daily-fix: HF upload/verify transient 429/500 retry robustness

Overview / Motivation

Auto-filed by /daily 2026-07-03 from a /daily 2026-07-03 finding.

Goal

longer/backoff-aware retry ceiling on tree-listing + xet-token paths, and retry on the _upload_tensors verify leg

Workflow gap

• Bug observed: (a) org-wide HF 429 storms on xet-read-token / /tree listing killed #931's staging via retry exhaustion and slowed #811/#813; (b) a transient HF 500 on the paginated list_repo_files verify leg of _upload_tensors crashed #920 AFTER all uploads succeeded (GCE EXIT trap then deleted the instance)
• Why it is a workflow gap: see candidate note
• Confidence (emitter): medium

Proposed change (candidate sketch — refine in planning)

longer/backoff-aware retry ceiling on tree-listing + xet-token paths, and retry on the _upload_tensors verify leg

Scope / surfaces

• Primary target: src/explore_persona_space/orchestrate/hub.py (upload/staging paths)
• Grep the workflow surface for the pattern before editing; list every hit in the plan.

Constraints / invariants

• Workflow-surface only; scripts/workflow_lint.py --check-asks passes; ruff on touched files passes.

Provenance

• workflow_fix_target: src/explore_persona_space/orchestrate/hub.py (upload/staging paths)
• fingerprint: 970e18ecb679

daily finding 4 (2026-07-03): HF 429 storms + transient 500 on verify leg killed #931 staging and crashed #920 post-upload.