workflow-fix: thread caps at VM launch surfaces despite stale worktrees

Overview / Motivation

Auto-filed from the 2026-07-02 #779 uncapped-grid launch: the #847 thread-cap fix (env.py OMP setdefault for shared-VM launches) merged to main, but the issue-779 worktree branched earlier and kept the pre-fix env.py; the session's VM-side grid launch ran 78 uncapped threads. The worktree HAS a spec-freshness sync mechanism for .claude/ files (commit e81357fd "sync workflow-surface specs from main") but nothing propagates src/ library infra fixes, and launch instructions do not require explicit caps.

Goal

Close the worktree-staleness hole for shared-infra fixes: VM-side compute launches from a worktree must either (a) explicitly export the thread-cap envs in the launch command (belt-and-suspenders, works regardless of branch age), or (b) the spec-freshness sync is extended to a small allowlist of infra-critical src files (orchestrate/env.py), applied before any VM-side CPU-phase dispatch.

Workflow gap

• Bug observed: a fix that existed on main for ~20h was absent from the running worktree; the launch surface had no fallback, so the exact failure #847 fixed recurred.
• Why it is a workflow gap: in-flight worktrees are pinned to their branch point by design; infra fixes with fleet-wide blast radius (thread caps) have no propagation or launch-time fallback path.
• Confidence (emitter): medium

Proposed change (refine in planning)

• .claude/skills/issue/SKILL.md (VM-side phase dispatch) + .claude/agents/experiment-implementer.md: VM-side CPU-phase launch commands MUST carry explicit OMP_NUM_THREADS=8 OPENBLAS_NUM_THREADS=8 MKL_NUM_THREADS=8 (values from CLAUDE.md/code-style), independent of worktree branch age.
• Optionally extend the spec-freshness sync allowlist with src/explore_persona_space/orchestrate/env.py (planner decides whether the sync or the explicit-caps route is the cleaner invariant).

Scope / surfaces

• Primary: .claude/skills/issue/SKILL.md, .claude/agents/experiment-implementer.md, possibly the spec-freshness sync helper.

Constraints / invariants

• Caps are explicit-launch-time only (pods/GCE/SLURM keep full width); no library behavior change without the planner's say.

Provenance

• workflow_fix_target: .claude/skills/issue/SKILL.md
• origin: PM-chat root-cause 2026-07-02 (#779 uncapped grid from a pre-#847 worktree)