behavior-contracts 0.2.2

Multi-language IR-Runtime common core (Python port). The COMMON 'thin core' primitives from dsl-contracts runtime-boundary.md — validate_envelope / evaluate_expression / render_template / run_plan / canonical_value / canonical_json / py_float_repr / assert_portable — with zero backend (DynamoDB/graphddb) dependencies.

behavior-contracts (Python)

The COMMON "thin core" runtime primitives from runtime-boundary.md, ported to Python from the TypeScript reference implementation (ts/src/*) with identical semantics.

This package contains only the DSL-agnostic primitives that WS1 classified as COMMON. It has zero backend (DynamoDB / graphddb) dependencies — no boto3, no key marshalling, no retry tuning, no hydrate, no bundle format. Those stay in the consumer (graphddb).

Public API

from behavior_contracts import (
    validate_envelope,     # spec-version fail-closed check
    evaluate_expression,   # expression-ir.md evaluator (i64-checked, truncated %, code-point cmp)
    render_template,        # {param} rendering (strict, Python str() parity)
    run_plan, final_tree,   # execution-plan skeleton (stage / Skip propagation / Policy Kind)
    canonical_value,        # key identity (top-level key sort)
    canonical_json,         # fingerprint (recursive key sort)
    py_float_repr,          # CPython repr(float) canonical decimal
    assert_portable,        # Portability Guard
    decode_value, deep_equals,  # conformance runner adapter (int/float type distinction)
    encode_value, resolve_partial, cmp_code_points,
    SPEC_VERSIONS, ENVELOPE_SPEC_VERSION,
)

Each COMMON primitive raises a typed *Failure exception carrying a .code string matching the conformance protocol's failure-code set.

§8 cross-language traps this port handles

• % sign: normative mod is truncated (dividend sign). Python's native % returns the divisor sign, so evaluate_expression({"mod":[-7,2]}) == -1 (native -7 % 2 == 1). Implemented via truncated-quotient correction; float mod via math.fmod.
• int is checked i64: Python int is arbitrary-precision, so i64 bounds are enforced manually; overflow → INT_OVERFLOW.
• string comparison: code-point order. Python str compares by code point already (no UTF-16 surrogate hazard) — verified in tests.
• NaN/Inf → Failure; div always float with |int| > 2^53 widening → PRECISION_LOSS; py_float_repr matches CPython repr(float) byte-for-byte (parametrized parity tests).
• bool is not int: isinstance(x, bool) is checked before int everywhere (Python's bool <: int).

Conformance

Runs the 7 shared suites (164 vectors) from ../conformance/vectors/*.json through this package per ../conformance/PROTOCOL.md, including the pre-flight version fail-closed sweep.

python -m behavior_contracts.conformance      # → "164 passed, 0 failed / 164 vectors across 7 suites"
# or the console script:
behavior-contracts-conformance

Override the vectors location with DSL_CONTRACTS_VECTORS=/path/to/vectors.

Tests

pip install -e ".[test]"
python -m pytest        # unit tests over the public API + the conformance runner as a test

Docker integration: N/A

This package has no external service dependency (no database, no network) — it is pure in-process logic over JSON-shaped values. There is therefore nothing for a docker-compose integration harness to stand up; the conformance runner and pytest exercise the full surface in-process. (The graphddb adapter PoC in WS4 Part B is where docker-backed integration applies, because graphddb talks to DynamoDB Local.)