Propose the fix

Input: DIAGNOSIS.md + REPRO.md. Output: FIX.md. You may read code freely now, but you still change nothing.

Design rules (DeepReason-specific)

• Smallest semantic change that makes the reproduction invert. If a comparison is wrong, fix the comparison — do not redesign the data it compares.
• The record is law. Never change what is WRITTEN to the append-only record to fix what is READ from it. Fix readers (validators, gates, accessors) so old committed roots stay valid. A fix that invalidates existing replay-valid roots is wrong by definition.
• Frozen surfaces need a flag, not a patch. Anything that alters state digests, event application order, manifest schemas, or qualification subjects is out of a normal tranche: FIX.md must say so and stop for operator approval.
• Budgets and priorities are guarantees. A scheduling or budget fix must state the guarantee in one sentence ("the operator's seed question always wins rank ties"; "simulation budgets meter only simulation records") and the fix must make that sentence true in EVERY selection/gate path, not just the default one.
• Counters count one thing. When filtering a pooled collection, filter by type (isinstance) at every consumer, and check for the mirror-image bug in the sibling capability before declaring done — note it in PARKED.md if real.

FIX.md template

# Fix: <one line>
Guarantee restored: <one sentence>
Change sites (exhaustive):
  - <file:line-range> — <what changes, one line each>
Regression artifact: <the REPRO artifact that must invert, plus
  any NEW conditions this fix must be tested against>
Existing tests at risk: <tests whose fixtures assumed the old
  behavior, from grep — name them and say whether each will be
  updated (fixture was defect-dependent) or must keep passing>
Explicitly not changed: <the tempting neighbor, and why>
Estimated diff: <n> lines across <n> files (must be <=150)

Approval gate

• Class defect (per GOAL.md) with diff estimate <=150 lines and no frozen surface: proceed to dr-implement-fix.
• Anything else: stop, present FIX.md, await operator direction.

Exit criteria

• FIX.md committed and pushed. No production code changed.
• Return to the orchestrator.