The ultra heuristic no longer prunes polarity and modality words (`never`, `always`, `not`, `must`, `should`, `do`/`does`/`did`, contractions…). They now score 1.0 instead of the 0.1 stopword score, so "must never be deleted" can no longer collapse into "must deleted". It also collapses only runs of spaces and tabs, keeping the newlines that carry bullets, headings and fences (#13454).
Maintainer fixes: (1) the new test imported `../../open-sse/…` from `tests/unit/compression/`, which does not resolve, so it had never run. It now passes with the rest of the compression suite (1,526 cases). (2) Dropped the unused `STOPWORDS` import. (3) `check:compression-budget` flagged the expected trade-off: ultra tokens-per-task goes prose 92→97, tool-output 116→117, json 117→126, the cost of keeping meaning-bearing words and line structure. The baseline was refreshed with `--update`, which also records a pre-existing caveman tightening (129/127/160 → 119/114/136). (4) The branch also carried the unrelated `feat(sveltekit)` commit and the #13523 commit, so it was reset to the release tip plus only this commit, authorship preserved.
Validated in one consolidated batch of this series (37 PRs boarded together on `release/v3.8.51`): `typecheck:core`, `check:open-sse-typecheck` and `check:dashboard-typecheck` clean; ESLint clean on every changed file; file-size, complexity, cognitive-complexity, changelog-integrity, docs-counts, docs-sync and migration-numbering gates green (only the pre-existing `open-sse/utils/stream.ts` file-size red remains, inherited from the base); 3,743 focused `node:test` cases plus 34 vitest cases green.
Thanks @KooshaPari!
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