feat(runtime+evals): warm-path pack grounding + three long-span lanes
Step 1 — warm_grounding_stability targeted patch
- chat/runtime.py:_maybe_pack_grounded_surface accepts allow_warm=True;
warm path invokes it after articulation and overrides
response_surface / articulation / grounding_source when pack-grounded
or teaching-grounded.
- CAUSE / VERIFICATION without a teaching chain on warm path emits the
unknown-domain disclosure (matches cold-path discovery-signal doctrine
— no fabricated vault content).
- warmed_session_consistency public lane: warm_grounding_stability
0.0 → 1.0, grounding_match_rate 1.0, telemetry_consistency 1.0.
- Cognition lane byte-identical (public 100/100/91.7/100, holdout
100/100/83.3/100). Full suite 2294 passed.
Step 2 — three new red eval lanes (measurement substrate)
- conversational_thread_coherence: 6 cases / 45 turns; per-turn
no_placeholder / not_walk_fragment / length / is_grounded predicates
+ per-case topic_anchor and no_topic_drift. Baseline: grounded
0.93, topic_anchor 0.50, no_topic_drift 0.83.
- multi_sentence_response: 15 cases over Explain/Tell/Describe/Walk/
Example/Essay shapes; predicates sentence_count >= 2, non-fragment,
connective_present, subject_named. Baseline: multi_sentence 0.53,
connective 0.10 — biggest architectural gap.
- self_consistency_over_time: 7 cases; same probe at multiple turn
indices with unrelated fillers interleaved. Baseline: byte_identical
0.86 (one CAUSE-no-chain disclosure drifts under accumulation).
All three lanes deterministic, lexical-predicate-only — no LLM judge,
no embedding similarity. Red-on-creation by design. See
notes/long_span_fluency_baseline_2026-05-19.md.
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