Phase A — RuntimeConfig flag:
core/config.py: adds `comprehension_reader_questions: bool = False`
Default OFF preserves byte-identical behaviour with today.
Phase B — Hybrid wiring in candidate-graph path:
generate/math_candidate_graph.py:
- _try_reader_for_question() dispatches to the comprehension reader
BEFORE the regex question parser; refusal falls through to regex
- reader_trace: tuple[str, ...] field on CandidateGraphResult captures
JSON-encoded admit/fallthrough events for audit
generate/comprehension/lifecycle_runtime_adapter.py (new):
- build_problem_state_from_candidates(): converts regex-parser output
to ProblemReadingState for the reader's pronoun-resolution step
- invoke_reader_for_question(): tokenises sentence, drives lifecycle
- project_to_candidate_unknown(): QuestionTargetSlot → CandidateUnknown
- trace-event constructors for admit and fallthrough
Phase C — Capability-axis regression:
All existing tests pass with flag OFF and ON; zero new regressions.
Two pre-existing failures on main are unrelated to this PR.
Phase D — GSM8K train_sample measurement:
evals/gsm8k_math/train_sample/v1/runner.py: --use-reader flag triggers
baseline-off + reader-on runs and writes reader_phase1_delta.json
evals/gsm8k_math/train_sample/v1/reader_phase1_delta.json (new):
baseline-off: correct=3 refused=47 wrong=0
reader-on: correct=3 refused=47 wrong=0
delta: all zeros — Mixed result expected (Phase 2 scope)
wrong=0 invariant preserved in both modes.
Phase E — Coexistence tests:
tests/test_reader_coexistence.py (new): 13 tests covering
flag-OFF byte-identity, flag-ON determinism, wrong=0 invariant,
trace shape validation, Brief-8 target admission, and fallthrough
preservation for unknown-unit words.
Admission gate result: Mixed (correct=3, below the ≥10 bar).
All statement-side barriers remain in place; Phase 2 (reader for
statement sentences) is required to drive correct≥10. Documented in
reader_phase1_delta.json and train_sample/v1/runner.py docstring.
