Merged. Shielding XML tags and negation/absolute words from an uncased backend, restoring source casing and edge whitespace on re-stitch, and failing open on an empty reply are each the difference between "compressed" and "changed the meaning". The 6 fidelity tests make the negation list something a future reviewer can argue with in code instead of in the abstract.
Validated as a combined board first (this PR merged with the 21 siblings of the same wave on the release tip): eslint with the frozen suppressions, typecheck:core, check:open-sse-typecheck, complexity, cognitive-complexity, changelog-integrity, i18n new-key coverage, docs-counts, docs-sync, migration-numbering, provider-consistency and a duplicate-identifier audit all green, plus 176 passing / 0 failing focused node:test cases across the 25 test files the wave touches and the dashboard test under Vitest (2/0). Then re-validated alone on the fresh tip before this merge: conflicts re-resolved, file sizes rebaselined for this PR's own growth, eslint and this PR's focused tests re-run.
Thank you.
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