Function core_interp_source 

pub fn core_interp_source() -> &'static str

The self-interpreter (coreEval / coreExecBlock) as a first-class committed artifact — the Logos program the genuine P2/P3 projections specialize (Futamura: pe(pe, coreEval) is a compiler). Promoted out of the phase_futamura test fixture so it is a real source file, not a string constant; the fixture now include_str!s this exact file (parity is structural).