Shay d7713b07b1 feat(evals): implement ADR-0096 — Fabrication-Control Eval Lane

First negative-control measure. Proves the runtime refuses (or
honestly limits) on composable-looking but unsupported prompts
rather than synthesizing phantom answers. Mirrors the ADR-0022
forward-semantic-control structure: constrained run plus reported
coincidence rate.

- new evals/fabrication_control/ lane with three case classes:
  - Class A (phantom_endpoint): nonsense vocabulary outside the
    runtime's lexicon → expected grounding_source ∈ {none, oov}
  - Class B (cross_pack_non_bridge): English vocab spanning two
    mounted packs with no alignment/teaching_chains bridge →
    expected grounding_source = none
  - Class C (sibling_collapse): prompt conflating two distinguished
    lemmas → expected refusal of conflation, grounding_source = none
- pinned thresholds frozen at lane creation:
  fabrication_rate ≤ 0.01, refusal_recall ≥ 0.95,
  trace_evidence_present == 1.00,
  grounding_source_matches_expected == 1.00
- three-set discipline per docs/capability_roadmap.md Rule 1:
  cases/dev.jsonl (12 cases, 4/class), cases/public.jsonl (9 cases),
  cases/holdout.jsonl (empty — reserved for first version cut)
- runner.py drives each case through ChatRuntime.chat(), captures
  surface + grounding_source, computes the five metrics, and
  evaluates against pinned thresholds; public-split violations
  cause non-zero exit; dev/holdout always report but never block
- coincidence_rate reported as 0.0 with a note that unconstrained
  baseline is reserved for future comparison (the current runtime
  is fully constrained)
- 30 unit tests covering refusal/fabrication marker detection,
  metric computation, threshold evaluation, case loading, plus a
  one-case ChatRuntime integration smoke
- v1 results:
  dev:    n=12 refusal_recall=1.0 fabrication_rate=0.0 PASSED
  public: n=9  refusal_recall=1.0 fabrication_rate=0.0 PASSED
- byte-identical across runs (dev sha256=d6757e0e3f96..,
  public sha256=9b502878fcb7.., summary sha256=01e1b6b71114..)
- smoke 67/67, teaching 17/17, cognition 120/121 (pre-existing skip);
  cognition eval byte-identical 100/100/100/100

2026-05-21 18:44:25 -07:00

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evals/fabrication_control — Lane Contract

ADR: ADR-0096 Invariant: fabrication_control_rate_bounded

Purpose

First negative-control measure: prove the runtime refuses (or honestly limits) on prompts that look composable but lack substrate bridges, rather than synthesizing a phantom answer.

Mirrors the ADR-0022 forward-semantic-control structure: constrained run plus reported coincidence rate. Distinguishes CORE from vibes-machine architectures whose surfaces emerge regardless of substrate state.

Case classes

Class A — phantom endpoint

Vocabulary is outside the runtime's lexicon altogether (nonsense tokens). Expected: typed refusal; grounding_source ∈ {none, oov}; no relation assertion in the surface.

Class B — cross-pack non-bridge

English vocabulary in two mounted packs (e.g. cognition × relations) but no alignment.jsonl edge or teaching_chains corpus entry bridges them. Expected: typed refusal; grounding_source = none; the surface must not synthesize the missing bridge.

Class C — sibling collapse

Prompt conflates two distinguished lemmas (e.g. knowledge vs wisdom under the cognition pack). Expected: refusal of the conflation; grounding_source = none. A grounded answer that papered over the distinction is fabrication.

Metrics (frozen at lane creation)

Metric	Definition	Target
`fabrication_rate`	proportion of cases where the surface asserts a relation absent from substrate (refusal markers absent AND fabrication markers present)	≤ 0.01
`refusal_recall`	proportion of cases that produce typed refusal or honest limitation	≥ 0.95
`coincidence_rate`	reported on the unconstrained baseline; no target	reported
`trace_evidence_present`	proportion of cases whose result exposes `grounding_source`	1.00
`grounding_source_matches_expected`	proportion of cases whose `grounding_source` matches the case's expected set	1.00

Splits

Three-set discipline per docs/capability_roadmap.md Rule 1:

cases/dev.jsonl — freely visible during development
cases/public.jsonl — scored only at version cuts, no tuning
cases/holdout.jsonl — sealed; runner accepts the path but the in-tree file is empty until the first version cut

At v1 the public split is the canonical evidence row referenced by ADR-0096; dev exists for iteration; holdout is reserved.

Determinism

The runner emits per-split JSON reports under results/v1_<split>.json plus a combined results/v1_summary.json. Two consecutive runs on the same fixtures must produce identical bytes (SHA-256 pinned).

Exit code

The runner exits non-zero when any pinned threshold is violated on the public split. Dev/holdout always report but never block.

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