# 02. Plant Disease Knowledge Base Schema, Seed Data, and API Endpoints

meta:
  id: hyper-specific-plant-disease-id-02
  feature: hyper-specific-plant-disease-id
  priority: P1
  depends_on: [hyper-specific-plant-disease-id-01]
  tags: [data, api, database]

objective:
- Define the data schema for plants and diseases, seed the knowledge base with ≥80 plant-disease pairs covering common houseplants and garden crops, and expose read-only API endpoints.

deliverables:
- `data/plants.json` — seed data for 20–30 common plants (id, common name, scientific name, family, care summary, image URL)
- `data/diseases.json` — seed data for 80–120 disease entries (id, plantId, name, scientific name, causal agent type [fungal/bacterial/viral/environmental], description, symptoms list, causes list, treatment steps, prevention tips, lookalike disease IDs, severity)
- `lib/api/diseases.ts` — typed helpers to query the knowledge base by plant ID, disease ID, or search term
- `app/api/plants/route.ts` — `GET /api/plants` (list all), `GET /api/plants?search=` (search)
- `app/api/plants/[id]/route.ts` — `GET /api/plants/:id` (single plant with its diseases)
- `app/api/diseases/route.ts` — `GET /api/diseases` (list all with optional plantId filter)
- `app/api/diseases/[id]/route.ts` — `GET /api/diseases/:id` (single disease with full detail)
- `lib/types.ts` — shared TypeScript interfaces for Plant, Disease, and related types

steps:
1. Define TypeScript interfaces in `lib/types.ts`: `Plant`, `Disease`, `CausalAgentType`, `Severity`.
2. Research and compile seed data for 20–30 common plants (tomato, basil, rose, monstera, pothos, snake plant, peace lily, orchid, succulent varieties, pepper, cucumber, squash, bean, strawberry, mint, lavender, etc.).
3. For each plant, research 2–5 common diseases (e.g., Tomato: early blight, late blight, septoria leaf spot, blossom end rot, powdery mildew).
4. Write `data/plants.json` and `data/diseases.json` with realistic, detailed entries — each disease must have ≥3 symptoms, ≥2 causes, ≥3 treatment steps, and ≥2 prevention tips.
5. Add `lookalikeDiseaseIds` to entries that are easily confused (e.g., early blight vs. septoria leaf spot).
6. Implement `lib/api/diseases.ts` with filter-by-plant, filter-by-id, full-text search (name + description), and lookalike resolution.
7. Build `app/api/plants/route.ts`, `app/api/plants/[id]/route.ts`, `app/api/diseases/route.ts`, `app/api/diseases/[id]/route.ts` — all return typed JSON with proper error handling (404 for missing IDs, 400 for invalid queries).
8. Add request logging middleware and response caching headers (`Cache-Control: public, max-age=3600`).
9. Write a smoke test script that validates all seed data has no missing references.

tests:
- **Unit:** Test `lib/api/diseases.ts` search and filter functions with known data.
- **Unit:** Validate every disease entry references a valid plant ID and has valid enum values.
- **Integration:** `GET /api/plants` returns 200 with plant array; `GET /api/plants/tomato` returns 200 or 404 for unknown ID.
- **Integration:** `GET /api/diseases?plantId=tomato` returns only tomato diseases.
- **Integration:** `GET /api/diseases/unknown-id` returns 404 with error message.

acceptance_criteria:
- ≥80 disease entries across ≥20 plants exist.
- All API endpoints return correct 200/404/400 responses.
- Search endpoint returns matches by common name, scientific name, and description.
- Lookalike references are bidirectional and valid.
- Seed data passes cross-reference validation (no orphan disease entries).

validation:
```bash
curl http://localhost:3000/api/plants | jq '.plants | length'
# → ≥20

curl http://localhost:3000/api/diseases | jq '.diseases | length'
# → ≥80

curl http://localhost:3000/api/plants/tomato | jq '.plant.diseases[0].name'
# → e.g., "Early Blight"

curl http://localhost:3000/api/diseases?search=blight | jq '.diseases | length'
# → ≥2
```

notes:
- Data is file-based JSON (no external DB) so the app remains simple to deploy on Vercel.
- Diseases should include both biotic (fungal, bacterial, viral) and abiotic (nutrient deficiency, overwatering, sunburn) conditions.
- Each disease entry should be detailed enough that a gardener can confidently diagnose and act.