2 commits

Author	SHA1	Message	Date
Shay	babcf2fdb2	feat(constraint): exact integer 2-var solver — Cramer's rule, refusal-first (R2 C3) ... generate/constraint_comprehension/solver.py: solve_two_var_linear (order-independent 2x2 integer Cramer's rule over typed constraints), the solve_two_var_count_weight specialization, and solve/answer_constraint_problem driving it from a ConstraintProblem. Four typed refusals: indistinguishable_weights (det==0), non_integer_solution (numer%det!=0, never rounds), negative_solution, verification_failed (identity backstop). Ties to the C2 gold: solves all 7 solved fixtures to their gold value and refuses all 3 solver_refuses fixtures with EXACTLY the gold-claimed reason (the gold's reason is now solver-verified, not just annotation). Per-refusal meaningful-fail + positive re-substitution. Off-serving. 9 tests.	2026-06-07 07:23:23 -07:00
Shay	e71531c0c9	feat(constraint): R2 linear-constraint IR — typed problem model (R2 C1) ... generate/constraint_comprehension/{expr,model}.py: frozen, slots'd dataclasses, no behavior. expr = LinearExpr (sum(coeff*symbol)+constant) + LinearConstraint (lhs eq rhs, optional source_span). model = Unknown (symbol/entity/unit/finite-integer domain), AttributeFact (per-category coefficient provenance), ConstraintQuery (symbol+unit), ConstraintProblem (unknowns/facts/constraints/query). Terms pinned as (symbol, coefficient) to match the gold serialization. Query is a minimal dedicated type, not R1's BoundUnknown (no degenerate fit). Off-serving package; no generate.derivation / reliability_gate import. 9 IR tests (shape + frozen + defaults).	2026-06-07 07:10:20 -07:00