Seed-packet capture: vision model, extraction, catalog match, create (backend) (#81)

Photograph a seed packet → it fills in the plant and the purchase. This is the
backend; the scan UI is a follow-up PR.

Vision model config (mirrors the agent model from #79):
- Migration 0011 adds instance_settings.vision_model; PANSY_VISION_MODEL is the
  env default. Precedence Settings → env → empty; the KEY stays in the env.
- EffectiveVision resolves it; /capabilities advertises "vision" only when a
  model + key are configured, so the UI offers the scan button only when it works.

Extraction is one-shot, NOT an agent loop (internal/vision):
- majordomo.Generate[SeedPacket] derives a JSON schema from the struct tags and
  hands the image to the vision model; it can't call a tool, so it can't touch
  the garden — it only reads a picture and returns data. Numeric fields are
  pointers, so a field the packet doesn't print comes back nil, not a made-up 0.
- Hermetic test: majordomo's fake provider returns canned packet JSON and
  Generate unmarshals it, image + derived schema included. No live model.

The image is normalized to JPEG at the upload boundary (imagenorm from #80),
which is where an iPhone HEIC becomes readable — majordomo's media path can't
decode HEIC. imagenorm now links into the binary (~7 MB, the cost #80 deferred).

The hard part is catalog matching, not OCR (internal/service/seed_packet.go):
- A wrong auto-match splits a variety's seed-lot history across duplicate rows,
  so the service NEVER auto-creates. matchPlants surfaces RANKED candidates
  (exact name → variety-in-name → same species, conservative and name-based),
  the user confirms, and CreateFromPacket makes the plant (new or existing) + the
  lot. Exactly one of plantId/newPlant, refused otherwise.
- Plants/lots aren't in the undo history (catalog/inventory), so no change set.
- The extractor is injectable (service.WithPacketExtractor) so ExtractSeedPacket
  and the /scan endpoint test end to end against a fake, no live model.

Endpoints: POST /seed-lots/scan (multipart image → proposal, reads only; extends
the read deadline for a slow phone upload, caps the body, maps too-large/unreadable
to clear statuses) and POST /seed-lots/from-packet (confirmed proposal → 201).

Docs: README (PANSY_VISION_MODEL), DESIGN (routes + the decision and why the
model can't touch the garden).

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01H3zbym8Doka2d7D48maSgZ

internal/service/seed_packet.go

@@ -0,0 +1,218 @@
+package service
+
+import (
+	"context"
+	"sort"
+	"strings"
+
+	"gitea.stevedudenhoeffer.com/steve/pansy/internal/domain"
+	"gitea.stevedudenhoeffer.com/steve/pansy/internal/vision"
+)
+
+// Seed-packet capture (#81): read a photographed packet, propose a plant + lot,
+// let the user confirm. The two halves are deliberately separate operations:
+// extraction only READS (a picture in, a proposal out — it can't touch the
+// garden), and creation happens later, from the confirmed proposal, so a
+// misread never writes anything on its own.
+
+// PacketPlantMatch is a candidate existing plant the packet might be, with why it
+// matched, so the UI can pre-select the likely one and let the user override.
+type PacketPlantMatch struct {
+	Plant domain.Plant `json:"plant"`
+	// Reason is a short human tag: "exact name", "variety in name", "same species".
+	Reason string `json:"reason"`
+}
+
+// PacketProposal is what a scan returns: the fields read off the packet, plus
+// candidate existing plants it might already be. Nothing is created yet.
+type PacketProposal struct {
+	Packet vision.SeedPacket `json:"packet"`
+	// Candidates are existing plants the packet may match, best first. Empty means
+	// "probably a new variety" — the UI then offers to create one.
+	Candidates []PacketPlantMatch `json:"candidates"`
+	// SuggestedName is the variety (or species) to prefill a new-plant name with.
+	SuggestedName string `json:"suggestedName"`
+	// SuggestedCategory is the packet's category if it's a valid one, for prefill.
+	SuggestedCategory string `json:"suggestedCategory"`
+}
+
+// ExtractSeedPacket reads a (JPEG) packet photo and proposes a plant + lot for
+// the actor to confirm. It needs a configured vision model; with none it returns
+// ErrInvalidInput (the API layer turns "not configured" into a clear message and
+// never offers the feature in the first place).
+//
+// The extraction runs as the actor only in the sense that the catalog match is
+// scoped to what they can see; the model call itself has no ACL — it just reads
+// a picture the actor uploaded.
+func (s *Service) ExtractSeedPacket(ctx context.Context, actorID int64, jpeg []byte) (*PacketProposal, error) {
+	if len(jpeg) == 0 {
+		return nil, domain.ErrInvalidInput
+	}
+	vis, err := s.EffectiveVision(ctx)
+	if err != nil {
+		return nil, err
+	}
+	if !vis.Ready() {
+		// No vision model configured — the feature isn't available.
+		return nil, domain.ErrInvalidInput
+	}
+
+	packet, err := s.extractPacket(ctx, vis.APIKey, vis.Model, jpeg)
+	if err != nil {
+		return nil, err
+	}
+
+	plants, err := s.store.ListPlantsForActor(ctx, actorID)
+	if err != nil {
+		return nil, err
+	}
+
+	return &PacketProposal{
+		Packet:            packet,
+		Candidates:        matchPlants(packet, plants),
+		SuggestedName:     suggestedName(packet),
+		SuggestedCategory: validCategory(packet.Category),
+	}, nil
+}
+
+// suggestedName is the variety if the packet named one, else the species — what
+// to prefill a new plant's name with. "Music" beats "garlic" when both are read.
+func suggestedName(p vision.SeedPacket) string {
+	if v := strings.TrimSpace(p.Variety); v != "" {
+		return v
+	}
+	return strings.TrimSpace(p.Species)
+}
+
+// validCategory returns the packet's category if it's one pansy knows, else "".
+func validCategory(c string) string {
+	switch c {
+	case domain.CategoryVegetable, domain.CategoryHerb, domain.CategoryFlower,
+		domain.CategoryFruit, domain.CategoryTreeShrub, domain.CategoryCover:
+		return c
+	default:
+		return ""
+	}
+}
+
+// matchPlants ranks existing plants the packet might already be, best first.
+//
+// This is the crux of "create both, linked" (#81): getting it wrong makes a
+// duplicate catalog entry that then splits a variety's seed-lot history across
+// two rows. So it NEVER decides — it only surfaces candidates for the user to
+// confirm. Matching is deliberately conservative and name-based (no fuzzy
+// scoring that could confidently mis-rank): exact variety name, variety appearing
+// within a plant's name, then same species word. Case-insensitive.
+func matchPlants(p vision.SeedPacket, plants []domain.Plant) []PacketPlantMatch {
+	variety := strings.ToLower(strings.TrimSpace(p.Variety))
+	species := strings.ToLower(strings.TrimSpace(p.Species))
+
+	// rank: lower is better; keep only matched plants.
+	type scored struct {
+		match PacketPlantMatch
+		rank  int
+	}
+	var out []scored
+	seen := map[int64]bool{}
+	add := func(pl domain.Plant, rank int, reason string) {
+		if seen[pl.ID] {
+			return
+		}
+		seen[pl.ID] = true
+		out = append(out, scored{PacketPlantMatch{Plant: pl, Reason: reason}, rank})
+	}
+
+	for _, pl := range plants {
+		name := strings.ToLower(pl.Name)
+		switch {
+		case variety != "" && name == variety:
+			add(pl, 0, "exact name")
+		case variety != "" && strings.Contains(name, variety):
+			add(pl, 1, "variety in name")
+		case species != "" && wordIn(name, species):
+			add(pl, 2, "same species")
+		}
+	}
+	sort.SliceStable(out, func(i, j int) bool { return out[i].rank < out[j].rank })
+
+	matches := make([]PacketPlantMatch, len(out))
+	for i, s := range out {
+		matches[i] = s.match
+	}
+	return matches
+}
+
+// wordIn reports whether word appears as a whole space-delimited token in name,
+// so "garlic" matches "German Garlic" but not "garlicky-thing".
+func wordIn(name, word string) bool {
+	for _, tok := range strings.Fields(name) {
+		if tok == word {
+			return true
+		}
+	}
+	return false
+}
+
+// PacketConfirm is a user-confirmed proposal to turn into rows.
+//
+// Plant selection is explicit: either PlantID names an existing plant to attach
+// the lot to, or NewPlant carries the fields to create one. Exactly one — the
+// service refuses both or neither, so an ambiguous confirm can't silently pick.
+type PacketConfirm struct {
+	// PlantID attaches the lot to an existing plant. Set this XOR NewPlant.
+	PlantID *int64
+	// NewPlant creates a variety. Set this XOR PlantID.
+	NewPlant *PlantInput
+	// Lot is the purchase to record against whichever plant results.
+	Lot SeedLotInput
+}
+
+// PacketResult is what a confirm produced.
+type PacketResult struct {
+	Plant      *domain.Plant   `json:"plant"`
+	Lot        *domain.SeedLot `json:"lot"`
+	PlantIsNew bool            `json:"plantIsNew"`
+}
+
+// CreateFromPacket turns a confirmed proposal into a plant (new or existing) plus
+// a seed lot attributed to it. Unlike garden edits these rows aren't in the undo
+// history — plants and lots are catalog/inventory, created directly — so there is
+// no change set to wrap; the two creations just happen in sequence.
+//
+// If a new plant is created but the lot then fails, the plant is left behind
+// rather than rolled back: a stray catalog entry is harmless and editable,
+// whereas silently discarding a variety the user just confirmed is worse. The
+// caller sees the error and can retry the lot against the now-existing plant.
+func (s *Service) CreateFromPacket(ctx context.Context, actorID int64, in PacketConfirm) (*PacketResult, error) {
+	hasID, hasNew := in.PlantID != nil, in.NewPlant != nil
+	if hasID == hasNew {
+		return nil, domain.ErrInvalidInput // exactly one of existing / new
+	}
+
+	res := &PacketResult{}
+	if hasNew {
+		plant, err := s.CreatePlant(ctx, actorID, *in.NewPlant)
+		if err != nil {
+			return nil, err
+		}
+		res.Plant = plant
+		res.PlantIsNew = true
+	} else {
+		// Attach to an existing plant the actor can see. visiblePlant enforces the
+		// ACL (built-ins + their own); a plant they can't see is ErrNotFound.
+		plant, err := s.visiblePlant(ctx, actorID, *in.PlantID)
+		if err != nil {
+			return nil, err
+		}
+		res.Plant = plant
+	}
+
+	lotIn := in.Lot
+	lotIn.PlantID = res.Plant.ID
+	lot, err := s.CreateSeedLot(ctx, actorID, lotIn)
+	if err != nil {
+		return nil, err
+	}
+	res.Lot = lot
+	return res, nil
+}