W0.3: delete fact_cardinality variant_mismatch nickname

[gunbai-bot]

Summary

Wave-0 §3 de-fork (re-scoped): delete the bare-alias fact_cardinality_cross_tree_variant_mismatch in src/v2/lens/fact_cardinality.dag — it was a plain forwarding alias of fact_cardinality_cross_tree_diverged_fork. The sole consumer (synthetic_unified_green_test.dag) now calls the canonical name.

Out of scope (reverted from earlier drafts): routing duplicate_computation onto LadderVerdict.AuthoredDuplication — that touches load-bearing dag/std/materialization_ladder.dag and is W1.2, not W0.

Test plan

• claim_batch — synthetic_unified_green_holds, synthetic_fork_red_holds (both PASS)

W1.2 investigation (not implemented)

Goal: collapse duplication verdict forks onto LadderVerdict per lens-consolidation-design §6.B — distinct from provenance verdicts (vacuity keeps VacuityEvidence; Share remedy must not be applied to vacuous tests).

duplicate_computation.DuplicateComputationViolation → LadderVerdict

• Today: DuplicateComputationViolation = DuplicateComputationDemand { computation_key, unguarded_count, sites }; emitted by duplicate_computation_violations/duplicate_computation_violation_count.
• Target: AuthoredDuplication { identity, lca, site_count } from std.materialization_ladder — remedy Share via ladder_verdict_prescribes.
• Mapping: computation_key → identity; unguarded_count → site_count; lca needs frame projection (today empty — placement/argv grain has no Frame path yet).
• Breaks: loses sites: List<String> on the verdict carrier (diagnostics move to projection layer or a located refusal type); all witnesses importing violation count APIs need enrollment review; materialize.dag / CI materialization gates are separate grain — must not conflate without frame+nature.
• Gate: operator sign-off before editing materialization_ladder.dag; needs discriminating witness on AuthoredDuplication shape at placement grain.

std.lens_verdict.LensVerdict split

• Today: generic envelope Holds | Violation | NotApplicable | Unrealized with LensVerdictDiagnostic — used by schedule, cache key completeness, table_decision_tree, host_language_transport_script, etc.
• Not a duplication fork: LensVerdict is cross-invariant plumbing; only duplication-specific per-lens enums are the fork (per §3 rubric Q3).
• W1.2 work: ensure duplication lenses emit LadderVerdict, not LensVerdict.Violation, for authored-duplication findings; keep LensVerdict for lenses whose invariant is genuinely envelope-shaped (schedule ordering, unrealized scaffolds). Registry/contracts must declare which verdict authority each lens uses.
• Breaks: consumers that pattern-match LensVerdict.Violation expecting duplication semantics; Rust seed std_lens_verdict.rs must stay in sync with dag/std/lens_verdict.dag; no merge of vacuity/oracle verdicts into LadderVerdict (review ruling: remedies differ).

[gunbai-bot]

CI failure is generated_artifact_drift_gate_passes — not the W0.3 fact_cardinality diff (2 files).

Pre-existing latent drift from #6638: hand-edited generated docs/plans/inert-layer-lens.md without updating authority dag/gunbc/plans/inert_layer_lens.dag. The authority fix is in #6667 (sole owner of that file).

Holding per operator re-scope: will not add a drift fix on this PR (avoids 3-way conflict with #6667). Once #6667 merges to main, will git merge origin/main here and the drift gate should go green.

Approvals (claude + cursor) and mergeable=CLEAN already hold; only CI floor is blocked on the external #6667 merge.

— sent from silent-heron-226