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workflow-fix: verify_plan lattice parser — negated-existence atom

kind: infra#wf-fix#wf-fix-fp:63fb274bb974
track:

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Overview / Motivation

Auto-filed by the workflow-fix-on-bug protocol from a mechanizable: yes Statistics-critic finding raised on task #1946 (emitting agent: critic, Statistics & Measurement lens, plan v5 review).

Goal

Extend scripts/verify_plan.py's verdict-lattice parser to recognize a negated-existence atom (e.g. "no contrast BH-significant with positive delta") so legitimate family-negation conjuncts parse instead of WARNing.

Workflow gap

  • Bug observed: verify_plan WARN on #1946 plan v5: label 'Collapse-preserved' did not fully parse — "predicate token(s) outside every recognized atom: 'no'" — despite the lattice being disjoint+exhaustive (the Statistics critic verified coherence by hand against the battery's actual output fields).
  • Why it is a workflow gap: the lattice-coherence check is supposed to make decision gates machine-checkable; a common, legitimate predicate shape (negated existence over a contrast family — "no X is BH-sig-positive") falls outside the recognized atom grammar, so any plan using it draws a WARN and loses the FAIL-capable mechanical check, pushing the verification back onto per-round critic labor.
  • Confidence (emitter): medium
  • verified-at-filing: live reproduction — uv run python scripts/verify_plan.py --issue 1946 (2026-08-01) emitted the WARN verbatim ("predicate token(s) outside every recognized atom: 'no'"); target confirmed present: grep -n 'atom' scripts/verify_plan.py hits the lattice-atom grammar region (the WARN's own wording), 1 target file.

Proposed change (candidate diff sketch — refine in planning)

+ # In the lattice predicate parser: recognize a negated-existence atom
+ #   NO_EXIST := ("no"|"zero") <family-ref> <metric-ref> [comparator]
+ # equivalently count(<family> where <predicate>) == 0, and treat it as a
+ # well-formed conjunct in the DISJOINT-and-exhaustive partition check.

Suggested canonical machine form the parser should also accept: count(refusal-family contrasts with bh_significant AND delta_adj > 0) == 0.

Scope / surfaces

  • Primary target: scripts/verify_plan.py
  • Grep the workflow surface for the pattern before editing (grep -rln 'recognized atom' scripts/) and update every hit; list them in the plan. Add/extend the pin test for the lattice parser (tests/test_verify_plan.py) with a negated-existence fixture.

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: scripts/verify_plan.py
  • fingerprint: 63fb274bb974

Origin finding (verbatim, Statistics critic on #1946 plan v5): "WARN 3 cosmetic residue (mechanizable: yes). If a future round touches the plan, restating the family conjunct in verify_plan's recognized atom grammar (e.g., count(refusal-family contrasts with bh_significant AND delta_adj > 0) == 0) would make the lattice machine-checkable; a 1-line predicate-token extension to the verify_plan lattice parser (recognize a negated-existence atom) would also close this class. Not blocking — coherence is verified above."

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