity: r.Quantity, Unit: r.Unit, CostCents: r.CostCents,
+		GerminationPct: r.GerminationPct, Notes: r.Notes,
+	}
+}
+
+// seedLotUpdateRequest is the body for PATCH /seed-lots/:id: every field
+// optional, plus the required current version. The nullable columns are
+// json.RawMessage so an explicit null (clear it) is distinguishable from an
+// absent field (leave it alone). plantId is not accepted — see SeedLotPatch.
+type seedLotUpdateRequest struct {
+	Vendor         *string         `json:"vendor"`
+	SourceURL      *string         `json:"sourceUrl"`
+	SKU            *string         `json:"sku"`
+	LotCode        *string         `json:"lotCode"`
+	PurchasedAt    json.RawMessage `json:"purchasedAt"`
+	PackedForYear  json.RawMessage `json:"packedForYear"`
+	Quantity       *float64        `json:"quantity"`
+	Unit           *string         `json:"unit"`
+	CostCents      json.RawMessage `json:"costCents"`
+	GerminationPct json.RawMessage `json:"germinationPct"`
+	Notes          *string         `json:"notes"`
+	Version        int64           `json:"version" binding:"required"`
+}
+
+func (r seedLotUpdateRequest) toPatch() (service.SeedLotPatch, error) {
+	p := service.SeedLotPatch{
+		Vendor: r.Vendor, SourceURL: r.SourceURL, SKU: r.SKU, LotCode: r.LotCode,
+		Quantity: r.Quantity, Unit: r.Unit, Notes: r.Notes,
+	}
+	var err error
+	if p.PurchasedAt, p.SetPurchasedAt, err = parseNullable[string](r.PurchasedAt); err != nil {
+		return p, err
+	}
+	if p.PackedForYear, p.SetPackedForYear, err = parseNullable[int](r.PackedForYear); err != nil {
+		return p, err
+	}
+	if p.CostCents, p.SetCostCents, err = parseNullable[int](r.CostCents); err != nil {
+		return p, err
+	}
+	if p.GerminationPct, p.SetGerminationPct, err = parseNullable[float64](r.GerminationPct); err != nil {
+		return p, err
+	}
+	return p, nil
+}
+
+func (h *handlers) listSeedLots(c *gin.Context) {
+	var plantID *int64
+	if raw := c.Query("plantId"); raw != "" {
+		id, err := strconv.ParseInt(raw, 10, 64)
+		if err != nil || id < 1 {
+			writeAPIError(c, http.StatusBadRequest, "INVALID_INPUT", "invalid plantId")
+			return
+		}
+		plantID = &id
+	}
+	lots, err := h.svc.ListSeedLots(c.Request.Context(), mustActor(c).ID, plantID)
+	if err != nil {
+		writeServiceError(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, lots)
+}
+
+func (h *handlers) createSeedLot(c *gin.Context) {
+	var req seedLotCreateRequest
+	if err := c.ShouldBindJSON(&req); err != nil {
+		writeAPIError(c, http.StatusBadRequest, "INVALID_INPUT", "invalid seed lot: plantId and unit are required")
+		return
+	}
+	lot, err := h.svc.CreateSeedLot(c.Request.Context(), mustActor(c).ID, req.toInput())
+	if err != nil {
+		writeServiceError(c, err)
+		return
+	}
+	c.JSON(http.StatusCreated, lot)
+}
+
+func (h *handlers) getSeedLot(c *gin.Context) {
+	id, ok := parseIDParam(c, "id")
+	if !ok {
+		return
+	}
+	lot, err := h.svc.GetSeedLot(c.Request.Context(), mustActor(c).ID, id)
+	if err != nil {
+		writeServiceError(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, lot)
+}
+
+func (h *handlers) updateSeedLot(c *gin.Context) {
+	id, ok := parseIDParam(c, "id")
+	if !ok {
+		return
+	}
+	var req seedLotUpdateRequest
+	if err := c.ShouldBindJSON(&req); err != nil {
+		writeAPIError(c, http.StatusBadRequest, "INVALID_INPUT", "invalid update: a current version is required")
+		return
+	}
+	patch, err := req.toPatch()
+	if err != nil {
+		writeAPIError(c, http.StatusBadRequest, "INVALID_INPUT", "invalid update payload")
+		return
+	}
+	lot, err := h.svc.UpdateSeedLot(c.Request.Context(), mustActor(c).ID, id, patch, req.Version)
+	if err != nil {
+		if errors.Is(err, domain.ErrVersionConflict) {
+			writeVersionConflict(c, lot)
+			return
+		}
+		writeServiceError(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, lot)
+}
+
+func (h *handlers) deleteSeedLot(c *gin.Context) {
+	id, ok := parseIDParam(c, "id")
+	if !ok {
+		return
+	}
+	if err := h.svc.DeleteSeedLot(c.Request.Context(), mustActor(c).ID, id); err != nil {
+		writeServiceError(c, err)
+		return
+	}
+	c.Status(http.StatusNoContent)
+}

internal/domain/domain.go

@@ -109,6 +109,14 @@ const (
 	OpCreate = "create"
 	OpUpdate = "update"
 	OpDelete = "delete"
+
+	// Units a seed lot's quantity can be counted in (mirrors the schema CHECK).
+	UnitSeeds   = "seeds"
+	UnitGrams   = "grams"
+	UnitOunces  = "ounces"
+	UnitPackets = "packets"
+	UnitBulbs   = "bulbs"
+	UnitPlants  = "plants"
 )
 
 // ChangeSet groups the revisions produced by one logical operation — the unit of
@@ -280,6 +288,11 @@ type GardenObject struct {
 }
 
 // Plant is a catalog entry. OwnerID nil means a read-only seeded built-in.
+//
+// SourceURL/Vendor are provenance for the variety itself — the page you'd go
+// back to in order to buy it again. What you actually bought, and how much is
+// left, lives in SeedLot instead: the same variety may come from two vendors in
+// two years, and a single pair of columns here would collapse that.
 type Plant struct {
 	ID             int64   `json:"id"`
 	OwnerID        *int64  `json:"ownerId,omitempty"` // nil = built-in
@@ -289,12 +302,44 @@ type Plant struct {
 	Color          string  `json:"color"`
 	Icon           string  `json:"icon"`
 	DaysToMaturity *int    `json:"daysToMaturity,omitempty"`
+	SourceURL      string  `json:"sourceUrl"`
+	Vendor         string  `json:"vendor"`
 	Notes          string  `json:"notes"`
 	Version        int64   `json:"version"`
 	CreatedAt      string  `json:"createdAt"`
 	UpdatedAt      string  `json:"updatedAt"`
 }
 
+// SeedLot is one purchase: a specific packet of a specific variety, from a
+// specific vendor, in a specific year. Owned by the buyer even when it points at
+// a built-in plant, and never shared along with a garden.
+type SeedLot struct {
+	ID             int64    `json:"id"`
+	OwnerID        int64    `json:"ownerId"`
+	PlantID        int64    `json:"plantId"`
+	Vendor         string   `json:"vendor"`
+	SourceURL      string   `json:"sourceUrl"`
+	SKU            string   `json:"sku"`
+	LotCode        string   `json:"lotCode"`
+	PurchasedAt    *string  `json:"purchasedAt,omitempty"`
+	PackedForYear  *int     `json:"packedForYear,omitempty"`
+	Quantity       float64  `json:"quantity"`
+	Unit           string   `json:"unit"`
+	CostCents      *int     `json:"costCents,omitempty"`
+	GerminationPct *float64 `json:"germinationPct,omitempty"`
+	Notes          string   `json:"notes"`
+	Version        int64    `json:"version"`
+	CreatedAt      string   `json:"createdAt"`
+	UpdatedAt      string   `json:"updatedAt"`
+
+	// Used is the summed effective count of active plantings attributed to this
+	// lot, and Remaining is Quantity - Used. Both are computed by the service and
+	// never stored: a stored running total drifts the moment anything edits a
+	// planting behind its back, and can't be audited afterwards.
+	Used      float64 `json:"used"`
+	Remaining float64 `json:"remaining"`
+}
+
 // Planting ("plop") is a circular patch of one plant, positioned in its parent
 // object's local frame. Count nil means it is derived from area / spacing².
 type Planting struct {
@@ -308,9 +353,13 @@ type Planting struct {
 	Label     *string `json:"label,omitempty"`
 	PlantedAt *string `json:"plantedAt,omitempty"`
 	RemovedAt *string `json:"removedAt,omitempty"`
-	Version   int64   `json:"version"`
+	// SeedLotID attributes this planting to a purchase, so a lot can report what
-	CreatedAt string  `json:"createdAt"`
+	// is left. Nullable: most plantings never name a lot, and retiring a lot sets
-	UpdatedAt string  `json:"updatedAt"`
+	// this back to NULL rather than destroying planting history.
+	SeedLotID *int64 `json:"seedLotId,omitempty"`
+	Version   int64  `json:"version"`
+	CreatedAt string `json:"createdAt"`
+	UpdatedAt string `json:"updatedAt"`
 
 	// DerivedCount is the plant count implied by the plop's area and the plant's
 	// mature spacing: max(1, round(π·r² / spacing²)). It is computed by the

internal/service/plantings.go

@@ -50,6 +50,9 @@ type PlantingInput struct {
 	Count     *int
 	Label     *string
 	PlantedAt *string
+	// SeedLotID attributes this planting to a purchase, so the lot can report
+	// what's left. Optional.
+	SeedLotID *int64
 }
 
 // PlantingPatch is a partial update. The nullable fields (Count/Label/PlantedAt/
@@ -68,6 +71,8 @@ type PlantingPatch struct {
 	PlantedAt    *string
 	SetRemovedAt bool
 	RemovedAt    *string
+	SetSeedLotID bool
+	SeedLotID    *int64
 }
 
 // CreatePlanting places a plop in a plantable object the actor can edit.
@@ -93,6 +98,7 @@ func (s *Service) CreatePlanting(ctx context.Context, actorID, objectID int64, i
 		Count:     in.Count,
 		Label:     trimStringPtr(in.Label),
 		PlantedAt: in.PlantedAt,
+		SeedLotID: in.SeedLotID,
 	}
 	if p.PlantedAt == nil {
 		today := s.now().UTC().Format(dateLayout)
@@ -101,6 +107,9 @@ func (s *Service) CreatePlanting(ctx context.Context, actorID, objectID int64, i
 	if err := finalizePlanting(p, o, true); err != nil {
 		return nil, err
 	}
+	if err := s.checkSeedLotForPlanting(ctx, actorID, p.SeedLotID, p.PlantID); err != nil {
+		return nil, err
+	}
 	created, err := s.store.CreatePlanting(ctx, p)
 	if err != nil {
 		return nil, err
@@ -148,6 +157,11 @@ func (s *Service) UpdatePlanting(ctx context.Context, actorID, plantingID int64,
 	if err := finalizePlanting(pl, o, checkBounds); err != nil {
 		return nil, err
 	}
+	// Re-checked on every update, not just when the lot changes: a plant swap can
+	// leave a previously-valid attribution pointing at a lot of the wrong variety.
+	if err := s.checkSeedLotForPlanting(ctx, actorID, pl.SeedLotID, pl.PlantID); err != nil {
+		return nil, err
+	}
 	pl.Version = version
 
 	updated, err := s.store.UpdatePlanting(ctx, pl)
@@ -249,6 +263,9 @@ func applyPlantingPatch(pl *domain.Planting, p PlantingPatch) {
 	if p.SetRemovedAt {
 		pl.RemovedAt = p.RemovedAt
 	}
+	if p.SetSeedLotID {
+		pl.SeedLotID = p.SeedLotID
+	}
 }
 
 // finalizePlanting validates a built/merged plop against its parent object.

internal/service/plants.go

@@ -18,6 +18,7 @@ const (
 	minPlantSpacingCM = 0.1
 	maxPlantSpacingCM = 10_000 // 100 m — headroom for large trees/shrubs
 	maxDaysToMaturity = 3650   // ~10 years
+	maxPlantVendorLen = 200
 )
 
 // plantCategories is the set of valid category enum values (mirrors the schema
@@ -40,7 +41,11 @@ type PlantInput struct {
 	Color          string
 	Icon           string
 	DaysToMaturity *int
-	Notes          string
+	// Where this variety came from — the page you'd go back to to buy it again.
+	// What you actually bought, and how much is left, is a SeedLot instead.
+	SourceURL string
+	Vendor    string
+	Notes     string
 }
 
 // PlantPatch is a partial update: nil fields are left unchanged. DaysToMaturity
@@ -54,6 +59,8 @@ type PlantPatch struct {
 	Icon           *string
 	SetDays        bool
 	DaysToMaturity *int
+	SourceURL      *string
+	Vendor         *string
 	Notes          *string
 }
 
@@ -73,6 +80,8 @@ func (s *Service) CreatePlant(ctx context.Context, actorID int64, in PlantInput)
 		Color:          in.Color,
 		Icon:           strings.TrimSpace(in.Icon),
 		DaysToMaturity: in.DaysToMaturity,
+		SourceURL:      strings.TrimSpace(in.SourceURL),
+		Vendor:         strings.TrimSpace(in.Vendor),
 		Notes:          strings.TrimSpace(in.Notes),
 	}
 	if err := finalizePlant(p); err != nil {
@@ -121,6 +130,12 @@ func (s *Service) UpdatePlant(ctx context.Context, actorID, plantID int64, patch
 // planting (even a removed one — the FK is RESTRICT) is refused with
 // ErrPlantInUse rather than orphaning history; the client clones-and-edits or
 // clears the plantings first.
+//
+// Seed lots are refused for a different reason: seed_lots.plant_id is ON DELETE
+// CASCADE, so without this check deleting a plant would silently destroy the
+// purchase records attached to it — vendor, cost, germination rate, all gone
+// with no warning. Refusing lets the owner delete the lots deliberately if that
+// is really what they meant.
 func (s *Service) DeletePlant(ctx context.Context, actorID, plantID int64) error {
 	if _, err := s.writablePlant(ctx, actorID, plantID); err != nil {
 		return err
@@ -132,6 +147,13 @@ func (s *Service) DeletePlant(ctx context.Context, actorID, plantID int64) error
 	if n > 0 {
 		return domain.ErrPlantInUse
 	}
+	lots, err := s.store.CountSeedLotsForPlant(ctx, plantID)
+	if err != nil {
+		return err
+	}
+	if lots > 0 {
+		return domain.ErrPlantInUse
+	}
 	return s.store.DeletePlant(ctx, plantID)
 }
 
@@ -155,6 +177,12 @@ func applyPlantPatch(p *domain.Plant, patch PlantPatch) {
 	if patch.SetDays {
 		p.DaysToMaturity = patch.DaysToMaturity
 	}
+	if patch.SourceURL != nil {
+		p.SourceURL = strings.TrimSpace(*patch.SourceURL)
+	}
+	if patch.Vendor != nil {
+		p.Vendor = strings.TrimSpace(*patch.Vendor)
+	}
 	if patch.Notes != nil {
 		p.Notes = strings.TrimSpace(*patch.Notes)
 	}
@@ -184,5 +212,13 @@ func finalizePlant(p *domain.Plant) error {
 	if len(p.Notes) > maxPlantNotesLen {
 		return domain.ErrInvalidInput
 	}
+	if len(p.Vendor) > maxPlantVendorLen {
+		return domain.ErrInvalidInput
+	}
+	// Rendered as a clickable link, so the scheme check is load-bearing (see
+	// validSourceURL) rather than tidiness.
+	if !validSourceURL(p.SourceURL) {
+		return domain.ErrInvalidInput
+	}
 	return nil
 }

internal/service/plants_test.go

@@ -184,12 +184,12 @@ func TestCreatePlantValidation(t *testing.T) {
 	owner := seedUser(t, s, "[email protected]")
 
 	bad := []PlantInput{
-		{Name: "", Category: domain.CategoryHerb, SpacingCM: 10, Color: "#4a7c3f", Icon: "🌿"},         // empty name
+		{Name: "", Category: domain.CategoryHerb, SpacingCM: 10, Color: "#4a7c3f", Icon: "🌿"},                                     // empty name
-		{Name: "x", Category: "spaceship", SpacingCM: 10, Color: "#4a7c3f", Icon: "🌿"},                // bad category
+		{Name: "x", Category: "spaceship", SpacingCM: 10, Color: "#4a7c3f", Icon: "🌿"},                                            // bad category
-		{Name: "x", Category: domain.CategoryHerb, SpacingCM: 0, Color: "#4a7c3f", Icon: "🌿"},         // zero spacing
+		{Name: "x", Category: domain.CategoryHerb, SpacingCM: 0, Color: "#4a7c3f", Icon: "🌿"},                                     // zero spacing
-		{Name: "x", Category: domain.CategoryHerb, SpacingCM: -5, Color: "#4a7c3f", Icon: "🌿"},        // negative spacing
+		{Name: "x", Category: domain.CategoryHerb, SpacingCM: -5, Color: "#4a7c3f", Icon: "🌿"},                                    // negative spacing
-		{Name: "x", Category: domain.CategoryHerb, SpacingCM: 10, Color: "nope", Icon: "🌿"},           // bad color
+		{Name: "x", Category: domain.CategoryHerb, SpacingCM: 10, Color: "nope", Icon: "🌿"},                                       // bad color
-		{Name: "x", Category: domain.CategoryHerb, SpacingCM: 10, Color: "#4a7c3f", Icon: ""},          // empty icon
+		{Name: "x", Category: domain.CategoryHerb, SpacingCM: 10, Color: "#4a7c3f", Icon: ""},                                     // empty icon
 		{Name: strings.Repeat("x", maxPlantNameLen+1), Category: domain.CategoryHerb, SpacingCM: 10, Color: "#4a7c3f", Icon: "🌿"}, // name too long
 		{Name: "x", Category: domain.CategoryHerb, SpacingCM: 10, Color: "#4a7c3f", Icon: "🌿", DaysToMaturity: ptrInt(0)},         // days must be >= 1
 	}

internal/service/revisions.go

@@ -417,6 +417,9 @@ type revertOps[T any] struct {
 	// remove undoes a creation. It returns the changes it made, because deleting
 	// an object also deletes the plantings hanging off it.
 	remove func(ctx context.Context, row *T) ([]change, error)
+	// beforeRestore fixes up a snapshot whose references may have gone stale
+	// while it sat in history.
+	beforeRestore func(ctx context.Context, row *T) error
 	// blockRemoval optionally refuses a removal, e.g. an object that has gained
 	// plantings since. Returns a conflict reason, or "" to allow it.
 	blockRemoval func(ctx context.Context, row *T) (string, error)
@@ -445,6 +448,11 @@ func revertEntity[T any](
 		if err := unsnapshot(r.Before, &target); err != nil {
 			return nil, nil, err
 		}
+		if ops.beforeRestore != nil {
+			if err := ops.beforeRestore(ctx, &target); err != nil {
+				return nil, nil, err
+			}
+		}
 		restored, err := ops.restore(ctx, &target)
 		if err != nil {
 			// The id may have been taken between the check above and this insert.
@@ -547,6 +555,22 @@ func plantingRevertOps(s *Service) revertOps[domain.Planting] {
 		get:        s.store.GetPlanting,
 		update:     s.store.UpdatePlanting,
 		restore:    s.store.RestorePlanting,
+		// A snapshot can name a seed lot that has since been deleted. The live
+		// rows got their link nulled by ON DELETE SET NULL, but the snapshot
+		// still holds the old id, and restoring it would violate the foreign key
+		// and abort the whole revert. Drop the dangling link instead: the plant
+		// really was in the ground, which is the part worth restoring.
+		beforeRestore: func(ctx context.Context, p *domain.Planting) error {
+			if p.SeedLotID == nil {
+				return nil
+			}
+			if _, err := s.store.GetSeedLot(ctx, *p.SeedLotID); errors.Is(err, domain.ErrNotFound) {
+				p.SeedLotID = nil
+			} else if err != nil {
+				return err
+			}
+			return nil
+		},
 		remove: func(ctx context.Context, p *domain.Planting) ([]change, error) {
 			if err := s.store.DeletePlanting(ctx, p.ID); err != nil {
 				return nil, err

internal/service/seed_lots.go

@@ -0,0 +1,347 @@
+package service
+
+import (
+	"context"
+	"log/slog"
+	"net/url"
+	"strings"
+
+	"gitea.stevedudenhoeffer.com/steve/pansy/internal/domain"
+)
+
+// Seed provenance and inventory (#50). A lot is one purchase — a specific packet
+// of a specific variety, from a specific vendor, in a specific year — and it is
+// owned by the buyer even when it points at a built-in plant. Lots are private:
+// they are never shared along with a garden, because what you paid for seed is
+// not part of a garden plan.
+
+const (
+	maxLotTextLen   = 200
+	maxLotNotesLen  = 10_000
+	maxSourceURLLen = 2000
+	maxLotQuantity  = 1_000_000
+	minPackedYear   = 1900
+	maxPackedYear   = 2200
+)
+
+// lotUnits is the set of valid quantity units (mirrors the schema CHECK).
+var lotUnits = map[string]struct{}{
+	domain.UnitSeeds:   {},
+	domain.UnitGrams:   {},
+	domain.UnitOunces:  {},
+	domain.UnitPackets: {},
+	domain.UnitBulbs:   {},
+	domain.UnitPlants:  {},
+}
+
+// SeedLotInput is the payload for recording a purchase.
+type SeedLotInput struct {
+	PlantID        int64
+	Vendor         string
+	SourceURL      string
+	SKU            string
+	LotCode        string
+	PurchasedAt    *string
+	PackedForYear  *int
+	Quantity       float64
+	Unit           string
+	CostCents      *int
+	GerminationPct *float64
+	Notes          string
+}
+
+// SeedLotPatch is a partial update; nil fields are left unchanged. The nullable
+// columns use a Set* flag to tell "clear to NULL" from "leave alone". PlantID is
+// absent deliberately: re-pointing a purchase at a different variety would
+// rewrite history rather than correct it.
+type SeedLotPatch struct {
+	Vendor            *string
+	SourceURL         *string
+	SKU               *string
+	LotCode           *string
+	SetPurchasedAt    bool
+	PurchasedAt       *string
+	SetPackedForYear  bool
+	PackedForYear     *int
+	Quantity          *float64
+	Unit              *string
+	SetCostCents      bool
+	CostCents         *int
+	SetGerminationPct bool
+	GerminationPct    *float64
+	Notes             *string
+}
+
+// ListSeedLots returns the actor's own lots, each with Used/Remaining filled in.
+// Optionally narrowed to one plant.
+func (s *Service) ListSeedLots(ctx context.Context, actorID int64, plantID *int64) ([]domain.SeedLot, error) {
+	lots, err := s.store.ListSeedLotsForOwner(ctx, actorID, plantID)
+	if err != nil {
+		return nil, err
+	}
+	if err := s.fillRemaining(ctx, actorID, lots); err != nil {
+		return nil, err
+	}
+	return lots, nil
+}
+
+// fillRemaining computes Used and Remaining for a slice of the actor's lots.
+//
+// Deliberately derived, never stored. The alternative — decrementing a column
+// when you plant — drifts the moment anything edits or removes a planting behind
+// its back, and once it has drifted there is no way to tell what the true number
+// was. Attribution plus arithmetic can always be recomputed and audited.
+// Remaining may go NEGATIVE, and that is deliberate: it means more was planted
+// than the lot recorded buying, which is a real thing that happens (a
+// miscounted packet, a lot entered after the fact). Clamping it to zero would
+// hide the discrepancy at exactly the moment it is worth seeing.
+func (s *Service) fillRemaining(ctx context.Context, actorID int64, lots []domain.SeedLot) error {
+	if len(lots) == 0 {
+		return nil
+	}
+	ids := make([]int64, 0, len(lots))
+	for i := range lots {
+		ids = append(ids, lots[i].ID)
+	}
+	uses, err := s.store.SeedLotUsage(ctx, actorID, ids)
+	if err != nil {
+		return err
+	}
+	used := make(map[int64]float64, len(lots))
+	for _, u := range uses {
+		n := derivedCount(u.RadiusCM, u.SpacingCM)
+		if u.Count != nil {
+			n = *u.Count
+		}
+		used[u.LotID] += float64(n)
+	}
+	for i := range lots {
+		lots[i].Used = used[lots[i].ID]
+		lots[i].Remaining = lots[i].Quantity - lots[i].Used
+	}
+	return nil
+}
+
+// ownSeedLot loads a lot and enforces that the actor owns it. Someone else's lot
+// is ErrNotFound, not ErrForbidden — existence stays masked, same as gardens and
+// other users' plants. A store failure that isn't "no such row" passes through
+// unchanged; it is not an authorization answer.
+func (s *Service) ownSeedLot(ctx context.Context, actorID, lotID int64) (*domain.SeedLot, error) {
+	l, err := s.store.GetSeedLot(ctx, lotID)
+	if err != nil {
+		return nil, err // ErrNotFound for a missing row; anything else is real
+	}
+	if l.OwnerID != actorID {
+		return nil, domain.ErrNotFound
+	}
+	return l, nil
+}
+
+// GetSeedLot returns one of the actor's own lots, with Used/Remaining filled in.
+func (s *Service) GetSeedLot(ctx context.Context, actorID, lotID int64) (*domain.SeedLot, error) {
+	l, err := s.ownSeedLot(ctx, actorID, lotID)
+	if err != nil {
+		return nil, err
+	}
+	return s.withRemaining(ctx, actorID, l)
+}
+
+// CreateSeedLot records a purchase owned by the actor. The plant must be one the
+// actor can see — a built-in or their own — since you can perfectly well buy
+// generic Garlic from a vendor.
+func (s *Service) CreateSeedLot(ctx context.Context, actorID int64, in SeedLotInput) (*domain.SeedLot, error) {
+	if _, err := s.visiblePlant(ctx, actorID, in.PlantID); err != nil {
+		return nil, err // ErrInvalidInput for an unknown or someone else's plant
+	}
+	l := &domain.SeedLot{
+		OwnerID:        actorID,
+		PlantID:        in.PlantID,
+		Vendor:         strings.TrimSpace(in.Vendor),
+		SourceURL:      strings.TrimSpace(in.SourceURL),
+		SKU:            strings.TrimSpace(in.SKU),
+		LotCode:        strings.TrimSpace(in.LotCode),
+		PurchasedAt:    in.PurchasedAt,
+		PackedForYear:  in.PackedForYear,
+		Quantity:       in.Quantity,
+		Unit:           in.Unit,
+		CostCents:      in.CostCents,
+		GerminationPct: in.GerminationPct,
+		Notes:          strings.TrimSpace(in.Notes),
+	}
+	if err := finalizeSeedLot(l); err != nil {
+		return nil, err
+	}
+	created, err := s.store.CreateSeedLot(ctx, l)
+	if err != nil {
+		return nil, err
+	}
+	// A fresh lot has used nothing, but say so explicitly rather than letting the
+	// zero value stand in: an unfilled Remaining reads as "none left" on a packet
+	// you just bought.
+	return s.withRemaining(ctx, actorID, created)
+}
+
+// withRemaining fills Used/Remaining on a single lot.
+func (s *Service) withRemaining(ctx context.Context, actorID int64, l *domain.SeedLot) (*domain.SeedLot, error) {
+	one := []domain.SeedLot{*l}
+	if err := s.fillRemaining(ctx, actorID, one); err != nil {
+		return nil, err
+	}
+	return &one[0], nil
+}
+
+// UpdateSeedLot applies a partial, version-guarded patch to the actor's own lot.
+func (s *Service) UpdateSeedLot(ctx context.Context, actorID, lotID int64, patch SeedLotPatch, version int64) (*domain.SeedLot, error) {
+	l, err := s.ownSeedLot(ctx, actorID, lotID)
+	if err != nil {
+		return nil, err
+	}
+	applySeedLotPatch(l, patch)
+	if err := finalizeSeedLot(l); err != nil {
+		return nil, err
+	}
+	l.Version = version
+	updated, err := s.store.UpdateSeedLot(ctx, l)
+	if err != nil {
+		// The conflict path carries the CURRENT row back to the client to rebase
+		// on, so it needs its computed fields too — a 409 body reporting
+		// remaining=0 would be worse than no number at all.
+		if updated != nil {
+			if filled, ferr := s.withRemaining(ctx, actorID, updated); ferr == nil {
+				updated = filled
+			}
+		}
+		return updated, err
+	}
+	// The write succeeded. If the follow-up read fails, return the row without
+	// its computed fields rather than reporting a failed update that applied.
+	filled, ferr := s.withRemaining(ctx, actorID, updated)
+	if ferr != nil {
+		slog.Error("service: lot updated but remaining could not be computed", "error", ferr, "lot", lotID)
+		return updated, nil
+	}
+	return filled, nil
+}
+
+// DeleteSeedLot removes the actor's own lot. Plantings attributed to it survive
+// with a null link (ON DELETE SET NULL) — the plants really were in the ground,
+// whatever happened to the record of the packet.
+func (s *Service) DeleteSeedLot(ctx context.Context, actorID, lotID int64) error {
+	if _, err := s.ownSeedLot(ctx, actorID, lotID); err != nil {
+		return err
+	}
+	return s.store.DeleteSeedLot(ctx, lotID)
+}
+
+// checkSeedLotForPlanting validates a planting's lot attribution: the lot must be
+// the actor's, and must be a lot OF the plant being planted. Attributing a garlic
+// planting to a tomato lot is a data error that would silently corrupt every
+// remaining count downstream, so it's refused rather than stored.
+func (s *Service) checkSeedLotForPlanting(ctx context.Context, actorID int64, lotID *int64, plantID int64) error {
+	if lotID == nil {
+		return nil
+	}
+	l, err := s.ownSeedLot(ctx, actorID, *lotID)
+	if err != nil {
+		return domain.ErrInvalidInput // unknown or not yours: an invalid reference
+	}
+	if l.PlantID != plantID {
+		return domain.ErrInvalidInput
+	}
+	return nil
+}
+
+func applySeedLotPatch(l *domain.SeedLot, p SeedLotPatch) {
+	if p.Vendor != nil {
+		l.Vendor = strings.TrimSpace(*p.Vendor)
+	}
+	if p.SourceURL != nil {
+		l.SourceURL = strings.TrimSpace(*p.SourceURL)
+	}
+	if p.SKU != nil {
+		l.SKU = strings.TrimSpace(*p.SKU)
+	}
+	if p.LotCode != nil {
+		l.LotCode = strings.TrimSpace(*p.LotCode)
+	}
+	if p.SetPurchasedAt {
+		l.PurchasedAt = p.PurchasedAt
+	}
+	if p.SetPackedForYear {
+		l.PackedForYear = p.PackedForYear
+	}
+	if p.Quantity != nil {
+		l.Quantity = *p.Quantity
+	}
+	if p.Unit != nil {
+		l.Unit = *p.Unit
+	}
+	if p.SetCostCents {
+		l.CostCents = p.CostCents
+	}
+	if p.SetGerminationPct {
+		l.GerminationPct = p.GerminationPct
+	}
+	if p.Notes != nil {
+		l.Notes = strings.TrimSpace(*p.Notes)
+	}
+}
+
+// finalizeSeedLot validates a built/merged lot. Shared by create and update.
+func finalizeSeedLot(l *domain.SeedLot) error {
+	if _, ok := lotUnits[l.Unit]; !ok {
+		return domain.ErrInvalidInput
+	}
+	if !isFinite(l.Quantity) || l.Quantity < 0 || l.Quantity > maxLotQuantity {
+		return domain.ErrInvalidInput
+	}
+	if len(l.Vendor) > maxLotTextLen || len(l.SKU) > maxLotTextLen || len(l.LotCode) > maxLotTextLen {
+		return domain.ErrInvalidInput
+	}
+	if len(l.Notes) > maxLotNotesLen {
+		return domain.ErrInvalidInput
+	}
+	if !validSourceURL(l.SourceURL) {
+		return domain.ErrInvalidInput
+	}
+	if !validDatePtr(l.PurchasedAt) {
+		return domain.ErrInvalidInput
+	}
+	if l.PackedForYear != nil && (*l.PackedForYear < minPackedYear || *l.PackedForYear > maxPackedYear) {
+		return domain.ErrInvalidInput
+	}
+	if l.CostCents != nil && *l.CostCents < 0 {
+		return domain.ErrInvalidInput
+	}
+	if l.GerminationPct != nil {
+		g := *l.GerminationPct
+		if !isFinite(g) || g < 0 || g > 100 {
+			return domain.ErrInvalidInput
+		}
+	}
+	return nil
+}
+
+// validSourceURL accepts an empty string or an absolute http(s) URL.
+//
+// This renders as a clickable link, so it is untrusted input in the way that
+// matters: without the scheme check a "javascript:" URL stored here becomes
+// script execution the moment someone clicks it. Only http and https, and only
+// with a host — a relative or schemeless URL would resolve against pansy's own
+// origin, which is never what a vendor link means.
+func validSourceURL(raw string) bool {
+	if raw == "" {
+		return true
+	}
+	if len(raw) > maxSourceURLLen {
+		return false
+	}
+	u, err := url.Parse(raw)
+	if err != nil {
+		return false
+	}
+	if u.Scheme != "http" && u.Scheme != "https" {
+		return false
+	}
+	return u.Host != ""
+}

internal/service/seed_lots_test.go

@@ -0,0 +1,519 @@
+package service
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	"gitea.stevedudenhoeffer.com/steve/pansy/internal/domain"
+)
+
+// seedLot records a purchase of plantID with the given quantity in seeds.
+func seedLot(t *testing.T, s *Service, owner, plantID int64, qty float64, over func(*SeedLotInput)) *domain.SeedLot {
+	t.Helper()
+	in := SeedLotInput{PlantID: plantID, Quantity: qty, Unit: domain.UnitSeeds}
+	if over != nil {
+		over(&in)
+	}
+	l, err := s.CreateSeedLot(context.Background(), owner, in)
+	if err != nil {
+		t.Fatalf("CreateSeedLot: %v", err)
+	}
+	return l
+}
+
+// builtinPlantID returns a seeded built-in's id — the case that proves a lot can
+// reference a plant it doesn't own.
+func builtinPlantID(t *testing.T, s *Service, actor int64) int64 {
+	t.Helper()
+	plants, err := s.ListPlants(context.Background(), actor)
+	if err != nil {
+		t.Fatalf("ListPlants: %v", err)
+	}
+	for _, p := range plants {
+		if p.OwnerID == nil {
+			return p.ID
+		}
+	}
+	t.Fatal("no built-in plants seeded")
+	return 0
+}
+
+// TestTwoLotsOfOnePlantTrackIndependently — the reason inventory belongs to a
+// purchase and not to a variety: the same garlic from two vendors in two years
+// is two different things.
+func TestTwoLotsOfOnePlantTrackIndependently(t *testing.T) {
+	s := newTestService(t, openConfig())
+	owner := seedUser(t, s, "[email protected]")
+	g := seedGarden(t, s, owner)
+	bed := seedBed(t, s, owner, g.ID)
+	plant := seedOwnPlant(t, s, owner, 15)
+	ctx := context.Background()
+
+	johnnys := seedLot(t, s, owner, plant.ID, 100, func(in *SeedLotInput) {
+		in.Vendor = "Johnny's"
+		in.SourceURL = "https://www.johnnyseeds.com/vegetables/garlic/german-red-garlic"
+		in.PackedForYear = ptrInt(2026)
+	})
+	fedco := seedLot(t, s, owner, plant.ID, 50, func(in *SeedLotInput) {
+		in.Vendor = "Fedco"
+		in.PackedForYear = ptrInt(2025)
+	})
+
+	// Plant 12 out of the Johnny's lot only.
+	twelve := 12
+	if _, err := s.CreatePlanting(ctx, owner, bed.ID, PlantingInput{
+		PlantID: plant.ID, XCM: 0, YCM: 0, RadiusCM: 20, Count: &twelve, SeedLotID: &johnnys.ID,
+	}); err != nil {
+		t.Fatalf("CreatePlanting: %v", err)
+	}
+
+	lots, err := s.ListSeedLots(ctx, owner, nil)
+	if err != nil {
+		t.Fatalf("ListSeedLots: %v", err)
+	}
+	byID := map[int64]domain.SeedLot{}
+	for _, l := range lots {
+		byID[l.ID] = l
+	}
+	if got := byID[johnnys.ID]; got.Used != 12 || got.Remaining != 88 {
+		t.Errorf("Johnny's lot: used=%v remaining=%v, want 12/88", got.Used, got.Remaining)
+	}
+	if got := byID[fedco.ID]; got.Used != 0 || got.Remaining != 50 {
+		t.Errorf("Fedco lot: used=%v remaining=%v, want 0/50", got.Used, got.Remaining)
+	}
+	if byID[johnnys.ID].Vendor != "Johnny's" || byID[johnnys.ID].SourceURL == "" {
+		t.Errorf("provenance lost: %+v", byID[johnnys.ID])
+	}
+}
+
+// TestRemainingReturnsWhenAPlantingIsRemoved — the acceptance criterion, and the
+// reason `remaining` is derived rather than decremented on planting: removing a
+// plop has to give the seed back, without anything having to remember to.
+func TestRemainingReturnsWhenAPlantingIsRemoved(t *testing.T) {
+	s := newTestService(t, openConfig())
+	owner := seedUser(t, s, "[email protected]")
+	g := seedGarden(t, s, owner)
+	bed := seedBed(t, s, owner, g.ID)
+	plant := seedOwnPlant(t, s, owner, 15)
+	lot := seedLot(t, s, owner, plant.ID, 100, nil)
+	ctx := context.Background()
+
+	ten := 10
+	pl, err := s.CreatePlanting(ctx, owner, bed.ID, PlantingInput{
+		PlantID: plant.ID, XCM: 0, YCM: 0, RadiusCM: 20, Count: &ten, SeedLotID: &lot.ID,
+	})
+	if err != nil {
+		t.Fatalf("CreatePlanting: %v", err)
+	}
+	if got, _ := s.GetSeedLot(ctx, owner, lot.ID); got.Remaining != 90 {
+		t.Fatalf("remaining after planting = %v, want 90", got.Remaining)
+	}
+
+	// Soft-remove ("cleared the bed"): only ACTIVE plantings count against a lot.
+	today := "2026-08-01"
+	if _, err := s.UpdatePlanting(ctx, owner, pl.ID, PlantingPatch{
+		SetRemovedAt: true, RemovedAt: &today,
+	}, pl.Version); err != nil {
+		t.Fatalf("UpdatePlanting: %v", err)
+	}
+	if got, _ := s.GetSeedLot(ctx, owner, lot.ID); got.Remaining != 100 || got.Used != 0 {
+		t.Errorf("after removal: used=%v remaining=%v, want 0/100", got.Used, got.Remaining)
+	}
+}
+
+// TestLotOnBuiltinPlantIsPrivate — you can buy generic Garlic from Johnny's, so
+// a lot may point at a plant it doesn't own; the LOT is still yours alone.
+func TestLotOnBuiltinPlantIsPrivate(t *testing.T) {
+	s := newTestService(t, openConfig())
+	owner := seedUser(t, s, "[email protected]")
+	other := seedUser(t, s, "[email protected]")
+	ctx := context.Background()
+
+	builtin := builtinPlantID(t, s, owner)
+	lot := seedLot(t, s, owner, builtin, 25, func(in *SeedLotInput) { in.Vendor = "Johnny's" })
+
+	if _, err := s.GetSeedLot(ctx, owner, lot.ID); err != nil {
+		t.Fatalf("owner can't read their own lot: %v", err)
+	}
+	// Another user gets ErrNotFound, not Forbidden: existence stays masked.
+	if _, err := s.GetSeedLot(ctx, other, lot.ID); !errors.Is(err, domain.ErrNotFound) {
+		t.Errorf("other user read err = %v, want ErrNotFound", err)
+	}
+	if _, err := s.UpdateSeedLot(ctx, other, lot.ID, SeedLotPatch{Notes: strPtr("mine now")}, lot.Version); !errors.Is(err, domain.ErrNotFound) {
+		t.Errorf("other user update err = %v, want ErrNotFound", err)
+	}
+	if err := s.DeleteSeedLot(ctx, other, lot.ID); !errors.Is(err, domain.ErrNotFound) {
+		t.Errorf("other user delete err = %v, want ErrNotFound", err)
+	}
+	if lots, _ := s.ListSeedLots(ctx, other, nil); len(lots) != 0 {
+		t.Errorf("other user sees %d lots", len(lots))
+	}
+}
+
+// TestSourceURLValidation — the field renders as a clickable link, so the scheme
+// check is what stops a stored javascript: URL from becoming script execution.
+func TestSourceURLValidation(t *testing.T) {
+	s := newTestService(t, openConfig())
+	owner := seedUser(t, s, "[email protected]")
+	plant := seedOwnPlant(t, s, owner, 15)
+	ctx := context.Background()
+
+	ok := []string{
+		"",
+		"https://www.johnnyseeds.com/x",
+		"http://example.com/seeds?sku=123",
+	}
+	for _, u := range ok {
+		if _, err := s.CreateSeedLot(ctx, owner, SeedLotInput{
+			PlantID: plant.ID, Unit: domain.UnitSeeds, SourceURL: u,
+		}); err != nil {
+			t.Errorf("SourceURL %q rejected: %v", u, err)
+		}
+	}
+	bad := []string{
+		"javascript:alert(1)",
+		"JavaScript:alert(1)",
+		"data:text/html,<script>alert(1)</script>",
+		"//evil.example.com", // schemeless: would resolve against pansy's origin
+		"/seeds/garlic",      // relative, same reason
+		"file:///etc/passwd",
+		"https://", // no host
+	}
+	for _, u := range bad {
+		if _, err := s.CreateSeedLot(ctx, owner, SeedLotInput{
+			PlantID: plant.ID, Unit: domain.UnitSeeds, SourceURL: u,
+		}); !errors.Is(err, domain.ErrInvalidInput) {
+			t.Errorf("SourceURL %q accepted (err=%v)", u, err)
+		}
+	}
+	// The same rule applies to the plant's own source link.
+	if _, err := s.CreatePlant(ctx, owner, PlantInput{
+		Name: "X", Category: domain.CategoryHerb, SpacingCM: 10, Color: "#4a7c3f", Icon: "🌿",
+		SourceURL: "javascript:alert(1)",
+	}); !errors.Is(err, domain.ErrInvalidInput) {
+		t.Errorf("plant SourceURL accepted a javascript: URL (err=%v)", err)
+	}
+}
+
+// TestPlantCarriesProvenance — the headline: "German Red Garlic" links back to
+// the page it came from, and the built-ins keep working untouched.
+func TestPlantCarriesProvenance(t *testing.T) {
+	s := newTestService(t, openConfig())
+	owner := seedUser(t, s, "[email protected]")
+	ctx := context.Background()
+
+	p, err := s.CreatePlant(ctx, owner, PlantInput{
+		Name: "German Red Garlic", Category: domain.CategoryVegetable, SpacingCM: 15,
+		Color: "#8a5a8a", Icon: "🧄",
+		SourceURL: "https://www.johnnyseeds.com/vegetables/garlic/german-red-garlic",
+		Vendor:    "Johnny's Selected Seeds",
+	})
+	if err != nil {
+		t.Fatalf("CreatePlant: %v", err)
+	}
+	if p.Vendor != "Johnny's Selected Seeds" || p.SourceURL == "" {
+		t.Errorf("provenance not stored: %+v", p)
+	}
+
+	// The built-ins predate these columns and must still read cleanly.
+	plants, _ := s.ListPlants(ctx, owner)
+	for _, b := range plants {
+		if b.OwnerID == nil && (b.SourceURL != "" || b.Vendor != "") {
+			t.Errorf("built-in %q gained provenance from nowhere: %+v", b.Name, b)
+		}
+	}
+}
+
+// TestPlantingRejectsMismatchedLot — attributing a garlic planting to a tomato
+// lot would silently corrupt every remaining count downstream.
+func TestPlantingRejectsMismatchedLot(t *testing.T) {
+	s := newTestService(t, openConfig())
+	owner := seedUser(t, s, "[email protected]")
+	other := seedUser(t, s, "[email protected]")
+	g := seedGarden(t, s, owner)
+	bed := seedBed(t, s, owner, g.ID)
+	garlic := seedOwnPlant(t, s, owner, 15)
+	ctx := context.Background()
+
+	tomato, err := s.CreatePlant(ctx, owner, PlantInput{
+		Name: "Tomato", Category: domain.CategoryVegetable, SpacingCM: 45, Color: "#c0392b", Icon: "🍅",
+	})
+	if err != nil {
+		t.Fatalf("CreatePlant: %v", err)
+	}
+	tomatoLot := seedLot(t, s, owner, tomato.ID, 20, nil)
+
+	if _, err := s.CreatePlanting(ctx, owner, bed.ID, PlantingInput{
+		PlantID: garlic.ID, XCM: 0, YCM: 0, RadiusCM: 20, SeedLotID: &tomatoLot.ID,
+	}); !errors.Is(err, domain.ErrInvalidInput) {
+		t.Errorf("a garlic planting was attributed to a tomato lot (err=%v)", err)
+	}
+
+	// Someone else's lot is an invalid reference, not a leak of its existence.
+	othersPlant := seedOwnPlant(t, s, other, 15)
+	othersLot := seedLot(t, s, other, othersPlant.ID, 10, nil)
+	if _, err := s.CreatePlanting(ctx, owner, bed.ID, PlantingInput{
+		PlantID: garlic.ID, XCM: 0, YCM: 0, RadiusCM: 20, SeedLotID: &othersLot.ID,
+	}); !errors.Is(err, domain.ErrInvalidInput) {
+		t.Errorf("another user's lot was accepted (err=%v)", err)
+	}
+}
+
+// TestDeletingALotKeepsPlantingHistory — the plants really were in the ground,
+// whatever happened to the record of the packet.
+func TestDeletingALotKeepsPlantingHistory(t *testing.T) {
+	s := newTestService(t, openConfig())
+	owner := seedUser(t, s, "[email protected]")
+	g := seedGarden(t, s, owner)
+	bed := seedBed(t, s, owner, g.ID)
+	plant := seedOwnPlant(t, s, owner, 15)
+	lot := seedLot(t, s, owner, plant.ID, 100, nil)
+	ctx := context.Background()
+
+	pl, err := s.CreatePlanting(ctx, owner, bed.ID, PlantingInput{
+		PlantID: plant.ID, XCM: 0, YCM: 0, RadiusCM: 20, SeedLotID: &lot.ID,
+	})
+	if err != nil {
+		t.Fatalf("CreatePlanting: %v", err)
+	}
+	if err := s.DeleteSeedLot(ctx, owner, lot.ID); err != nil {
+		t.Fatalf("DeleteSeedLot: %v", err)
+	}
+	survived, err := s.store.GetPlanting(ctx, pl.ID)
+	if err != nil {
+		t.Fatalf("planting was destroyed with its lot: %v", err)
+	}
+	if survived.SeedLotID != nil {
+		t.Errorf("seedLotId = %v, want null after the lot was deleted", *survived.SeedLotID)
+	}
+}
+
+// TestSeedLotVersionGuard — lots are version-guarded like every other mutable row.
+func TestSeedLotVersionGuard(t *testing.T) {
+	s := newTestService(t, openConfig())
+	owner := seedUser(t, s, "[email protected]")
+	plant := seedOwnPlant(t, s, owner, 15)
+	lot := seedLot(t, s, owner, plant.ID, 100, nil)
+	ctx := context.Background()
+
+	updated, err := s.UpdateSeedLot(ctx, owner, lot.ID, SeedLotPatch{Notes: strPtr("half used")}, lot.Version)
+	if err != nil {
+		t.Fatalf("UpdateSeedLot: %v", err)
+	}
+	if updated.Notes != "half used" || updated.Version != lot.Version+1 {
+		t.Errorf("unexpected update: %+v", updated)
+	}
+	// Stale version → conflict, carrying the current row.
+	current, err := s.UpdateSeedLot(ctx, owner, lot.ID, SeedLotPatch{Notes: strPtr("stale")}, lot.Version)
+	if !errors.Is(err, domain.ErrVersionConflict) {
+		t.Fatalf("err = %v, want ErrVersionConflict", err)
+	}
+	if current == nil || current.Notes != "half used" {
+		t.Errorf("conflict should carry the current row, got %+v", current)
+	}
+}
+
+// TestSeedLotUnitAndQuantityValidation
+func TestSeedLotUnitAndQuantityValidation(t *testing.T) {
+	s := newTestService(t, openConfig())
+	owner := seedUser(t, s, "[email protected]")
+	plant := seedOwnPlant(t, s, owner, 15)
+	ctx := context.Background()
+
+	if _, err := s.CreateSeedLot(ctx, owner, SeedLotInput{PlantID: plant.ID, Unit: "handfuls"}); !errors.Is(err, domain.ErrInvalidInput) {
+		t.Errorf("unknown unit accepted: %v", err)
+	}
+	if _, err := s.CreateSeedLot(ctx, owner, SeedLotInput{
+		PlantID: plant.ID, Unit: domain.UnitSeeds, Quantity: -1,
+	}); !errors.Is(err, domain.ErrInvalidInput) {
+		t.Errorf("negative quantity accepted: %v", err)
+	}
+	pct := 140.0
+	if _, err := s.CreateSeedLot(ctx, owner, SeedLotInput{
+		PlantID: plant.ID, Unit: domain.UnitSeeds, GerminationPct: &pct,
+	}); !errors.Is(err, domain.ErrInvalidInput) {
+		t.Errorf("140%% germination accepted: %v", err)
+	}
+	if _, err := s.CreateSeedLot(ctx, owner, SeedLotInput{
+		PlantID: plant.ID, Unit: domain.UnitSeeds, PurchasedAt: strPtr("not-a-date"),
+	}); !errors.Is(err, domain.ErrInvalidInput) {
+		t.Errorf("malformed purchase date accepted: %v", err)
+	}
+}
+
+// TestDeletingAPlantWithLotsIsRefused — seed_lots.plant_id is ON DELETE CASCADE,
+// so without a guard, deleting a plant would silently destroy the purchase
+// records attached to it: vendor, cost, germination rate, gone with no warning.
+func TestDeletingAPlantWithLotsIsRefused(t *testing.T) {
+	s := newTestService(t, openConfig())
+	owner := seedUser(t, s, "[email protected]")
+	plant := seedOwnPlant(t, s, owner, 15)
+	lot := seedLot(t, s, owner, plant.ID, 100, func(in *SeedLotInput) { in.CostCents = ptrInt(499) })
+	ctx := context.Background()
+
+	if err := s.DeletePlant(ctx, owner, plant.ID); !errors.Is(err, domain.ErrPlantInUse) {
+		t.Fatalf("DeletePlant err = %v, want ErrPlantInUse", err)
+	}
+	if _, err := s.GetSeedLot(ctx, owner, lot.ID); err != nil {
+		t.Errorf("the lot was destroyed anyway: %v", err)
+	}
+
+	// Deleting the lot deliberately then frees the plant.
+	if err := s.DeleteSeedLot(ctx, owner, lot.ID); err != nil {
+		t.Fatalf("DeleteSeedLot: %v", err)
+	}
+	if err := s.DeletePlant(ctx, owner, plant.ID); err != nil {
+		t.Errorf("DeletePlant after clearing lots: %v", err)
+	}
+}
+
+// TestFreshLotReportsItsFullQuantity — an unfilled Remaining reads as "none
+// left" on a packet you just bought, which is the opposite of the truth.
+func TestFreshLotReportsItsFullQuantity(t *testing.T) {
+	s := newTestService(t, openConfig())
+	owner := seedUser(t, s, "[email protected]")
+	plant := seedOwnPlant(t, s, owner, 15)
+
+	lot := seedLot(t, s, owner, plant.ID, 100, nil)
+	if lot.Remaining != 100 || lot.Used != 0 {
+		t.Errorf("fresh lot: used=%v remaining=%v, want 0/100", lot.Used, lot.Remaining)
+	}
+}
+
+// TestVersionConflictCarriesRemaining — the 409 body is what the client rebases
+// on, so it needs the computed fields too.
+func TestVersionConflictCarriesRemaining(t *testing.T) {
+	s := newTestService(t, openConfig())
+	owner := seedUser(t, s, "[email protected]")
+	g := seedGarden(t, s, owner)
+	bed := seedBed(t, s, owner, g.ID)
+	plant := seedOwnPlant(t, s, owner, 15)
+	lot := seedLot(t, s, owner, plant.ID, 100, nil)
+	ctx := context.Background()
+
+	ten := 10
+	if _, err := s.CreatePlanting(ctx, owner, bed.ID, PlantingInput{
+		PlantID: plant.ID, XCM: 0, YCM: 0, RadiusCM: 20, Count: &ten, SeedLotID: &lot.ID,
+	}); err != nil {
+		t.Fatalf("CreatePlanting: %v", err)
+	}
+	if _, err := s.UpdateSeedLot(ctx, owner, lot.ID, SeedLotPatch{Notes: strPtr("first")}, lot.Version); err != nil {
+		t.Fatalf("first update: %v", err)
+	}
+	current, err := s.UpdateSeedLot(ctx, owner, lot.ID, SeedLotPatch{Notes: strPtr("stale")}, lot.Version)
+	if !errors.Is(err, domain.ErrVersionConflict) {
+		t.Fatalf("err = %v, want ErrVersionConflict", err)
+	}
+	if current == nil || current.Remaining != 90 || current.Used != 10 {
+		t.Errorf("conflict row: used=%v remaining=%v, want 10/90", current.Used, current.Remaining)
+	}
+}
+
+// TestRemainingGoesNegativeRatherThanHidingIt — planting more than you recorded
+// buying is a real thing; clamping to zero would hide the discrepancy at exactly
+// the moment it is worth seeing.
+func TestRemainingGoesNegativeRatherThanHidingIt(t *testing.T) {
+	s := newTestService(t, openConfig())
+	owner := seedUser(t, s, "[email protected]")
+	g := seedGarden(t, s, owner)
+	bed := seedBed(t, s, owner, g.ID)
+	plant := seedOwnPlant(t, s, owner, 15)
+	lot := seedLot(t, s, owner, plant.ID, 5, nil)
+	ctx := context.Background()
+
+	twenty := 20
+	if _, err := s.CreatePlanting(ctx, owner, bed.ID, PlantingInput{
+		PlantID: plant.ID, XCM: 0, YCM: 0, RadiusCM: 20, Count: &twenty, SeedLotID: &lot.ID,
+	}); err != nil {
+		t.Fatalf("CreatePlanting: %v", err)
+	}
+	got, err := s.GetSeedLot(ctx, owner, lot.ID)
+	if err != nil {
+		t.Fatalf("GetSeedLot: %v", err)
+	}
+	if got.Remaining != -15 {
+		t.Errorf("remaining = %v, want -15 (20 planted from a lot of 5)", got.Remaining)
+	}
+}
+
+// TestCopiedGardenDoesNotInheritSeedLots — a copy is a plan, not a second
+// planting out of the same packet. Carrying the link would double-count the
+// original lot's usage and quietly attach a private lot to a garden that may
+// later be shared.
+func TestCopiedGardenDoesNotInheritSeedLots(t *testing.T) {
+	s := newTestService(t, openConfig())
+	owner := seedUser(t, s, "[email protected]")
+	g := seedGarden(t, s, owner)
+	bed := seedBed(t, s, owner, g.ID)
+	plant := seedOwnPlant(t, s, owner, 15)
+	lot := seedLot(t, s, owner, plant.ID, 100, nil)
+	ctx := context.Background()
+
+	ten := 10
+	if _, err := s.CreatePlanting(ctx, owner, bed.ID, PlantingInput{
+		PlantID: plant.ID, XCM: 0, YCM: 0, RadiusCM: 20, Count: &ten, SeedLotID: &lot.ID,
+	}); err != nil {
+		t.Fatalf("CreatePlanting: %v", err)
+	}
+
+	copied, err := s.CopyGarden(ctx, owner, g.ID, "Copy")
+	if err != nil {
+		t.Fatalf("CopyGarden: %v", err)
+	}
+	full, err := s.GardenFull(ctx, owner, copied.ID)
+	if err != nil {
+		t.Fatalf("GardenFull: %v", err)
+	}
+	if len(full.Plantings) != 1 {
+		t.Fatalf("copy has %d plantings, want 1", len(full.Plantings))
+	}
+	if full.Plantings[0].SeedLotID != nil {
+		t.Errorf("the copy inherited seed lot %v", *full.Plantings[0].SeedLotID)
+	}
+	// And the original lot's usage is unchanged: still 10, not 20.
+	got, _ := s.GetSeedLot(ctx, owner, lot.ID)
+	if got.Used != 10 {
+		t.Errorf("copying double-counted the lot: used = %v, want 10", got.Used)
+	}
+}
+
+// TestRevertRestoresAPlantingWhoseLotIsGone — a snapshot can name a lot that has
+// since been deleted; restoring it verbatim would violate the FK and abort the
+// whole revert.
+func TestRevertRestoresAPlantingWhoseLotIsGone(t *testing.T) {
+	s := newTestService(t, openConfig())
+	owner := seedUser(t, s, "[email protected]")
+	g := seedGarden(t, s, owner)
+	bed := seedBed(t, s, owner, g.ID)
+	plant := seedOwnPlant(t, s, owner, 15)
+	lot := seedLot(t, s, owner, plant.ID, 100, nil)
+	ctx := context.Background()
+
+	pl, err := s.CreatePlanting(ctx, owner, bed.ID, PlantingInput{
+		PlantID: plant.ID, XCM: 0, YCM: 0, RadiusCM: 20, SeedLotID: &lot.ID,
+	})
+	if err != nil {
+		t.Fatalf("CreatePlanting: %v", err)
+	}
+	if err := s.DeletePlanting(ctx, owner, pl.ID); err != nil {
+		t.Fatalf("DeletePlanting: %v", err)
+	}
+	del := history(t, s, owner, g.ID)[0]
+
+	// The lot goes away while the deletion sits in history.
+	if err := s.DeleteSeedLot(ctx, owner, lot.ID); err != nil {
+		t.Fatalf("DeleteSeedLot: %v", err)
+	}
+
+	if _, conflicts, err := s.RevertChangeSet(ctx, owner, del.ID, domain.SourceUI); err != nil || len(conflicts) != 0 {
+		t.Fatalf("revert: err=%v conflicts=%+v", err, conflicts)
+	}
+	restored, err := s.store.GetPlanting(ctx, pl.ID)
+	if err != nil {
+		t.Fatalf("planting not restored: %v", err)
+	}
+	if restored.SeedLotID != nil {
+		t.Errorf("a dangling lot reference was restored: %v", *restored.SeedLotID)
+	}
+}

internal/store/gardens.go

@@ -234,6 +234,11 @@ func (d *DB) CopyGarden(ctx context.Context, srcID, ownerID int64, name string)
 			// Unreachable: every active planting joins an object we just copied.
 			return nil, fmt.Errorf("store: copy planting %d: source object %d not copied", p.ID, p.ObjectID)
 		}
+		// A copy must not inherit the source's seed-lot attribution. The copied
+		// plops are a plan, not a second planting out of the same packet, and
+		// carrying the link would double-count that lot's usage — and quietly
+		// attach a private lot to a garden that may later be shared.
+		p.SeedLotID = nil
 		if _, err := scanPlanting(tx.QueryRowContext(ctx, plantingInsert, plantingInsertArgs(objectID, &p)...)); err != nil {
 			return nil, fmt.Errorf("store: copy planting: %w", err)
 		}

internal/store/migrations/0007_seed_lots.sql

@@ -0,0 +1,53 @@
+-- Seed provenance and inventory (#50): where "German Red Garlic" came from, and
+-- how much of it is left.
+--
+-- Two modelling calls worth stating, because both look like omissions otherwise:
+--
+--   1. The plant catalog stays FLAT. No species→variety hierarchy. A row in your
+--      catalog just is the thing you plant — "German Red Garlic" is a plant row,
+--      and the built-in "Garlic" is a generic starting point you clone. A
+--      hierarchy buys taxonomy nobody asked for and complicates every join.
+--
+--   2. Inventory belongs to a PURCHASE, not to a variety. You might buy the same
+--      garlic from two vendors in two years at two prices and two germination
+--      rates. Quantity columns on plants would collapse all of that into one
+--      number and lose it, so lots get their own table.
+--
+-- Nothing here is destructive: plants gains two defaulted columns, the built-ins
+-- keep working with empty strings, and plantings gains a nullable link.
+ALTER TABLE plants ADD COLUMN source_url TEXT NOT NULL DEFAULT '';
+ALTER TABLE plants ADD COLUMN vendor     TEXT NOT NULL DEFAULT '';
+
+-- owner_id sits on the LOT rather than being inherited from the plant, because a
+-- lot may reference a built-in plant (you can buy generic Garlic from Johnny's)
+-- while still being nobody's business but yours. Lots are never shared along
+-- with a garden.
+CREATE TABLE seed_lots (
+    id              INTEGER PRIMARY KEY,
+    owner_id        INTEGER NOT NULL REFERENCES users (id)  ON DELETE CASCADE,
+    plant_id        INTEGER NOT NULL REFERENCES plants (id) ON DELETE CASCADE,
+    vendor          TEXT    NOT NULL DEFAULT '',
+    source_url      TEXT    NOT NULL DEFAULT '',
+    sku             TEXT    NOT NULL DEFAULT '',
+    lot_code        TEXT    NOT NULL DEFAULT '',
+    purchased_at    TEXT,                                   -- 'YYYY-MM-DD'
+    packed_for_year INTEGER,
+    quantity        REAL    NOT NULL DEFAULT 0,
+    unit            TEXT    NOT NULL CHECK (unit IN ('seeds','grams','ounces','packets','bulbs','plants')),
+    cost_cents      INTEGER,
+    germination_pct REAL,
+    notes           TEXT    NOT NULL DEFAULT '',
+    version         INTEGER NOT NULL DEFAULT 1,
+    created_at      TEXT    NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
+    updated_at      TEXT    NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%SZ', 'now'))
+);
+
+CREATE INDEX idx_seed_lots_owner ON seed_lots (owner_id);
+CREATE INDEX idx_seed_lots_plant ON seed_lots (plant_id);
+
+-- Which lot a planting came out of. ON DELETE SET NULL rather than CASCADE:
+-- retiring a lot must never destroy planting history — the plants really were in
+-- the ground, whatever happened to the record of the packet.
+ALTER TABLE plantings ADD COLUMN seed_lot_id INTEGER REFERENCES seed_lots (id) ON DELETE SET NULL;
+
+CREATE INDEX idx_plantings_seed_lot ON plantings (seed_lot_id) WHERE seed_lot_id IS NOT NULL;

internal/store/plantings.go

@@ -12,13 +12,13 @@ import (
 // plantingColumns lists plantings columns in the order scanPlanting expects.
 // Used unqualified for direct selects; the /full read below qualifies with pl.
 const plantingColumns = `id, object_id, plant_id, x_cm, y_cm, radius_cm, count, label,
-	planted_at, removed_at, version, created_at, updated_at`
+	planted_at, removed_at, seed_lot_id, version, created_at, updated_at`
 
 func scanPlanting(s scanner) (*domain.Planting, error) {
 	var p domain.Planting
 	if err := s.Scan(
 		&p.ID, &p.ObjectID, &p.PlantID, &p.XCM, &p.YCM, &p.RadiusCM,
-		&p.Count, &p.Label, &p.PlantedAt, &p.RemovedAt,
+		&p.Count, &p.Label, &p.PlantedAt, &p.RemovedAt, &p.SeedLotID,
 		&p.Version, &p.CreatedAt, &p.UpdatedAt,
 	); err != nil {
 		return nil, err
@@ -89,12 +89,12 @@ func (d *DB) RestorePlanting(ctx context.Context, p *domain.Planting) (*domain.P
 	restored, err := scanPlanting(d.sql.QueryRowContext(ctx,
 		`INSERT INTO plantings
 		   (id, object_id, plant_id, x_cm, y_cm, radius_cm, count, label, planted_at, removed_at,
-		    version, created_at, updated_at)
+		    seed_lot_id, version, created_at, updated_at)
-		 VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?,
+		 VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?,
 		         strftime('%Y-%m-%dT%H:%M:%SZ', 'now'))
 		 RETURNING `+plantingColumns,
 		p.ID, p.ObjectID, p.PlantID, p.XCM, p.YCM, p.RadiusCM, p.Count, p.Label,
-		p.PlantedAt, p.RemovedAt, p.Version, p.CreatedAt,
+		p.PlantedAt, p.RemovedAt, p.SeedLotID, p.Version, p.CreatedAt,
 	))
 	if err != nil {
 		return nil, fmt.Errorf("store: restore planting: %w", err)
@@ -153,14 +153,14 @@ func (d *DB) GetPlanting(ctx context.Context, id int64) (*domain.Planting, error
 // — with plantingInsertArgs supplying its parameters — so all three stay in step
 // with the table. removed_at is never set here: a new plop is active, and "clear
 // bed" sets removed_at later via UpdatePlanting.
-const plantingInsert = `INSERT INTO plantings (object_id, plant_id, x_cm, y_cm, radius_cm, count, label, planted_at)
+const plantingInsert = `INSERT INTO plantings (object_id, plant_id, x_cm, y_cm, radius_cm, count, label, planted_at, seed_lot_id)
-	 VALUES (?, ?, ?, ?, ?, ?, ?, ?)
+	 VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)
 	 RETURNING ` + plantingColumns
 
 // plantingInsertArgs builds plantingInsert's parameters, parenting p to objectID
 // (p's own object normally, and the copied object when copying a garden).
 func plantingInsertArgs(objectID int64, p *domain.Planting) []any {
-	return []any{objectID, p.PlantID, p.XCM, p.YCM, p.RadiusCM, p.Count, p.Label, p.PlantedAt}
+	return []any{objectID, p.PlantID, p.XCM, p.YCM, p.RadiusCM, p.Count, p.Label, p.PlantedAt, p.SeedLotID}
 }
 
 // CreatePlanting inserts a plop (fields already validated by the service) and
@@ -207,12 +207,12 @@ func (d *DB) UpdatePlanting(ctx context.Context, p *domain.Planting) (*domain.Pl
 	updated, err := scanPlanting(d.sql.QueryRowContext(ctx,
 		`UPDATE plantings
 		    SET plant_id = ?, x_cm = ?, y_cm = ?, radius_cm = ?, count = ?, label = ?,
-		        planted_at = ?, removed_at = ?,
+		        planted_at = ?, removed_at = ?, seed_lot_id = ?,
 		        version = version + 1,
 		        updated_at = strftime('%Y-%m-%dT%H:%M:%SZ', 'now')
 		  WHERE id = ? AND version = ?
 		  RETURNING `+plantingColumns,
-		p.PlantID, p.XCM, p.YCM, p.RadiusCM, p.Count, p.Label, p.PlantedAt, p.RemovedAt,
+		p.PlantID, p.XCM, p.YCM, p.RadiusCM, p.Count, p.Label, p.PlantedAt, p.RemovedAt, p.SeedLotID,
 		p.ID, p.Version,
 	))
 	if errors.Is(err, sql.ErrNoRows) {

internal/store/plants.go

@@ -11,13 +11,13 @@ import (
 
 // plantColumns lists plants columns in the order scanPlant expects.
 const plantColumns = `id, owner_id, name, category, spacing_cm, color, icon,
-	days_to_maturity, notes, version, created_at, updated_at`
+	days_to_maturity, source_url, vendor, notes, version, created_at, updated_at`
 
 func scanPlant(s scanner) (*domain.Plant, error) {
 	var p domain.Plant
 	if err := s.Scan(
 		&p.ID, &p.OwnerID, &p.Name, &p.Category, &p.SpacingCM, &p.Color, &p.Icon,
-		&p.DaysToMaturity, &p.Notes, &p.Version, &p.CreatedAt, &p.UpdatedAt,
+		&p.DaysToMaturity, &p.SourceURL, &p.Vendor, &p.Notes, &p.Version, &p.CreatedAt, &p.UpdatedAt,
 	); err != nil {
 		return nil, err
 	}
@@ -111,10 +111,11 @@ func (d *DB) GetPlant(ctx context.Context, id int64) (*domain.Plant, error) {
 // migration only, never through this path.
 func (d *DB) CreatePlant(ctx context.Context, p *domain.Plant) (*domain.Plant, error) {
 	created, err := scanPlant(d.sql.QueryRowContext(ctx,
-		`INSERT INTO plants (owner_id, name, category, spacing_cm, color, icon, days_to_maturity, notes)
+		`INSERT INTO plants (owner_id, name, category, spacing_cm, color, icon, days_to_maturity, source_url, vendor, notes)
-		 VALUES (?, ?, ?, ?, ?, ?, ?, ?)
+		 VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
 		 RETURNING `+plantColumns,
-		p.OwnerID, p.Name, p.Category, p.SpacingCM, p.Color, p.Icon, p.DaysToMaturity, p.Notes,
+		p.OwnerID, p.Name, p.Category, p.SpacingCM, p.Color, p.Icon, p.DaysToMaturity,
+		p.SourceURL, p.Vendor, p.Notes,
 	))
 	if err != nil {
 		return nil, fmt.Errorf("store: insert plant: %w", err)
@@ -130,12 +131,13 @@ func (d *DB) UpdatePlant(ctx context.Context, p *domain.Plant) (*domain.Plant, e
 	updated, err := scanPlant(d.sql.QueryRowContext(ctx,
 		`UPDATE plants
 		    SET name = ?, category = ?, spacing_cm = ?, color = ?, icon = ?,
-		        days_to_maturity = ?, notes = ?,
+		        days_to_maturity = ?, source_url = ?, vendor = ?, notes = ?,
 		        version = version + 1,
 		        updated_at = strftime('%Y-%m-%dT%H:%M:%SZ', 'now')
 		  WHERE id = ? AND version = ?
 		  RETURNING `+plantColumns,
-		p.Name, p.Category, p.SpacingCM, p.Color, p.Icon, p.DaysToMaturity, p.Notes,
+		p.Name, p.Category, p.SpacingCM, p.Color, p.Icon, p.DaysToMaturity,
+		p.SourceURL, p.Vendor, p.Notes,
 		p.ID, p.Version,
 	))
 	if errors.Is(err, sql.ErrNoRows) {

internal/store/seed_lots.go

@@ -0,0 +1,217 @@
+package store
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"fmt"
+
+	"gitea.stevedudenhoeffer.com/steve/pansy/internal/domain"
+)
+
+// maxSeedLotsPerRead caps a lot listing. Far past any real seed shelf; it exists
+// so the read is bounded rather than trusting it to stay small.
+const maxSeedLotsPerRead = 1000
+
+// seedLotColumns lists seed_lots columns in the order scanSeedLot expects.
+const seedLotColumns = `id, owner_id, plant_id, vendor, source_url, sku, lot_code,
+	purchased_at, packed_for_year, quantity, unit, cost_cents, germination_pct, notes,
+	version, created_at, updated_at`
+
+func scanSeedLot(s scanner) (*domain.SeedLot, error) {
+	var l domain.SeedLot
+	if err := s.Scan(
+		&l.ID, &l.OwnerID, &l.PlantID, &l.Vendor, &l.SourceURL, &l.SKU, &l.LotCode,
+		&l.PurchasedAt, &l.PackedForYear, &l.Quantity, &l.Unit, &l.CostCents,
+		&l.GerminationPct, &l.Notes, &l.Version, &l.CreatedAt, &l.UpdatedAt,
+	); err != nil {
+		return nil, err
+	}
+	return &l, nil
+}
+
+// CreateSeedLot inserts a lot (fields already validated by the service).
+func (d *DB) CreateSeedLot(ctx context.Context, l *domain.SeedLot) (*domain.SeedLot, error) {
+	created, err := scanSeedLot(d.sql.QueryRowContext(ctx,
+		`INSERT INTO seed_lots
+		   (owner_id, plant_id, vendor, source_url, sku, lot_code, purchased_at,
+		    packed_for_year, quantity, unit, cost_cents, germination_pct, notes)
+		 VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
+		 RETURNING `+seedLotColumns,
+		l.OwnerID, l.PlantID, l.Vendor, l.SourceURL, l.SKU, l.LotCode, l.PurchasedAt,
+		l.PackedForYear, l.Quantity, l.Unit, l.CostCents, l.GerminationPct, l.Notes,
+	))
+	if err != nil {
+		return nil, fmt.Errorf("store: insert seed lot: %w", err)
+	}
+	return created, nil
+}
+
+// GetSeedLot returns a lot by id, or domain.ErrNotFound. Ownership is the
+// service's check, not this one's.
+func (d *DB) GetSeedLot(ctx context.Context, id int64) (*domain.SeedLot, error) {
+	l, err := scanSeedLot(d.sql.QueryRowContext(ctx,
+		`SELECT `+seedLotColumns+` FROM seed_lots WHERE id = ?`, id))
+	if errors.Is(err, sql.ErrNoRows) {
+		return nil, domain.ErrNotFound
+	}
+	if err != nil {
+		return nil, fmt.Errorf("store: get seed lot: %w", err)
+	}
+	return l, nil
+}
+
+// ListSeedLotsForOwner returns every lot the actor owns, newest purchase first
+// (undated lots last), then by id. Optionally narrowed to one plant. Always a
+// non-nil slice.
+func (d *DB) ListSeedLotsForOwner(ctx context.Context, ownerID int64, plantID *int64) ([]domain.SeedLot, error) {
+	query := `SELECT ` + seedLotColumns + ` FROM seed_lots WHERE owner_id = ?`
+	args := []any{ownerID}
+	if plantID != nil {
+		query += ` AND plant_id = ?`
+		args = append(args, *plantID)
+	}
+	// NULL purchased_at sorts last: an undated lot is the least useful to see
+	// first. Capped like every other list read so one runaway account can't ask
+	// for an unbounded result set.
+	query += ` ORDER BY purchased_at IS NULL, purchased_at DESC, id DESC LIMIT ?`
+	args = append(args, maxSeedLotsPerRead)
+
+	rows, err := d.sql.QueryContext(ctx, query, args...)
+	if err != nil {
+		return nil, fmt.Errorf("store: list seed lots: %w", err)
+	}
+	defer rows.Close()
+
+	lots := []domain.SeedLot{}
+	for rows.Next() {
+		l, err := scanSeedLot(rows)
+		if err != nil {
+			return nil, fmt.Errorf("store: scan seed lot: %w", err)
+		}
+		lots = append(lots, *l)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, fmt.Errorf("store: iterate seed lots: %w", err)
+	}
+	return lots, nil
+}
+
+// UpdateSeedLot applies a version-guarded update of every mutable column (the
+// service merges partial patches onto the current row first). Same contract as
+// the other mutable resources: the updated row, or (current, ErrVersionConflict).
+// plant_id and owner_id are immutable — re-pointing a purchase at a different
+// variety or user would rewrite history rather than correct it.
+func (d *DB) UpdateSeedLot(ctx context.Context, l *domain.SeedLot) (*domain.SeedLot, error) {
+	updated, err := scanSeedLot(d.sql.QueryRowContext(ctx,
+		`UPDATE seed_lots
+		    SET vendor = ?, source_url = ?, sku = ?, lot_code = ?, purchased_at = ?,
+		        packed_for_year = ?, quantity = ?, unit = ?, cost_cents = ?,
+		        germination_pct = ?, notes = ?,
+		        version = version + 1,
+		        updated_at = strftime('%Y-%m-%dT%H:%M:%SZ', 'now')
+		  WHERE id = ? AND version = ?
+		  RETURNING `+seedLotColumns,
+		l.Vendor, l.SourceURL, l.SKU, l.LotCode, l.PurchasedAt, l.PackedForYear,
+		l.Quantity, l.Unit, l.CostCents, l.GerminationPct, l.Notes,
+		l.ID, l.Version,
+	))
+	if errors.Is(err, sql.ErrNoRows) {
+		current, gerr := d.GetSeedLot(ctx, l.ID)
+		if gerr != nil {
+			return nil, gerr
+		}
+		return current, domain.ErrVersionConflict
+	}
+	if err != nil {
+		return nil, fmt.Errorf("store: update seed lot: %w", err)
+	}
+	return updated, nil
+}
+
+// DeleteSeedLot removes a lot. Plantings attributed to it survive with a NULL
+// seed_lot_id (see the migration): the plants really were in the ground,
+// whatever happened to the record of the packet.
+func (d *DB) DeleteSeedLot(ctx context.Context, id int64) error {
+	res, err := d.sql.ExecContext(ctx, `DELETE FROM seed_lots WHERE id = ?`, id)
+	if err != nil {
+		return fmt.Errorf("store: delete seed lot: %w", err)
+	}
+	n, err := res.RowsAffected()
+	if err != nil {
+		return fmt.Errorf("store: seed lot delete rows: %w", err)
+	}
+	if n == 0 {
+		return domain.ErrNotFound
+	}
+	return nil
+}
+
+// CountSeedLotsForPlant returns how many lots reference a plant. Used to refuse
+// deleting a plant that has purchase records: the FK is ON DELETE CASCADE, so
+// without this check the delete would silently destroy them.
+func (d *DB) CountSeedLotsForPlant(ctx context.Context, plantID int64) (int, error) {
+	var n int
+	if err := d.sql.QueryRowContext(ctx,
+		`SELECT COUNT(*) FROM seed_lots WHERE plant_id = ?`, plantID).Scan(&n); err != nil {
+		return 0, fmt.Errorf("store: count seed lots for plant: %w", err)
+	}
+	return n, nil
+}
+
+// SeedLotUse is one active planting attributed to a lot, carrying just enough to
+// compute its effective plant count.
+type SeedLotUse struct {
+	LotID     int64
+	RadiusCM  float64
+	Count     *int
+	SpacingCM float64
+}
+
+// SeedLotUsage returns the ACTIVE plantings attributed to the given lots — the
+// "used" half of a lot's remaining quantity. Scoped to the lots the caller
+// actually needs, so reading one lot doesn't scan every planting the owner has.
+//
+// It returns the raw ingredients rather than a SUM, because the effective count
+// of a planting is its explicit count when it has one and the derived
+// π·r²/spacing² formula otherwise. That formula lives in the service; reproducing
+// it in SQL would guarantee the two drift apart.
+//
+// ownerID is still in the WHERE clause even though the ids come from rows the
+// service already checked: a scoping query should not depend on its caller
+// having checked scope.
+func (d *DB) SeedLotUsage(ctx context.Context, ownerID int64, lotIDs []int64) ([]SeedLotUse, error) {
+	if len(lotIDs) == 0 {
+		return nil, nil
+	}
+	args := make([]any, 0, len(lotIDs)+1)
+	args = append(args, ownerID)
+	for _, id := range lotIDs {
+		args = append(args, id)
+	}
+	rows, err := d.sql.QueryContext(ctx,
+		`SELECT pl.seed_lot_id, pl.radius_cm, pl.count, p.spacing_cm
+		   FROM plantings pl
+		   JOIN seed_lots sl ON sl.id = pl.seed_lot_id
+		   JOIN plants p     ON p.id = pl.plant_id
+		  WHERE sl.owner_id = ? AND pl.removed_at IS NULL
+		    AND sl.id IN (`+placeholders(len(lotIDs))+`)`,
+		args...)
+	if err != nil {
+		return nil, fmt.Errorf("store: seed lot usage: %w", err)
+	}
+	defer rows.Close()
+
+	uses := []SeedLotUse{}
+	for rows.Next() {
+		var u SeedLotUse
+		if err := rows.Scan(&u.LotID, &u.RadiusCM, &u.Count, &u.SpacingCM); err != nil {
+			return nil, fmt.Errorf("store: scan seed lot usage: %w", err)
+		}
+		uses = append(uses, u)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, fmt.Errorf("store: iterate seed lot usage: %w", err)
+	}
+	return uses, nil
+}