Closes the gap the 2026-05-19 design review flagged:
> Some evals are too permissive to protect fluency; they accept
> fragments or ungrammatical strings.
This lane defines fluency as six DETERMINISTIC predicates over the
user-facing surface — no LLM judge, no embedding similarity, no
aesthetics. Each predicate is a testable bool.
The six predicates:
no_placeholder — no ..., <pending>, <prior>, <empty>
no_provenance_only — surface is not bare structured disclosure
complete_punctuation — ends with . / ? / ! / ;
finite_predicate_shape — at least one finite-verb token present
no_dotted_inventory — no 3+ dotted-paths joined by ;
surface_provenance_match — grounding_source agrees with surface text
Each is a regex / substring check. Subjective fluency (rhythm,
idiom, register) is deliberately out of scope — that would require
an LLM judge (doctrine violation) or human review (not CI-pinnable).
Baseline measured on current main (this commit, all v1 public cases):
cases: 15
no_placeholder_rate: 1.0000 (hard floor — pinned)
complete_punctuation_rate: 1.0000 (hard floor — pinned)
finite_predicate_shape_rate: 1.0000 (>= 0.90 — pinned)
no_provenance_only_rate: 1.0000 (varies — lift target)
no_dotted_inventory_rate: 0.3333 (varies — lift target)
surface_provenance_match_rate: 1.0000
expected_predicates_pass_rate: 1.0000 (per-case contracts hold)
The dotted-inventory rate at 33% is the exact gap the gloss feature
is designed to close. Today 10 of 15 cases emit surfaces like
doubt — pack-grounded (en_core_meta_v1):
meta.mental_state.uncertainty; meta.mental_state; cognition.epistemic.
No session evidence yet.
After glosses land:
Doubt is a mental state of uncertainty about a claim.
Pack-grounded (en_core_meta_v1).
The lane records both metrics today; thresholds are extended in the
gloss-wiring commit so the rates DROP if the lift fails to land.
Files:
evals/deterministic_fluency/contract.md
The six predicates with implementation notes and pass thresholds.
Documents which thresholds are pinned today vs. which are gloss-
landing lift targets.
evals/deterministic_fluency/public/v1/cases.jsonl
15 cases across four categories: pack_definition (10),
oov_invitation (2), cause_no_chain_unknown_domain (2),
teaching_grounded (1). Each case declares its own
``expected_predicates`` — the subset of the six it must satisfy
today; e.g. OOV cases don't assert finite_predicate_shape because
the invitation surface is intentionally explanatory.
evals/deterministic_fluency/dev/cases.jsonl
2 representative cases for fast iteration.
evals/deterministic_fluency/runner.py
Six predicate functions + framework-compliant run_lane. Returns
per-predicate rates + per-case predicate dicts so debugging a
regression is one read of case_details away.
tests/test_deterministic_fluency_lane.py
14 contract tests covering: case-set integrity, valid predicate
names, lane discovery, every predicate rate emitted, per-case
predicates dict carries every signal, the three hard invariants
(no_placeholder == 1, complete_punctuation == 1,
finite_predicate_shape >= 0.90), expected_predicates_pass_rate
== 1 (every case satisfies its own contract), lift-target
metrics are recorded for the gloss-feature substrate.
Verification: 14/14 lane tests green on current main.
Shay