A marathon tool turn burned all compression_attempts on *successful*
pre-API compactions; the gate then went permanently dark and the context
grew unchecked until the provider rejected the request terminally
("Context length exceeded: max compression attempts (3) reached", session
f087963205f9, 2026-08-01). The budget now refunds at loop top when the
assembled request is back under threshold * 0.8 AND the compressor's own
should_compress() agrees the pressure is gone.
Anti-thrash intent of the cap is preserved (#11529): no-progress passes
never reach the refund margin, divergent-signal cases (should_compress
still True) keep the budget burnt, and the insufficient-progress blocker
is untouched.
Validation: new behavioral suite (7) + all 130 compression/context tests
via scripts/run_tests_hermetic.py.
Rückbau: Commit revertieren; kein Zustand, keine Migration.
(cherry picked from commit 041b489d566bfb1d6816d53d9acd5ac50b8d5af0)