Adversarial review: survived a hostile reviewer plus two independent refuters, each told to assume the PR was broken and to default to refuting when uncertain.
`GBRAIN_FTS_LANGUAGE` was absent from the query-cache key, so a language switch served stale pre-switch rows. The hash now folds it (v14→15) with all five pin sites updated; reverting the fix fails 4 of 15 tests at the exact claimed step. Landing first in the knobs_hash cluster — the constant is single-writer, so #3617 rebases onto this and takes 16.
Verified before merge: the PR's own tests fail when the production change is reverted (11 of the previous 32 PRs failed exactly there — one had 7 of 8 new tests passing on master); typecheck clean; MERGEABLE/CLEAN with 22/22 checks green on the current base, not a stale one.
paul-0320
b4a9c7683d