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+# BREEDR Database Schema
+
+## Overview
+
+This document describes the clean database schema for BREEDR. **NO migrations** - fresh installs create the correct schema automatically.
+
+## Schema Design
+
+### Core Principle: Parents Table Approach
+
+The `dogs` table **does NOT have sire/dam columns**. Parent relationships are stored in the separate `parents` table. This design:
+- Keeps the schema clean and normalized
+- Allows flexible parent relationships
+- Supports future extensions (multiple sires, surrogates, etc.)
+
+## Tables
+
+### dogs
+
+Core registry for all dogs.
+
+```sql
+CREATE TABLE dogs (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  name TEXT NOT NULL,
+  registration_number TEXT UNIQUE,
+  breed TEXT NOT NULL,
+  sex TEXT NOT NULL CHECK(sex IN ('male', 'female')),
+  birth_date DATE,
+  color TEXT,
+  microchip TEXT,
+  photo_urls TEXT,  -- JSON array
+  notes TEXT,
+  litter_id INTEGER,  -- Links to litters table
+  is_active INTEGER DEFAULT 1,
+  created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+  updated_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+  FOREIGN KEY (litter_id) REFERENCES litters(id) ON DELETE SET NULL
+);
+```
+
+**Important:** NO `sire_id` or `dam_id` columns!
+
+### parents
+
+Stores sire/dam relationships.
+
+```sql
+CREATE TABLE parents (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  dog_id INTEGER NOT NULL,  -- The puppy
+  parent_id INTEGER NOT NULL,  -- The parent
+  parent_type TEXT NOT NULL CHECK(parent_type IN ('sire', 'dam')),
+  FOREIGN KEY (dog_id) REFERENCES dogs(id) ON DELETE CASCADE,
+  FOREIGN KEY (parent_id) REFERENCES dogs(id) ON DELETE CASCADE,
+  UNIQUE(dog_id, parent_type)  -- One sire, one dam per dog
+);
+```
+
+### litters
+
+Breeding records and litter tracking.
+
+```sql
+CREATE TABLE litters (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  sire_id INTEGER NOT NULL,
+  dam_id INTEGER NOT NULL,
+  breeding_date DATE NOT NULL,
+  whelping_date DATE,
+  puppy_count INTEGER DEFAULT 0,
+  notes TEXT,
+  created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+  FOREIGN KEY (sire_id) REFERENCES dogs(id) ON DELETE CASCADE,
+  FOREIGN KEY (dam_id) REFERENCES dogs(id) ON DELETE CASCADE
+);
+```
+
+### health_records
+
+Health tests, vaccinations, exams, treatments.
+
+```sql
+CREATE TABLE health_records (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  dog_id INTEGER NOT NULL,
+  record_type TEXT NOT NULL CHECK(record_type IN ('test', 'vaccination', 'exam', 'treatment', 'certification')),
+  test_name TEXT,
+  test_date DATE NOT NULL,
+  result TEXT,
+  document_url TEXT,
+  notes TEXT,
+  created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+  FOREIGN KEY (dog_id) REFERENCES dogs(id) ON DELETE CASCADE
+);
+```
+
+### heat_cycles
+
+Female heat cycle tracking for breeding timing.
+
+```sql
+CREATE TABLE heat_cycles (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  dog_id INTEGER NOT NULL,
+  start_date DATE NOT NULL,
+  end_date DATE,
+  progesterone_peak_date DATE,
+  breeding_date DATE,
+  breeding_successful INTEGER DEFAULT 0,
+  notes TEXT,
+  created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+  FOREIGN KEY (dog_id) REFERENCES dogs(id) ON DELETE CASCADE
+);
+```
+
+### traits
+
+Genetic trait tracking and inheritance.
+
+```sql
+CREATE TABLE traits (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  dog_id INTEGER NOT NULL,
+  trait_category TEXT NOT NULL,
+  trait_name TEXT NOT NULL,
+  trait_value TEXT NOT NULL,
+  inherited_from INTEGER,  -- Parent dog ID
+  notes TEXT,
+  FOREIGN KEY (dog_id) REFERENCES dogs(id) ON DELETE CASCADE,
+  FOREIGN KEY (inherited_from) REFERENCES dogs(id) ON DELETE SET NULL
+);
+```
+
+## API Usage
+
+### Creating a Dog with Parents
+
+```javascript
+POST /api/dogs
+{
+  "name": "Puppy Name",
+  "breed": "Breed Name",
+  "sex": "male",
+  "sire_id": 5,  // Parent male dog ID
+  "dam_id": 8,   // Parent female dog ID
+  "litter_id": 2  // Optional: link to litter
+}
+```
+
+The API route automatically:
+1. Inserts the dog into `dogs` table (without sire/dam columns)
+2. Creates entries in `parents` table linking to sire and dam
+
+### Querying Parents
+
+```sql
+-- Get a dog's parents
+SELECT p.parent_type, d.* 
+FROM parents p 
+JOIN dogs d ON p.parent_id = d.id 
+WHERE p.dog_id = ?;
+
+-- Get a dog's offspring
+SELECT d.* 
+FROM dogs d
+JOIN parents p ON d.id = p.dog_id
+WHERE p.parent_id = ?;
+```
+
+## Fresh Install
+
+For a fresh install:
+
+1. **Delete the old database** (if upgrading):
+   ```bash
+   rm data/breedr.db
+   ```
+
+2. **Start the server** - it will create the correct schema automatically:
+   ```bash
+   npm run dev
+   ```
+
+3. **Verify the schema**:
+   ```bash
+   sqlite3 data/breedr.db ".schema dogs"
+   ```
+   
+   You should see `litter_id` but **NO** `sire_id` or `dam_id` columns.
+
+## Troubleshooting
+
+### "no such column: weight" or "no such column: sire_id"
+
+**Solution:** Your database has an old schema. Delete it and let the app recreate it:
+
+```bash
+rm data/breedr.db
+npm run dev
+```
+
+### Parent relationships not saving
+
+Check server logs. You should see:
+```
+✓ Dog inserted with ID: 123
+  Adding sire relationship: dog 123 -> sire 5
+  ✓ Sire relationship added
+  Adding dam relationship: dog 123 -> dam 8
+  ✓ Dam relationship added
+```
+
+If relationships aren't being created, check that `sire_id` and `dam_id` are being sent in the API request.
+
+## Database Files
+
+- `server/db/init.js` - Creates clean schema, no migrations
+- `server/routes/dogs.js` - Handles parent relationships via `parents` table
+- `server/index.js` - Initializes database on startup
+
+**NO MIGRATIONS!** The init file is the source of truth.