v2.0.4 — Verifier-collapse detector

Patch release. Adds a stdlib-only verifier-collapse detector to the
consistency dimension and wires the resulting flag into both the
/judge --explain output (Markdown + explain.v1 JSON) and the
Stop-hook ship-gate. Closes a latent bug in
_analyze_consistency: the prior low-variance branch would
reward a flatlined verifier with a +1 "highly consistent"
bonus — the new detector composes with that path so collapsed
verifiers net to a dock instead.

Added

• skills/judge/scripts/score.py::_detect_verifier_collapse —
  offline statistics over the rolling window of recent scorecards
  for the same skill. Flags verifier_collapse=true when, over at
  least min_samples of the last window cards (defaults 5/10):

  • fraction of composites >= top_threshold (default 8.5)
    crosses top_bucket_fraction (default 0.95), and
  • std_dev of composites < max_std_dev (default 0.3 —
    tighter than the existing 0.8 "highly consistent" cutoff).

  On a hit, _analyze_consistency docks the dimension by
  consistency_dock (default 3) and appends a one-line reason.
  The dock is wide enough to net out the existing low-variance
  +1 bonus that the same data would otherwise trigger.

• dimensions.consistency.verifier_collapse /
  verifier_collapse_reason / verifier_collapse_stats on the
  scorecard, mirrored at the scorecard top level as
  verifier_collapse: bool for one-jq-query CI consumption.

• judge-config.json.verifier_collapse block (enabled by default;
  set enabled: false to disable). Knobs: window, min_samples,
  top_threshold, top_bucket_fraction, max_std_dev,
  consistency_dock, gate_mode.

• explain.v1 JSON surfaces verifier_collapse (top-level) plus
  per-dimension verifier_collapse / verifier_collapse_reason /
  verifier_collapse_stats on the consistency entry. The Markdown
  renderer adds a "⚠️ Verifier collapse detected" callout above
  the dimension table, anchored on Verdict's own consistency
  dimension plus the Soft-SVeRL project anchor (no sibling
  benchmark analogies, per the G13 cross-pollination rule).

• hooks/judge-on-stop.sh honours
  judge-config.json.verifier_collapse.gate_mode:

  • warn (default) — stderr Verdict WARNING: verifier collapse detected for $SKILL_NAME — $REASON, exit code unchanged.
  • fail — stderr Verdict BLOCKED: ... + exit 2 (same shape
    as the existing threshold-breach gate).
  • off — silent.

• schemas/scorecard.v1.schema.json now declares the new optional
  fields (top-level verifier_collapse plus the three new
  per-dimension keys). Backward-compatible additive extension; no
  required-field change.

Tests

• tests/test_verifier_collapse.py (new): clean varied history
  produces no flag; collapsed history (10× 9.5) flags + docks the
  consistency dim; below-min_samples produces no flag;
  enabled: false produces no flag; explain.v1 JSON carries
  top-level + per-dim fields; Markdown renderer emits the callout
  with the Soft-SVeRL anchor; hook gate-mode warn exits 0,
  fail exits 2, off is silent.

Notes

• The detector is offline-only (pure stdlib statistics over
  scores/) and is the default-on companion to the off-by-default
  LLM second-opinion analyzer. LLM judging is not made the default
  by this change — the offline heuristic is the moat.

• The signal is derived from Verdict's own consistency dimension
  plus the Soft-SVeRL project anchor. Sibling-benchmark analogies
  were considered and dropped per the G13 anti-cross-pollination
  rule; no external evaluation suites are named in code, docs, or
  CHANGELOG for this change.