When retrying after a REFUTED proposal, the prompt includes:

1. ANTI-PATTERNS block: every prior attempt's gate_sv + counterexample
   + which properties PROVED (preserve those) + measured synthesis delta.

2. Cumulative context: proposer sees the FULL retry history, not just
   the immediate prior attempt. Avoids re-making old mistakes.

3. Guidance text (single attempt):
   "Propose a DIFFERENT transformation that avoids this counterexample."

4. Guidance text (multi-attempt):
   "Avoid the failure modes from EVERY attempt above. If the same
   transformation class kept refuting, pick a fundamentally different
   class OR rethink the encoding/indexing relationship."
