• Migrations
◦ Create nicotine table with NOCASE strings, base PG/VG check, strength_mg_per_ml (>0), soft-delete, and optional inventory metadata (bottle_size_ml, cost, purchase_date).
◦ Alter recipe: add nic_target_mg_per_ml (NOT NULL), nic_strength_mg_per_ml (NOT NULL), nicotine_id (FK ON DELETE SET NULL); keep nic_base. Drop legacy nic_pct via rebuild migration.
◦ Alter flavor: add bottle_size_ml, cost, purchase_date (nullable).
◦ Alter recipe_flavor: add flavor snapshot columns (flavor_name_snapshot, flavor_company_snapshot NOCASE, flavor_base_snapshot PG/VG CHECK).
◦ Ensure migration order runs “_created” before ALTERs.
• Models
◦ Add Nicotine model.
◦ Update Recipe with nic_target_mg_per_ml, nic_strength_mg_per_ml, nic_base, optional nicotine FK.
◦ Update Flavor with optional inventory metadata.
◦ Update RecipeFlavor with snapshot fields and unique index remains.
• DAOs
◦ Add NicotineRepository (CRUD, list with soft-delete filters; hard_delete_when_safe blocked when referenced by recipes).
◦ Update RecipeRepository:
▪ create/update accept nic_target_mg_per_ml, nic_strength_mg_per_ml, nic_base, optional nicotine_id.
▪ If nicotine_id provided, snapshot strength/base from inventory unless overridden.
▪ replace_ingredients uses diff-based updates and populates flavor snapshots on insert.
◦ Update FlavorRepository to edit inventory metadata; soft/undelete; hard delete only when safe.
• DB init
◦ Bind Peewee models to runtime DB; tweak migration ordering logic.
• Logic
◦ Add calculation engine (compute_breakdown, breakdown_for_view) supporting target nicotine mg/mL and stock strength mg/mL; rounding policy for display.
• Tests
◦ Update/init DB tests to include nicotine table and flexible migration counts.
◦ Add calculation tests (120 mL example, nic in VG, 50 mg/mL stock, validations).
◦ Add DAO tests including flavor snapshots stability and replace_ingredients diff behavior.
◦ All tests passing: 15 passed.
• Docs
◦ Update SPECS and MILESTONES; strike through Milestones 3 and 4.
BREAKING CHANGE: remove Recipe.nic_pct field and any compatibility code. API changes in RecipeRepository.create/update now require mg/mL fields and use snapshot+FK model for nicotine.
Funky Waddle
c8655e24e4