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name: grocery-meal-plan-cost-estimator description: Builds a weekly meal plan with portion estimates and a grocery list rolled up by store section, then estimates total cost from unit prices you provide or simple defaults. Use when planning meals on a budget, batch cooking, or asking "what should I buy for 4 people this week?". Includes a stdlib Python cost estimator with --self-test.

Grocery Meal Plan Cost Estimator

You help households plan a week of meals, scale portions to headcount, build a grocery list grouped by store section, and estimate cost from unit prices. You are practical about leftovers and pantry staples. You do not give medical diet therapy; you note allergies and preferences the user states.

Files in this skill

• scripts/estimate_cost.py - sums a grocery list with unit prices and prints section totals (Python 3 standard library only)
• references/portion-guide.md - rough per-person amounts for common foods
• references/store-section-map.md - where items usually live in a supermarket
• templates/meal-plan.md - weekly plan + list structure
• examples/sample-week.md - worked example for 2 adults

Workflow

1. Collect constraints

Ask for: headcount and ages, nights cooking at home, budget and currency, diet rules (veg, halal, allergies), appliances/time, and pantry items already owned.

2. Draft the week

Propose breakfast / lunch / dinner / snacks with leftover reuse. Keep variety without requiring 21 unique recipes.

3. Explode to groceries

Using references/portion-guide.md, convert meals to ingredients and quantities. Deduplicate (one bottle of oil, not seven).

4. Map to store sections

Group with references/store-section-map.md so the list is walkable.

5. Estimate cost

python3 scripts/estimate_cost.py --list groceries.json
python3 scripts/estimate_cost.py --self-test

If the user has no prices, use clearly labeled default unit prices and say they are placeholders.

6. Answer

Return: meal plan table, grocery list by section with qty, estimated total, cost per person-day, and 2 to 3 swap ideas if over budget.

Rules

• Never invent that something is "healthy" as medical advice; stick to preferences and macros only if asked.
• Prefer grams and milliliters plus a household measure.
• Flag perishable items that should be bought mid-week. FILE:references/portion-guide.md

Rough per-person cooked portions (adjust for appetite)

Food	Per adult	Per child (5–10)
Cooked rice / grains	150–180 g	80–100 g
Dry pasta	80–100 g	50–70 g
Protein (raw meat/fish)	120–150 g	70–90 g
Beans/lentils (dry)	50–70 g	30–40 g
Vegetables (raw weight)	150–200 g	80–120 g
Fruit	1 piece or 120 g	1 small piece
Milk / alt milk	200–250 ml	150 ml
Bread	2 slices	1 slice
Oil for cooking	~10 ml per saute	shared
Eggs	2	1

Scaling tips

• Soups/stews: scale liquid 90% when going from 2 to 4 (pot efficiency).
• Spices: do not scale linearly past 4 portions; taste and adjust.
• Leftovers lunch: cook +40% dinner on two weeknights instead of separate recipes. FILE:references/store-section-map.md

Typical supermarket section map

Use these buckets on the grocery list (adapt names to local stores):

1. Produce — fruit, vegetables, herbs, salad
2. Bakery — bread, tortillas, buns
3. Meat & seafood — fresh/cooled protein
4. Dairy & eggs — milk, yogurt, cheese, butter, eggs
5. Deli / prepared — if used
6. Pantry dry — rice, pasta, beans, flour, sugar, cereal
7. Cans & jars — tomatoes, tuna, sauces
8. Oils & spices — cooking oil, salt, spices, vinegar
9. Frozen — vegetables, frozen protein, ice cream
10. Beverages — coffee, tea, juice, sparkling water
11. Household — if buying soap/bags on the same trip

Walk order suggestion: produce → bakery → meat → dairy → center aisles → frozen → beverages. FILE:templates/meal-plan.md

Weekly meal plan

• People:
• Budget / currency:
• Diet notes:

Meals

Day	Breakfast	Lunch	Dinner	Notes
Mon
Tue
Wed
Thu
Fri
Sat
Sun

Grocery list by section

Produce

• item — qty — est. price

Dairy & eggs

• [ ]

Cost summary

• Estimated total:
• Per person-day:
• Mid-week top-up: FILE:examples/sample-week.md

Sample week — 2 adults, flexible omnivore, EUR

Budget target: €70

Meals (short)

Day	Dinner highlight	Lunch plan
Mon	Chickpea curry + rice	Leftover curry
Tue	Pasta aglio e olio + salad	Egg sandwiches
Wed	Sheet-pan chicken + veg	Leftover chicken bowls
Thu	Lentil soup + bread	Soup + fruit
Fri	Fish tacos (frozen fish)	Rice fried with leftover veg
Sat	Veggie omelette feast	Eating out / skip
Sun	Batch chili for Mon lunch	Chili

Grocery excerpt (for estimate_cost.py)

See accompanying JSON shape:

{
  "currency": "EUR",
  "items": [
    {"name": "rice 1kg", "section": "Pantry dry", "qty": 1, "unit_price": 2.2},
    {"name": "chickpeas canned x4", "section": "Cans & jars", "qty": 4, "unit_price": 0.9},
    {"name": "pasta 500g", "section": "Pantry dry", "qty": 2, "unit_price": 1.1},
    {"name": "chicken thighs 1kg", "section": "Meat & seafood", "qty": 1, "unit_price": 6.5},
    {"name": "mixed veg 1kg", "section": "Produce", "qty": 1, "unit_price": 3.0},
    {"name": "eggs 12", "section": "Dairy & eggs", "qty": 1, "unit_price": 3.2},
    {"name": "milk 1L", "section": "Dairy & eggs", "qty": 2, "unit_price": 1.1},
    {"name": "frozen white fish 500g", "section": "Frozen", "qty": 1, "unit_price": 4.5}
  ]
}

FILE:scripts/estimate_cost.py #!/usr/bin/env python3 """Estimate grocery cost from a JSON list.

Usage: python3 estimate_cost.py --list groceries.json python3 estimate_cost.py --self-test

JSON shape: { "currency": "EUR", "items": [{"name": "...", "section": "...", "qty": 1, "unit_price": 2.5}] }

Python 3 standard library only. """ from future import annotations

import argparse import json import sys from collections import defaultdict from typing import Any, Dict, List

def load_list(path: str) -> dict: return json.load(open(path, encoding="utf-8"))

def estimate(data: dict) -> dict: currency = data.get("currency") or "USD" items = data.get("items") or [] by_section: Dict[str, float] = defaultdict(float) lines = [] total = 0.0 for it in items: name = it["name"] section = it.get("section") or "Other" qty = float(it.get("qty", 1)) price = float(it["unit_price"]) line_total = qty * price total += line_total by_section[section] += line_total lines.append({ "name": name, "section": section, "qty": qty, "unit_price": price, "line_total": round(line_total, 2), }) return { "currency": currency, "total": round(total, 2), "by_section": {k: round(v, 2) for k, v in sorted(by_section.items())}, "lines": lines, "item_count": len(lines), }

def format_report(result: dict) -> str: cur = result["currency"] lines = [f"Estimated total: {result['total']:.2f} {cur} ({result['item_count']} lines)"] lines.append("By section:") for sec, amt in result["by_section"].items(): lines.append(f" - {sec}: {amt:.2f} {cur}") return "\n".join(lines)

def self_test() -> int: sample = { "currency": "EUR", "items": [ {"name": "rice", "section": "Pantry dry", "qty": 1, "unit_price": 2.2}, {"name": "eggs", "section": "Dairy & eggs", "qty": 1, "unit_price": 3.2}, {"name": "milk", "section": "Dairy & eggs", "qty": 2, "unit_price": 1.1}, ], } r = estimate(sample) cases = [ ("total", r["total"], 7.6), ("dairy_section", r["by_section"]["Dairy & eggs"], 5.4), ("pantry", r["by_section"]["Pantry dry"], 2.2), ("count", r["item_count"], 3), ("currency", r["currency"], "EUR"), ("empty", estimate({"items": []})["total"], 0.0), ("qty_scale", estimate({"items": [{"name": "x", "section": "A", "qty": 3, "unit_price": 1.5}]})["total"], 4.5), ("default_section", estimate({"items": [{"name": "y", "qty": 1, "unit_price": 2}]})["by_section"]["Other"], 2.0), ("round", estimate({"items": [{"name": "z", "section": "A", "qty": 1, "unit_price": 1.005}]})["total"], 1.0), ] failed = 0 for name, got, expected in cases: if isinstance(expected, float): ok = abs(float(got) - expected) < 1e-9 else: ok = got == expected failed += not ok print(f"{'PASS' if ok else 'FAIL'} {name}: got={got!r} expected={expected!r}") print(f"\n{len(cases) - failed}/{len(cases)} passed") return 1 if failed else 0

def main(argv=None) -> int: p = argparse.ArgumentParser(description="Estimate grocery list cost.") p.add_argument("--list", help="Path to groceries JSON") p.add_argument("--json", action="store_true") p.add_argument("--self-test", action="store_true") a = p.parse_args(argv) if a.self_test: return self_test() if not a.list: p.error("--list is required (or use --self-test)") result = estimate(load_list(a.list)) if a.json: print(json.dumps(result, indent=2)) else: print(format_report(result)) return 0

if name == "main": sys.exit(main())