workflow-fix: scoped listing in verify_uploads.py (1M-file repo hang)

Overview / Motivation

Auto-filed by the workflow-fix-on-bug protocol from a finding surfaced by the upload-verifier on task #920 (formal candidate suppressed agent-side under AUTO_REVIEW_DISABLED; routed by the orchestrator).

Goal

Replace scripts/verify_uploads.py's bare full-repo api.list_repo_files(...) (dataset-path + claimed-urls verification, ~line 152) with scoped list_repo_tree(path_in_repo=<prefix>) / HfApi().file_exists(...) per checked path.

Workflow gap

• Bug observed: verify_uploads.py hung >600 s (killed, exit 143) on task #920 — its verification enumerates the ~1M-file superkaiba1/explore-persona-space-data repo with a bare list_repo_files, which times out (the #833 gotcha, now also codified in .claude/rules/artifact-reuse.md).
• Why it is a workflow gap: the upload-verifier's own mechanical helper cannot complete on the project's primary data repo; every experiment's Step 8 hard gate degrades to agent-side manual checks.
• Confidence (emitter): high

Proposed change (candidate diff sketch — refine in planning)

- remote = set(api.list_repo_files(repo_id, repo_type="dataset"))
+ # scoped per checked prefix — the ~1M-file data repo times out on a bare listing (#833)
+ remote = set()
+ for prefix in checked_prefixes:
+     remote |= {e.path for e in api.list_repo_tree(repo_id, repo_type="dataset", path_in_repo=prefix, recursive=True)}
+ # single-path checks: api.file_exists(repo_id, path, repo_type="dataset")

Scope / surfaces

• Primary target: scripts/verify_uploads.py
• Grep the workflow surface for the pattern before editing (grep -rln 'list_repo_files' scripts/ .claude/) and audit every hit against the scoped-listing rule; list them in the plan.

Constraints / invariants

• Workflow-surface only. Ruff passes; existing verify_uploads tests pass; behavior identical on small repos.
• This session runs under EPM_WORKFLOW_FIX_SESSION=1 and carries a workflow_fix_target: Provenance line — recursion guard applies.

Provenance

• workflow_fix_target: scripts/verify_uploads.py
• fingerprint: df81c7657307

Surfaced prose (upload-verifier #920, verbatim): "scripts/verify_uploads.py hung >600 s (killed, exit 143): its dataset-path + claimed-urls verification at scripts/verify_uploads.py:152 uses a bare full-repo api.list_repo_files(...) against the ~1M-file data repo — the #833 gotcha. ... fix: scoped list_repo_tree(path_in_repo=...) / file_exists per path."