* fix(sse): forward the upstream's real trailing usage in passthrough; estimate only at flush
#12151 injected estimated usage into the finish chunk and dropped the real
trailing usage block that genuine OpenAI upstreams send afterwards — metered
clients got estimates instead of real token counts. The estimate now leaves
via a canonical usage-only chunk at flush, only when the upstream stayed
silent; a real trailing block is forwarded verbatim and wins. The tool_calls
finish_reason normalization now materializes its own rewrite (it piggybacked
on the removed finish-time rewrite), and the dead collectSSE helper goes with
it (subsumes #12324).
* fix(i18n): seed the radarPage limits/training keys the #12320 UI already consumes
RadarCatalogTable.tsx references radarPage.colLimits / trainsOnPrompts /
trainsOnPromptsHelp but #12320 never added them to en.json, so the EN
fallback could not resolve the __MISSING__ markers across 42 locales.
Real translations for pt-BR and vi; the rest resolve via the EN fallback.
* fix(sse): carry the chat stream id into flush-time synthetic chunks
The estimated usage-only chunk emitted at flush used passthroughResponsesId,
which is only ever set on the Responses path — on the chat path the synthetic
chunk shipped id: null, breaking the string-id invariant pinned by
stream-numeric-ids.test.ts. Track the upstream chat-completion id in the
passthrough loop and reuse it (falling back to the Responses id, then a
generated one). Sibling sweep: 74 files importing utils/stream — 603/603.
A passthrough stream could end with no usage even though the client asked for it via stream_options: {include_usage: true}, so providers that do not meter always showed 0 tokens. The fix estimates usage at the finish marker when the upstream stays silent (flagged estimated: true) and drops any duplicate trailing usage chunk so the client never sees two.
open-sse/utils/stream.ts:1982,1749 · open-sse/utils/usageTracking.ts:651,664
Six cases: the predicate (finish without usage but with content, trailing valid, empty response, tool-only) plus two SSE harness cases through createSSEStream passthrough.
Note on base: this branch forked 442 commits back and carried a base-red marker for #12109, which is now closed — the release tip has no open base-red issue. It merged cleanly against the current tip regardless.
Verified in a combined batch worktree: 174/174 focused tests across all 11 PRs of this batch (this PR's stream-passthrough-usage-estimation suite included), typecheck:core clean, check:cycles and check:docs-counts green.
Thanks @maxmad64bis.
