v2.0.0

Added

• Semantic fidelity release gate: scripts/run_semantic_fidelity_gate.py writes gnn_semantic_fidelity_ledger_v1 artifacts for maintained model families.
• Strict semantic contracts: representative fixtures now preserve model identity, variables, edges, dimensions, parameter shapes, equations, time, and ontology mappings across JSON parse/serialize/parse checks.
• Cross-framework reliability release gate: scripts/run_cross_framework_reliability.py writes gnn_cross_framework_reliability_ledger_v1 artifacts with compatible, required, and unsupported backend statuses.
• GridWorld three-backend comparison: GridWorld is profiled for PyMDP, RxInfer, and ActiveInference.jl, including seed, trace length, matrix-shape, and matrix-provenance parity.

Changed

• GridWorld model-family acceptance now requests PyMDP, RxInfer, and ActiveInference.jl for the v2 comparison fixture instead of a PyMDP-only profile.
• Roadmap next target moves to v3.0.0 for durable streams, long-running sessions, and auditable container plans.

Fixed

• JSON serialization now emits equation objects instead of lossy stringified dataclasses, preventing silent semantic round-trip drift.
• Cross-framework reliability no longer certifies aggregate Step 12 success without successful non-skipped execution-detail rows and current simulation payloads for required backends.

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