[b-re-w]

Refs #143 (design only; implementation waits for the decision below).

Documentation added: SPEC N-12 (Status: planned (design)) and design §4.3.4.

• Identity is defined as: every execution of compiled code is indistinguishable from some valid CPython execution.
• Virtual objects (partial escape analysis plus deferred materialisation) apply to N-11 classes without __del__ and without __weakref__. They are materialised before every observation point, in allocation order. The observation points include any unknown call while the object is alive, because gc.get_objects() and tracemalloc see objects that were never passed. is, type and isinstance are decided statically.
• Refcount elision applies only with a keeping reference and no unknown code in between, so every observable refcount is exact.
• Regions hold virtual objects only (never real PyObjects) and are tied to the innermost scope that bounds their lifetime. A failed region allocation raises MemoryError at the CPython allocation point.
• The verifier must prove four properties. Anything unproved compiles as N-11. The differential and mutation tests are listed.

Needs a user decision (via the leader), §4.3.4 마.1: is garbage-collection timing part of the identity? Not allocating moves collections, and with them the finalisers of unrelated cyclic garbage.

• Keeping the timing needs synthetic allocation counts and running scheduled collections in place, through CPython-internal structures.
• The language reference leaves the timing to the implementation, and CPython 3.14's incremental GC already changed it.

Pre-existing gaps found while writing this (separate issues, not caused by N-12):

• TypedPython: compiled code never checks the eval breaker (signals, GC, GIL hand-off) #141: compiled loops never check the eval breaker, which defers signals, GC and pending calls, and starves other threads of the GIL.
• TypedPython: compiled functions emit no sys.settrace / setprofile / sys.monitoring events #142: compiled functions emit no trace, profile or monitoring events.

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