# Learning the method from history

The operator has been pricing jobs for years. That method already exists — it lives in their past
quotes, estimates, invoices, and spreadsheets. This pillar derives it from those artifacts so the
assistant can apply the same method going forward. The source is whatever the operator actually used:
a workbook, a folder of PDFs, photographed handwritten estimates, a price list. Work from what they
have.

## What a complete derivation captures

From the operator's own artifacts, recover four things, and nothing the artifacts do not show:

- **The priceable things.** Each distinct thing the operator charges for. Two lines that are the same
  priced thing under different wording are one method entry, not two — collapse repeated instances of
  the same thing across jobs into a single entry, and let the variation across those instances tell you
  how the thing is quantified and priced.
- **How each is quantified.** For each thing, how a job turns into a quantity. Some quantities are
  derived from a measurement the operator takes (a length, an area, a volume, a weight); some are
  counted directly (how many doors, heads, units); some are simply one of a thing. Read which it is
  from how the past jobs got their numbers — do not assume a unit.
- **How each is priced.** The rule that turns a quantity into a line price. It may be a rate per unit,
  a tiered or banded price, a price that steps at break quantities, a fixed amount, or something else
  entirely. Capture the form the operator's history actually shows; do not flatten everything into
  "rate × quantity" if their numbers say otherwise.
- **How lines roll up.** The sequence the operator applies above the line items to reach the total —
  any markups, overheads, contingencies, discounts, and taxes, **in the order their arithmetic
  reveals.** Do not assume a markup-then-overhead-then-tax chain; discover the operator's actual
  sequence, including adjustments that apply to only part of the work.

## Standing rule vs per-job judgement

Classify each priceable thing as you derive it (the rule and why it matters are in
[../SKILL.md](../SKILL.md)). On this path the signal is **variance across the operator's own jobs**: a
price that follows a consistent rule from job to job is a standing rule; one that moves unpredictably
is priced by judgement.

## Faithfulness over tidiness

The aim is the operator's method as it really is, including its irregularities. If their margin
differs by category, capture that. If one adjustment applies before tax and another after, capture
that. A clean, regular method that does **not** reproduce their past quotes is wrong; an irregular one
that does is right. Reproduction is the test (see [verification.md](verification.md)).

## Provenance and under-capture are recorded

Every derived element carries where it came from — which artifact, which job. And every part of a
source that could not be confidently encoded is logged as skipped, ambiguous, or guessed, rather than
silently dropped or invented. A derivation that quietly omits a section the operator charges for will
surface later as a quote that is wrong by exactly that section; logging the gap at onboarding is what
prevents that. Under-capture you can see is a question to ask the operator; under-capture you cannot
see is a future wrong quote.
