The core could report one provider. It now covers all eight of them from the same definitions the typescript side uses, which is what makes the tray able to drop its own six fetchers. - `usage_advance` (ABI 2) is the host-driven protocol: hand it the credential and whatever responses you already have, get back either the requests to send or the report. hyper's teams-then-billing is just another round, not a second concept. - providers/: antigravity (pools 33 model buckets into Gemini/Claude/GPT-OSS families, drops the internal `chat_*`/`tab_*` ones, and keeps the `antigravity/...` user-agent its endpoint gates on), hyper (credits allocated vs remaining, dollar balance), opencode-go, zai, deepseek (balance-only), alibaba (three console-gateway calls behind a captured session), plus the codex and anthropic ports. - `iso8601.zig`: Zig's std has no parser and four providers hand back ISO strings, with and without fractional seconds and with `Z` or `±hh:mm` offsets. Its unit tests were recomputed independently. - `packages/ai/test/usage-zig-parity.test.ts` now compares all eight providers against the typescript feeds on the recorded bodies, deeply, so a conversion that drifts on either side fails the build. The child proved the comparison bites: dropping the remaining-fraction inversion in antigravity turns 83.4% into 16.6% and fails the antigravity case. - `swift/` is a SwiftPM package: `UsageCore` (the C bridge, with strings freed and NULL turned into a thrown error), `UsageDriver` (the host loop over URLSession, where a transport failure becomes a response with status 0 so the feed reports it as data), and `usage-smoke`, which pins the things most likely to be "fixed" wrongly: codex's three windows, anthropic's ISO reset becoming epoch milliseconds, antigravity's 83.4% inversion and its user-agent requirement, and alibaba's three calls carrying the captured cookies, csrf token and region in the form body. - `npm run check:zig` builds and runs the Swift smoke test where a swift toolchain exists, and says so when it skips. Verified: zig unit + C ABI tests, the eight-provider parity suite, the Swift smoke test against the recorded fixtures, and npm run check end to end.