workflow-fix: smoke outputs must not clobber committed artifacts

Overview / Motivation

Auto-filed by the workflow-fix-on-bug protocol from an orchestrator observation on task #722 (emitting agent: orchestrator, /issue 722 resume session).

Goal

Add an output-path hygiene rule to the smoke-run contract: smoke invocations that write under eval_results/ or figures/ must redirect output to a scratch dir (e.g. --out-dir /tmp/... / env override) OR restore the committed artifacts immediately after the smoke, so implementer/reviewer smokes never leave committed production artifacts clobbered in the worktree.

Workflow gap

• Bug observed: During #722's round-2 review window (04:22–05:04Z, 2026-07-02), a --layers 0 18 smoke wrote 2-layer outputs to the canonical eval_results/issue_722/base-skill-over-mean-cC-to-v0/{krr_vs_linear,mlp_epoch_curves,mlp_width_sweep}.json and figures/issue_722/{krr_vs_linear_nonlinearity,mlp_epoch_curves,mlp_width_sweep}.* paths, truncating the committed 28-layer production artifacts (−2966 lines) in the issue-722 worktree. Caught pre-commit by the resume session and restored via git checkout -- <paths>; had it been swept into a later explicit-path commit, production artifacts on the branch would have been silently replaced by smoke output.
• Why it is a workflow gap: The smoke-run contract (experiment-implementer.md § End-to-end smoke run PER PHASE; code-reviewer.md Step 0.6) mandates tiny-slice smokes but says nothing about WHERE their outputs land. Experiment scripts default to canonical output paths, so any conforming smoke on an already-produced arm clobbers committed artifacts by default. No grep hit for scratch-dir/clobber guidance in either file.
• Confidence (emitter): medium

Proposed change (candidate diff sketch — refine in planning)

+ (experiment-implementer.md § End-to-end smoke run PER PHASE, new bullet)
+ - **Smoke outputs never overwrite committed artifacts.** When the smoke
+   command writes under eval_results/ or figures/, redirect its output to a
+   scratch dir (--out-dir /tmp/issue-<N>-smoke/ or the script's env override);
+   if the script has no output override, restore the touched committed paths
+   immediately after the smoke (git -C "$WT" checkout -- <paths>) and say so
+   in the ## Smoke run sub-section. A dirty worktree of smoke-truncated
+   production JSONs is a latent clobber (incident #722, 2026-07-02).
+ (code-reviewer.md Step 0.6, one line)
+ - Verification smokes the reviewer runs itself follow the same rule.

Scope / surfaces

• Primary target: .claude/agents/experiment-implementer.md, .claude/agents/code-reviewer.md
• Grep the workflow surface for the pattern before editing (grep -rln 'Smoke run' .claude/ CLAUDE.md scripts/) and update every hit that states the smoke contract; 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; if workflow.yaml or CLAUDE.md change, they stay consistent with the rule file.
• 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/agents/code-reviewer.md
• fingerprint: 316546eddfbf

Surfaced prose (orchestrator observation, task #722 resume session, 2026-07-02): review-window smoke overwrote committed 28-layer production artifacts at canonical paths with 2-layer smoke output; smoke-run contract lacks any output-path hygiene rule; propose scratch-dir redirect or restore-after-smoke requirement in experiment-implementer.md + code-reviewer.md.