Add Steam Currency Converter

[Jidos86]

Steam Currency Converter

Shows an approximate price in the currency you pick next to any Steam price — store, cart, checkout, community market, and the in-game overlay. It detects the account's wallet currency and appends ≈ N <cur>, computed from public exchange-rate JSON (fawazahmed0/exchange-api, 3 mirrors, cached 6 h). Not an official regional price — a raw exchange-rate estimate for quick comparison.

Maintained fork of the existing (unlisted) https://github.com/KuroKim/steam-currency-to-rub. Differences:

• Target currency is user-selectable in the plugin settings (was hard-coded to RUB); all 40 Steam wallet currencies, as source and target.
• Injection: moved from a Lua add_browser_js <script src> (silently blocked by the store CSP in some regions, e.g. the Steam China store) to a webkit/ module that Millennium loads with Page.setBypassCSP.
• Format-agnostic price parser (1,234.56, 1.234,56, 1 199, zero-decimal currencies).
• Full-precision rate (the original rounded to 2 decimals, breaking every sub-1 rate — USD/EUR/GBP/CNY, error up to tens of percent).
• Works on the new React cart/checkout.
• DOM-only rendering — createElement / textContent, no innerHTML, no eval, no remote code. Network is limited to the exchange-rate endpoints in webkit/index.tsx.

Settings persistence goes through the lua backend (get_settings / set_target_currency via millennium.config) because usePluginConfig / pluginConfig were unreliable in the current Millennium build.

No RUB/currency-conversion plugin is currently on the store.

Task Checklist

Developer

• I am the original author or an authorized maintainer of this plugin.
• I have complied with all license requirements for the libraries used, including providing appropriate notices where necessary.
• My plugin is fully open source and does not depend on any external paid services, except for widely trusted and well-known platforms. Additionally, neither I nor anyone associated with me profits from any such services.

Plugin Functionality

• I have tested the plugin on both the Stable and Beta Steam update channels.
• My plugin is unique, or provides additional or alternative functionality to plugins already on the store.

Backend Configuration

• No: I use a standard Millennium python backend in my plugin.
• No: I use custom binaries that or rely on other FOSS projects that aren't written directly using Millennium's python backend.

Community Contribution

• I have tested and left feedback on two other plugin pull requests.
• I have added links to those feedback comments in this PR.

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Testing Instructions

• Verified by a third party on Steam Client Stable.
• Verified by a third party on Steam Client Beta.

[Jidos86]

Converting this to a draft — please hold off reviewing for now.

Two things are landing before it's ready:

1. Renamed the plugin steam-currency-to-rub → steam-currency-converter (id steam_currency_converter). The submodule pointer/URL in this PR is already updated.
2. Adding a settings panel so the target currency is user-selectable (currently hard-coded to RUB). This means moving to the @steambrew build (frontend/index.tsx + webkit/index.tsx + lua backend).

I'll mark it ready for review and advance the submodule pointer once that's done and tested on Stable + Beta.

[Jidos86]

Out of draft and ready for review.

• Renamed steam-currency-to-rub → steam-currency-converter; submodule pointer advanced to 9aa0b08 (v2.0.0).
• Target currency is now user-selectable (settings panel); default RUB.
• Tested on Steam Stable and Beta (incl. a CN-region account).

Still open: feedback on two other plugin PRs — will follow up.

[kuusei]

Disclosure: I am the author of #241 and tested this PR as part of the Community Contribution requirement.

Fallback currency detection will mis-label JPY and SEK

Primary detection (wallet id, then meta[itemprop="priceCurrency"]) looks correct. The formatter fallback is not:

const SIGN_TO_CURRENCY: Record<string, string> = {
  '¥': 'CNY',
  '$': 'USD',
  // …
};

¥ is also JPY. kr is both NOK (id 9) and SEK (id 33); it is not in SIGN_TO_CURRENCY, so STEAM_CURRENCIES.find((c) => c.symbol === sign) returns NOK first. A Japanese or Swedish account that misses wallet + schema.org detection gets converted as CNY or NOK.

Wallet id is the right source of truth — if it is missing, skipping conversion is better than a silently wrong rate.

[Jidos86]

Thanks for testing, @kuusei — good catch.

Fixed in v2.0.1 (pinned commit updated): the symbol-based formatter fallback is gone entirely. Source currency now comes only from the wallet id and the priceCurrency meta; if neither is available the plugin skips conversion instead of guessing. SIGN_TO_CURRENCY stays only as a "looks like a price" hint for the DOM scan, where an exact match isn't needed.

[Jidos86]

Community Contribution — review 1 of 2: #241 (comment) (Sort As Display — found 2 bugs worth fixing before merge: hooks not removed on unmount, and the SetCustomSortAs hook not retrying on a failed install).

[Jidos86]

Community Contribution — review 2 of 2: #231 (comment) (Sortium — flagged the Augmented Steam / Steam Hunters API fan-out without a User-Agent or coordination, stringly-typed rate-limit detection, a NaN-comparator sort for missing data, and an O(n²) non-atomic cache write).

Both required reviews done: #241 and #231.

[kuusei]

Thanks for testing, @kuusei — good catch.

Fixed in v2.0.1 (pinned commit updated): the symbol-based formatter fallback is gone entirely. Source currency now comes only from the wallet id and the priceCurrency meta; if neither is available the plugin skips conversion instead of guessing. SIGN_TO_CURRENCY stays only as a "looks like a price" hint for the DOM scan, where an exact match isn't needed.

Confirmed on 678e071. Formatter fallback is gone, and it skips conversion when wallet id / priceCurrency are both missing. LGTM.

[Jidos86]

Pinned commit advanced to v2.0.2 (ad4e309). Since the last update, from user testing on a CN-region account:

• discount blocks: parse each price token separately and take the final one (was concatenating -15% ¥98.00 ¥83.30 into a billions figure)
• render by appending a hint span, never rewriting the price element — keeps Steam's own discount badge / strikethrough / layout intact
• convert on /search, the discovery feed, the instant-search dropdown and the (React) inventory market price; source currency is cached once wallet-id / priceCurrency detection succeeds so pages exposing neither still work
• never annotate a struck-through original price (checked via computed text-decoration)
• pick up prices that load asynchronously into existing nodes

CI green.

[Jidos86]

Pinned commit advanced to 0d4c29b. Added a generic leaf-price scan: the new React store widgets (recommendation lists, feeds, capsules, the instant-search dropdown) render the price as a leaf element whose text is exactly a wallet-currency price, so those are converted directly, skipping struck originals via the computed text-decoration. CI green.