Deduction serving stops being a bare flag and becomes an EARNED capability
governed by the ADR-0175 reliability gate over the ADR-0199 learning arena
-- the arena's second concrete instance (GSM8K math is the first) and the
reliability substrate's first non-estimation serving consumer, a concrete
dent in that zone's standing 'designed, not wired' critique.
Non-circular thesis: the ROBDD engine is sound+complete (never wrong on the
problem it's handed), so the license does NOT certify it. It certifies the
full pipeline (reader -> projector -> engine) per argument shape -- the
FALLIBLE part is the template reader, which can misparse an argument and
hand the engine the wrong problem. The arena catches that as a 'wrong' by
comparing the pipeline's committed outcome to by-construction gold.
New: generate/proof_chain/shape.py (4 exhaustive structural shape-bands, the
capability axis, shared by arena + serving), evals/deduction_serve/practice/
(the deduction arena instance: deterministic synthetic corpus, by-construction
gold independent of the reader per ADR-0199 L-2, cross-checked against the
INDEPENDENT truth-table oracle before sealing), chat/data/deduction_serve_
ledger.json (committed SHA-sealed ledger, 4 bands x 720 correct/0 wrong),
chat/deduction_serve_license.py (tamper-evident serving reader, mirrors
estimation_license.py), tests/test_deduction_serve_license.py (13 tests),
docs/adr/ADR-0256 (+ resolves the ADR-0206 numbering collision in doc form).
Changed: chat/deduction_surface.py (composer consults the license: earned
band -> authoritative Phase-1 surface; unearned/stripped ledger -> same sound
answer served DISCLOSED/hedged -- authority now rests on committed evidence,
not a boolean), core/config.py (flag docstring: enables an EARNED path),
core/cli_test.py (deductive suite runs the license test).
All four structural bands earn SERVE at reliability 0.99087 (>= theta_SERVE
0.99) with wrong=0, so Phase-1 behavior is preserved byte-for-byte; the
gate's teeth are proven by injecting an empty ledger (the same sound answer
degrades to a disclosed hedge). Did NOT reuse the ADR-0206 govern_response
bridge (its STRICT/APPROXIMATE 'widen-past-strict' semantics are the opposite
shape from deduction's always-sound answer); did NOT rewrite report.json's
stale adr field (SHA-pinned bytes, documented in ADR-0256 s2a instead).
[Verification]: smoke 180 passed; cognition 122 passed/1 skipped;
core test --suite deductive 38 passed; architectural_invariants 75 passed;
practice runner 4 bands all SERVE wrong=0.
c98f1e07b2