[cskwork]

The compaction browser check reads a shared provider-request capture. An unrelated request arriving after compaction can make its global last-request assertion fail; accepting any historical match would hide missing focus in the current operation. The request sequence from the earlier PR #53 failure was not captured, so its historical cause remains unknown.

Select the current summary using a pre-action capture cursor, a unique conversation marker, and the pinned summarizer system message. Require every matching attempt to carry the exact user-role focus instruction. Add eight pure regression tests and run them in chat-browser CI. Preserve the existing 120-case matrix, assertions, waits, busy-button mutation, /usage, and /compress checks. Shutdown changes are already in the base through #54.

Validation:

• Eight pure regression tests pass; the old last-request assertion fails the interleaving regression.
• Production frontend export, Go build/vet, syntax, and diff checks pass on the integrated base.
• Spanish mobile compaction passes. After an earlier valid English request, removing only the current Spanish POST focus fails specifically on the current-focus assertion, with the current summary selected. Disposable databases were dropped.
• Independent diff review passes. The full 120-case matrix and all seven exact-candidate CI checks remain merge gates; final dev E2E must pass before Promote dev to main: complete six-language localization #53 promotes to main.