Publish the rate card as a feed, and diff it against DeepSeek daily

[lroolle]

lib/core.js was already the single source of the plugin, the bundle and the site. Two things were still missing: nobody outside this repo could read the card, and its "verbatim from the published table" claim was re-established by a human remembering to look.

docs/pricing.json

Served at https://dsh.works/dsh-meter/pricing.json (Pages = main + /docs, and the host already answers access-control-allow-origin: *).

Both currencies, both live tariffs, the 24-hour UTC schedule, the retired flat card with the date it stopped applying, and the definition of each billed bucket — which is the half of a cost estimate a price list cannot give you. Generated from lib/core.js by scripts/build-pricing.mjs, checked by pnpm test. It is a pure function of the card (no timestamp, no fetch), so the file changes exactly when the price does.

JS consumers can skip the fetch entirely: import { costOf, tariffAt } from '@dshworks/dsh-meter/core' — core.js imports nothing.

Why publish it at all

Because no external source is right. Checked 2026-08-20, four days after the switchover:

Source	v4-pro cache-miss input	Verdict
models.dev	$0.435	the retired flat card, last_updated: 2026-08-12
LiteLLM	$0.435	the same retired card
OpenRouter /api/v1/models	$1.60	accurate, different question — what OpenRouter charges to resell
this feed	$0.66 off-peak / $1.32 peak	matches both published tables

Both aggregators understate a v4-pro bill by 1.5x off-peak, 3x at peak, and 12x on cached input at peak. Neither can fix it by refreshing: both schemas hold one flat price per model per bucket, with nowhere to put a tariff. A rate that doubles for seven hours of every UTC day cannot be represented in either.

Keeping it honest

scripts/verify-pricing.mjs scrapes DeepSeek's own two pricing pages — English and Chinese — and diffs every rate, the peak windows, and the model list (a model priced upstream and missing here would meter at zero). A page it can no longer parse exits non-zero too: the alarm should fire when the source changes shape, not only when a number moves.

.github/workflows/pricing-watch.yml runs it daily and opens or comments on a pricing-drift issue. Deliberately outside pnpm test: a unit suite must not fail because a documentation site is slow, and a price alarm must not stay silent because nobody opened a PR this week. The last price change arrived with no announcement in any channel we watch.

Verification

• The card matches both published tables as of 2026-08-20 (npm run verify:pricing, exit 0).
• The verifier catches an injected 0.66 → 0.60 rate and a widened peak window (exit 1, both named in the report).
• 56 tests green, including 6 new ones pinning the feed's published shape and the rule that a retired price never appears as a live one.
• Site re-rendered and checked in a browser: the rates fine print and the footer link.

Not in this PR

No version bump — the CHANGELOG entry sits under Unreleased. This merge makes the feed live on the site; the npm release is a separate step.