sim-lib-lang-python

Embedded, capability-scoped, agent-authored Python scripting over SIM values. It is deliberately not a CPython replacement. Thin, bounded Python core evaluation enters through codec/python; the profile directly interprets the stable lowering and composes shared runtime organs, numbers, managed arena, and optional tracing collection.

PYTHON_FIDELITY reports syntax, lowering, direct evaluation, object/control, module/library, boundedness, and expected gaps separately. PYTHON_EVIDENCE_CASES publishes frozen call, cycle, exception, generator, matching, import, and capability-refusal cases. CPython 3.14.6 supplied offline expected values for simple differential cases only; it is never linked, imported, spawned, or used as a fallback. There is no bytecode, compiler IR, optimizer, project graph, or private language organ.

Capability-gated eval, exec, and imports

Dynamic Python is safer than ambient CPython evaluation by construction. dynamic_python_policy builds both eval and exec entries over the shared source policy and the canonical diminished read-eval broker. The caller must supply a trusted ReadPolicy, already hold every required capability, and choose the smaller capability set visible to decoded code. Source text cannot mint authority.

python_module_policy likewise builds the shared policy that resolves only through a caller-supplied Dir, then delegates decoding, failure/cycle caching, live exports, and receipts to the shared namespace module lifecycle. It never searches host paths.

python_library_manifest() derives present members from the checked Python matrix. Host-facing names such as open, os, subprocess, and socket are explicit absences; they never fall back to CPython or ambient host services. Structural cases compose ordered Shape checks and case-local captures. Guards run only after a shape accepts, and unsupported Python pattern forms remain a no-match gap instead of acquiring a second matcher.

PythonObjectSpace supplies checked class construction, C3 MRO, Python data/non-data descriptor precedence, bound methods, and super while leaving storage and interception in sim-lib-dispatch. PythonGenerator projects start/send/throw/close over sim-lib-control's bounded resumable frame; checked exceptions, groups, chaining, and synchronous context cleanup add no scheduler.

Tracing collection is the default constructor. PythonHeap::retaining is an explicit supported alternative and reports its strong-cycle leak gap.

The public PYTHON_OBJECT_CONTROL_GAPS list is the precise fail-closed boundary: custom metaclasses, post-construction descriptor-protocol mutation, weak-reference callbacks/proxies, __del__ resurrection, and async scheduling remain unclaimed.