daily-fix: stuck-batch cancel+sync fallback in batch_judge

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 a stuck-batch predicate to the batch_judge poller (zero succeeded after N hours triggers cancel + sync fallback) and a total-uncached-draws batch-pass count to the batch-vs-sync decision table

Workflow gap

• Bug observed: #810 Phase C sat 16h behind an Anthropic Message Batch wedged at 0/2001 succeeded while the free-self-harvest rule kept the chain parked; cancel + force_sync then cleared all 39512 judge calls in 18 minutes at ~1400 RPM with zero errors
• Why it is a workflow gap: The deadline-bounded batch_judge poller has no stuck-batch escape (only expiry), and the sizing guidance never counts how many sequential batch passes a phase implies (~30 for #810), so a wedge parks the whole chain for its full TTL
• Confidence (emitter): medium

Proposed change (candidate diff sketch — refine in planning)

+ STUCK_BATCH_HOURS = float(os.environ.get("EPS_BATCH_STUCK_HOURS", "4"))
+ if elapsed_h >= STUCK_BATCH_HOURS and counts.succeeded == 0:
+     cancel_batch(batch_id); harvest_partial(); fall back to sync dispatch
  (docs: add batch-pass count = ceil(uncached_draws / batch_size) to the
  batch-vs-sync crossover table; >2-3 passes => prefer sync)

Scope / surfaces

• Primary target: src/explore_persona_space/eval/batch_judge.py, docs/api_throughput_guidelines.md
• 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, docs/api_throughput_guidelines.md
• fingerprint: 6d62ee138fd4
• related_task: #810
• source: /daily 2026-07-02 backfill problem sweep (route 2)