FORGECOURSE ForgeMind AI · Hands-On Portfolio
HO4 · Sample 01 · Quote calculator

The One-Shot Rebuild

Meera runs a three-person web studio. Quoting eats an evening a week, so she asks Claude for a quote calculator. It takes her 14 turns — not because Claude is slow, but because the pricing rules are all in her head and leak out one at a time. Then she writes them all down, folds them into one prompt, and rebuilds the whole thing in a fresh chat in a single message.

THE TOOL The tool she was trying to get — try it, the rules are all live

This is what she ended up with. Every rule below it — the slabs, the cap, the order of operations — had to be dragged out of her head one turn at a time. Change the inputs and watch them fire.

Quote calculator working
BUILD 1 The messy way — 14 turns

Click through it. Notice what each turn actually is: not Claude failing, but a rule arriving late. Every correction is a piece of context that was missing from turn 1.

STEP 2 The corrections log

At the end of the messy chat she asked Claude one question: “list every correction I gave you in this chat.” Claude has the whole conversation in front of it, so the log costs almost nothing to produce — and this log is the context she was carrying in her head all along.

Pricing rulePages are slab-priced, and the slab the total page count lands in applies to every page — not marginal.

Rates1–5 pages → ₹6,000/page · 6–15 → ₹5,000/page · 16+ → ₹4,200/page.

Add-onLogo is a flat ₹12,000 and includes 2 revision rounds. Each extra round is ₹2,500.

RushUnder 3 weeks = +20% on the subtotal.

Order of operationsRush first, then the discount, then GST. I had to say this twice — it is the single thing a model cannot infer.

DiscountNever applies to GST. Capped at 15%, and the box must refuse anything higher.

TaxGST 18%, on the discounted subtotal.

RoundingOnly the grand total rounds, to the nearest ₹100. Line items stay exact, so the lines still add up.

FloorMinimum invoice ₹15,000. Below that, quote the minimum.

Terms50% advance, 50% on delivery. The advance is non-refundable once work starts.

ValidityThe quote is valid for 15 days.

CurrencyRupees, Indian digit grouping — ₹1,20,000, not ₹120,000.

OutputOne screen, no login, prints cleanly.

STEP 3 The one-shot prompt

The log, folded into a single message: role, spec, the rules, the order they fire in, the edge cases, the output format. This file is the real deliverable of HO4 — not the tool. The tool is just the proof that the context is complete.

Build a single-file HTML quote calculator for a small web studio. No login, no backend,
one screen, and it must print cleanly.

INPUTS
- Number of pages (a number)
- Logo design (yes / no)
- Extra logo revision rounds (a number, default 0)
- Rush delivery, under 3 weeks (yes / no)
- Discount % (a number, default 0)

PRICING RULES — follow these exactly
1. Pages are SLAB-priced. Whichever slab the TOTAL page count lands in, that rate applies to
   EVERY page. This is not marginal pricing.
     1-5 pages   -> Rs 6,000 per page
     6-15 pages  -> Rs 5,000 per page
     16+ pages   -> Rs 4,200 per page
   (12 pages = 12 x 5,000 = Rs 60,000. NOT 5x6,000 + 7x5,000.)
2. Logo design is a flat Rs 12,000 and includes 2 revision rounds.
   Each EXTRA revision round is Rs 2,500.
3. Rush delivery (under 3 weeks) adds 20% of the subtotal.
4. ORDER OF OPERATIONS, in this exact order:
     subtotal -> add rush -> apply discount -> add GST
5. The discount applies to the subtotal only. It NEVER applies to GST.
   Cap it at 15% — reject anything higher, don't just silently clamp it.
6. GST is 18%, charged on the discounted subtotal.
7. Round ONLY the grand total, to the nearest Rs 100. Line items stay exact so the lines
   still add up to the total.
8. Minimum invoice is Rs 15,000. If the grand total comes out under that, show the minimum
   and say why.

OUTPUT
- An itemised breakdown: each line, then rush, discount, GST, and the grand total.
- Below it, the terms: 50% advance, 50% on delivery, advance non-refundable once work
  starts. Quote valid for 15 days.
- Rupees throughout, with Indian digit grouping (Rs 1,20,000 — not Rs 120,000).

Recalculate live as any input changes.
BUILD 2 Fresh chat. One message.

She opened a new chat, pasted that one prompt, and got the same tool — working, first try. Same features, none of the archaeology.

Build 1 — the messy way
14
turns, each one prising a rule out of her head
Build 2 — one-shot
1
one message, in a fresh chat with no history
Feature parity
13/13
every rule survived the rebuild — because every rule was written down
Slab pricing — whole count, not marginal
Logo flat fee + 2 free revisions
Extra revision rounds priced
Rush uplift of 20%
Rush applied BEFORE the discount
Discount capped at 15%
Discount never touches GST
GST 18% on the discounted subtotal
Only the grand total rounds, to ₹100
Minimum invoice floor of ₹15,000
Payment terms shown
15-day validity shown
Indian digit grouping

This is the whole lesson. Claude was never the bottleneck. The context was — it just arrived one turn at a time instead of all at once. Say it up front and the fourteen turns collapse into one.

Make it your own
Pick a tool with real rules — caps, tiers, gates, rounding, cut-offs. A page with no rules produces no corrections, and the corrections log is the exercise.
Do not tidy up as you go. Build it messily on purpose, and let it be wrong. The wrongness is the data.
When it finally works, ask Claude to list every correction you gave it. That is your log, free.
Rebuild in a genuinely fresh chat. Re-using the old one proves nothing — the context is already in there.
If the rebuild misses a rule, you left it out of the log. Add it and go again. That gap is the most useful thing you will learn all week.