Monster Coffer Helper (1.0)

Mystery Coffer or curated coffer which is cheaper?

At Glirion, Maj and Urgarlag that question is just arithmetic. The problem is
that the arithmetic needs three numbers the game never shows you in one place:
which sets this vendor stocks, how many shoulder variants each of those sets
has, and how many of them you already own. Working it out by hand means paging
through the whole stickerbook.

This addon goes and gets those numbers, then does the arithmetic.

How it decides

Because the goal is to collect every shoulder, one new shoulder is worth
exactly as much as any other. So both offers reduce to a single comparable
number keys spent per new shoulder:

mystery = cost / P(the roll is something you don’t own)
curated = cost (P is 1 by definition)

Buy whichever is lower. A Mystery Coffer rolls uniformly across every shoulder
the vendor stocks, collected or not, so with N shoulders on the shelf and
M still missing, P = M/N. A 1-key Mystery Coffer therefore beats an 8-key
curated one for as long as more than an eighth of the stock is missing.

It also projects the whole remaining run. Mystery gets steadily worse as
your collection fills while curated stays flat, so the cheapest strategy is
mystery early and curated for the tail and the addon tells you where the two
cross:

Finish this vendor ~55 keys the smart way (all mystery 98 / all curated 64)

Where it shows up

A panel at the vendor, with the verdict and every number behind it.
A chat line when the store opens.
Tooltip lines on the coffers themselves including a warning when a
curated coffer is for a set you have already completed.
/coffer anywhere in the world, when you are nowhere near a vendor.

Commands

/coffer all three vendors
/coffer 2 or /coffer maj just one of them
/coffer settings the options panel

It keeps itself accurate

Vendor stock and prices are read off the store window rather than trusting a
bundled table, so stock rotations and price changes are picked up on their own.
What it learns is saved account-wide, so /coffer stays accurate away from
the vendor.

Requirements

LibSets required, the addon will not load without it
LibAddonMenu-2.0 optional, only powers the settings panel

Available in English and French.

Source and feedback

Source, issues and pull requests:
github.com/mounirlamouri/eso-monster-coffer-helper
Released under the GPL-3.0.

Bug reports are welcome especially if you find a vendor stocking a set the
addon does not recognise.