workflow-fix: artifact-reuse check (i) also covers Hub-API call scoping

Overview / Motivation

Auto-filed by the workflow-fix-on-bug protocol from a workflow-fix candidate raised on task #810 (emitting agent: orchestrator, /issue 810 btdr round).

Goal

Extend the artifact-reuse fitness check (i) (throughput fitness of reused fit/analysis code) to also cover Hub-API call scoping: reused code's post-upload verify / staging calls must be prefix-scoped (list_repo_tree(path_in_repo=...) / file_exists), never an unscoped full-tree list_repo_files or snapshot_download against the ~1M-file data repo.

Workflow gap

• Bug observed: the #810 btdr follow-up round reused the parent extractor/upload helpers (issue810_extract_positions.py / issue810_common.py) whose post-upload verify ran an unscoped list_repo_files full-tree crawl of the data repo; live on 2026-07-04 it wedged in 429 retry storms (retry 20/20 reached) against the 2500-req/5-min org quota while an A100 idled at 0%.
• Why it is a workflow gap: .claude/rules/artifact-reuse.md check (i) mandates inspecting reused code's inner loop batching + device routing, but NOT its Hub-API call scoping — so a reused (not-touched-this-round) helper carrying the gotchas.md #833 anti-pattern passes plan review, the consistency-checker, and code review (which sees only the round's diff) un-inspected.
• Confidence (emitter): high

Proposed change (candidate diff sketch — refine in planning)

In .claude/rules/artifact-reuse.md, fitness check (i):

- (i) throughput fitness of reused fit/analysis CODE — inner
-     per-cell/per-fold/per-draw loop batched + device parametrized
+ (i) throughput fitness of reused fit/analysis CODE — inner
+     per-cell/per-fold/per-draw loop batched + device parametrized, AND
+     Hub-API calls scoped: post-upload verifies / staging enumerate a
+     prefix (list_repo_tree path_in_repo= / file_exists), never a
+     full-tree list_repo_files / snapshot_download of the data repo
+     (gotchas.md #833; #810 btdr 429 wedge, 2026-07-04); a first-page
+     429 needs a bounded outer retry (the #658 rule)

Also consider a one-line pointer in .claude/agents/code-reviewer.md Step 0.68 (throughput checklist) so a NEW diff introducing the pattern is caught too.

Scope / surfaces

• Primary target: .claude/rules/artifact-reuse.md
• Secondary (planner's call): .claude/agents/code-reviewer.md
• Grep the workflow surface for the pattern before editing (grep -rln 'list_repo_files' .claude/ CLAUDE.md) 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: .claude/rules/artifact-reuse.md
• fingerprint: 03a052106e6c

Surfaced prose (orchestrator observation, /issue 810 btdr round, 2026-07-04): reused upload/verify helpers carried an unscoped full-tree list_repo_files verify that wedged the live GPU run in 429 storms; hot-fixed in-flight as 04701b2d56; the reuse checklist should have surfaced it at plan time.