# TODO — one unit inside, feet-and-inches out

Decision: **the whole project moves to inches internally, and every number shown
to a person is formatted `xx'-xx"`.** Not started. Will says when.

Measured scope, 2026-08-27: 237 occurrences of `_ft` across `panellift/src`
(151) and `WillTools.extension/lib/vibe` (86). `length_ft` appears 68 times and
`width_ft` 52 — those two are the `Panel` model that the statics, the job-file
contract and 175 tests are all written against.

**Why this is worth doing carefully.** The most expensive incident this project
has had was a 12x unit error: an inch value fed to `XYZ()`, which takes feet,
put copies 6,500 ft away and manufactured a week of false symptoms. A refactor
whose whole purpose is to remove unit ambiguity is exactly the place to
reintroduce it. Every step below is ordered so a mistake shows up as a failing
test rather than as a wrong number in a report.

---

## Step 0 — the output formatter, first and on its own

Do this before touching any internals; it is pure gain and it stands alone.

- `ticketqc.fmt_feet` / `fmt_inches` / `parse_feet` / `parse_inches` already
  exist. Move them somewhere both halves can import — they are currently only
  reachable from the Revit side.
- Every number a person reads goes through it: findings, reports, the HTML,
  the config dump's comments. A raw `18.9167` never reaches a page again.
- Round-trip test: `parse(fmt(x)) == x` to the nearest 1/16", across a range
  that includes the values this job actually uses.

## Step 1 — make every name state its unit, truthfully

Cheap, mechanical, and it removes the bug class on its own.

- `read_ticket` returns `thickness` as **0.667, which is feet**, under a name
  that reads as inches. Fix that and audit every sibling field the same way.
- Any field whose name carries no unit gets one. `length`, `width`,
  `thickness` are the offenders.
- After this step the codebase is still in feet, but nothing lies about it.

## Step 2 — the boundary, not the core

Revit's API returns feet. Convert **once**, at the point of reading, and never
again:

- `liftexport.export` and `ticketqc.read_ticket` are the two doors. Everything
  the model hands them is feet; everything they hand on is inches.
- Do NOT sprinkle `* 12` through the callers. One conversion per door, named.

## Step 3 — the job-file contract

`schema: "panellift/1"` carries `length_ft`, `width_ft`, `thickness_in`,
`extra_cast_ft3` and more. There are 184 saved job files in the sweep directory
and they must keep working.

- Bump to `panellift/2` with inch fields.
- `cli.read_panel` accepts both: a `panellift/1` file is converted on read.
  Keep that reader until the saved files are regenerated, and test it against a
  real `panellift/1` file, not a synthetic one.

## Step 4 — panellift's core, last

`Panel.length_ft` -> `Panel.length_in`, and the 151 sites that follow from it.

- The statics were validated against published PCI examples. Convert the model
  and the solver in one commit, and require the PCI example tests to pass
  unchanged — they are the acceptance criterion for this step.
- `pci.py`'s published constants stay in whatever unit the source uses;
  convert at the call, not in the table.
- Watch the compound units: `unit_weight_pcf` is per cubic FOOT, `extra_cast_ft3`
  is cubic feet, section modulus is in3, stresses are psi. Only lengths move.
  A blanket rename would break the ones that are already inches.

## Step 5 — sweep the defaults

`group_tolerance_ft` (28 occurrences), `min_edge_distance_in`,
`transfer_length_in` and the rest live in the knowledge file, where a plant has
already set values. Changing a key's unit silently reinterprets a number
somebody chose.

- Rename the key when the unit changes, so an old key is a *missing* key rather
  than a wrong one, and `config_problems` reports it.
- Never leave a key whose name kept its unit but whose meaning changed.

---

## Acceptance

- panellift and vibe test suites green, including the PCI example cases.
- One `panellift/1` job file from the sweep directory still analyses, and
  produces the same numbers it produced before the refactor.
- `grep -rE "[a-z_]+_ft\b"` over `panellift/src` returns only genuinely
  cubic-foot or per-cubic-foot names.
- No report anywhere prints a bare decimal length.