workflow-fix: signature-bind fenced calls in the deferred-import sweep

Overview / Motivation

Auto-filed by the workflow-fix-on-bug protocol from a code-reviewer prose follow-up raised on task #1332 (emitting agent: code-reviewer, round 1).

Goal

Extend the deferred-import sweep (the #606 --verify-imports pattern) to signature-bind fenced calls: for each call to an imported helper inside a skip-flag-fenced branch, dry-run inspect.signature(fn).bind(...) with the call-site's argument shape.

Workflow gap

• Bug observed: the AST deferred-import sweep green-lit two production bind/target errors on calls inside --skip-upload / not smoke fenced branches (#1332 round 1: verify_repo_paths_uploaded called with a mismatched signature → TypeError at the terminal upload stage; plus a 404'd Hub prefix probed only in the fenced branch).
• Why it is a workflow gap: the sweep verifies that imported symbols EXECUTE (import-time), but not that fenced CALLS bind — so the exact class of deterministic post-GPU crash the sweep exists to prevent (#606) still ships whenever the crash site is a call-arity/target error inside a smoke-fenced branch.
• Confidence (emitter): medium
• verified-at-filing: grep -rln "verify-imports\|deferred.import\|deferred import" .claude/agents/experiment-implementer.md .claude/rules/gotchas.md → 6 hits in 2 files (experiment-implementer.md: 2; gotchas.md: 4) (2026-07-15)

Proposed change (candidate diff sketch — refine in planning)

(none — synthesized from prose follow-up)

Sketch: in .claude/agents/experiment-implementer.md § After-implementation deferred-imports step, add: for each imported helper called inside a skip-flag-fenced branch, dry-run inspect.signature(fn).bind(<call-site args shape>); in .claude/rules/gotchas.md "Lazy imports inside smoke-skipped branches" entry, extend the recipe with the bind check.

Scope / surfaces

• Primary target: .claude/agents/experiment-implementer.md, .claude/rules/gotchas.md
• Grep the workflow surface for the pattern before editing (grep -rln 'verify-imports' .claude/ CLAUDE.md scripts/) 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/agents/experiment-implementer.md, .claude/rules/gotchas.md
• fingerprint: 9017c3d9ada2

Verbatim surfaced prose (code-reviewer #1332 round 1):

Follow-ups (orchestrator should consider): the implementer's AST deferred-import sweep (the #606 --verify-imports pattern referenced in .claude/rules/gotchas.md and experiment-implementer.md) verifies imported symbols EXECUTE but not that fenced CALLS bind — both Criticals here were bind/target errors on calls inside --skip-upload/not smoke branches that the import sweep green-lit. A concrete extension: for each call to an imported helper inside a skip-flag-fenced branch, dry-run inspect.signature(fn).bind(...) with the call-site's argument shape (target files: .claude/agents/experiment-implementer.md § After implementation deferred-imports step, and/or .claude/rules/gotchas.md "Lazy imports inside smoke-skipped branches" entry).