daily-fix: rubric-bearing JudgeCache._hash_key

Overview / Motivation

Auto-filed by the /daily 2026-07-02 backfill problem sweep (route 2 — behavior/logic change, independent review required). Emitting context: transcript mining of the 2026-07-02 sessions.

Goal

Add rubric/judge-prompt hash + judge model id to JudgeCache._hash_key so cached judgments cannot leak across rubrics

Workflow gap

• Bug observed: JudgeCache._hash_key keys on (question, completion) only; refusal-rubric judgments leaked into harmful_compliance E0 scores on #810 (64 percent of high scores shared exact reasoning/score pairs with the refusal file)
• Why it is a workflow gap: llm-judging.md rule 22 (#882) documented the keying requirement but explicitly deferred the batch_judge.py code fix as a separate follow-up that was never filed; the per-rubric cache_dir is only an accepted surrogate
• Confidence (emitter): high

Proposed change (candidate diff sketch — refine in planning)

- def _hash_key(question: str, completion: str) -> str:
-     content = f"{question}\n---\n{completion}"
+ def _hash_key(question, completion, rubric_key) -> str:
+     # rubric_key = sha256 of the full judge prompt (+ judge model id)
+     content = f"{rubric_key}\n---\n{question}\n---\n{completion}"
  (thread rubric_key through get()/put(); bust or namespace existing
  content-keyed cache dirs so stale cross-rubric entries cannot be read)

Scope / surfaces

• Primary target: src/explore_persona_space/eval/batch_judge.py
• Grep the workflow surface for the pattern before editing and update every hit; list them in the plan.

Constraints / invariants

• Workflow-surface only — never experiment code, configs/, or tasks/.
• scripts/workflow_lint.py --check-asks passes; ruff on touched files passes.
• This session runs under EPM_WORKFLOW_FIX_SESSION=1 and carries a workflow_fix_target: Provenance line — it MUST NOT auto-route any of its own subagents' workflow-fix candidates (recursion guard).

Provenance

• workflow_fix_target: src/explore_persona_space/eval/batch_judge.py
• fingerprint: fe8ef634bf02
• related_task: #810
• source: /daily 2026-07-02 backfill problem sweep (route 2)